Superbugs: The Evolution of Gonorrhea

Contributed by Nyasia Jones, Chris Richardson and Kari Tyler

A common misconception regarding evolution it that it is slow, and because it is slow, humans are not influencing it. This is completely false. Humans have and are continuing to make major changes that are not only influencing the course of our own evolution, but are also influencing the evolution of other species we interact with. Especially in medicine, human advancement is occurring at an amazing pace and thus allowing us to witness evolution in response to our actions.

Over the past century, the use of antibiotics to treat bacterial pathogens has become a widespread practice. Starting around 1930, medical practitioners began discovering several drugs that successfully rid patients of a particular bacterial pathogen Neisseria gonorrhoeae. The first successful therapy was administration of a class of chemicals called sulfonamides. For years, treatment with sulfonamides proved successful in patient after patient until about the mid-1940s when reports of N. gonorrhoeae resistance to sulfonamides increased. Fortunately, at this time, the “miracle drug” penicillin was found to be highly effective at bacterial treatment and become the number one treatment option. After ten to fifteen years though, low doses of penicillin were no longer as effective, and by the 1980s strains with high-level penicillin resistance had emerged.

So what happened with both penicillin and the sulfonamides?  Nothing.

But something did happen to the N. gonorrhoeae. They evolved.

Sequential chromosomal mutations allowed some bacteria to incur resistance to penicillin. With penicillin treatment, the bacteria with resistance survived while those without it did not. The resistant individuals reproduced thereby creating a new generation of bacteria in which all individuals were penicillin resistant. This, my friends, is evolution.

Unlike the billions and billions of years it took to create modern-day humans, this evolution took less than a century to change these N. gonorrhoeae bacteria into “superbugs” which are becoming increasingly harder to treat. And it doesn’t stop there. N. gonorrhoeae has also become resistant to more recent treatment options, such as tetracycline and fluoroquinolones. Now, with less and less success to current methods of treatment, namely cefixime and ceftriaxone, scientists are worried history will repeat itself and strains of N. gonnorhoeae with complete cefixime and ceftriaxone resistance will emerge. With dwindling options for treatment, N. gonorrhoeae resistance and that of other superbugs remains a major problem in the fields of medicine and epidemiology.

So are humans influencing evolution? N. gonorrhoeae tell us, loud and clear: yes!

For more information:

Anderson, M. T., & Seifert, H. S. (2011). Neisseria gonorrhoeae and humans perform an evolutionary LINE dance. Mobile Genetic Elements, 1(1), 85-87.

Mavroidi, A., Tzelepi, E., Siatravani, E., Godoy, D., Miriagou, V., & Spratt, B. G. (2011). Analysis of emergence of Quinolone-resistant gonococci in Greece by combined use of Neisseria gonorrhoeae multiantigen sequence typing and multilocus sequence typing. Journal of Clinical Microbiology, 49(4), 1196-1201.

Unemo, M., & Shafer, W. M. (2011). Antibiotic resistance in Neisseria gonorrhoeae: Origin, evolution, and lessons learned for the future. Annals of the New York Academy of Sciences, 1230(1), E19-E28.

Rise of Antibiotic Resistance

Contributed by Richard Parilla

In 1928 a discovery made by Scottish scientist Alexander Fleming would change modern medicine. Fleming observed that the fungus Penicillium was able to kill disease causing pathogens. This discovery won Fleming a Nobel Prize in 1945 and led to development of antibiotics. The effectiveness of these drugs, once referred to as “miracle drugs”, led them to become used very regularly to treat a variety of illnesses. However, these lifesaving antibiotics have become far less effective due to the increasingly more common bacterial strains that are antibiotic resistant.

Antibiotics function by either directly killing bacteria themselves or by inhibiting their growth and reproduction. So how does bacterial strains resistance to certain antibiotics come about? Well an easy way to think about this is in evolutionary terms. The use of antibiotics selects for bacterial strains that are resistant to the mechanism by which the antibiotic targets the pathogen. Since all the non-resistant bacteria are wiped out by the antibiotic, only the resistant bacteria can reproduce and spread. This is an interesting perspective since it shows that humans can have an impact on the evolution of a species through implementation of novel selective pressures such as antibiotics.

Over the past decade antibiotic resistance has become a very threatening problem to society. It is has been a topic which has continually made headlines over the past few years. Why has the threat of antibiotic resistant microbes risen? The World Health Organization points to the misuse of antibiotics and over prescription as the cause of the accelerated emergence of the resistant bacteria strains. Due to the nature of this problem it would seem that it will be a frequent topic of discussion in the near future.

For Further Further Reading:

“Antimicrobial Resistance.” WHO. N.p., May 2013. Web. 20 Apr. 2014.

Austin, D. J. “The Relationship between the Volume of Antimicrobial Consumption in Human Communities and the Frequency of Resistance.” Proceedings of the National Academy of Sciences 96.3 (1999): 1152-156. Print.

Bonhoeffer, S. “Evaluating Treatment Protocols to Prevent Antibiotic Resistance.” Proceedings of the National Academy of Sciences 94.22 (1997): 12106-2111. Print.
Centers for Disease Control and Prevention. Centers for Disease Control and Prevention, 16 Sept. 2013. Web. 20 Apr. 2014.

“General Background: About Antibiotic Resistance.” Tufts University. N.p., n.d. Web. 20 Apr. 2014.

Hampton, L. M., M. M. Farley, W. Schaffner, A. Thomas, A. Reingold, L. H. Harrison, R. Lynfield, N. M. Bennett, S. Petit, K. Gershman, J. Baumbach, B. Beall, J. Jorgensen, A. Glennen, E. R. Zell, and M. Moore. “Prevention of Antibiotic-Nonsusceptible Streptococcus Pneumoniae With Conjugate Vaccines.”Journal of Infectious Diseases 205.3 (2012): 401-11. Print.

Levy, Stuart B. “The Challenge of Antibiotic Resistance.” Diss. Texas U, 1998. Web.

Lupo, Agnese, Sébastien Coyne, and Thomas Ulrich Berendonk. “Origin and Evolution of Antibiotic Resistance: The Common Mechanisms of Emergence and Spread in Water Bodies.” Frontiers in Microbiology 3 (2012): n. pag. Print.

Stöppler, Melissa C., M.D. “Antibiotics 101 –” MedicineNet. N.p., 3 Sept. 2012. Web. 20 Apr. 2014.

Woodford, Neil, Jane F. Turton, and David M. Livermore. “Multiresistant Gram-negative Bacteria: The Role of High-risk Clones in the Dissemination of Antibiotic Resistance.” FEMS Microbiology Reviews 35.5 (2011): 736-55. Print.