Antimicrobial Susceptibility Pattern of Biofilm Producing Escherichia coli of Urinary Tract Infections

Urinary tract infections is a serious health threat with respect to antibiotic resistance and biofilms formation being the prime cause for the antibiotic resistance, the present study aimed at performing in vitro detection of biofilm formation in E. coli strains isolated from urine cultures and to determine their susceptibility pattern using 14 commonly used antibiotics. The present study comprised of 210 urine samples collected from tertiary care hospitals in Palakkad, South India. All the samples were subjected to gram staining, bacterial culture and the E. coli isolates were screened for biofilm formation using Tube Method (TM) and Congo Red Agar (CRA) method. Subsequently, the antibiotic sensitivity test was performed by Kirby Bauer-disk diffusion method for the biofilm producing E. coli isolates. E. coli ATCC 25922 was used as the control strain. Of the 96 (71.0%) E. coli isolates, 81 (84.37%) displayed a biofilm positive phenotype under the optimized conditions in the Tube Method and the strains were further classified as strong positive 9 (9.4%), positive 33 (34.4%), weakly positive 39 (40.6%) while in 15 (15.6%) isolates, no biofilm was detected. Screening on CRA does not correlate well with the tube method for detecting biofilm formation in E. coli. The rates of antibiotic resistance were 90.6% for erythromycin, 71.9% for amikacin, 65.6% for cotrimoxazole, 59.3% for ampicillin, 56.3% for meropenem and chloramphenicol, 53.1 and 50.0% for tobromycin and gentamicin respectively. Biofilm production in E. coli may promote the colonization and lead to increased rate of UTIs and such infections may be difficult to tres as they exhibit multi drug resistance.