ABSTRACT
The aim of this study was to investigate the frequency of betalactamase producing EAEC isolates among young children with diarrhea in Zanjan, Iran. Entero aggregative Escherichia coli [EAEC] is an emerging enteric pathogen associated with acute and persistent diarrhea and the evolution and spread of acquired extended spectrum betalactamases [ESBLs] among these strains has become a serious problem in the management of infectious diseases in developing countries. During the period from March 2011 to January 2012, 140 isolates of E. coli from diarrheal children aged 0-60 months and 90 isolates from age-matched controls without diarrhea were investigated for EAEC using PCR. Antimicrobial susceptibility testing was performed as CLSI guidelines and betalactamase genes, including blaTEM, blaCTX-M, blaIMP, blaVIM and blaNDM-1 investigated in EAEC isolates. In this study, EAEC was detected with slightly higher frequency in children with [8%] than in children without [4.6%] diarrhea [P>0.05]. Diarrheagenic E. coli exhibited high level resistance to aztreonam [80.7%], amoxicillin [74.4%] and tetracycline [69.3%]. Also, 86.4% of E. coli isolates were resistant to at least three different classes of antimicrobial agents and considered as multidrug resistance. Molecular characterization of betalactamase genes showed that blaTEM was the most frequently isolated betalactamase. It was detected in 78.9% of ESBL producing EAEC isolates. Also, the frequency of blaCTX-M was 63.1% [12/19] and 8 [42.1%] isolates carried the blaTEM and blaCTX-M, simultaneously. None MBL producing EAEC was detected in our study. Our results indicate that ESBLs especially blaTEM and blaCTX-M are widespread among EAEC isolates and appropriate surveillance and control measures are essential to prevent further dissemination of betalactamases in our country.