Prevalence and Antimicrobial Susceptibility Patterns of Extended-Spectrum Beta-Lactamase-Producing Enterobacteriaceae Isolated from Patients with Urinary Tract Infections at a Tertiary Care Centre

Abstract

Background: Urinary tract infections (UTIs) are among the most common bacterial infections encountered in clinical practice. The increasing prevalence of extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae complicates treatment because these organisms can hydrolyse several beta-lactam antibiotics, including third-generation cephalosporins.

Aim: To determine the prevalence of ESBL-producing Enterobacteriaceae isolated from patients with suspected UTI and describe the antimicrobial susceptibility patterns of the isolates at a tertiary care centre.

Materials and Methods: This hospital-based observational study included 400 urine samples collected from patients with clinically suspected UTI. Samples were processed by standard urine culture methods, and bacterial isolates were identified using conventional microbiological procedures. Antimicrobial susceptibility testing was performed using the Kirby–Bauer disc diffusion method on Mueller–Hinton agar, following the applicable laboratory standards. ESBL production was assessed using screening and confirmatory phenotypic methods. Data were analysed descriptively and expressed as frequencies and percentages.

Results: Of the 400 urine samples examined, 304 (76.0%) yielded significant bacterial growth. Enterobacteriaceae accounted for 258 isolates, representing 84.8% of culture-positive samples. Escherichia coli was the predominant organism (157/258; 60.9%), followed by Klebsiella pneumoniae (70/258; 27.1%), Proteus spp. (21/258; 8.1%) and Enterobacter spp. (10/258; 3.9%). ESBL production was detected in 107 of the 258 Enterobacteriaceae isolates (41.5%). Among ESBL-positive isolates, E. coli accounted for 79 (73.8%), followed by K. pneumoniae (25; 23.4%), Proteus spp. (2; 1.9%) and Enterobacter spp. (1; 0.9%). Among all Enterobacteriaceae isolates, the highest reported antimicrobial resistance was to ampicillin (219/258; 84.9%), followed by ceftriaxone (55.4%), cefotaxime (50.4%) and ceftazidime (41.9%).

Conclusion: ESBL production was detected in 41.5% of Enterobacteriaceae isolated from urine samples in this study. E. coli was the predominant isolate and contributed the largest proportion of ESBL-positive organisms. The observed resistance to commonly used antibiotics highlights the importance of routine urine culture, ESBL detection and antimicrobial susceptibility testing to support appropriate treatment and local antimicrobial-resistance surveillance.