Bacteriological profile and antimicrobial susceptibility pattern of the commonest isolate in clinically diagnosed urinary tract infection among patients attending OPD in a tertiary care hospital

Background: Urinary tract infections (UTIs) are common bacterial infections, with Escherichia coli as the leading pathogen. Rising antimicrobial resistance poses challenges for effective management. This study investigates the bacteriological profile and antimicrobial sensitivity patterns of the commonest urinary isolates from UTI cases among the OPD patients attending a tertiary care hospital in Kolkata, India. Materials and methods: A descriptive cross-sectional study was conducted at the Microbiology Department, Nil Ratan Sircar Medical College and Hospital, from July to August 2024. Urine samples from 1090 clinically suspected UTI cases were processed using standard microbiological techniques, including microscopy, culture, and biochemical identification. Antibiotic susceptibility testing followed Clinical and Laboratory Standards Institute (CLSI) guidelines. Results: Significant bacteriuria was found in 144 (13.21%) samples, with a higher prevalence in females (58%) with the most affected age group being 13–45 years. Gram-negative bacteria accounted for 93% of isolates, with Escherichia coli (79%) as the predominant pathogen, followed by Klebsiella pneumoniae (11.1%). Gram-positive bacteria (6.9%) were mainly Enterococcus faecalis. Antibiotic susceptibility testing of E.coli revealed high sensitivity to fosfomycin (90.4%), colistin (89.7%), piperacillin-tazobactam (78.5%), and nitrofurantoin (85.2%), while resistance to cotrimoxazole and ampicillin was noted.Conclusion: This study highlights the increase prevalence of UTIs among females, particularly in reproductive age groups. Escherichia coli remains the predominant pathogen in OPD patients, reflecting global trends. The observed resistance to commonly used antibiotics, such as cotrimoxazole and ampicillin, emphasizes the urgent need for local antimicrobial surveillance and stewardship programs. The emergence of extended-spectrum beta-lactamase (ESBL) producers among Escherichia coli (17.5%) and Klebsiella pneumoniae (21%) further complicates treatment strategies. Nitrofurantoin, fosfomycin, and piperacillin-tazobactam demonstrate significanct efficacy and Nitrofurantoin being the first line of drug, is a viable options for empirical therapy. These findings underscore the importance of tailored antibiotic policies and the judicious use of antimicrobials to combat resistance and improve treatment outcomes.