Biofilm Formation and Antimicrobial Resistance Pattern of Uropathogenic E. Coli : Comparison of Phenotypic and Molecular Methods

Abstract

Background: Biofilm structure is considered an important virulence factor and is associated with UPEC that is formed within the bladder and act as a reservoir for recurrent or/and persistent infection. Biofilm is formed from multiple adherent colonies surrounded by polysaccharide matrix that protects bacterial pathogens from an innate immune response and have major role in antibiotic resistance. Objectives: to determine biofilm production in UPEC phenotypically and genotypically by detection of the genes responsible for biofilm production (pap, fimH and sfa) and to assess their correlation with multi-drug resistance. Methodology: A total 278 catheterized and non-catheterized urine samples from clinically suspected UTI patients were processed by standard microbiological procedures. One hundred E. coli were isolated and analyzed for the production of biofilm by modified congo-red agar (MCRA) and microtitre plate (MTP) methods. Subsequently, the antimicrobial susceptibility test was performed by Kirby Bauer-disk diffusion method for both the biofilm and non-biofilm-producing E. coli strains. The presence of pap, fimH and sfa virulence genes was examined by conventional multiplex PCR assay. Results: One hundred UPEC were isolated from 278 catheterized and non-catheterized urine samples (35.97 %). A positive biofilm phenotype was detected in 75% and 68% on MCRA and MTP respectively. UPEC isolates in catheter-associated infection produced biofilm by MTP (73.0%) and MCRA (81.1%) methods. E. coli strains forming biofilm had significantly higher resistance to antibiotics than non-biofilm producer strains regarding tetracycline, cefotaxime, ciprofloxacin and amikacin. The frequency of detection of the virulence genes (fimH, Pap and sfa) among biofilm producing UPEC were 89.7 % vs. 81.3 %, 80.9 % vs. 73.3 % and 67.6 % vs. 61. 3 % as detected by MTP vs. MCRA respectively. Conclusion: Biofilm formation was more common in catheterized patients and there was an association between biofilm production and antimicrobial resistance. PCR was more reliable for the detection of biofilm forming UPEC as compared to MCRA and MTP methods. The adhesion gene fimH was the most common among those uropathogenic E. coli strains.