Antimicrobial Effects of Honey: Difference between revisions

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[http://en.wikipedia.org/wiki/Honey/: Honey] has seen a revival recently in the Western medical field, as it has shown inhibitory activity against a range of detrimental and [http://en.wikipedia.org/wiki/Antibiotic_resistance: antibiotic-resistant] microbes of infected wounds [http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3255743/: <sup>1</sup>] (Nassar et al. 2012). Honey may be the first recorded medicine, having been documented in the Smith Papyrus of Egypt, which dates to between 2200-2600 BC [http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1292197/: <sup>2</sup>] (Zumla 1989).  Since ancient times, honey has been renowned for its wound-healing properties [http://www.ncbi.nlm.nih.gov/pubmed/20228250/: <sup>3</sup>] (Kwakman et al. 2010).  With the advent of antibiotics, clinical application of honey was neglected in modern Western medicine, although it is still used in many cultures [http://www.ncbi.nlm.nih.gov/pubmed/20228250/: <sup>3</sup>] (Kwakman et al. 2010).  The overwhelming use of antibiotics has resulted in widespread resistance and the development of new antibiotics is lagging behind, therefore alternative antimicrobial strategies are necessary [http://www.ncbi.nlm.nih.gov/pubmed/20228250/: <sup>3</sup>] (Kwakman et al. 2010).   
[http://en.wikipedia.org/wiki/Honey Honey] has seen a revival recently in the Western medical field, as it has shown inhibitory activity against a range of detrimental and [http://en.wikipedia.org/wiki/Antibiotic_resistance antibiotic-resistant] microbes of infected wounds [http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3255743/: <sup>1</sup>]. Honey may be the first recorded medicine, having been documented in the Smith Papyrus of Egypt, which dates to between 2200-2600 BC [http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1292197/: <sup>2</sup>].  Since ancient times honey has been renowned for its wound-healing properties [http://www.ncbi.nlm.nih.gov/pubmed/20228250/: <sup>3</sup>].  With the advent of [http://en.wikipedia.org/wiki/Antibiotics antibiotics], clinical application of honey has been neglected in modern Western medicine, although it is still used in many cultures [http://www.ncbi.nlm.nih.gov/pubmed/20228250/: <sup>3</sup>].  The overwhelming use of antibiotics has resulted in widespread resistance, therefore alternative antimicrobial strategies are necessary [http://www.ncbi.nlm.nih.gov/pubmed/20228250/: <sup>3</sup>].   


[[Image:chunk of honey.jpg|thumb|400px|right|A freshly cut piece of honeycomb from the Dallmayr store in Germany. [https://www.flickr.com/photos/bionicgrrl/3535805377/ By bionicgrrrl].[https://www.flickr.com/photos/bionicgrrl/3535805377/ <sup>11</sup>]]]


Honey has demonstrated potent in vitro activity against antibiotic-resistant bacteria and it has been successfully applied as treatment of chronic wound infections not responding to antibiotic therapy [http://www.ncbi.nlm.nih.gov/pubmed/20228250/: <sup>3</sup>] (Kwakman et al. 2010)Furthermore, honey has received attention as an important tool against strains of bacteria such as Methicillin-resistant <i>Staphylococcus aureus</i>, which have become resistant to current antibiotics [http://jrs.sagepub.com/content/92/6/283/: <sup>4</sup>] (Cooper 1999). There is no such resistance build-up involving honey, making it attractive as a treatment for wound infections [http://jrs.sagepub.com/content/92/6/283/: <sup>4</sup>] (Cooper 1999).  Honey possesses several antimicrobial propertis and can act via various mechanisms of action.  There are many different types of honey from around the world, made from different floral sources and these different types of honey can have variable antimicrobial effects and mechanisms of action.  The antimicroial potency and medical applications of honey are tremendous as it has demonstrated inhibitory effects against a number of pathogenic bacteria.   
 
Honey has demonstrated potent [http://en.wikipedia.org/wiki/In_vitro <i>in vitro</i>] activity against antibiotic-resistant bacteria and it has been successfully applied as treatment of chronic wound infections not responding to antibiotic therapy [http://www.ncbi.nlm.nih.gov/pubmed/20228250/: <sup>3</sup>] .  For example, honey has received attention as an important tool against strains of bacteria such as Methicillin-resistant [https://microbewiki.kenyon.edu/index.php/Staphylococcus_aureus <i>Staphylococcus aureus</i>] [http://jrs.sagepub.com/content/92/6/283/: <sup>4</sup>]. No microbial resistance against honey has been observed, making it attractive as a treatment for wound infections [http://jrs.sagepub.com/content/92/6/283/: <sup>4</sup>].  Honey possesses several antimicrobial properties and can act via various mechanisms of action.  There are many different types of honey from around the world, made from different [http://en.wikipedia.org/wiki/Floral floral] sources with variable mechanisms of action.  The antimicrobial [http://en.wikipedia.org/wiki/Potency_(pharmacology) potency] and medical applications of honey are tremendous as it has demonstrated inhibitory effects against a number of pathogenic bacteria [http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3255743/: <sup>1</sup>][http://www.ncbi.nlm.nih.gov/pubmed/20228250/: <sup>3</sup>][http://jrs.sagepub.com/content/92/6/283/: <sup>4</sup>].   




==Mechanisms of Action==
==Mechanisms of Action==


Honey prevents microbial growth through the use of [http://en.wikipedia.org/wiki/Hydrogen_peroxide: hydrogen peroxide] (H<sub>2</sub>O<sub>2</sub>), [http://en.wikipedia.org/wiki/Hydrogen_peroxide: methylglyoxal (MGO)], bee defensin-1, [http://en.wikipedia.org/wiki/Flavonoid: flavonoids], and a relatively low [http://en.wikipedia.org/wiki/PH: pH] (~3.3) [http://www.ncbi.nlm.nih.gov/pubmed/20228250/: <sup>3</sup>][http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3255743/: <sup>1</sup>] (Kwakman et al. 2010, Nassar et al. 2012). Not all of the factors listed are present in all types of honey, and these compounds must be tested for and considered for clinical applications [http://www.ncbi.nlm.nih.gov/pubmed/20228250/: <sup>3</sup>] (Kwakman et al. 2010).
Honey prevents microbial growth through the use of [http://en.wikipedia.org/wiki/Hydrogen_peroxide hydrogen peroxide] (H<sub>2</sub>O<sub>2</sub>), [http://en.wikipedia.org/wiki/Hydrogen_peroxide methylglyoxal (MGO)], bee defensin-1, [http://en.wikipedia.org/wiki/Flavonoid flavonoids], and a relatively low [http://en.wikipedia.org/wiki/PH pH] (~3.3) [http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3255743/: <sup>1</sup>][http://www.ncbi.nlm.nih.gov/pubmed/20228250/: <sup>3</sup>]. As shown in Figure 1, the different active components in honey have been isolated by neutralizing each one individually and observing the effect on its antimicrobial activity. Not all of the factors listed are present in all types of honey, and these compounds must be tested for and considered for clinical applications [http://www.ncbi.nlm.nih.gov/pubmed/20228250/: <sup>3</sup>].
 
===Osmolarity===
 
The high [http://en.wikipedia.org/wiki/Osmotic_concentration osmolarity] of honey can also contribute to the inhibition of growth, although this is true of sugar solutions as well [http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3255743/: <sup>1</sup>][http://www.ncbi.nlm.nih.gov/pubmed/20228250/: <sup>3</sup>].  Honey is 70 to 80% sugar and this high percentage causes hypertonic conditions that may lead to lysis of microbial cell walls [http://www.sciencedirect.com/science/article/pii/S0924857911001300/: <sup>5</sup>]. 
 
===H<sub>2</sub>O<sub>2</sub>===
 
Hydrogen peroxide is produced by the [http://en.wikipedia.org/wiki/Apis_mellifera <i>Apis mellifera</i>] (honeybee) glucose oxidase enzyme on dilution of honey, and is produced in low but effective concentrations [http://www.ncbi.nlm.nih.gov/pubmed/20228250/: <sup>3</sup>][http://online.liebertpub.com/doi/abs/10.1089/10755530360623383/: <sup>6</sup>]. Due to the slow release of H<sub>2</sub>O<sub>2</sub>, there is much less [http://en.wikipedia.org/wiki/Cytotoxic cytotoxic] damage to the patient’s cells, providing a better method than applying H<sub>2</sub>O<sub>2</sub> directly to wounds [http://online.liebertpub.com/doi/abs/10.1089/10755530360623383/: <sup>6</sup>].  
 
