Relationship between antibiotic use and incidence of MexXY-OprM overproducers among clinical isolates of Pseudomonas aeruginosa.

In a university hospital, time-series analysis revealed a significant relationship between antibiotic (aminoglycoside, fluoroquinolone, and cefepime) use and incidence of MexXY-OprM-overproducing Pseudomonas aeruginosa. In vitro experiments confirm that such mutants were readily selected from both PAO1 and clinical strains when grown in the presence of these antibiotics.