Effect of drug treatment options on the mobility and expression of bla sub(KPC)

• Published in: Journal of antimicrobial chemotherapy Vol. 68; no. 12; pp. 2779 - 2785
• Main Authors: Roth, Amanda L, Lister, Philip D, Hanson, Nancy D
• Format: Journal Article
• Language: English
• Published: 01.12.2013
• Subjects: Enterobacteriaceae
• ISSN: 0305-7453; 1460-2091
• DOI: 10.1093/jac/dkt280

Objectives Both transposition and increases in gene expression have been implicated in the success of KPC-producing pathogens, but the stimulus required for these phenomena are unknown. It is possible that exposure to antimicrobials during patient treatment increases bla sub(KPC) 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 bla sub(KPC) 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 from isolates exposed to subinhibitory levels of antibiotics. Results There were subtle changes in bla sub(KPC) RNA expression following antibiotic exposure that were both strain and drug dependent. Multiple plasmids ranging from similar to 8 to >200 kb were observed for the Enterobacteriaceae isolates, whereas the Pseudomonas aeruginosa isolate had one similar to 55 kb plasmid. No changes in hybridization patterns or binding intensity for the bla sub(KPC) probe were observed after antibiotic exposure. Conclusions While the changes in bla sub(KPC) RNA expression are subtle, the different responses observed suggest both strain- and genera-specific variations in response to different antibiotic treatments.