PgmNr P328: The antibiotic-independent evolution of antibiotic resistance.

Authors:
R. Hershberg; W. Field; S. Katz


Institutes
Technion, Israel Institute of Technology, Haifa, IL.


Abstract:

It has been demonstrated that when bacterial colonies are starved, the frequency of antibiotic resistance tends to increase, even in the absence of any antibiotic exposure. We were able to demonstrate that, contrary to widespread assumption, such starvation-induced increases in antibiotic resistance frequencies were not due to increases in mutagenesis. Rather, it appears that specific resistance mutations to a variety of antibiotics are beneficial to bacterial growth under starvation. We could further demonstrate that one such resistance allele that we identified as adaptive under starvation is alarmingly frequent within natural bacterial populations. This antibiotic resistance allele is particularly frequent within-host environments, where on average ~40% of bacteria carry the allele, independent of levels of antibiotic exposure. Our results suggest that the antibiotic-independent fitness effects of resistance alleles may strongly affect the frequency with which resistance segregates within natural bacterial populations.