Prevalence of Extended Spectrum β-Lactamase, AmpC β-Lactamase and Metallo-β-Lactamase Among Gram Negative Bacilli Recovered From Clinical Specimens in Benin City, Nigeria

Background: Multidrug resistant bacteria continue to be a bane in the treatment of clinical infections in Nigeria. Knowledge of trends in resistance mechanisms is vital in determining available therapeutic options. Objective: This study was aimed at determining the prevalence, distribution and antimicrobial susceptibility of extended spectrum β-lactamase (ESBL), AmpC β-lactamase and metallo-β-lactamase (MBL)-producing gram negative bacteria (GNB) recovered from clinical specimens in a tertiary hospital in Southern Nigeria. Materials and Methods: A total of 309 consecutive non-repetitive clinical bacterial isolates were recovered from various clinical specimens. The presence of ESBL, AmpC β-lactamase and MBL as well as the susceptibility profiles were determined using standard microbiological techniques. Results: ESBL was the most prevalent (P 0.0001) of the 3 enzymes detected in this study. Bacterial isolates recovered from inpatients had a higher likelihood of producing ESBL than those recovered from out-patients (odds ratio [OR] = 2.225, 95% CI = 1.375, 3.599; P = 0.0015). The highest prevalence of ESBL, AmpC and MBL enzyme was observed for Providencia species, Pseudomonas aeruginosa and Citrobacter species respectively. β-Lactamase positive isolates showed poor activity against cephalosporin, amoxicillin-clavulanate, gentamicin and the fluoroquinolones. Isolates that produced any of the three β-lactamase enzymes showed more resistance to antibacterial drugs than β-lactamase negative bacterial isolates. Conclusion: A prevalence of 41.7%, 15.2% and 28.5% was observed for ESBL, AmpC β-lactamase and MBL respectively in this study. Isolates that produced any of the enzymes were more resistant to antibacterial agents. Prudence in antibiotic use is strongly advocated.