KPC-Producing Klebsiella pneumoniae Isolates in Croatia: A Nationwide Survey

Background: In the last few years, Klebsiella pneumoniae strains producing K. pneumoniae carbapenemase (KPC) enzymes have emerged as important multidrug-resistant pathogens in hospitalized patients. This report describes KPC-producing isolates collected through the Croatian antimicrobial resistance surveillance program in the early stage of their dissemination in Croatia. Materials and Methods: Forty-eight KPC-producing K. pneumoniae isolates, collected during a period from February 2011 to August 2013, were analyzed in this study. Antimicrobial susceptibility profiles were determined using disk diffusion and E-test. Pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) were used for epidemiological analysis. Identification of -lactamase genes and associated antibiotic resistance mechanisms was performed by polymerase chain reaction and positive products were sequenced. Localization of bla(KPC) was investigated by S1 PFGE and Southern hybridization. Results: Of 40 participating centers in Croatia, KPC isolates were recorded in 9 of them. They all had multidrug-resistant phenotype, but showed varying levels of resistance to carbapenems. All isolates displayed ST258, and PFGE showed that all but one were closely related. All isolates harbored bla(KPC-2). Isolate with a unique PFGE pattern produced TEM-1, while others produced TEM-116. All isolates harbored bla(SHV-11), but were negative for bla(CTX-M) and bla(AmpC) genes. All isolates contain one KPC-harboring plasmid, ranging in size from approximate to 60 to approximate to 210kb, characterized as FIIs and IncR. Conclusion: This report describes that the early stage of KPC-producing K. pneumoniae dissemination in Croatia is associated with a prolific PFGE type belonging to ST258. So far, the spread of an outbreak strain is limited to the northwest region of the country.