Integrated Phenotypic and Molecular Characterization of Biofilm Formation, Virulence Determinants, and Multidrug Resistance in Clinical Escherichia Coli

Abstract

Background: Escherichia coli is responsible for the majority of UTI cases, with an increasing number of multidrug resistance (MDR) and biofilm-forming E. coli isolates being isolated from such cases. In this study, we assessed the MDR profile, biofilm formation ability, and occurrence of specific biofilm-associated and MDR-related genes in isolates.
Methods: One hundred isolates of non-duplicate UP E. coli EC were tested for their antibiotic susceptibility using the Kirby-Bauer disc diffusion technique according to CLSI guidelines. Biofilm formation was evaluated using the MTP and CRA tests. The presence of fimH, csgA, luxS, bcsA, acrB, and blaCTX-M genes was determined by conventional PCR. Statistical correlations among biofilm formation, distribution of genes, and MDR were established.
Results: Nitrofurantoin had the highest sensitivity (92%), while the highest levels of resistance were seen with amoxicillin-clavulanate (95%), cefixime (83%), tetracycline (79%), ceftriaxone (78%), ceftazidime (78%), cefepime (77%), and trimethoprim-sulfamethoxazole (71%). MDR isolates were found in 95% of the isolates. Production of biofilm was seen in 98% of the isolates, with 18% as strong, 24% as moderate, and 56% as weak producers. CRA method yielded 81.6% sensitivity and 100% specificity than MTP test. Common gene targets included fimH (93%), acrB (90%), csgA (77%), luxS (72%), blaCTX-M (69%), and bcsA (58%). Significance was found in association of biofilm genes to biofilm phenotype while acrB and blaCTX-M were independent predictors of MDR.
Conclusions: MDR was highly prevalent in isolates. The presence of biofilm formation and virulence factors was also high. Combination of both phenotypic and molecular approaches offers useful epidemiologic information which can lead to better antibiotic stewardship.