===Methylglyoxal===


The high [http://en.wikipedia.org/wiki/Osmotic_concentration: osmolarity] of honey can also contribute to the inhibition of growth, although this is true of sugar solutions as well [http://www.ncbi.nlm.nih.gov/pubmed/20228250/: <sup>3</sup>][http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3255743/: <sup>1</sup>] (Kwakman et al. 2010, Nassar et al. 2012).  Honey is 70 to 80% sugar and this high percentage causes hypertonic conditions that may lead to lysis of microbial cell walls [http://www.sciencedirect.com/science/article/pii/S0924857911001300/: <sup>5</sup>] (Cushnie and Lamb 2011).
Methylglyoxal is a compound found in manuka honey that was reported to have an antibacterial property [http://www.sciencedirect.com/science/article/pii/S0924857911001300/: <sup>5</sup>].  MGO can be converted into its inactive form, S-lactoylglutathione, by glyoxalase I and this was done in an experiment to test the effects of MGO on honey’s bactericidal activity (unprocessed Revamil honey was used in this experiment) [http://www.ncbi.nlm.nih.gov/pubmed/20228250/: <sup>3</sup>].  [http://en.wikipedia.org/wiki/Neutralization_(chemistry) Neutralization] of MGO or H<sub>2</sub>O<sub>2</sub> alone did not alter bactericidal activity of RS honey, but simultaneous neutralization of MGO and H<sub>2</sub>O<sub>2</sub> in a solution diluted with water to 10% honey reduced the killing of <i>B. subtilis</i> by 4-logs [http://www.ncbi.nlm.nih.gov/pubmed/20228250/: <sup>3</sup>]. At higher concentrations of honey, the bactericidal activity was not affected by neutralization of MGO and H<sub>2</sub>O<sub>2</sub> [http://www.ncbi.nlm.nih.gov/pubmed/20228250/: <sup>3</sup>].


Hydrogen peroxide is produced by the <i>Apis mellifera</i> (honeybee) glucose oxidase enzyme on dilution of honey, and is produced in low but effective concentrations [http://online.liebertpub.com/doi/abs/10.1089/10755530360623383/: <sup>6</sup>][http://www.ncbi.nlm.nih.gov/pubmed/20228250/: <sup>3</sup>] (Bang 2003, Kwakman et al. 2010). Due to the slow release of H<sub>2</sub>O<sub>2</sub>, there is much less cytotoxic damage to the patient’s cells, providing a better method than applying H<sub>2</sub>O<sub>2</sub> directly to wounds [http://online.liebertpub.com/doi/abs/10.1089/10755530360623383/: <sup>6</sup>] (Bang 2003).
[[Image:Honey Mechanism 1.jpeg|thumb|600px|right|Figure 1. The different antimicrobial compounds in honey were sequentially neutralized in order to determine their individual effects on different strains of bacteria. A plus sign indicates the use of different neutralization agents. [http://en.wikipedia.org/wiki/Catalase Catalase] (cat.) inhibits production of hydrogen peroxide, [http://en.wikipedia.org/wiki/Glyoxalase_I glyoxyalase 1] (gly 1) inhibits methylglyoxal (MGO), and sodium polyanetholsulfonate (SPS) neutralizes bee defensin-1. There was also a [http://en.wikipedia.org/wiki/Sugar sugar] control group on the right of each graph. The difference in effects on different bacterial strains indicates that there are [http://en.wikipedia.org/wiki/Synergistic synergistic] and redundant components of honey, and that these effects are microbe-specific. [http://www.ncbi.nlm.nih.gov/pubmed/20228250/: By Dr. Paulus H.S. Kwakman], Department of Medical Microbiology, Center for Infection and Immunity Amsterdam.[http://www.ncbi.nlm.nih.gov/pubmed/20228250/: <sup>3</sup>]]]


Methylglyoxal is a compound found in manuka honey that was reported to have an antibacterial property [http://www.sciencedirect.com/science/article/pii/S0924857911001300/: <sup>5</sup>] (Cushnie and Lamb 2011).  MGO can be converted into its inactive form, S-lactoylglutathione, by glyoxalase I and this was done in an experiment to test the effects of MGO on honey’s bactericidal activity (unprocessed Revamil honey was used in this experiment) [http://www.ncbi.nlm.nih.gov/pubmed/20228250/: <sup>3</sup>] (Kwakman et al. 2010).  Neutralization of MGO or H<sub>2</sub>O<sub>2</sub> alone did not alter bactericidal activity of RS honey, but simultaneous neutralization of MGO and H2O2 in 10% honey reduced the killing of <i>B. subtilis</i> by 4-logs [http://www.ncbi.nlm.nih.gov/pubmed/20228250/: <sup>3</sup>] (Kwakman et al. 2010).  At higher concentrations of honey, the bactericidal activity was not affected by neutralization of MGO and H2O2 [http://www.ncbi.nlm.nih.gov/pubmed/20228250/: <sup>3</sup>] (Kwakman et al. 2010).
===Bee defensin-1===


[[Image:Honey Mechanism 1.jpeg|thumb|600px|right|The different antimicrobial compounds in honey were sequentially neutralized in order to determine their individual effects on different strains of bacteria. A plus sign indicates the use of different neutralization agents. Catalase (cat.) inhibits production of hydrogen peroxide, glyoxyalase 1 (gly 1) inhibits methylglyoxal (MGO), and sodium polyanetholsulfonate (SPS) neutralizes bee defensin-1. There was also a sugar control group on the right of each graph. The difference in effects on different bacterial strains indicates that there are synergistic and redundant components of honey, and that these effects are microbe-specific. [http://www.ncbi.nlm.nih.gov/pubmed/20228250/: By Dr. Paulus H.S. Kwakman], Department of Medical Microbiology, Center for Infection and Immunity Amsterdam.[http://www.ncbi.nlm.nih.gov/pubmed/20228250/: <sup>3</sup>]]]
Bee defensin-1 is found in honey and is the only [http://en.wikipedia.org/wiki/Cationic#Anions_and_cations cationic] bactericidal compound currently identified [http://www.ncbi.nlm.nih.gov/pubmed/20228250/: <sup>3</sup>]. In dilutions of 20% honey and greater, when H<sub>2</sub>O<sub>2</sub> and MGO were neutralized bactericidal activity was retained [http://www.ncbi.nlm.nih.gov/pubmed/20228250/: <sup>3</sup>]. When bee defensin-1 was also neutralized, the bactericidal activity was strongly reduced at 20% but was not affected at 30 and 40% honey solutions [http://www.ncbi.nlm.nih.gov/pubmed/20228250/: <sup>3</sup>]. Bee defensin-1 was previously isolated from [http://en.wikipedia.org/wiki/Royal_jelly royal jelly], the major food source for bee queen [http://en.wikipedia.org/wiki/Larvae larvae] and was identified in honeybee [http://en.wikipedia.org/wiki/Hemolymph hemolymph] [http://www.ncbi.nlm.nih.gov/pubmed/20228250/: <sup>3</sup>].  This peptide is secreted by the hypopharyngeal gland of worker bees into collected nectar along with carbohydrate-metabolizing enzymes and bee defensin-1 presumably contributes to protection of royal jelly and honey against microbial spoilage [http://www.ncbi.nlm.nih.gov/pubmed/20228250/: <sup>3</sup>]


Bee defensin-1 is found in honey and is the only cationic bactericidal compound currently identified [http://www.ncbi.nlm.nih.gov/pubmed/20228250/: <sup>3</sup>] (Kwakman et al. 2010).  In honey dilutions of 20% and greater, when H<sub>2</sub>O<sub>2</sub> and MGO were neutralized bactericidal activity was retained but when bee defensin-1 was also neutralized, the bactericidal activity was strongly reduced at 20% but was not affected at 30 and 40% [http://www.ncbi.nlm.nih.gov/pubmed/20228250/: <sup>3</sup>] (Kwakman et al. 2010).  Bee defensin-1 was previously isolated from royal jelly, the major food source for bee queen larvae and was identified in honeybeen hemolymph [http://www.ncbi.nlm.nih.gov/pubmed/20228250/: <sup>3</sup>] (Kwakman et al. 2010).  This peptide is secreted by the hypopharyngeal gland of worker bees into collected nectar along with carbohydrate-metabolizing enzymes and bee defensin-1 presumably contributes to protection of royal jelly and honey against microbial spoilage [http://www.ncbi.nlm.nih.gov/pubmed/20228250/: <sup>3</sup>] (Kwakman et al. 2010). 
===Flavonoids===


