Experimental Prediction of the Evolution of Ceftazidime Resistance in the CTX-M-2 Extended-Spectrum Beta-Lactamase

Abstract

We applied in vitro evolution to an Escherichia coli strain containing bla(CTX-M-2) and obtained 10 independent mutant bla(CTX-M-2) alleles that confer elevated resistance to ceftazidime (MIC > or = 32 microg/ml) but lost the ability to confer resistance to cefepime. All alleles had a Pro-to-Ser substitution at position 167.