Characteristics of meropenem heteroresistance in Klebsiella pneumoniae carbapenemase (KPC)-producing clinical isolates of K. pneumoniae.
Meropenem heteroresistance was investigated in six apparently meropenem-susceptible, Klebsiella pneumoniae carbapenemase (KPC)-producing K. pneumoniae (KPC-KP) clinical isolates, compared with that in carbapenemase-negative, meropenem-susceptible controls. In population analyses, the KPC-KP isolates grew at meropenem concentrations of 64 to 256 microg/ml. Heteroresistant colonies had significantly elevated expression of the bla(KPC) gene compared with the native populations but did not retain heteroresistance when subcultured in drug-free media. Time-kill assays indicated that meropenem alone was not bactericidal against KPC-KP but efficiently killed the control strains.
Pournaras
Spyros
S
Department of Microbiology, Medical School, University of Thessaly, Larissa, Greece. pournaras@med.uth.gr
Kristo
Ioulia
I
Vrioni
Georgia
G
Ikonomidis
Alexandros
A
Poulou
Aggeliki
A
Petropoulou
Dimitra
D
Tsakris
Athanassios
A
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics*; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D006801:Humans; D007710:Klebsiella Infections / Q000382:microbiology; D007711:Klebsiella pneumoniae / Q000187:drug effects* / Q000235:genetics; D000077731:Meropenem; D008826:Microbial Sensitivity Tests; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013845:Thienamycins / Q000494:pharmacology*; D001618:beta-Lactamases / Q000235:genetics*
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D013845:Thienamycins; D001618:beta-Lactamases; D000077731:Meropenem