Cloning and sequence analysis of a class A β-lactamase from Mycobacterium tuberculosis H37Ra

Abstract

A cosmid library from Mycobacterium tuberculosis H37Ra was introduced into Mycobacterium smegmatis, and eight recombinant clones with increased resistance to cefoxitin were identified. Isoelectric focusing detected an M. tuberculosis-derived β-lactamase in one of these recombinant clones. A sequence analysis identified it as a class A β-lactamase whose expression correlated with the increased resistance phenotype.