Question: Recently I have seen a lot of stories in the news about antibiotic resistance and the risks it poses. This seems like a serious health problem and it is something I would like to do some research on. I have some background knowledge of beta lactam antibiotics from previous biology classes so I would like to know more about how and why bacteria become resistant to these drugs.
Beta lactams antibiotics are a class of antibiotic which act by interfering with the synthesis of the bacterial cell wall. The beta lactam ring (Figure 1), after which the drug is named, irreversibly binds to penicillin binding proteins in the bacterial cell membrane. These proteins are responsible for the growth of the bacterial cell wall and are unable to function once bound to a beta lactam ring.
Bacteria use three methods to develop resistance to these drugs: production of beta lactam hydrolyzing enzymes (known as beta lactamases), development of enzymes which are insensitive to beta lactams to build their cell walls, and using efflux pumps to clear the cell of beta lactams. The use of beta lactamase to break down the drug before it can act is the most widespread mechanism of resistance. This may be partly due to the fact that the genes for this enzyme are found in plasmids and transposons and may be spread to new populations quickly through horizontal gene transfer.
Antibiotics have applications in various fields from medicine to agriculture to food preservation. This, coupled with their low cost and effectiveness, has resulted in their rampant overuse in many of these fields. This overuse, in both healthcare and non-healthcare settings, has resulted in antibiotic resistance becoming very common in bacterial populations. Awareness of this fact has increased in recent times and efforts have been made to reduce the prevalence of these drugs. These include reducing the number of prescriptions for antibiotics and reducing the amount of antibiotics used in food. Hopefully this will prevent or slow the rate of resistance to new antibiotics.
Figure 1. Beta lactam antibiotics with characteristic beta lactam ring in red (Wikipedia).
- Debanjan D.
1) Beta Lactam Antibiotics. East Lansing (MI): Michigan State University; 2011 [6/28/2016].
2) Poole K. “Resistance to β-lactam antibiotics” Cellular and Molecular Life Sciences CMLS. 2004; 10.1007/s00018-004-4060-9