Actinomyces gerencseriae: Difference between revisions
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The most common infection related to ''Actinomyces'' is actinomycosis. Gram stains for infected tissues are used as the main method for diagnosing actinomycosis. Once ''Actinomyces'' infects the host, sulfur granules, which are tiny yellow clumps, create a chronic granulomatous infection. The clump is stabilized by a protein-polysaccharide complex which provides antibiotic resistant properties. <sup>6</sup> | |||
A study was conducted on the susceptibility of ''Actinomyces'' in response to antibiotic treatments. The ''Actinomyces'' genus does not respond successfully to conventional root canal therapy like the other microbes that reside in the oral flora, so oral penicillin treatment is recommended first to heal oral diseases. In order to measure the susceptibility of the ''Actinomyces genus'' in the oral cavity, researchers collected samples from the periodontal and strained against antibiotics such as amoxicillin, clindamycin, doxycycline, metronidazole, and moxifloxacin. The author used the E-test methodology that provides an antibiotic gradient and circumferential measure of the zone of inhibition. Between the different species in ''Actinomyces'', there was no significant difference as to which was more susceptible. <sup>7</sup> | |||
=7. Key microorganisms= | =7. Key microorganisms= | ||
Include this section if your Wiki page focuses on a microbial process, rather than a specific taxon/group of organisms | Include this section if your Wiki page focuses on a microbial process, rather than a specific taxon/group of organisms | ||
Revision as of 00:40, 11 December 2017
1. Classification
a. Higher order taxa
Domain: Bacteria
Phylum: Actinobacteria
Class: Actinobacteria
Order: Actinomycetales
Family: Actinomycetaceae
Genus: Actinomyces
Species: Actinomyces gerencseriae
2. Description and significance
Actinomyces is a genus of bacteria that consists of a widely varied number of species that can exist both in the soil microbiome as well as within human and animal bodies. The Actinomyces genus mostly consists of Gram-positive bacilli that are facultatively anaerobic or microaerophilic rods. 1 Species from the Actinomyces genus often live primarily within the oral cavities of humans as part of the natural endogenous microbiome, but can become pathogenic when they are able to enter the body through open wounds, such as those stemming from poor dental hygiene. Members of the Actinomyces genus are significant because certain species (primarily A. gerencseriae and A. israelii) are known to cause the disease actinomycosis. Actinomycosis is a chronic and inflammatory granulomatous infection. This infection is referred to as granulomatous due to the granuloma, or inflammation, caused by an accumulation of macrophage immune cells that is a reaction of the host body to the invading pathogen. Actinomycosis can result in abscesses in the mouth, lungs, breast, and gastrointestinal tract in humans. While the incidence of this disease is rare, it can be particularly detrimental if and when it spreads to other tissues.
3. Genome structure
Actinomyces gerencseriae possesses a GC-rich genome, composed of 70% GC pairs.
The strain type of A. gerencseriae is ATCC 23860 = CCUG 32936 = CCUG 34703 = CDC W 838 = CIP 105418 = DSM 6844 = JCM 12963 = VPI 12594. 2
4. Cell structure
The entirety of the Actinomyces genus consists of gram positive bacteria. These gram positive bacilli bacteria possess cell walls consisting of a large external peptidoglycan layer threaded with teichoic acids and lipoteichoic acids. This peptidoglycan layer is separated from the cell membrane bilayer by the periplasmic space. The cell membrane bilayer is interspersed with important membrane proteins.
When Actinomyces was initially discovered in the late 1800s as a source of oral infection first in cows (A. Bovis) and then humans (A. Israelii), it was mistakenly identified as a fungal genus. The reason for this was the tendency for Actinomyces species to grow in a filamentous manner, and form hyphaes similar to eukaryotic fungi. Although this has been the typical classification of Actinomyces, several more recently discovered of these species lack the ‘typical’ branching rod appearance. 3
Actinomyces gerencseriae is a nonmotile, Gram positive bacterial species. The average Actinomyces gerencseriae colony is around 0.2 mm in diameter, circular in shape, are branching filamentous and white in color. Actinomyces gerencseriae have an incubation period of 2 days and is a non-spore forming bacterial species.
5. Metabolic processes
The ability to metabolize certain substances is an important distinguishing factor for the different Actinomyces species. The primary tests used in research include the ability for nitrate reduction, CAMP test reaction, as well as tests for the production of β-galactosidase, β-NAG, β-xylosidase, and 𝛼-fucosidase. Esculin hydrolysis is also a useful test for distinguishing certain species within the genus. Actinomyces as a genus has also been found to produce lactic acid in addition to succinic acid.
A common problem in recent years after the determination of A. gerencseriae as a separate species from A. israelii has been the separation of the two on a biochemical basis. It has been discovered, however, that these two species can be distinguished by their differential abilities to ferment different metabolites. A. israelii was found to possess the ability to ferment arabinose, while A. gerencseriae cannot. 3 Additional research has showed that these two species show differing abilities in the degradation of two mannopyranoside isomers. A. israelii can degrade the β-mannoside isomer, while A. gerencseriae can degrade the 𝛼-mannoside isomer. 4
6. Ecology
The genus normally presents itself in the oral cavity. A study on biofilm growth of the Actinomyces species found that in the presence of Actinomyces gerencseriae, Lactobacillus plantarum and Lactobacillus rhamnosus grew 4-20 times more than in a presence of another bacterial species in the oral community. Lactobacillus plantarum and Lactobacillus rhamnosus are examples of bacterial species commonly found in the oral cavity of humans, and their accelerated growth in this case demonstrate that overall, A. gerencseriae promotes growth in its ecological niche. Actinomyces gerencseriae are primarily microaerophilic, though some strains appear to be anaerobic. The significance of research in this area reveals itself when the features of the Lactobacillus genus, which can tolerate and utilize lactic acid in plaque under anaerobic conditions, are coupled with the growth promoting effects of the Actinomyces genus. Actinomyces promoted the growth of lactobicilli by providing a biofilm matrix. 5
7. Pathology
The most common infection related to Actinomyces is actinomycosis. Gram stains for infected tissues are used as the main method for diagnosing actinomycosis. Once Actinomyces infects the host, sulfur granules, which are tiny yellow clumps, create a chronic granulomatous infection. The clump is stabilized by a protein-polysaccharide complex which provides antibiotic resistant properties. 6 A study was conducted on the susceptibility of Actinomyces in response to antibiotic treatments. The Actinomyces genus does not respond successfully to conventional root canal therapy like the other microbes that reside in the oral flora, so oral penicillin treatment is recommended first to heal oral diseases. In order to measure the susceptibility of the Actinomyces genus in the oral cavity, researchers collected samples from the periodontal and strained against antibiotics such as amoxicillin, clindamycin, doxycycline, metronidazole, and moxifloxacin. The author used the E-test methodology that provides an antibiotic gradient and circumferential measure of the zone of inhibition. Between the different species in Actinomyces, there was no significant difference as to which was more susceptible. 7
7. Key microorganisms
Include this section if your Wiki page focuses on a microbial process, rather than a specific taxon/group of organisms
8. Current Research
Include information about how this microbe (or related microbes) are currently being studied and for what purpose
9. References
It is required that you add at least five primary research articles (in same format as the sample reference below) that corresponds to the info that you added to this page. [Sample reference] Faller, A., and Schleifer, K. "Modified Oxidase and Benzidine Tests for Separation of Staphylococci from Micrococci". Journal of Clinical Microbiology. 1981. Volume 13. p. 1031-1035.
