Prevalence and Antimicrobial Susceptibility Pattern of Extended Spectrum Beta Lactamase Producers in Gram-negative Urine Isolates at MBN Clinical Laboratories, Kampala Uganda

Author(s): Simon Dembe Kasango, Stephen Lutoti, Izale Wewedru, Emmanuel Aboce, Denish Calmax Angol

Introduction: Occurrence of Extended Spectrum beta-lactamase (ESBLs) producing bacteria have presented impediment in treatment choices for urinary tract infections. ESBLs embody a major cluster of lactamases accountable for resistance to novel generations of ß-lactam drugs worldwide. The study determined prevalence of ESBL organisms in urine isolates and susceptibility patterns to 13 antibacterial agents.

Materials and methods: Two hundred samples were cultured on blood agar, MacConkey agar and incubated at 37°C utmost 48 hours. Isolates identified based on standard bacteriological culture and biochemical characteristics. Drug susceptibility centered on Clinical Laboratory Standard Institute recommended and WHO modified Kirby- Bauer disc diffusion methods. Isolates with reduced susceptibility to Ceftazidime were considered to be possible ESBL producers. Phenotypically confirmed ESBL required use of Ceftazidime in combination with Clavulanic acid. A five milimeter increase zone diameter for Ceftazidime in combination with Clavulanic acid versus its zone tested alone was considered as ESBL.

Results: Out of 200 samples, 45 (22.5%) had significant growth, majority Escherichia coli 28 (62.2%), Klebsiella pneumonae 11 (24.4%) followed and Citrobacter fruendii 2 (4.4%). Enterobacter species, Morganella morganii, Proteus mirabilis and Seratia marcescens each 1 (2.2%). Prevalence of ESBLs was 56%. Out of 25 (56%) ESBLs, highest prevalence was among Escherichia coli (15/25; 60%) followed by Klebsiella pneumonae (5/25; 24%) while Citrobacter fruendii, Enterobacter species, Morganella morganii and Proteus mirabilis each had (1/25; 4%). Susceptibility was highest to Imipenem 22 (88%) and least to Ampicillin, Amoxicillin-Clavulanic acid and Tetracycline each 1 (4%). No susceptibility t