Dedeic-Ljubovic A, Hukic M, Pfeifer Y, Witte W, Padilla E, López-Ramis I, Albertí S (2010): Emergence of CTX-M-15 extended-spectrum beta-lactamase-producing Klebsiella pneumoniae isolates in Bosnia and Herzegovina
Clin. Microbiol. Infect. 16 (2): 152-156. Epub 2009 Aug 17.

Fifty seven nosocomial Klebsiella pneumoniae isolates producing extended-spectrum β-lactamases (ESBLs) were collected between February 2007 and November 2007 in different wards of the Sarajevo (Bosnia-Herzegovina) reference hospital. These isolates comprise 2 major epidemic pulsed-field electrophoresis defined clones plus two minor clones. In addition to the ESBL-mediated resistance, all strains uniformly showed resistance to ciprofloxacin, gentamicin, and tobramycin. The β-lactamases involved were TEM-1, SHV-1, and CTX-M-15 as demonstrated by isoelectric focusing, PCR amplification, and sequencing. TEM-1 and CTX-M-15 β-lactamases as well as the aminoglycoside resistance determinants were encoded in plasmids that could be transferred to Escherichia coli by conjugation. In three of the infected patients with the predominant clone, cefoxitin resistance development (MICs >128 μg/ml) was documented. The analysis of the outer membrane proteins of the cefoxitin-susceptible and -resistant isolates revealed that the former expressed only one of the two major porins, OmpK36, whereas in the latter, the expression of Ompk36 was altered or abolished. This is the first report of CTX-M-15-producing K. pneumoniae in Bosnia-Herzegovina. Furthermore, we document and characterize for the first time cefoxitin resistance development in CTX-M-15-producing K. pneumoniae.