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BioMed Research International
Volume 2014, Article ID 171548, 8 pages
http://dx.doi.org/10.1155/2014/171548
Research Article

Phenotypic and Molecular Characterization of Plasmid Mediated AmpC β-Lactamases among Escherichia coli, Klebsiella spp., and Proteus mirabilis Isolated from Urinary Tract Infections in Egyptian Hospitals

1Department of Microbiology & Immunology, Faculty of Medicine, Zagazig University, Zagazig, Sharqia,, Egypt
2Department of Microbiology and Immunology, Faculty of Pharmacy, October University for Modern Sciences and Arts (MSA), 26 July Road Intersection with El Wahat Road, 6th of October, Giza, Egypt

Received 14 February 2014; Revised 16 May 2014; Accepted 18 May 2014; Published 9 June 2014

Academic Editor: Frederick D. Quinn

Copyright © 2014 Mai M. Helmy and Reham Wasfi. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The incidence of resistance by Enterobacteriaceae to β-lactam/β-lactamase inhibitors combination is increasing in Egypt. Three phenotypic techniques, comprising AmpC disk diffusion and inhibition dependent methods using phenylboronic acid (PBA) and cloxacillin, were compared to PCR based method for detection of plasmid mediated AmpC β-lactamase in common urinary tract isolates. A total of 143 isolates, including E. coli, Klebsiella pneumonia, and Proteus mirabilis, were collected from urinary tract infections cases in Egyptian hospitals. Plasmid encoded AmpC genes were detected by PCR in 88.46% of cefoxitin resistant isolates. The most prevalent AmpC gene family was CIT including CMY-2, CMY-4, and two CMY-2 variants. The second prevalent gene was DHA-1 which was detected in E. coli and Klebsiella pneumonia. The genes EBC, FOX, and MOX were also detected but in small percentage. Some isolates were identified as having more than one pAmpC gene. The overall sensitivity and specificity of phenotypic tests for detection of AmpC β-lactamase showed that AmpC disk diffusion and inhibition dependent method by cloxacillin were the most sensitive and the most specific disk tests. PCR remains the gold standard for detection of AmpC β-lactamases. This study represents the first report of CMY-2 variants of CMY-42 and CMY-102 β-lactamase-producing E. coli, Klebsiella pneumonia, and Proteus mirabilis isolates in Egypt.