Molecular Detection of Extended-Spectrum Beta- Lactamases inClinical Isolates of Acinetobacterbaumannii

Abstract

Resistance to third-generation oxyimino cephalosporins is emerging, and it is considered a problem in medical field. Extended spectrum ?-lactamase (ESBL) producing Acinetobacter baumannii have been noticed to be important cause of hospital infections. This study aimed to undertaken and determinethe occurrence of ESBLs especially SHV, TEM and VEB ?-lactamase types. A total of 770 clinical samples were collected from February to June, 2011. TheA. baumanniiisolates were identified according to API 20NE system. Phenotypic detection of ESBL was performed by using the combination disk, disk approximation  methods then confirmed by culturing on  ESBL CHROM agar medium.  The isolates were subjected to polymerase chain reaction (PCR) assays with specific primers for bla_SHV, bla_TEM and  bla_VEB. Twelve (1.5%) A. baumanniiisolates were recovered from clinical infections. All of them were ?-lactam resistant (resistant to both ampicillin and amoxicillin). Of the ?-lactam resistant isolates, 8/12 (66.7%)were found to be disk combination test positive, and 10 (83.3%) isolates were confirmed as ESBL producers and gave heavy growth on ESBL CHROM agar. In PCR experiments using specific primers for bla_SHV, bla_TEM and  bla_VEB genes, out of 12 A. baumanniiisolates, three (25%) were harbored bla_SHV gene and only one (8.3%) isolate gave positive PCR results for bla_TEM gene. This study demonstrate all isolates were bla_VEB negative. The present study concluded that the emerging of dissemination of ESBL producing A. baumannii in Najaf hospitals.

Keywords:key words,Acinetobacterbaumannii , Extended-Spectrum Beta- Lactamases, Molecular Detection