What causes the development of antibiotic-resistant strains of bacteria?

Question

I understand bacteria have become resistant to antibiotics due to selection pressures, but how do resistant bacteria process antibiotics when exposed to it, compared to non-resistant bacteria. Also, what research is being conducted to combat bacteria resistant to antibiotics?

Answer 1

There are many mechanisms by which bacteria can inhibit or degrade antibiotics, thus rendering them ineffective. Here are a few items you could look further into:

1. Bacteria can produce enzymes that directly target and cleave the antibiotic
2. Bacteria can produce low-affinity homologues of the antibiotic target, i.e. the antibiotic will not be able to act on the target as effectively
3. Bacteria can encode for efflux pumps that pump the antibiotics out.

Many of these determinants of antimicrobial resistant are carried on "mobile genomic elements" (MGE's). These MGE's are "mobile" meaning that the genes can come and go, and can be horizontally transferred between bacteria. Antibiotic use may create a selection pressure that gives rise to antimicrobial resistant pathogens, mediated through the horizontal transfer of MGE encoded antimicrobial resistance genes. Thus, bacterial populations, under the pressure of antibiotics, can rapidly develop antimicrobial resistant properties.

Methods to combat AMR is a major focus of research right now. There are a lot of smart people approaching the issue from many different angles. Here are a few items that I would recommend you look further into:

1. vaccines
2. bacteriophage therapy
3. new antibiotics (although many major pharmaceutical companies are currently backing out of antibiotic development)
4. hospital infection control programs
5. policy interventions, i.e. judicious use of critically important antibiotics in humans and livestock