Flavonoids are a group of pigments produced by plants and their presence was suggested to contribute to the antimicrobial properties of honey [http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3255743/: <sup>1</sup>] (Nassar et al. 2012).  Actions of flavonoids include direct antibacterial activity, synergism with antibiotics, and suppression of bacterial virulence [http://www.sciencedirect.com/science/article/pii/S0924857911001300/: <sup>5</sup>] (Cushnie and Lamb 2011).  The direct antibacterial activity of flavonoids may be attributable to several tested mechanisms: cytoplasmic membrane damage (caused by perforation and/or a reduction in membrane fluidity possibly by generating hydrogen peroxide), inhibition of nucleic acid synthesis (caused by topoisomerase inhibition and/or dihydrofolate reductase inhibition), inhibition of energy metabolism (caused by NADH-cytochrome c reducatse inhibition and ATP synthase inhibition), inhibition of cell wall synthesis (caused by D-alanine-D-alanine ligase inhibition) and inhibition of cell membrane synthesis (caused by inhibition of several enzymes) [http://www.sciencedirect.com/science/article/pii/S0924857911001300/: <sup>5</sup>] (Cushnie and Lamb 2011).  There are 14 classes of flavonoids in total, categorized by their chemical nature and structure [http://www.sciencedirect.com/science/article/pii/S0924857911001300/: <sup>5</sup>] (Cushnie and Lamb 2011).  Because most studies on the mechanism of action of flavonoids were conducted on only one or two types of flavonoids, it remains unclear as to whether flavonoids have multiple mechanisms of action or flavonoids have a single mechanism that has yet to be convincingly determined [http://www.sciencedirect.com/science/article/pii/S0924857911001300/: <sup>5</sup>] (Cushnie and Lamb 2011).
Flavonoids are a group of pigments produced by plants and their presence was suggested to contribute to the antimicrobial properties of honey [http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3255743/: <sup>1</sup>].  Actions of flavonoids include direct antibacterial activity, synergism with antibiotics, and suppression of bacterial virulence [http://www.sciencedirect.com/science/article/pii/S0924857911001300/: <sup>5</sup>].  The direct antibacterial activity of flavonoids may be attributable to several tested mechanisms: cytoplasmic membrane damage (caused by perforation and/or a reduction in membrane fluidity possibly by generating hydrogen peroxide), inhibition of nucleic acid synthesis (caused by [http://en.wikipedia.org/wiki/Topoisomerase topoisomerase] inhibition and/or [http://en.wikipedia.org/wiki/Dihydrofolate_reductase dihydrofolate reductase] inhibition), inhibition of energy metabolism (caused by NADH-cytochrome c reductsse inhibition and [http://en.wikipedia.org/wiki/Atp_synthase ATP synthase] inhibition), inhibition of cell wall synthesis (caused by [http://en.wikipedia.org/wiki/D-alanine%E2%80%94D-alanine_ligase D-alanine-D-alanine ligase] inhibition) and inhibition of cell membrane synthesis (caused by inhibition of several enzymes) [http://www.sciencedirect.com/science/article/pii/S0924857911001300/: <sup>5</sup>].  There are 14 classes of flavonoids in total, categorized by their chemical nature and structure [http://www.sciencedirect.com/science/article/pii/S0924857911001300/: <sup>5</sup>].  Because most studies on the mechanism of action of flavonoids were conducted on only one or two types of flavonoids, it remains unclear as to whether flavonoids have multiple mechanisms of action or flavonoids have a single mechanism that has yet to be convincingly determined [http://www.sciencedirect.com/science/article/pii/S0924857911001300/: <sup>5</sup>].


Honey has a low pH primarily due to the conversion of glucose into hydrogen peroxide and gluconic acid by glucose oxidase [http://www.ncbi.nlm.nih.gov/pubmed/20228250/: <sup>3</sup>] (Kwakman et al.2010).  This low pH might also contribute to the bactericidal activity of honey, demonstrated by the titration of the pH of 10-40% honey from 3.4-3.5 to 7.0 combined with neutralization of other bactericidal factors (H<sub>2</sub>O<sub>2</sub>, MGO and bee defensin-1) reduced the bactericidal activity of honey to the same level of a honey-equivalent sugar solution [http://www.ncbi.nlm.nih.gov/pubmed/20228250/: <sup>3</sup>] (Kwakman et al. 2010). 
===pH===


<br> <br>
Honey has a low pH primarily due to the conversion of glucose into hydrogen peroxide and gluconic acid by glucose oxidase [http://www.ncbi.nlm.nih.gov/pubmed/20228250/: <sup>3</sup>].  This low pH might also contribute to the bactericidal activity of honey, demonstrated by the titration of the pH of 10-40% honey solutions from 3.4-3.5 to 7.0 combined with neutralization of other bactericidal factors (H<sub>2</sub>O<sub>2</sub>, MGO and bee defensin-1) reduced the bactericidal activity of honey to the same level of a honey-equivalent sugar solution [http://www.ncbi.nlm.nih.gov/pubmed/20228250/: <sup>3</sup>].
<br>


==Effectiveness of Different Types of Honey==
==Effectiveness of Different Types of Honey==
<br>The minimum inhibitory concentration (MIC) of [http://en.wikipedia.org/wiki/M%C4%81nuka_honey: manuka honey] on [https://microbewiki.kenyon.edu/index.php/Staphylococcus_aureus: <i>Stayphylococcus aureus</i>] was between 2 and 3% (v/v) ([(volume of solute)/(volume of solution)] x 100%) [http://jrs.sagepub.com/content/92/6/283/: <sup>4</sup>] (Cooper et al. 1999).  Manuka honey is from <i>Leptospermum</i> trees. The MIC of honey from a mixed pasture source was between 3 and 4% on <i>S. aureus</i> [http://jrs.sagepub.com/content/92/6/283/: <sup>4</sup>] (Cooper et al. 1999).  These honeys prevent growth of <i>S. aureus</i> even when diluted by body fluids a further seven-fold to fourteen-fold beyond the point where their osmolarity ceased to be completely inhibitory [http://jrs.sagepub.com/content/92/6/283/: <sup>4</sup>] (Cooper et al. 1999).  Pasture honey acts by releasing H<sub>2</sub>O<sub>2</sub>, while manuka honey’s action also has a phytochemical component [http://jrs.sagepub.com/content/92/6/283/: <sup>4</sup>] (Cooper et al. 1999)In this study by Cooper et al. (1999) the antibacterial activity of manuka and pasture honeys on <i>S. aureus</i> were determined by an agar well diffusion bioassay using phenol as a reference standard antiseptic both in the presence of catalase and not in the presence of catalase, to detect any non-peroxide antibacterial activity; the MIC of each honey was determined by an agar incorporation technique.
===Manuka Honey===
Manuka honey is predominantly harvested in New Zealand and Australia, from bees visiting [http://en.wikipedia.org/wiki/Leptospermum <i>Leptospermum</i>] trees. The minimum inhibitory concentration (MIC) of [http://en.wikipedia.org/wiki/M%C4%81nuka_honey manuka honey] on [https://microbewiki.kenyon.edu/index.php/Staphylococcus_aureus <i>Stayphylococcus aureus</i>] was between 2 and 3% (v/v) ([(volume of solute)/(volume of solution)] x 100%) [http://jrs.sagepub.com/content/92/6/283/: <sup>4</sup>]. While manuka honey does release H<sub>2</sub>O<sub>2</sub>, its anitmicrobial action also has a phytochemical component [http://jrs.sagepub.com/content/92/6/283/: <sup>4</sup>].  In this study by Cooper et al. (1999) the antibacterial activity of manuka and pasture honeys on <i>S. aureus</i> were determined by an agar well diffusion bioassay using phenol as a reference standard antiseptic both in the presence of catalase and not in the presence of catalase, to detect any non-peroxide antibacterial activity; the MIC of each honey was determined by an agar incorporation technique. Manuka honey has received more attention for antimicrobial work recently due to its additional phytochemical compounds.
 
===Pasture Honey===
 
The MIC of honey from a mixed pasture source was between 3 and 4% on <i>S. aureus</i> [http://jrs.sagepub.com/content/92/6/283/: <sup>4</sup>].  These honeys prevent growth of <i>S. aureus</i> even when diluted by body fluids a further seven-fold to fourteen-fold beyond the point where their osmolarity ceased to be completely inhibitory [http://jrs.sagepub.com/content/92/6/283/: <sup>4</sup>] Pasture honey acts by releasing H<sub>2</sub>O<sub>2</sub>, but often lacks significant amounts of the extra phytochemical components of manuka honey.
 
One brand of commercial honey called Black Forest honey from Langaneza, Germany was tested and found to inhibit eight different types of microbes at concentrations between 10 to 100% honey solutions[http://www.cabdirect.org/abstracts/20113072555.html/: <sup>7</sup>].  Growth of all microbes was reduced at 10% honey solutions and completely inhibited at 20% honey solutions for Methicillin-Sensitive <i>S. aureus</i>, Methicillin-Resistant <i>S. aureus</i>, and [https://microbewiki.kenyon.edu/index.php/Escherichia_coli <i>E. coli</i>], and at 50% honey solutions for [https://microbewiki.kenyon.edu/index.php/Pseudomonas_aeruginosa <i>P. aeruginosa</i>] and [https://microbewiki.kenyon.edu/index.php/Candida_albicans <i>C. albicans</i>], and at 100% honey for [https://microbewiki.kenyon.edu/index.php/Streptococcus_pyogenes <i>S. pyogenes</i>], Vancomycin-sensitive <i>enterococci</i> and Vancomycin-resistant <i>enterococci</i> [http://www.cabdirect.org/abstracts/20113072555.html/: <sup>7</sup>].
 
