الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Enterobacteriaceae are inhabitants of the intestinal flora and are among the most common cause of community and hospital acquired infections. They have the ability to spread easily between humans and to acquire genetic material through horizontal gene transfer, mediated mostly by plasmids and transposons. Carbapenems are crucial for the management of life-threatening healthcare-associated infections. Recently, alarm has been raised over the spread of CRE mostly due to production of carbapenemases. These strains are resistant not only to carbapenems but also to almost all β-lactam as well as many other non–β-lactam antibiotics giving rise to multidrug- and pandrug-resistant isolates. Rapid detection of these mechanisms of resistance is crucial for appropriate antimicrobial therapy and infection control measures.
MBL, one type of carbapenemases, are broad-spectrum and hydrolyze all beta lactams except monobactams and they are not susceptible to therapeutic β-lactam inhibitors such as clavulanate, sulbactam and tazobactam. MBLs require zinc-ions to catalyze the hydrolysis of beta-lactam antibiotics so MBL catalysis is inhibited in presence of EDTA.
Accurate and rapid detection of MBL producing organisms is crucial to establish appropriate antimicrobial therapy and to prevent their inter-hospital and intra-hospital dissemination. Microbiology laboratories must be prepared to screen for MBL-producing isolates by a low cost, convenient and sensitive procedure.
The aim of the present study was to estimate the prevalence of MBL among CRE isolated from AMUH, to evaluate the performance of different phenotypic methods for the detection of MBL, and to establish a rapid, sensitive and cost effective phenotypic test for MBL
A total of 706 EB isolates recovered from specimens delivered to the Routine Microbiology Laboratory at AMUH over 6 months’ period starting from January 2015 till the end of July 2015 were tested for carbapenem resistance. The isolates were subjected to initial screening for carbapenem resistance by Ertapenem (ETP) 10 µg, Meropenem (MEM) 10 µg and Imipenem (IPM) 10 µg discs using disc diffusion method. Two hundred and forty isolates were resistant to one or more of the carbapenem discs. Of which 80 CRE isolates constituting the sample size of the study were subjected to IPM MIC testing by broth micro dilution according to CLSI guidelines, to carbapenemase production confirmatory tests (Modified Hodge test, RAPIDEC®CarbaNP test; only for ten isolates) and were tested for MBL production by Etest® MBL MP/MPI, EDTA double disc synergy test, and EDTA combined disc test. Also the 80 isolates were tested for MBL production by PCR to detect MBL genes (IMP, VIM, and NDM). Antibiotic sensitivity testing as well as ESBLwas performed to isolates possessing MBL gene using disc diffusion method according to CLSI recommendations.