Antibiotic Resistance Profiling and Molecular Phylogeny of Biofilm Forming Bacteria From Clinical and Non-clinical Environment in Southern Part of Bangladesh

Biofilm is a surface adhered extracellular polymer matrix produced by bacteria. The establishment of biofilms is considered as an important pathogenic trait in many chronic infections and antibiotic resistance. The present study was intended to evaluate biofilm forming potency and antibiotic resistance (AR) pattern in clinical and non-clinical bacterial isolates, and their phylogenetic characterization. A total of 82 bacterial isolates were obtained from clinical settings and animal farms from southern (Kushtia-Jhenaidah) region of Bangladesh. Biofilm forming potentials and AR profile were evaluated by standard biofilm assay and Kirby-Bauer disk diffusion method, respectively. Further, antibiotic exposure was assessed by multiple antibiotic resistance (MAR) value indexing. Furthermore, statistical methods were applied to estimate the relationship between AR and biofilm formation. Finally, selected isolates were characterized by morphological and biochemical tests, as well as 16S rRNA gene sequencing. Clinical isolates showed higher biofilm formation (OD595=1.17±0.03) than non-clinical isolates (OD595=0.68±0.03). Among all, Pseudomonas isolates produced the highest amount of biofilms (OD595=2.08±0.02). The AR profiles fell within 46.67-86.67% and MAR index ranged from 0.47 to 0.87. Moreover, a significant positive correlation (P<0.05) was found between biofilm formation and AR. Eventually, heavy biofilm producers with ≥60% resistance profile were characterized and identified as Escherichia coli, Cronobacter sakazakii, Pseudomonas aeruginosa, Staphylococcus sciuri, and Staphylococcus aureus. In general, biofilm formation and MAR were highly correlated regardless of the source, type, and environment of the isolates. Therefore, a rigorous evaluation of both biofilm formation and AR is demanded to minimize AR and associated problems.