[[Image:Different Honey Types.jpg|thumb|800px|left|Figure 2. A chart illustrating Australian honeys with different floral sources, and their non-peroxide antibacterial activity. [http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0018229: By Julie Irish], School of Molecular Bioscience, University of Sydney, Camperdown, Australia.[http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0018229: <sup>9</sup>]]]


[[Image:Different Honey Types.jpg|thumb|800px|left|A chart illustrating Australian honeys with different floral sources, and their non-peroxide antibacterial activity. [http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0018229: By Julie Irish], School of Molecular Bioscience, University of Sydney, Camperdown, Australia.[http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0018229: <sup>9</sup>]]]


In a study on the effect of honey on [https://microbewiki.kenyon.edu/index.php/Streptococcus_mutans: <i>Streptococcus mutans</i>], natural honey bought from a local grocery store in Jeddah, Saudi Arabia was compared to artificial honey composed of 40.5% fructose, 33.5% glucose, 7.5% maltose and 1.5% sucrose dissolved in deionized water [http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3255743/: <sup>1</sup>] (Nassar et al. 2012).  Different natural and artificial honey concentrations were obtained using serial dilutions with tryptic soy broth (TSB) and at 12.5%, natural honey supported less bacterial growth and biofilm formation an artificial honey with the same amount of sugars, suggesting that sugar content is not the only antibacterial factor [http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3255743/: <sup>1</sup>] (Nassar et al. 2012).  Natural honey was able to decrease the maximum velocity of <i>S. mutans</i> growth compared to artificial honey [http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3255743/: <sup>1</sup>] (Nassar et al. 2012).  Overall, natural honey demonstrated more inhibition of bacterial growth, viability, and biofilm formation than artificial honey [http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3255743/: <sup>1</sup>] (Nassar et al. 2012). 
===Medical Honey===


Unprocessed Revamil source honey was effective at killing several different strains of bacteria at 10-20% (v/v), while greater than 40% (v/v) of a honey-equivalent sugar solution was required for similar activity [http://www.ncbi.nlm.nih.gov/pubmed/20228250/: <sup>3</sup>]. Another medical grade honey, [http://en.wikipedia.org/wiki/Medihoney Medihoney], comes from honey from <i>Leptospermum</i> flowers, making it very similar to manuka honey. In Medihoney, however, there are numerous steps taken to guarantee the sterility of the honey.


Unprocessed Revamil source honey was effective at killing several different strains of bacteria at 10-20% (v/v), while greater than 40% (v/v) of a honey-equivalent sugar solution was required for similar activity [http://www.ncbi.nlm.nih.gov/pubmed/20228250/: <sup>3</sup>] (Kwakman et al. 2010). 
===Artificial Honey===


In a study on the effect of honey on [https://microbewiki.kenyon.edu/index.php/Streptococcus_mutans <i>Streptococcus mutans</i>], natural honey bought from a local grocery store in Jeddah, Saudi Arabia was compared to artificial honey composed of 40.5% fructose, 33.5% glucose, 7.5% maltose and 1.5% sucrose dissolved in deionized water [http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3255743/: <sup>1</sup>].  Different natural and artificial honey concentrations were obtained using serial dilutions with tryptic soy broth (TSB) and at 12.5%, natural honey supported less bacterial growth and biofilm formation than artificial honey with the same amount of sugars, suggesting that sugar content is not the only antibacterial factor [http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3255743/: <sup>1</sup>].  Natural honey was able to decrease the maximum velocity of <i>S. mutans</i> growth compared to artificial honey [http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3255743/: <sup>1</sup>].  Overall, natural honey demonstrated more inhibition of bacterial growth, viability, and biofilm formation than artificial honey [http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3255743/: <sup>1</sup>]. 


One brand of commercial honey called Black Forest honey from Langaneza, Germany was tested and found to inhibit eight different types of microbes at concentrations between 10 to 100% [http://www.cabdirect.org/abstracts/20113072555.html/: <sup>7</sup>] (Masaudi and Albureikan 2013).  Growth of all microbes was reduced at 10% and completely inhibited at 20% for Methicillin-Sensitive <i>S. aureus</i>, Methicillin-Resistant <i>S. aureus</i>, and [http://en.wikipedia.org/wiki/Escherichia_coli: <i>E. coli</i>], and at 50% for [http://en.wikipedia.org/wiki/Pseudomonas_aeruginosa: <i>P. aeruginosa</i>] and <i>C. albicans</i>, and at 100% for <i>S. pyogenes</i>, Vancomycin-sensitive <i>enterococci</i> and Vancomycin-resistant <i>enterococci</i> [http://www.cabdirect.org/abstracts/20113072555.html/: <sup>7</sup>] (Masaudi and Albureikan 2013).
<br>
<br>


==Microbes Inhibited by Honey==
==Microbes Inhibited by Honey==
<br>Coagulase-positive <i>Staphylococcus aureus</i> has been shown to be sensitive to both pasture and manuka honeys [http://jrs.sagepub.com/content/92/6/283/: <sup>4</sup>] (Cooper et al. 1999).  In this study there was a lack of significant variance in the sensitivity of a large number of clinical isolates collected from a wide range of wounds, which indicates that there is no mechanism of resistance to the antibacterial activity of honey [http://jrs.sagepub.com/content/92/6/283/: <sup>4</sup>] (Cooper et al. 1999).
===<i>Staphylococcus</i>===
Coagulase-positive [https://microbewiki.kenyon.edu/index.php/Staphylococcus_aureus <i>Staphylococcus aureus</i>] has been shown to be sensitive to both pasture and manuka honeys [http://jrs.sagepub.com/content/92/6/283/ <sup>4</sup>]. In this study there was a lack of significant variance in the sensitivity of a large number of clinical isolates collected from a wide range of wounds, which indicates that there is no mechanism of resistance to the antibacterial activity of honey [http://jrs.sagepub.com/content/92/6/283/: <sup>4</sup>]. [http://en.wikipedia.org/wiki/Methicillin Methicillin]-resistant <i>Staphylococcus aureus</i> (MRSA) growth has been shown to be inhibited by Revamil medical honey and manuka honey, as shown in Figure 3[http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0017709#pone-0017709-g004: <sup>10</sup>].


===<i>Streptococcus</i>===


<i>Streptococcus mutans</i> growth, viability, and biofilm formation were inhibited by natural honey at concentrations between 25 and 12.5% [http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3255743/: <sup>1</sup>] (Nassar et al. 2012).  Bacterial growth and biofilm formation were determined using a microplate spectrophotometer on wells inoculated with <i>S. mutans</i> containing varying concentrations of natural and artificial honey and biofilms were fixed using formaldehyde solution, followed by crystal violet, and then isopropanol, after that the wells were aspirated and their absorbances were read [http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3255743/: <sup>1</sup>] (Nassar et al. 2012).  The number of colony-forming units (CFU) for varying concentrations of honey was determined using an automated colony counter and compared to values from the tryptic soy broth (TSB) control culture to determine the effect of honey on <i>S. mutans</i> viability [http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3255743/: <sup>1</sup>] (Nassar et al. 2012).   
[https://microbewiki.kenyon.edu/index.php/Streptococcus_mutans <i>Streptococcus mutans</i>] growth, [http://en.wikipedia.org/wiki/Viability viability], and [http://en.wikipedia.org/wiki/Biofilm biofilm] formation were inhibited by concentrations between 25 and 12.5% of natural honey[http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3255743/: <sup>1</sup>].  Bacterial growth and biofilm formation were determined using a microplate [http://en.wikipedia.org/wiki/Spectrophotometry spectrophotometer] on wells [http://en.wikipedia.org/wiki/Inoculate inoculated] with <i>S. mutans</i> containing varying concentrations of natural and artificial honey[http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3255743/: <sup>1</sup>]. Biofilms were fixed using [http://en.wikipedia.org/wiki/Formaldehyde formaldehyde] solution, followed by [http://en.wikipedia.org/wiki/Crystal_violet crystal violet], and then [http://en.wikipedia.org/wiki/Isopropanol isopropanol], after that the wells were aspirated and their [http://en.wikipedia.org/wiki/Absorbance absorbances] were read [http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3255743/: <sup>1</sup>].  The number of colony-forming units (CFU) for varying concentrations of honey was determined using an automated colony counter and compared to values from the [http://en.wikipedia.org/wiki/Tryptic_soy_broth tryptic soy broth] (TSB) control culture to determine the effect of honey on <i>S. mutans</i> viability [http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3255743/: <sup>1</sup>].   


