Characterization of virulence factors and antibiotic resistance pattern of uropathogenic Escherichia coli strains in a tertiary care center

Abstract

Background: Urinary tract infections (UTI) are the most prevalent bacterial infection in humans. The uropathogenic E. coli (UPEC) expresses a range of virulence factors that contribute to their pathogenicity. The emergence of multidrug resistance (MDR)-associated UTI is increasing. This study monitors the distribution of virulence factors among UPEC strains to note the antibiogram, outcome and type of associated UTI. Methods: A prospective cross-sectional time-bound study of six months was done on clinically significant urinary isolates of Escherichia coli. Detection of haemolysin production and serum resistance was done by phenotypic methods. Genotypic characterization of the virulence genes (papC, iutA, hlyA, cnf1) was done by multiplex PCR. Demographic data, clinical history, antibiogram and type of UTI was collected from clinical case records. Results:75 E.coli isolates from patients with suspected UTIs were included. Females had a higher preponderance of UTI (66.7%). 93% of patients were adults and the remaining 7% were from paediatrics.  24 (32%) isolates showed haemolysis by plate haemolysis and all isolates were serum-resistant. Out of 75 isolates, 65 were positive for at least one of four targeted genes, while remaining ten isolates were negative for all four genes. Multidrug resistance was found in 40 (53.3%) isolates. 97.4% of the UTI cases had a favourable clinical outcome at discharge. Mortality due to urosepsis was 2.6%. Conclusion: Association of hemolysin production with resistance to imipenem and norfloxacin in UPEC strains was significant. Presence of hlyA gene is positively associated with ceftazidime resistance. Nitrofurantoin, piperacillin, tazobactam, and cefaperazone sulbactam are possible candidates for empirical therapy of UTIs. Drugs like aminoglycosides, carbapenems and fosfomycin may be used as reserve drugs in the treatment of MDR-UTI. However, inappropriate usage can increase antibiotic resistance. Hence proper selection of antibiotics in hospitals taking into account the local antibiogram is needed to reduce the emergence of antibiotic resistance.