Meropenem stability to beta-lactamase hydrolysis and comparative in vitro activity against several beta-lactamase-producing Gram-negative strains

The interaction between meropenem and class A, B, C and D β-lactamases was studied by a spectrophotometric method. Class A, C and D β-lactamases were unable to confer in vitro resistance to carbapenems. Surprisingly, several class B metallo-β-lactamases expressed in Escherichia coli failed to confer resistance when a conventional inoculum (105 cfu/mL) was used.