[[Image:Inhibited Microbes.jpg|thumb|600px|right|Different bacteria inhibited by medical grade Revamil and manuka honey. Open bars were incubated for 2 hours, hatched bars for 24 hours. [http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0017709#pone-0017709-g004: By Dr. Paulus H.S. Kwakman], Department of Medical Microbiology, Center for Infection and Immunity Amsterdam.[http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0017709#pone-0017709-g004: <sup>10</sup>]]]
[https://microbewiki.kenyon.edu/index.php/Streptococcus_pyogenes <i>Streptococcus pyogenes</i>] and [http://en.wikipedia.org/wiki/Streptococcus_faecalis <i>Streptococcus faecalis</i>] were tested on blood agar and honey-blood agar plates [http://www.ncbi.nlm.nih.gov/pubmed/3983773/: <sup>8</sup>] to test for the effectiveness of honey in a diluted, nutrient rich environment. In these tests, <i>Streptococcus pyogenes</i> was inhibited in concentrations of honey below 20%, and all microbes tested were inhibited in solutions with greater than 50% honey content [http://www.ncbi.nlm.nih.gov/pubmed/3983773/: <sup>8</sup>].


Unprocessed Revamil source honey effectively killed <i>Bacillus subtilis</i>, methicillin-resistant <i>Staphylococcus aureus</i>, extended-spectrum β-lactamase producing <i>Escheria coli</i>, ciprofloxacin-resistant <i>Pseudomonas aeruginosa</i>, and vancomycin-resistant <i>Enterococcus faecium</i> [http://www.ncbi.nlm.nih.gov/pubmed/20228250/: <sup>3</sup>] (Kwakman et al. 2010). The activity of honey against <i>E. coli</i>  and <i>P. aeruginosa</i> was markedly reduced when either H<sub>2</sub>O<sub>2</sub> or MGO was neutralized [http://www.ncbi.nlm.nih.gov/pubmed/20228250/: <sup>3</sup>] (Kwakman et al. 2010).
[[Image:Inhibited Microbes.jpg|thumb|600px|right|Figure 3. Different bacteria inhibited by medical grade Revamil and manuka honey. Open bars were incubated for 2 hours, hatched bars for 24 hours. [http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0017709#pone-0017709-g004: By Dr. Paulus H.S. Kwakman], Department of Medical Microbiology, Center for Infection and Immunity Amsterdam.[http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0017709#pone-0017709-g004: <sup>10</sup>]]]


===Other===


The relationship between the presence of honey and bacterial growth was tested on the following bacteria on nutrient-agar and honey-nutrient agar plates: <i>Vibrio cholerae</i>, enteropathogenic <i>E. coli</i>, <i>Salmonella typhi, Shigella boydii, Klebsiella pneumoniae, P. mirabilis, Psuedomonas aeruginosa</i> and <i>Serratia marcescens</i> [http://www.ncbi.nlm.nih.gov/pubmed/3983773/: <sup>8</sup>] (Jeddar et al. 1985). <i>Staphylococcus aureus, Streptococcus pyogenes, Streptococcus faecalis</i>, and <i>Listeria</i> monocytogenes were tested on blood agar and honey-blood agar plates [http://www.ncbi.nlm.nih.gov/pubmed/3983773/: <sup>8</sup>] (Jeddar et al. 1985). Finally, chocolate-agar and honey-chocolate agar plates were used to test the growth of <i>Haemophilus influenzae</i> [http://www.ncbi.nlm.nih.gov/pubmed/3983773/: <sup>8</sup>] (Jeddar et al. 1985).  There was good growth of all bacteria on their respective control plates and all intestinal bacterial pathogens tested failed to grow in honey at concentrations of 40% and above [http://www.ncbi.nlm.nih.gov/pubmed/3983773/: <sup>8</sup>] (Jeddar et al. 1985)Furthermore, the growth of <i>V. cholerae</i>, <i>S. pyogenes</i>, and <i>H. influenzae</i> were inhibited in honey at concentrations as low as 20% and the growth of all bacteria tested was inhibited at honey concentrations of 50% [http://www.ncbi.nlm.nih.gov/pubmed/3983773/: <sup>8</sup>] (Jeddar et al. 1985).
Unprocessed Revamil source honey effectively killed [https://microbewiki.kenyon.edu/index.php/Bacillus_subtilis <i>Bacillus subtilis</i>], Methicillin-resistant <i>Staphylococcus aureus</i>, extended-spectrum [http://en.wikipedia.org/wiki/Β-lactamase β-lactamase] producing [https://microbewiki.kenyon.edu/index.php/Escherichia_coli <i>Escherichia coli </i>], [http://en.wikipedia.org/wiki/Ciprofloxacin ciprofloxacin]-resistant [https://microbewiki.kenyon.edu/index.php/Pseudomonas_aeruginosa <i>Pseudomonas aeruginosa</i>], and [http://en.wikipedia.org/wiki/Vancomycin vancomycin]-resistant [https://microbewiki.kenyon.edu/index.php/Enterococcus_faecium <i>Enterococcus faecium</i>] [http://www.ncbi.nlm.nih.gov/pubmed/20228250/: <sup>3</sup>].  The activity of honey against <i>E. coli</i> and  <i>P. aeruginosa</i> was markedly reduced when either H<sub>2</sub>O<sub>2</sub> or MGO was neutralized [http://www.ncbi.nlm.nih.gov/pubmed/20228250/: <sup>3</sup>].


The relationship between the presence of honey and bacterial growth was tested on the following bacteria on nutrient-[http://en.wikipedia.org/wiki/Agar agar] and honey-nutrient agar plates: [https://microbewiki.kenyon.edu/index.php/Vibrio_cholerae <i>Vibrio cholerae</i>], enteropathogenic <i>E. coli</i>, [https://microbewiki.kenyon.edu/index.php/Salmonella_typhi <i>Salmonella typhi], [https://microbewiki.kenyon.edu/index.php/Shigella_boydii Shigella boydii], [https://microbewiki.kenyon.edu/index.php/Klebsiella_pneumoniae Klebsiella pneumoniae], [https://microbewiki.kenyon.edu/index.php/Proteus_mirabilis Proteus mirabilis], Pseudomonas aeruginosa</i>  and [https://microbewiki.kenyon.edu/index.php/Serratia_marcescens <i>Serratia marcescens</i>] [http://www.ncbi.nlm.nih.gov/pubmed/3983773/: <sup>8</sup>].  <i>Staphylococcus aureus</i> and [http://en.wikipedia.org/wiki/Listeria_monocytogenes <i>Listeria monocytogenes</i>] were tested on blood agar and honey-blood agar plates [http://www.ncbi.nlm.nih.gov/pubmed/3983773/: <sup>8</sup>].  Finally, chocolate-agar and honey-chocolate agar plates were used to test the growth of [https://microbewiki.kenyon.edu/index.php/Haemophilus_influenzae <i>Haemophilus influenzae</i>] [http://www.ncbi.nlm.nih.gov/pubmed/3983773/: <sup>8</sup>].  There was good growth of all bacteria on their respective control plates and all intestinal bacterial [http://en.wikipedia.org/wiki/Pathogens pathogens] tested failed to grow in honey at concentrations of 40% and above [http://www.ncbi.nlm.nih.gov/pubmed/3983773/: <sup>8</sup>].  Furthermore, the growth of <i>V. cholerae</i>, <i>S. pyogenes</i>, and <i>H. influenzae</i> were inhibited in honey at concentrations as low as 20% and the growth of all bacteria tested was inhibited at honey concentrations of 50% [http://www.ncbi.nlm.nih.gov/pubmed/3983773/: <sup>8</sup>].


