Disruption of mpl Activates {beta}-Lactamase Production in Stenotrophomonas maltophilia and Pseudomonas aeruginosa Clinical Isolates. [PublishAheadOfPrint]

The hyperproduction of chromosomally encoded β-lactamases is a key method of acquired resistance to ceftazidime, aztreonam, and when seen in backgrounds having reduced envelope permeability, carbapenems. Here we show that loss of Mpl, a UDP-muramic acid/peptide ligase, is a common and previously overlooked cause of chromosomally encoded β-lactamase hyperproduction in clinical isolates of Stenotrophomonas maltophilia and Pseudomonas aeruginosa, important pathogens notorious for their β-lactam resistant phenotypes.

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