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

Abstract

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 ^1,2. 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) ³ . In some countries, CTX-M β-lactamases are the most prevalent types of ESBLs, for instance in Russia ⁴, Greece ⁵ , Spain ⁶ , Switzerland ⁷, Japan ⁸, Taiwan ⁹,   China ¹⁰ and Argentina ¹¹ .  These enzymes have been identified in countries near Croatia such is Italy ¹², Hungary¹³  and Austria¹⁴

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 ¹⁵ .