Langaneza Black Forest honey inhibited the growth of <i>S. pyogenes, E. coli, P. aeruginosa, C. albicans</i>, Methicillin-sensitive and Methicillin-resistant <i>S. aureus</i>, and Vancomycin-sensitive and Vancomycin-resistant <i>enterococci</i> [http://www.cabdirect.org/abstracts/20113072555.html/: <sup>7</sup>] (Masaudi and Albureikan 2013).   
Langaneza [http://en.wikipedia.org/wiki/Black_Forest Black Forest] honey inhibited the growth of <i>S. pyogenes, E. coli, P. aeruginosa, [https://microbewiki.kenyon.edu/index.php/Candida_albicans Candida albicans</i>], Methicillin-sensitive and Methicillin-resistant <i>S. aureus</i>, and Vancomycin-sensitive and Vancomycin-resistant [http://en.wikipedia.org/wiki/Enterococci <i>enterococci</i>] [http://www.cabdirect.org/abstracts/20113072555.html/: <sup>7</sup>].   
<br>
<br>


==Further Reading==
==Further Reading==
[http://ijl.sagepub.com/content/5/1/40: Evidence Supporting the Use of Honey as a Wound Dressing] Molan (2006) reviewed 17 randomized controlled trials involving a total of 1,965 participants, 5 clinical trials of other forms involving 97 participants treated with honey, and 16 trials on a total of 533 wounds on experimental animals all with findings that demonstrate the effectiveness of honey in assisting wound healing. This review found that honey has antibacterial activity capable of rapidly clearing infection and protecting wounds from becoming infected, while providing a moist healing environment without the risk of bacterial growth (Molan 2006). This review also reports that honey produces anti-inflammatory effects to reduce edema and exudate and prevent or minimize hypertrophic scarring (Molan 2006).  Honey also stimulates the growth of granulation tissue and epithelial tissue so that healing is hastened (Molan 2006).  
[[Image:LAB photo.jpg|thumb|400px|right|A SEM photograph of lactobacilli (light blue) in the [http://en.wikipedia.org/wiki/Crop_(anatomy) crop] of a honeybee. The attachment structures appear to be [http://en.wikipedia.org/wiki/Extracellular_polymeric_substance extracellular polymeric substances]. Figures A,B, and C are all at similar magnification. Figure D shows a larger area of the crop. [http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0033188: By Lennart Nilsson] from Karolinska Institutet, Sweden. [http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0033188: <sup>12</sup>]]]
 
[http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0033188 Symbionts as Major Modulators of Insect Health Lactic Acid Bacteria and Honeybees] Vásquez et al. (2012) found that the crop of bees contains [http://en.wikipedia.org/wiki/Lactic_acid lactic acid] bacteria (LAB), the predominant one being [http://en.wikipedia.org/wiki/Lactobacillus <i>Lactobacillus] kunkeei</i> (pictured at right) [http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0033188 <sup>12</sup>]. Commercial antibiotics commonly administered to bees were shown to be detrimental for the LAB, and may end up being more of a hindrance than a help for bees. There may very well be a connection between LAB and the antimicrobial effects of honey [http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0033188 <sup>12</sup>].


[http://www.ncbi.nlm.nih.gov/pubmed/10085281: Effect of Honey on Wound Healing Time] Effects of topical honey on post-operative wound infections due to gram positive and gram negative bacteria following caesarean sections and hysterectomies by Al-Waili and Saloom (1999)Topical application of crude undiluted honey resulted in faster eradication of bacterial infections, reduced period of antibiotic use and hospital stay, accelerated wound healing, reduced occurrence of wound dehiscence and need for re-suturing and minimized scar formation.
[http://ijl.sagepub.com/content/5/1/40 Evidence Supporting the Use of Honey as a Wound Dressing] Molan (2006) reviewed 17 randomized controlled trials involving a total of 1,965 participants, 5 clinical trials of other forms involving 97 participants treated with honey, and 16 trials on a total of 533 wounds on experimental animals all with findings that demonstrate the effectiveness of honey in assisting wound healing[http://ijl.sagepub.com/content/5/1/40 <sup>13</sup>]This review found that honey has antibacterial activity capable of rapidly clearing [http://en.wikipedia.org/wiki/Infection infection] and protecting wounds from becoming infected, while providing a moist healing environment without the risk of bacterial growth[http://ijl.sagepub.com/content/5/1/40 <sup>13</sup>].  This review also reports that honey produces [http://en.wikipedia.org/wiki/Anti-inflammatory anti-inflammatory] effects to reduce [http://en.wikipedia.org/wiki/Edema edema] and [http://en.wikipedia.org/wiki/Exudate exudate] and prevent or minimize [http://en.wikipedia.org/wiki/Hypertrophic_scar hypertrophic scarring] [http://ijl.sagepub.com/content/5/1/40 <sup>13</sup>].  Honey also stimulates the growth of [http://en.wikipedia.org/wiki/Granulation_tissue granulation tissue] and [http://en.wikipedia.org/wiki/Epithelial_tissue epithelial tissue] so that healing is hastened[http://ijl.sagepub.com/content/5/1/40 <sup>13</sup>].  


   
[http://www.ncbi.nlm.nih.gov/pubmed/10085281 Effect of Honey on Wound Healing Time] Effects of topical honey on post-operative wound infections due to gram positive and gram negative bacteria following [http://en.wikipedia.org/wiki/Caesarean Caesarean sections] and [http://en.wikipedia.org/wiki/Hysterectomies hysterectomies] were investigated[http://www.ncbi.nlm.nih.gov/pubmed/10085281 <sup>14</sup>].  Topical application of crude undiluted honey resulted in faster eradication of bacterial infections, reduced period of antibiotic use and hospital stay, accelerated wound healing, reduced occurrence of wound [http://en.wikipedia.org/wiki/Wound_dehiscence dehiscence] and need for [http://en.wikipedia.org/wiki/Suturing re-suturing] and minimized scar formation[http://www.ncbi.nlm.nih.gov/pubmed/10085281 <sup>14</sup>].


==References==
==References==
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5. [http://www.sciencedirect.com/science/article/pii/S0924857911001300/ Cushnie, T. P., and Andrew J. Lamb. "Recent advances in understanding the antibacterial properties of flavonoids." International journal of antimicrobial agents 38.2 (2011): 99-107.]
5. [http://www.sciencedirect.com/science/article/pii/S0924857911001300/ Cushnie, T. P., and Andrew J. Lamb. "Recent advances in understanding the antibacterial properties of flavonoids." International journal of antimicrobial agents 38.2 (2011): 99-107.]


6. [http://online.liebertpub.com/doi/abs/10.1089/10755530360623383/ Bang LM, Buntting C, Molan P (2003) The effect of dilution on the rate of hydrogen peroxide production in honey and its implications for wound healing. J Altern Complement Med 9(2):267–273.]
6. [http://www.ncbi.nlm.nih.gov/pubmed/12804080/ Bang LM, Buntting C, Molan P (2003) The effect of dilution on the rate of hydrogen peroxide production in honey and its implications for wound healing. J Altern Complement Med 9(2):267–273.]


7. [http://www.cabdirect.org/abstracts/20113072555.html/ Al-Masaudi, S. B., & Al-Bureikan, M. O. (2010). Antimicrobial activity of different types of honey on some multiresistant microorganisms. In Proceedings of the 3rd Scientific Conference of Animal Wealth Research in the Middle East and North Africa, Foreign Agricultural Relations (FAR), Egypt, 29 November-1 December 2010. (pp. 512-526). Massive Conferences and Trade Fairs.]
7. [http://www.cabdirect.org/abstracts/20113072555.html Al-Masaudi, S. B., & Al-Bureikan, M. O. (2010). Antimicrobial activity of different types of honey on some multiresistant microorganisms. In Proceedings of the 3rd Scientific Conference of Animal Wealth Research in the Middle East and North Africa, Foreign Agricultural Relations (FAR), Egypt, 29 November-1 December 2010. (pp. 512-526). Massive Conferences and Trade Fairs.]


8. [http://www.ncbi.nlm.nih.gov/pubmed/3983773/ Jeddar, A., et al. "The antibacterial action of honey. An in vitro study." South African medical journal= Suid-Afrikaanse tydskrif vir geneeskunde 67.7 (1985): 257.]
8. [http://www.ncbi.nlm.nih.gov/pubmed/3983773/ Jeddar, A., et al. "The antibacterial action of honey. An in vitro study." South African medical journal= Suid-Afrikaanse tydskrif vir geneeskunde 67.7 (1985): 257.]


9. [http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0018229/ Irish, Julie, Shona Blair, and Dee A. Carter. "The antibacterial activity of honey derived from Australian flora." PLoS One 6.3 (2011): e18229.]
9. [http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0018229 Irish, Julie, Shona Blair, and Dee A. Carter. "The antibacterial activity of honey derived from Australian flora." PLoS One 6.3 (2011): e18229.]


10. [http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0017709#pone-0017709-g004/ Kwakman, Paulus HS, et al. "Two major medicinal honeys have different mechanisms of bactericidal activity." PLoS One 6.3 (2011): e17709.]
10. [http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0017709#pone-0017709-g004/ Kwakman, Paulus HS, et al. "Two major medicinal honeys have different mechanisms of bactericidal activity." PLoS One 6.3 (2011): e17709.]
11. [https://www.flickr.com/photos/bionicgrrl/3535805377/ Bionicgrrrl. "Comb honey from Alois Dallmayr." Flickr (May 16, 2009).]
12. [http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0033188 Vásquez A, Forsgren E, Fries I, Paxton RJ, Flaberg E, et al. (March 12 2012) Symbionts as Major Modulators of Insect Health: Lactic Acid Bacteria and Honeybees. PLoS ONE 7(3): e33188. doi:10.1371/journal.pone.0033188.]
13. [http://ijl.sagepub.com/content/5/1/40.short Molan, Peter C. "The evidence supporting the use of honey as a wound dressing." The International Journal of Lower Extremity Wounds 5.1 (2006): 40-54.]
14. [http://www.ncbi.nlm.nih.gov/pubmed/10085281 Al-Waili, N. S., and K. Y. Saloom. "Effects of topical honey on post-operative wound infections due to gram positive and gram negative bacteria following caesarean sections and hysterectomies." European journal of medical research 4.3 (1999): 126.]


