Microbial Etiology and Resistance Patterns of Urinary Tract Infection at a Tertiary Care Centre - A Hospital based Study

Urinary tract infections (UTIs) are among the most common infections diagnosed in clinical practice. Treatment is often initiated before microbiological confirmation and anti-microbial susceptibility testing. With the rapidly rising antibiotic resistance treatment failures are not uncommon. Beta-lactamase production by gram-negative bacteria causing UTI is the commonest mode of drug resistance. The aim of current study was to detect and determine the hospital based prevalence of UTI, causative uropathogens and their antimicrobial susceptibility patterns. A total of 9,518 clean catch, mid stream urine samples were processed over 2 years. Semi-quantitative urine cultures and AST were performed. Diverse underlying resistance mechanisms were determined by detecting ESBLs, Carbapenemases, AmpC b-Lactamases, and Metallo-b-Lactamases through various standardized phenotypic methods. Out of the 9,518 samples tested 1171 (12.3%) were culture positive. Majority (66.7%) were from female patients. Highest prevalence (60%) was seen in patients > 40 years of age. E. coli (48%) was the predominant causative organism, followed by Enterococcus spp. (23%). Among GNB high resistance rates were observed against Beta-lactams, Beta-lactam/b-lactamase inhibitor combinations, and fluoroquinolones. 34.5% of GNB were confirmed as ESBL, 40% as carbapenemase, 36.5% as AmpC b-Lactamase, and 41.5% as MBL producers. We found very high levels of resistance against a broad range of antibiotics including the most widely used b-lactam group. With the resistance slopes getting steeper and steeper empirical treatment of UTIs might be fraught with the danger of many failures. Culturing and performing AST for all patients with UTI might be a prudent step for their rationale treatment and a step forward in halting the emergence of further resistance.

Automated summary

Urinary tract infections (UTIs) are common in clinical practice, but rising antibiotic resistance is leading to treatment failures. This study found that beta-lactamase production by gram-negative bacteria is the most common mechanism of drug resistance in UTIs. The survey identified E. coli as the predominant causative organism, with high resistance rates against commonly used antibiotics. Culturing and performing antimicrobial susceptibility testing for UTI patients could be an important step in rational treatment and preventing further resistance.