The effectiveness of antibiotics against a major uropathogen- Escherichia coli and its biofilm assay by phenotypic methods

Nachammai S. M., Karthika Jayakumar, Anbu N. Aravazhi


Background: Urinary tract infection (UTI), an inflammatory disease occurs to a high multiplication of pathogenic microbes in the urinary system. Escherichia coli, a major uropathogen accounting for up to 80% UTI. Activity of antibiotics against E.coli is decreasing due to enzymatic, genetic and various other factors resulting in multidrug resistance. Biofilm is a great threat as it interferes antibiotic therapy, undergoes gene transformation, making the bacteria more virulent. Objectives of the study were to isolate the E. coli from the urine sample of symptomatic UTI patients, to study the effectiveness of antibiotics against E.coli by antibiotic susceptibility pattern, ESBL detection and to biofilm phenotype assay by four different methods.

Methods: A total of 400 urine samples from symptomatic UTI patients, October 2015 to March 2016 and processed. E.coli was isolated and antibiotic susceptibility was done as per CLSI guidelines. Biofilm detection by a) Congo red agar (CRA), b) Modified Congo red agar (MCRA), c) Tube adherence assay, d) Microtitre plate method.

Results: A total of 100 E. coli (69%) was obtained from 400 samples, 49% were ESBL producers and 84% shows multi drug resistant. Biofilm positive isolates shows 70% positivity by CRA, 91% by MCRA, 57% in tube adherence assay and 99% via microtitre plate method.

Conclusions: Resistance to antibiotics ladder is increasing and it’s necessary to take actions to reduce its hindrance in the future. Advanced studies in biofilm will help to prevent the more virulence without any critical complications in therapy.  


Biofilm, Escherichia coli, ESBL, Multi drug resistance, UTI

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