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Latest revision as of 03:48, 15 April 2014

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Honey has seen a revival recently in the Western medical field, as it has shown inhibitory activity against a range of detrimental and antibiotic-resistant microbes of infected wounds 1. Honey may be the first recorded medicine, having been documented in the Smith Papyrus of Egypt, which dates to between 2200-2600 BC 2. Since ancient times honey has been renowned for its wound-healing properties 3. With the advent of antibiotics, clinical application of honey has been neglected in modern Western medicine, although it is still used in many cultures 3. The overwhelming use of antibiotics has resulted in widespread resistance, therefore alternative antimicrobial strategies are necessary 3.

A freshly cut piece of honeycomb from the Dallmayr store in Germany. By bionicgrrrl.11


Honey has demonstrated potent in vitro activity against antibiotic-resistant bacteria and it has been successfully applied as treatment of chronic wound infections not responding to antibiotic therapy 3 . For example, honey has received attention as an important tool against strains of bacteria such as Methicillin-resistant Staphylococcus aureus 4. No microbial resistance against honey has been observed, making it attractive as a treatment for wound infections 4. Honey possesses several antimicrobial properties and can act via various mechanisms of action. There are many different types of honey from around the world, made from different floral sources with variable mechanisms of action. The antimicrobial potency and medical applications of honey are tremendous as it has demonstrated inhibitory effects against a number of pathogenic bacteria 134.


Mechanisms of Action

Honey prevents microbial growth through the use of hydrogen peroxide (H2O2), methylglyoxal (MGO), bee defensin-1, flavonoids, and a relatively low pH (~3.3) 13. As shown in Figure 1, the different active components in honey have been isolated by neutralizing each one individually and observing the effect on its antimicrobial activity. Not all of the factors listed are present in all types of honey, and these compounds must be tested for and considered for clinical applications 3.

Osmolarity

The high osmolarity of honey can also contribute to the inhibition of growth, although this is true of sugar solutions as well 13. Honey is 70 to 80% sugar and this high percentage causes hypertonic conditions that may lead to lysis of microbial cell walls 5.

H2O2

Hydrogen peroxide is produced by the Apis mellifera (honeybee) glucose oxidase enzyme on dilution of honey, and is produced in low but effective concentrations 36. Due to the slow release of H2O2, there is much less cytotoxic damage to the patient’s cells, providing a better method than applying H2O2 directly to wounds 6.

Methylglyoxal

Methylglyoxal is a compound found in manuka honey that was reported to have an antibacterial property 5. MGO can be converted into its inactive form, S-lactoylglutathione, by glyoxalase I and this was done in an experiment to test the effects of MGO on honey’s bactericidal activity (unprocessed Revamil honey was used in this experiment) 3. Neutralization of MGO or H2O2 alone did not alter bactericidal activity of RS honey, but simultaneous neutralization of MGO and H2O2 in a solution diluted with water to 10% honey reduced the killing of B. subtilis by 4-logs 3. At higher concentrations of honey, the bactericidal activity was not affected by neutralization of MGO and H2O2 3.

Figure 1. The different antimicrobial compounds in honey were sequentially neutralized in order to determine their individual effects on different strains of bacteria. A plus sign indicates the use of different neutralization agents. Catalase (cat.) inhibits production of hydrogen peroxide, glyoxyalase 1 (gly 1) inhibits methylglyoxal (MGO), and sodium polyanetholsulfonate (SPS) neutralizes bee defensin-1. There was also a sugar control group on the right of each graph. The difference in effects on different bacterial strains indicates that there are synergistic and redundant components of honey, and that these effects are microbe-specific. By Dr. Paulus H.S. Kwakman, Department of Medical Microbiology, Center for Infection and Immunity Amsterdam.3

Bee defensin-1

Bee defensin-1 is found in honey and is the only cationic bactericidal compound currently identified 3. In dilutions of 20% honey and greater, when H2O2 and MGO were neutralized bactericidal activity was retained 3. When bee defensin-1 was also neutralized, the bactericidal activity was strongly reduced at 20% but was not affected at 30 and 40% honey solutions 3. Bee defensin-1 was previously isolated from royal jelly, the major food source for bee queen larvae and was identified in honeybee hemolymph 3. This peptide is secreted by the hypopharyngeal gland of worker bees into collected nectar along with carbohydrate-metabolizing enzymes and bee defensin-1 presumably contributes to protection of royal jelly and honey against microbial spoilage 3.

Flavonoids

Flavonoids are a group of pigments produced by plants and their presence was suggested to contribute to the antimicrobial properties of honey 1. Actions of flavonoids include direct antibacterial activity, synergism with antibiotics, and suppression of bacterial virulence 5. The direct antibacterial activity of flavonoids may be attributable to several tested mechanisms: cytoplasmic membrane damage (caused by perforation and/or a reduction in membrane fluidity possibly by generating hydrogen peroxide), inhibition of nucleic acid synthesis (caused by topoisomerase inhibition and/or dihydrofolate reductase inhibition), inhibition of energy metabolism (caused by NADH-cytochrome c reductsse inhibition and ATP synthase inhibition), inhibition of cell wall synthesis (caused by D-alanine-D-alanine ligase inhibition) and inhibition of cell membrane synthesis (caused by inhibition of several enzymes) 5. There are 14 classes of flavonoids in total, categorized by their chemical nature and structure 5. Because most studies on the mechanism of action of flavonoids were conducted on only one or two types of flavonoids, it remains unclear as to whether flavonoids have multiple mechanisms of action or flavonoids have a single mechanism that has yet to be convincingly determined 5.

pH

Honey has a low pH primarily due to the conversion of glucose into hydrogen peroxide and gluconic acid by glucose oxidase 3. This low pH might also contribute to the bactericidal activity of honey, demonstrated by the titration of the pH of 10-40% honey solutions from 3.4-3.5 to 7.0 combined with neutralization of other bactericidal factors (H2O2, MGO and bee defensin-1) reduced the bactericidal activity of honey to the same level of a honey-equivalent sugar solution 3.

Effectiveness of Different Types of Honey

Manuka Honey

Manuka honey is predominantly harvested in New Zealand and Australia, from bees visiting Leptospermum trees. The minimum inhibitory concentration (MIC) of manuka honey on Stayphylococcus aureus was between 2 and 3% (v/v) ([(volume of solute)/(volume of solution)] x 100%) 4. While manuka honey does release H2O2, its anitmicrobial action also has a phytochemical component 4. In this study by Cooper et al. (1999) the antibacterial activity of manuka and pasture honeys on S. aureus were determined by an agar well diffusion bioassay using phenol as a reference standard antiseptic both in the presence of catalase and not in the presence of catalase, to detect any non-peroxide antibacterial activity; the MIC of each honey was determined by an agar incorporation technique. Manuka honey has received more attention for antimicrobial work recently due to its additional phytochemical compounds.

Pasture Honey

The MIC of honey from a mixed pasture source was between 3 and 4% on S. aureus 4. These honeys prevent growth of S. aureus even when diluted by body fluids a further seven-fold to fourteen-fold beyond the point where their osmolarity ceased to be completely inhibitory 4 Pasture honey acts by releasing H2O2, but often lacks significant amounts of the extra phytochemical components of manuka honey.

One brand of commercial honey called Black Forest honey from Langaneza, Germany was tested and found to inhibit eight different types of microbes at concentrations between 10 to 100% honey solutions7. Growth of all microbes was reduced at 10% honey solutions and completely inhibited at 20% honey solutions for Methicillin-Sensitive S. aureus, Methicillin-Resistant S. aureus, and E. coli, and at 50% honey solutions for P. aeruginosa and C. albicans, and at 100% honey for S. pyogenes, Vancomycin-sensitive enterococci and Vancomycin-resistant enterococci 7.

Figure 2. A chart illustrating Australian honeys with different floral sources, and their non-peroxide antibacterial activity. By Julie Irish, School of Molecular Bioscience, University of Sydney, Camperdown, Australia.9


Medical Honey

Unprocessed Revamil source honey was effective at killing several different strains of bacteria at 10-20% (v/v), while greater than 40% (v/v) of a honey-equivalent sugar solution was required for similar activity 3. Another medical grade honey, Medihoney, comes from honey from Leptospermum flowers, making it very similar to manuka honey. In Medihoney, however, there are numerous steps taken to guarantee the sterility of the honey.

