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

Background: Urinary tract infections (UTIs) are the most prevalent
bacterial infection in humans. The uropathogenic E. coli (UPEC) express a
wide range of virulence factors that contribute to their pathogenicity.
The emergence of Multidrug resistance(MDR)-associated UTI is increasing
off late. Hence this study was undertaken to monitor the distribution of
virulence factors among UPEC strains and to note the antibiogram, outcome
and type of associated UTI. Methods: A prospective cross-sectional
time-bound study of 6 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 were
collected from clinical case records. Results: 75 E. coli isolates from
patients with suspected urinary tract infections were included. Females
had a higher preponderance of UTI (66.7%).93% of the patients were adults
and the remaining 7% were from the paediatric population.  24
(32%) isolates showed haemolysis by plate haemolysis method, and all 75
(100%) isolates were serum resistant. Out of 75 isolates, 65 were positive
for at least one of the four targeted genes, while the remaining 10
isolates were negative for all 4 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: The
association of hemolysin production with resistance to imipenem and
norfloxacin in UPEC strains was significant. The presence of the hlyA gene
is positively associated with ceftazidime resistance. Nitrofurantoin,
piperacillin tazobactam and cefaperazone sulbactam maybe suitable
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 gradually 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.