Bacteria: Good or Bad
Bacteria: Good or Bad
Public perception of bacteria over the last twenty years has been fairly negative. Bacteria are often perceived as disease causing pathogens that menace human society and their surroundings. Bacteria have caused diseases that mankind has been able to treat and control in the developed world, such as dysentery (Shigella), Typhoid (Salmonella typhi) and Cholera (Vibrio cholerae) (Postgate, 2000) (Engleberg et al, 2007). However in undeveloped nations the rate of disease has been more virulent. This is due to insufficient healthcare and hygiene, leading to higher mortality rates. During the 16th century the bacteria Yersinia pestis caused disease and death rates of between a third and a half of the European population (Keeling and Gilligan, 2000), the disease was known as The Plague or the Black Death. Bacteria also can cause food borne diseases, for example pathogenic strains of Escherichia coli (E.coli), particularly O157:H7. This bacterium flourishes in food preparation areas with poor hygiene standards. E.coli strains have had a high profile in the media for causing food poisoning; however it is rarely stated that certain strains of E.coli are part of our natural flora in the gut, and are important to our digestive system. The presence of E.coli in our gut is also thought to play a key role in keeping less desirable bacteria from colonising (Postgate, 2000). E.coli is not only present in humans but also in mammals. The bacterium is disposed of through faecal matter and its presence in rivers, soils and foods are used as an indicator of faecal contamination. This can be used as a test in public health laboratories. There are other ways of contracting of E.coli. When farm animals are slaughtered, E.coli can easily transmit from the intestines onto the surfaces of the meat, where it can spread from surface to surface and multiply. This has been a major problem in the last twenty years, especially with the strain O157:H7 (Postgate, 2000).
Society also now has problems with strains of bacteria that have become resistant to antibiotics; such cases have been Staphylococcus aureus, which has become widely resistant to a number of antibiotics, the resistant forms are generally named Multi-resistant Staphylococcus aureus (MRSA), however initially they were named Methicillin-resistant after becoming resistant to the antibiotic Methicillin (Engleberg et al, 2007). More recently Clostridium difficile, another natural flora of the gut, have caused disease outbreaks of diarrhoea and in more severe cases inflammation of the bowl (HPA, 2008). There has been a steady increase of bacterial disease in hospital patients. These bacterial diseases are believed to have been caused by the use of broad spectrum antibiotics (BSAC, 2008). Overuse of these antibiotics disturbs the natural flora in the gut, allowing Clostridium difficile to multiply quickly and produce toxins (HPA, 2008). Tuberculosis has also been highlighted by the World Health Organisation as a growing concern. Results from a survey between 2002 and 2006, on Tuberculosis drug resistance, in 81 countries showed higher numbers of multi resistant forms of the bacteria. Consequently the treatment has been extended from six months to two years with more expensive and toxic drugs (BBC News, 2008).
Although the bacteria discussed have negative impacts on society, there are many strains of bacteria that are crucial to mankind and the surrounding environment. An example of a bacterium’s capabilities in aiding mankind has been the cleaning up of pollutants, through a process known as bioremediation. An example of this was after the disaster of the Exxon Valdez oil spill that affected an Alaskan beach. Bacteria from the genus Pseudomonas was used to digest the carbon from the oil and effectively clean up the area effected (Tortora et al, 2007). Bacteria also play a role in the cycling of nutrients throughout the environment. A wide range of aerobic and anaerobic bacteria in the soil, such as Azotobacter and Clostridium species (Freeland, 1991), fix nitrogen from the environment and convert it into a form that can be utilised by both animals and plants. This is also true in the carbon cycle where bacteria decompose organic matter returning carbon dioxide back to the atmosphere. Other essential elements such as oxygen, sulphur and phosphorus are also returned to the environment by bacteria (Tortora et al, 2007). Bacteria play an important role in the food industry, for example the production of yoghurt uses two bacteria Lactobacillus bulgaricus and Lactococcus thermophilus to modify milk proteins and pH to make thick yoghurt (Freeland, 1991). Probiotics, which contain beneficial bacteria, can also be used in yoghurts and are referred to as being ’Live’. In ‘live’ yoghurt the bacteria, Lactobacillus bulgaricus are replaced with bacteria from the genus Bifidobacterium. Bifidobacterium are a natural flora of the intestines (Postgate, 2000). This aids the human digestive system and enhances immunity, by replacing the ‘bad’ bacteria such as E.coli and Candida albicans with a top up of ‘good’ bacteria (Microbewiki, 2008).
Bacteria and society have very much, a ‘love/hate’ relationship, and society tend to focus on the negatives bacteria bring. It has only been recently that bacteria have had their benefits highlighted. Education is needed to persuade the public that bacteria play an important role in our lifestyle from the food we eat, to break down of waste and pollutants and replenishment of the environments nutrients. Although bacteria can be a causative agent in disease, the overuse of drugs and cleaning products than can ‘kill up to 99% of bacteria’ could have a detrimental effect on the natural balance of flora. This has already been seen in the cases of Clostridium difficile. What if the natural flora of nutrient cycling bacteria was to be disturbed? Would the equilibrium of the planets essential cycles be affected? The symbiotic relationship many bacteria have with the planet and its occupants could be altered permanently. This is a negative view of what could happen and it is very difficult for society not to take a consequentialist view of controlling disease causing bacteria. Educating people on the benefits of bacteria, and not to focus wholly on their negative features can only be beneficial for the future.
References.
Foulkes, I., 2008. Drug resistant TB 'at new high'. BBC News, Geneva. Available from: http://news.bbc.co.uk/2/hi/health/7265464.stm [Accessed on 5/5/08]
BSAC, 2008. Clostridium difficile: British Society for Antimicrobial Chemotherapy. Available from: http://www.bsac.org.uk/pyxis/Gastrointestinal%20infections/Clostridium%20difficile%20colitis/Clostridium%20difficile%20colitis.htm [Accessed on 5/5/08]
Englerberg, N. C. DiRita, V., Dermondy, T. S., 2007. Mechanisms of Microbial Disease. 4th Edition. Lippincott Williams & Wilkins: London.
Freeland, P., 1991. Micro-organisms in Action. Hodder & Stoughton: Great Britain
HPA, 2008. Clostridium difficile: Health Protection Agency. Available from: http://www.hpa.org.uk/webw/HPAweb&Page&HPAwebAutoListName/Page/1179744911867 [Accessed on 5/5/08]
Keeling, M. J., Gilligan, C. A., 2000. Bubonic Plague: a metapopulation model of a zoonosis. The Royal Society – depts. of Zoology and Plant Sciences. University of Cambridge. Vol 267, pg 2219-2230.
Microbewiki, 2008. Bifidobacterium. Available from: http://microbewiki.kenyon.edu/index.php/Bifidobacterium [Accessed on 6/5/08]
Prescott, J., 2000. Microbes and Man. 4th Edition. Cambridge University Press: Cambridge.
Tortora, G. J., Funke, B. R., Case, C. L., 2007. Microbiology: an Introduction. Pearson Benjamin Cummings: London.
WHO, 2002 – 2007. Anti – Tuberculosis Drug Resistance in the World. The WHO/IUATLD Global Project. Report No.4. Available from: http://www.who.int/tb/publications/2008/drs_report4_26feb08.pdf [Accessed on 5/5/08]
