Detection of Extended Spectrum Beta-Lactamases in Gram Negative Bacilli from Clinical Specimens in a Teaching Hospital in South Eastern Nigeria.

Abstract

Antimicrobial drug resistance seen among many gram-negative bacteria, especially those expressing the extended-spectrum β-lactamase (ESBL) enzymes that hydrolyze the expandedspectrum cephalosporins has been on the increase. This has compromised treatment options and thus a threat to the containment of bacterial infections. To determine the existence of the extended-spectrum β-lactamase enzymes in Nnewi, 250 clinical isolates of members of the family Enterobacteriaceae and Pseudomonas species from Nnamdi Azikiwe University Teaching Hospital, Nnewi were identified by conventional methods. These include Klebsiella species (96), E. coli (90),Pseudomonas species (37), Enterobacter species (13), Proteus species (6), Citrobacter species (5) and Salmonella species (3). Antimicrobial drug susceptibility testing was carried out on all the isolates by the disc diffusion method. Extended Spectrum Beta- lactamases were detected by the double disc synergy test. High level of antimicrobial resistance was noted in test organisms against some of the antimicrobial drugs: Ampicillin + Cloxacillin (93.2%), Tetracycline (90.8%), Streptomycin (82.4%), and Nalidixic acid (62%), and low level of resistance was observed against Ofloxacin (26.4%), Cefotaxime (28.8%) and Nitrofurantoin (28.8%). One hundred and forty four isolates (57.6%) were suspected ESBL-producers judged by their resistance to any of the third
generation cephalosporins used but 40 (16%) actually produced the extended spectrum beta- lactamase enzymes. This shows the existence of Extended Spectrum Beta- Lactamase producing gram negative organisms in Nnewi. Considering the treatment difficulties, as well as the high cost of treatment associated with these organisms, concerted efforts are needed
to contain their spread.

Niger Med J. Vol. 51, No. 4,Oct. – Dec., 2010: 141 – 146.

Keywords: Extended spectrum Beta- lactamases, Gram negative bacill