Artificial Honey

In a study on the effect of honey on Streptococcus mutans, natural honey bought from a local grocery store in Jeddah, Saudi Arabia was compared to artificial honey composed of 40.5% fructose, 33.5% glucose, 7.5% maltose and 1.5% sucrose dissolved in deionized water 1. Different natural and artificial honey concentrations were obtained using serial dilutions with tryptic soy broth (TSB) and at 12.5%, natural honey supported less bacterial growth and biofilm formation than artificial honey with the same amount of sugars, suggesting that sugar content is not the only antibacterial factor 1. Natural honey was able to decrease the maximum velocity of S. mutans growth compared to artificial honey 1. Overall, natural honey demonstrated more inhibition of bacterial growth, viability, and biofilm formation than artificial honey 1.


Microbes Inhibited by Honey

Staphylococcus

Coagulase-positive Staphylococcus aureus has been shown to be sensitive to both pasture and manuka honeys 4. In this study there was a lack of significant variance in the sensitivity of a large number of clinical isolates collected from a wide range of wounds, which indicates that there is no mechanism of resistance to the antibacterial activity of honey 4. Methicillin-resistant Staphylococcus aureus (MRSA) growth has been shown to be inhibited by Revamil medical honey and manuka honey, as shown in Figure 310.

Streptococcus

Streptococcus mutans growth, viability, and biofilm formation were inhibited by concentrations between 25 and 12.5% of natural honey1. Bacterial growth and biofilm formation were determined using a microplate spectrophotometer on wells inoculated with S. mutans containing varying concentrations of natural and artificial honey1. Biofilms were fixed using formaldehyde solution, followed by crystal violet, and then isopropanol, after that the wells were aspirated and their absorbances were read 1. The number of colony-forming units (CFU) for varying concentrations of honey was determined using an automated colony counter and compared to values from the tryptic soy broth (TSB) control culture to determine the effect of honey on S. mutans viability 1.

Streptococcus pyogenes and Streptococcus faecalis were tested on blood agar and honey-blood agar plates 8 to test for the effectiveness of honey in a diluted, nutrient rich environment. In these tests, Streptococcus pyogenes was inhibited in concentrations of honey below 20%, and all microbes tested were inhibited in solutions with greater than 50% honey content 8.

Figure 3. Different bacteria inhibited by medical grade Revamil and manuka honey. Open bars were incubated for 2 hours, hatched bars for 24 hours. By Dr. Paulus H.S. Kwakman, Department of Medical Microbiology, Center for Infection and Immunity Amsterdam.10

Other

Unprocessed Revamil source honey effectively killed Bacillus subtilis, Methicillin-resistant Staphylococcus aureus, extended-spectrum β-lactamase producing Escherichia coli , ciprofloxacin-resistant Pseudomonas aeruginosa, and vancomycin-resistant Enterococcus faecium 3. The activity of honey against E. coli and P. aeruginosa was markedly reduced when either H2O2 or MGO was neutralized 3.

The relationship between the presence of honey and bacterial growth was tested on the following bacteria on nutrient-agar and honey-nutrient agar plates: Vibrio cholerae, enteropathogenic E. coli, Salmonella typhi, Shigella boydii, Klebsiella pneumoniae, Proteus mirabilis, Pseudomonas aeruginosa and Serratia marcescens 8. Staphylococcus aureus and Listeria monocytogenes were tested on blood agar and honey-blood agar plates 8. Finally, chocolate-agar and honey-chocolate agar plates were used to test the growth of Haemophilus influenzae 8. There was good growth of all bacteria on their respective control plates and all intestinal bacterial pathogens tested failed to grow in honey at concentrations of 40% and above 8. Furthermore, the growth of V. cholerae, S. pyogenes, and H. influenzae were inhibited in honey at concentrations as low as 20% and the growth of all bacteria tested was inhibited at honey concentrations of 50% 8.

Langaneza Black Forest honey inhibited the growth of S. pyogenes, E. coli, P. aeruginosa, Candida albicans, Methicillin-sensitive and Methicillin-resistant S. aureus, and Vancomycin-sensitive and Vancomycin-resistant enterococci 7.

Further Reading

A SEM photograph of lactobacilli (light blue) in the crop of a honeybee. The attachment structures appear to be extracellular polymeric substances. Figures A,B, and C are all at similar magnification. Figure D shows a larger area of the crop. By Lennart Nilsson from Karolinska Institutet, Sweden. 12

Symbionts as Major Modulators of Insect Health Lactic Acid Bacteria and Honeybees Vásquez et al. (2012) found that the crop of bees contains lactic acid bacteria (LAB), the predominant one being Lactobacillus kunkeei (pictured at right) 12. Commercial antibiotics commonly administered to bees were shown to be detrimental for the LAB, and may end up being more of a hindrance than a help for bees. There may very well be a connection between LAB and the antimicrobial effects of honey 12.

Evidence Supporting the Use of Honey as a Wound Dressing Molan (2006) reviewed 17 randomized controlled trials involving a total of 1,965 participants, 5 clinical trials of other forms involving 97 participants treated with honey, and 16 trials on a total of 533 wounds on experimental animals all with findings that demonstrate the effectiveness of honey in assisting wound healing13. This review found that honey has antibacterial activity capable of rapidly clearing infection and protecting wounds from becoming infected, while providing a moist healing environment without the risk of bacterial growth13. This review also reports that honey produces anti-inflammatory effects to reduce edema and exudate and prevent or minimize hypertrophic scarring 13. Honey also stimulates the growth of granulation tissue and epithelial tissue so that healing is hastened13.

Effect of Honey on Wound Healing Time Effects of topical honey on post-operative wound infections due to gram positive and gram negative bacteria following Caesarean sections and hysterectomies were investigated14. Topical application of crude undiluted honey resulted in faster eradication of bacterial infections, reduced period of antibiotic use and hospital stay, accelerated wound healing, reduced occurrence of wound dehiscence and need for re-suturing and minimized scar formation14.

References

1. Nassar, H. M., Li, M., & Gregory, R. L. (2012). Effect of honey on Streptococcus mutans growth and biofilm formation. Applied and environmental microbiology, 78(2), 536-540.

2. Zumla, A., & Lulat, A. (1989). Honey--a remedy rediscovered. Journal of the Royal Society of Medicine, 82(7), 384.

3. Kwakman, P. H., Te Velde, A. A., de Boer, L., Speijer, D., Vandenbroucke-Grauls, C. M., & Zaat, S. A. (2010). How honey kills bacteria. The FASEB Journal, 24(7), 2576-2582.

4. Cooper, R. A., P. C. Molan, and K. G. Harding. "Antibacterial activity of honey against strains of Staphylococcus aureus from infected wounds." Journal of the royal society of medicine 92.6 (1999): 283-285.

5. Cushnie, T. P., and Andrew J. Lamb. "Recent advances in understanding the antibacterial properties of flavonoids." International journal of antimicrobial agents 38.2 (2011): 99-107.

6. Bang LM, Buntting C, Molan P (2003) The effect of dilution on the rate of hydrogen peroxide production in honey and its implications for wound healing. J Altern Complement Med 9(2):267–273.

7. Al-Masaudi, S. B., & Al-Bureikan, M. O. (2010). Antimicrobial activity of different types of honey on some multiresistant microorganisms. In Proceedings of the 3rd Scientific Conference of Animal Wealth Research in the Middle East and North Africa, Foreign Agricultural Relations (FAR), Egypt, 29 November-1 December 2010. (pp. 512-526). Massive Conferences and Trade Fairs.

8. Jeddar, A., et al. "The antibacterial action of honey. An in vitro study." South African medical journal= Suid-Afrikaanse tydskrif vir geneeskunde 67.7 (1985): 257.

9. Irish, Julie, Shona Blair, and Dee A. Carter. "The antibacterial activity of honey derived from Australian flora." PLoS One 6.3 (2011): e18229.

10. Kwakman, Paulus HS, et al. "Two major medicinal honeys have different mechanisms of bactericidal activity." PLoS One 6.3 (2011): e17709.

11. Bionicgrrrl. "Comb honey from Alois Dallmayr." Flickr (May 16, 2009).

12. Vásquez A, Forsgren E, Fries I, Paxton RJ, Flaberg E, et al. (March 12 2012) Symbionts as Major Modulators of Insect Health: Lactic Acid Bacteria and Honeybees. PLoS ONE 7(3): e33188. doi:10.1371/journal.pone.0033188.

13. Molan, Peter C. "The evidence supporting the use of honey as a wound dressing." The International Journal of Lower Extremity Wounds 5.1 (2006): 40-54.

14. Al-Waili, N. S., and K. Y. Saloom. "Effects of topical honey on post-operative wound infections due to gram positive and gram negative bacteria following caesarean sections and hysterectomies." European journal of medical research 4.3 (1999): 126.

Edited by Celina Hayashi, a student of Nora Sullivan in BIOL168L (Microbiology) in The Keck Science Department of the Claremont Colleges Spring 2014.