Wednesday, September 18, 2013

Antibiotic Resistance: CDC Threat Report

Pseudomonas bacteria
A big story on the news right now is the recent report by the US Centers for Disease Control (CDC) that calculated the number of deaths each year caused by antibiotic-resistant bacteria. They estimate that at least 23,000 people die each year Americans die each year directly as a consequence of infection with antibiotic resistant bacteria. They warn that the potential rise of more and more antibiotic-resistant "super bugs" could result in a potential public health emergency.

You can read more about the CDC report at the New York Times or Washington Post, or you can access the full CDC report here (but be warned, it's pretty long), but I wanted to write just a little bit about antibiotic resistance and these so-called "super bugs." You may have heard of such bacteria as methicillin-resistant Staphylococcus aureus (MRSA), multi-drug resistant Pseudomonas, vancomycin-resistant Staphylococcus aureus (VRSA), or vancomycin-resistant Enterococcus (VRE).  These resistant bacteria are becoming more common in human infections, and doctors epidemiologists are worried that as bacteria develop more and more resistance to commonly used antibiotics, we may run out of effective drugs to treat bacterial infections. 

Methicillin-resistant Staphylococcus aureus (MRSA)
Most antibiotics kill bacteria. Some antibiotics kill types of fungus that also cause disease, but often these are referred to as a separate class of drugs (antifungals instead of antibiotics). Most importantly, though antibiotics don't help against viral infections like colds or the flu.  

The development of antibiotic resistance is a story all about evolution and "selective pressure." When we use antibiotics, we put these bacteria-killing or fungus-killing chemicals out into the environment (usually in or on our bodies, but sometimes also onto plants or pets).  This creates "selective pressure" that gives an advantage to any bacteria that are resistant to these antibiotics.  These bacteria can still grow and thrive while the antibiotic-sensitive bacteria die off.   

Bacteria can develop resistance to certain antibiotics through random genetic mutations or by mating with other bacteria that have the genes that confer resitance. In the absence of antibiotics, these antibiotic-resistant bacteria are seemingly no different from any other bacteria, with which they have to compete for resources. However, when antibiotics wipe out a lot of the population of antibiotic-sensitive bacteria, suddenly the resistant bacteria have no competition. The resistant bacteria can still multiply. They outcompete the antibiotic-sensitive bacteria and start to make up a much larger percentage of the bacterial population. The next time antibiotics are used, they then are able to kill a much smaller percentage of the bacteria population. Repeated and improper use of antibiotics is the main driving force for the increasing numbers of antibiotic-resistant bacteria. Not only is it bad to use antibiotics when they are unnecessary, but it is also bad to use antibiotics longer than their prescribed duration.

Enterococcus bacteria
What can you do about the problem? It is simple: reduce unnecessary antibiotic use. Only use antibiotics when your doctor tells you to and only use them for the prescribed duration. We also need to limit the unnecessary uses of antibiotics in food animals and pets. Antibiotics, when necessary, are great drugs and are really critical to public health, but people need to realize that using antibiotics when they aren't necessary can actually do longterm harm.

Antibiotic-resistant bacteria aren't going to just go away. Combating them will require research and development of new antibiotic types, which is yet another reason why we need to keep funding NIH research. One of the reasons that antibiotic resistance is so scary is that the development of antibiotic-resistant strains of bacteria appears to be increasing far faster than our development of new drugs to overcome this resistance.  A recent report from the World Economic Forum wrote about the immense challenge that we face in antibiotic resistance:

...arguably the greatest risk … to human health comes in the form of antibiotic-resistant bacteria. We live in a bacterial world where we will never be able to stay ahead of the mutation curve. A test of our resilience is how far behind the curve we allow ourselves to fall.

As a society, we need to invest in our future by funding reserach into the development of new antibiotics and into better understanding how bacteria evolve antibiotic resistance. However, reducing unnecessary antibiotic use is also important to help reduce the selective pressure for the development of these bacteria and thus slow their spread. To help people better understand antibiotic resistance and what that means to them, I wanted put out some links to a few things that you might not get from mainstream news websites. First, I want to point you toward some useful information put out by the CDC on what everybody can do to minimize the use of antibiotics. The first is the CDC "Get Smart" pages on knowing when antibiotics work, antibiotic resistance FAQs, and antibiotic resistance fast facts. There's also another really good pages about antibiotic resistance from the US National Institutes of Health and the World Health Organization.

Sources and Further Reading (All Freely Available)
  • Bacteria images are pseudocolored scanning electron micrographs (SEM) from the CDC Public Health Image Library of Pseudomonas (image #10043), methicillin-resistant Staphylococcus aureus (MRSA; image #9994 and #10048), Enterococcus bacteria (image #209)
  • F. Baquero, A. P. Tedim, and T.M. Coque. "Antibiotic resistance shaping multi-level population biology of bacteria." Frontiers in Microbiology. 2013. 4:15. Available here.
  • J. Davies and D. Davies. "Origins and Evolution of Antibiotic Resitance." Microbiol Mol Biol Rev. 2010. 74:417-433. Available here.
  • M. J. Fonseca, C. L. Santos, P. Costa, L. Lencastre, and F. Tavares. "Increasing awareness about antibiotic use and reistance: A Hands-On Project for High School Students." PLoS One. 2012. 7:e44699. Available here.
  • I. M. Gould and A. M. Bal. "New Antibiotic Agents in the Pipeline and How They Can Help Overcome Microbial Resistance." Virulence. 2013. 4:185-191. Available here.
  • S. Hojgard. "Antibiotic Resistance -- Why is the problem so difficult to solve?" Infect. Ecol. Epidemiol. 2012. 2:10.3402. Available here.
  • T. F. Landers, B. Cohen, T. E. Wittum, E. L. Larson. "A Review of Antibiotic Use in Food Animals: Perspective, Policy, and Potential." Public Health Reports. 2012. 127:4-22. Available here.
  • B. M. Marshall and S. B. Levy. "Food Animals and Antimicrobials: Impacts on Human Health." Clinical Microbiological Reviews. 2011. 24:718-733. Available here.
  • B. Spellberg, J.G. Bartlett, and D.N. Gilbert. "The future of antibiotics and resistance." New England Journal of Medicine. 2013. 368:299-302. Available here.
  • World Economic Forum. Global Risks: An Initiative of the Risk Response Network. 8th Edition. 2013. Ed, L. Howell. Available here.
  • F. Walsh. "The multiple roles of antibiotics and antibiotics resistance in nature." Frontiers in Microbiology. 2013. 4:255. Available here.
  • G. D. Wright. "Q&A: Antibiotic Resistance: What More Do We Know and What More Can We Do?" BMC Biology. 2013. 11:51. Available here.

1 comment:

  1. According to the Antibiotic analysis, we can know that the antibiotic resistance is really dangerous for human beings' health. This is because many companies want to benefit a lot through, so they conduct bad-quality products.