12. Biofilm eradication studies on uropathogenic E. coli using ciprofloxacin and nitrofurantoin

The chronic nature of some urinary tract infections (UTI) is being attributed to the ability of E. coli to form a biofilm. The armament of therapeutic agents available to treat bacterial infections today is restricted to antibiotics developed specifically to kill (bactericidal) or stop the growth of bacteria (bacteriostatic) in planktonic form and not the biofilm. Bacteria growing within a biofilm lose their sensitivity to antibiotic quickly thus resulting in persistent infections that cannot be resolved with standard antibiotic treatment. The present study was aimed at; in vitro qualitative estimation of biofilm production of E. coli isolated from UTI and correlates it with antibiotic resistance. Minimum inhibitory concentration (MIC) and minimum biofilm eradicating concentration (MBEC) to determine changes in the pattern of antibiotic sensitivity of uropathogenic E. coli (UPEC) from the planktonic to the biofilm phase of growth was evaluated. The uropathogenic E. coli isolated from 600 samples were tested for antimicrobial susceptibility by disc diffusion method. In vitro quantitative estimation of biofilm formation by the isolates was determined by tube method. From 308 isolates of E. coli, 160 were positive for in vitro biofilm production. Among them 44 were classified as strong biofilm producers and 116 as moderate. It was observed that the MIC of ciprofloxacin and nitrofurantoin for the biofilm forming UPEC was more as compared to the non biofilm forming strains and the MBEC of the strong biofilm producers was more than ten folds higher than its MIC. There was a significant correlation between biofilm production and antibiotic resistance. The present study demonstrated that uropathogenic E.coli have high propensity to form biofilm that renders it resistant to conventional antimicrobial therapy