Nationwide Survey of Klebsiella Pneumoniae Strains Producing CTX-M Extended-spectrum β-lactamases in Croatia.

Extended-spectrum β-lactamases (ESBL) producing bacteria have been increasingly reported in both hospital and community patients. Production of ESBLs is the major mechanism of resistance to oxymino-cephalosporins and aztreonam in Gram-negative bacteria. Recently a new family of ESBLs with predominant activity against cefotaxime (CTX-M β-lactamases) has been reported. Over 80 CTX-M enzymes have been described so far, which can be grouped into five main subgroups according to amino acid sequence identity (CTX-M-1, CTX-M-2, CTX-M-8, CTX-M-9 and CTX-M-25). In some countries, CTX-M β-lactamases are the most prevalent types of ESBLs, for instance in Russia, Greece, Spain, Switzerland, Japan, Taiwan, China and Argentina. These enzymes have been identified in countries near Croatia such is Italy, Hungary and Austria. The aim of this study was to determine the prevalence and the types of CTX-M β lactamases produced by Klebsiella pneumoniae clinical isolates collected from October 2006 to January 2007 from both community- and hospital-based isolates were included (Figure 1.). 128 ESBL isolates were subjected to further analysis: screening with double disc diffusion test and confirmed by ESBL E test.