Evaluation of CHROMagar ESBL and Double Disk Synergy Test (DDST) for Screening of Extended Spectrum Beta-lactamase Producing Uropathogens in South-South Nigeria

Background/Purpose: The aim of this study was to evaluate the effectiveness of CHROMagar ESBL in comparison with Double Disc Synergy Test (DDST) for the detection of ESBL producing uropathogens.

Methods: Six hundred and sixty urine samples were collected from pregnant women attending antenatal at General hospital Ikot Ekpene, Eket and Oron. Two hundred and fifty eight isolates were obtained while two hundred and thirty one isolates were ESBL producers. Microbact 24E(Oxoid, UK) was used in the identification of bacterial isolates, antibiotic susceptibility test was done using Kirby-Bauer disk diffusion method following CLSI guidelines using commercially available disc (Oxoid Ltd). Double disk synergy test was carried out on the isolates and inoculation was done using CHROMagar ESBL (France).

Results: The prevalence of ESBL 35% was recorded. The sensitivity and specificity of DDST was 88% and 89%, respectively. CHROMagar showed an increase in sensitivity and specificity at 48 h with 98% and 99.0%, respectively. 80% of the ESBL producing isolates were multi drugs resistant. The predominant bacterial pathogens were Enterobacter cloacae (23%), Proteus mirabilis (14%) and Acinetobacter baumanii (13.4%).The ESBL producing isolates showed maximum resistance against Ceftazidime (90%), Cefotaxime (91%), Azetronam (95%), Amikacin (68.2%) followed by ofloxacin (70%) while maximum sensitivity was seen for imipenem (90%) and Augumentin (80%). The study demonstrated that CHROMagar was superior and more sensitive than DDST.

Conclusion: CHROMagar ESBL seems to be the most reliable method among phenotypic methods for detection of ESBL in the absence of PCR.