Phenotypic ESBL Production and Antibiotic Resistance Patterns in Pseudomonas aeruginosa Isolates from Female UTI Patients in Enugu, Nigeria

Abstract

Background: The increasing antimicrobial resistance (AMR) among uropathogens; particularly extended-spectrum beta-lactamase (ESBL)-producing Pseudomonas aeruginosa; poses a significant therapeutic challenge for urinary tract infections (UTIs). This study determined the prevalence of phenotypic ESBL production and the antibiotic resistance patterns of P. aeruginosa isolated from female UTI patients in Enugu; Nigeria. Methods: A cross-sectional study was conducted among 200 adult female patients with suspected UTIs attending a tertiary hospital in Enugu. Mid-stream urine samples were collected and processed bacteriologically. P. aeruginosa isolates were identified using standard microbiological techniques. Phenotypic ESBL production was confirmed using the Double Disc Synergy Test (DDST). Antibiotic susceptibility was determined using the Kirby-Bauer disc diffusion method against 17 antibiotics; and results were interpreted per CLSI guidelines. The Multiple Antibiotic Resistance (MAR) index was calculated; and statistical associations with age were analyzed using Chi-square tests (p<0.05). Results: Out of 200 urine samples; 78 (39.0%) yielded positive bacterial growth. P. aeruginosa was isolated from 58 samples (29.0% of total; 74.4% of positive cultures). The highest isolation rate was in the 32-38 years age group (45.6%). Of the 58 P. aeruginosa isolates; 35 (60.3%) were phenotypically confirmed as ESBL producers. ESBL-producing isolates showed alarmingly high resistance rates (≥90%) to cefoxitin; ertapenem; levofloxacin; trimethoprim-sulfamethoxazole; tetracycline; nalidixic acid; and piperacillin-tazobactam. Complete resistance (100%) was observed to cefoxitin; levofloxacin; TMP-SMX; tetracycline; and nalidixic acid. Gentamicin (71.4% susceptible) and imipenem (65.7% susceptible) were the most effective agents. The mean MAR index for ESBL-producers was 0.78; significantly higher than for non-producers (0.41; p<0.001). The 32-38 years age group had the highest proportion of ESBL-producers (80.9%; p=0.018). Conclusion: This study reports a high prevalence (60.3%) of ESBL-producing; multidrug-resistant P. aeruginosa among female UTI patients in Enugu. The alarming resistance to multiple antibiotic classes; including carbapenems; coupled with high MAR indices; underscores an urgent public health threat. Gentamicin and imipenem remain relatively effective but require judicious use. Enhanced antimicrobial stewardship and routine surveillance are critically needed.