Objectives: Both transposition and increases in gene expression have been implicated in the success of KPCproducing pathogens, but the stimulus required for these phenomena are unknown. It is possible that exposure to antimicrobials during patient treatment increases blaKPC expression or induces Tn4401 transposition. The purpose of this study was to determine if exposure to carbapenems or other antimicrobial drug classes could stimulate expression of blaKPC or the in vitro transposition of Tn4401. Methods: Five KPC-producing clinical isolates were evaluated in this study. Gene expression of RNA from each isolate exposed to subinhibitory, MIC or suprainhibitory levels of antibiotics was evaluated using real-time RT-PCR. Southern blots were performed on plasmids fromisolates exposed to subinhibitory levels of antibiotics. Results: Therewere subtle changes in blaKPC RNA expression following antibiotic exposure that were both strain and drug dependent. Multiple plasmids ranging from~8 to.200 kbwere observed for the Enterobacteriaceae isolates, whereas the Pseudomonas aeruginosa isolate had one ~55 kb plasmid. No changes in hybridization patterns or binding intensity for the blaKPC probe were observed after antibiotic exposure. Conclusions: While the changes in blaKPC RNA expression are subtle, the different responses observed suggest both strain- and genera-specific variations in response to different antibiotic treatments.
All Science Journal Classification (ASJC) codes
- Microbiology (medical)
- Infectious Diseases
- Pharmacology (medical)