Antibiotic Resistance: Mechanisms and Outlook
The current issue of antibiotic resistance is being referred to as a ‘perfect storm’, as research on the subject has declined while the amount and severity of multidrug resistance have increased. Antibiotics are an integral part of modern medicine and have safeguarded humans from bacterial diseases for decades. However, due to rapid reproduction rates and flexibility in receiving genetic material, bacteria have quickly evolved resistance to many of the available antibiotics. In the past decade, efforts have been made to slow the development of resistant strains of bacteria.
The creation of drug-resistant bacterial strains is sometimes quite simple. In order to illustrate the process, let’s look at a scenario. Within a colony of bacteria, only a few cells actually possess the gene or trait for resistance. If a person develops a bacterial infection, it is usually treated by antibiotics. When the bacterial infection is treated by antibiotics, the cells that possess resistance to the antibiotic will not be eliminated. Then, those bacteria reproduce rapidly and pass the resistant trait to their offspring. However, this, referred to as vertical gene transfer, is only one process by which resistance can be conferred.
The issue gets a bit more complicated when horizontal gene transfer mechanisms like bacterial conjugation, transformation, and transduction make it possible for bacteria to receive genes from many different sources. Bacterial conjugation facilitates the transfer of genetic material between two bacteria through direct contact. The bacteria are linked and the donor bacterium passes genetic material in the form of a plasmid, DNA that isn’t part of the organism’s chromosome(s). Bacterial transformation occurs when bacteria can incorporate genetic material from the environment or from outside sources into its own genetic code. Transduction adds a whole new group of organisms into the problem – viruses. When bacteriophages (viruses that replicate in bacteria) go from one bacterium to another, occasionally antibiotic resistance genes get taken along for the ride.
The number of bacteria in the world and the variety of mechanisms they use to grab new genetic material make it easy for antibiotic resistance to become a big issue for us. After a bacterial infection evolves resistance, the treatment options for the disease become very limited and expensive. In the case of resistant bacteria, doctors will administer stronger antibiotics, which are known as second or third generation, or a mix of antibiotics. However, in the case of multidrug-resistant bacteria, treatment is often ineffective, especially when the bacteria have evolved resistance to the strongest available antibiotics.
While research continues into developing better, stronger antibiotics, consumers can take several measures to help stop the effects of antibiotic resistance. When prescribed antibiotics, taking the full course of medicine enables the drug to function at its highest potential and will help eliminate the possibility of bacteria surviving the antibiotic.
References and further reading:
Costerton, J.W., Stewart, P.S., & Greenberg, E.P. (1999). Bacterial biofilms: a common cause of persistent infections.Science, 284(5418): 1318-1322.
Fard, R.M.N., Barton, M.D., & Heuzenroeder, M.W. (2011). Bacteriophage-mediated transduction of antibiotic resistance in enterococci. Letters in Applied Microbiology, 52(6): 559-564.
Levy, S.B. (2002). Factors impacting on the problem of antibiotic resistance. Journal of Antimicrobial Chemotherapy, 49(1): 25-30.
Severini, C., & Menegon, M. (2015). Resistance to antimalarial drugs: an endless world war against Plasmodiumthat we risk losing. Journal of Global Antimicrobial Resistance, 3(2): 58-63.
Spellberg, B., Guidos, R., Gilbert, D., Bradley, J., Boucher, H.W., Scheld, W.M., Bartlett, J.G., & Edwards, J. (2008). The epidemic of antibiotic-resistant infections: a call to action for the medical community from the Infectious Diseases Society of America. Clinical Infectious Diseases, 46(2): 155-164.
Wilkins, A.S. (1996). Antibiotic resistance: origins, evolution and spread. BioEssays, 18(10): 847-848.
Edited by James H., Editor
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