Phenotypic methods to detect virulence factors of uropathogenic e.coli isolates and their antimicrobial susceptibility pattern

Introduction: Urinary tract infection caused by uropathogenic Escherichia coli (UPEC) strains is one of the most important infections in the world. The UPEC strains harbor many genes which encode for various virulence factors, like production of biofilms, deploying toxins- hemolysin and production of various antimicrobial resistance genes.
Aim of study: To determine the prevalence and correlation of phenotypic virulence traits (biofilm and hemolysin production) and antibiotic resistance profile among the UPEC isolated from UTIs.
Material and method: A prospective study was done among patients presenting with symptoms of UTI. The uropathogenic E. coli (UPEC) isolated from samples were processed to check for biofilm production using Congo Red agar and Christensen Tube Adherence methods. Hemolysin production was checked using 5% sheep blood agar and antimicrobial susceptibility testing was done as per CLSI guidelines.
Results: out of the 100 UPEC isolates- 65% were in vitro positive for the biofilm production. Biofilm production by both the Congo Red agar method and the tube adherence method was seen in 52% of the total isolates, whereas 35% of the strains were found to be negative by both the methods. Hemolysin production was seen in 22 isolates and of these, 17 produced biofilms by either Congo Red Agar or tube adherence method. Antimicrobial susceptibility testing showed that overall among the 100 UPEC isolates, multidrug resistance was seen more among biofilm producers.
Conclusion: Better understanding of virulence factors using phenotypic methods in laboratories can be useful in understanding pathogenesis and thereby modify the antibiotic therapy.