Carbapenem resistance in Klebsiella pneumoniae clinical isolates from urinary tract infections

UNLABELLED: Resistance to carbapenems by KPC (Klebsiella pneumoniae carbapenemase) production in Klebsiella pneumoniae clinical isolates was first described ten years ago in the U.S.A. and recently reported in other countries. This enzyme inactivates all beta-lactam antibiotics and is associated with fluoroquinolone and aminoglycoside resistance. MATERIAL AND METHODS: We investigated the carbapenem resistance in 498 Escherichia coli and Klebsiella pneumoniae strains isolated from urinary tract infections during 2009 in the lasi "Dr. C. I. Parhon" Clinical Hospital. Antimicrobial susceptibility testing was performed according to CLSI guidelines. To detect ESBL (extended spectrum beta-lactamase) and KPC production we used phenotypic tests and molecular biology methods (PCR). RESULTS: From all tested strains, only two K. pneumoniae strains showed modified susceptibility to carbapenems. The modified Hodge test was positive for the strain resistant to ertapenem, meropenem, imipenem (KA) and negative for the strain resistant only to ertapenem (K(B)). Both KA and K(B) isolates were negative for blaKPC and blaTEM genes, but harbored blaSHV and bla(CTX-M) genes, respectively. CONCLUSIONS: We report the first carbapenem resistant K. pneumoniae strains from Northeast Romania. The resistance is not mediated by KPC-carbapenemase; the possibility of dual mechanisms through cefalosporinases production and porins loss is suggested.