Biofilm associated growth inhibition of XDR Escherichia fergusonii strain ACE12 isolated from soil.

Biofilm formation by bacteria is highly recognized for virulence factors resulting in their resistance to antimicrobials that lead to biofilm-associated infections. In this study, we isolated Escherichia fergusonii from soil, characterized its biofilm-associated growth, and evaluated the inhibitory potential of anti-biofilm compounds. Test isolate ACE12 was precisely identified as E. fergusonii based on the morphological and 16S rRNA gene sequence analysis. The antibiotic susceptibility pattern of ACE12 showed its resistance to β-Lactams, Aminoglycosides, Macrolides, Tetracycline, Trimethoprim, Vancomycin, & Nitrofurans and on the basis of its resistant pattern the isolate was categorized as extensively drug-resistant (XDR) bacteria. In addition, the research isolate ACE12 was found to harbor four distinct antibiotic resistant genes including dfrA1, blaTem-1, tetC, and sul1, encoding the resistant determinants for trimethoprim, β-lactam, tetracycline, and sulfonamide antibiotics, respectively. Initial screening of biofilm formation by Congo-Red Agar (CRA) and Tube method demonstrated that E. fergusonii ACE12 is a biofilm-forming bacterium. The respective biofilm was characterized by estimating the optical density (OD595) of crystal violet (CV)-stained biofilm by Microtiter plate assay, confirming E. fergusonii as a strong biofilm former. Evaluation of anti-biofilm activity of metal salt of zinc (ZnSO4.7H2O), 1,1-Diphenyl-2-Picrylhydrazyl (DPPH), and two phenolic acids including tannic acid (TA) and trans-cinnamic acid (trans-CA) showed that ≥80 % of biofilm was inhibited at their minimum inhibitory concentrations of 15-100 μg/ml for ZnSO4.7H2O, 250-500 μg/ml for DPPH, 40-50 μg/ml for TA, and 500-1000 μg/ml for Trans-CA. Additionally, at a concentration of 2500 μg/ml, ZnO-1 exhibited approximately 80 % biofilm reduction whereas 70 % biofilm was inhibited by ZnO-6. These findings exhibit that, the studied anti-biofilm compounds can effectively inhibit the biofilm associated growth of E. fergusonii.