Plasmid Mediated Antibiotic and Heavy Metal Co-Resistance in Bacterial Isolates from Mahananda River Water (Malda, India)

Abstract

Aims: The current investigation stands for the determination of MAR (multiple antibiotic resistance) indices of antibiotic resistant and heavy metal (HM) tolerant bacterial isolates from Mahananda river water near Malda (West Bengal state, India) and profiling of R-plasmids of the isolated bacteria. Methods: The water samples (n=5), collected from Mahananda river water, Malda town, (India), were checked for the presence of bacterial growth in nutrient broth cultures. The pure bacteria colonies, procured from each of the nutrient broth cultures, were identified by conventional methods. The susceptibilities to antibiotics and HMs of the isolated bacteria were determined by disc diffusion and agar dilution, respectively. Plasmid curing of the resistant bacteria was done with SDS treatment, and the isolated plasmids were screened through agarose gel electrophoresis. The MAR indices for the isolates were calculated. Results: The isolated bacteria were identified as Escherichia coli (n=3), and Pseudomonas aeruginosa (n=2). The bacterial isolates showed various patterns of resistance to antibiotics and heavy metals. The MAR indices for the bacterial isolates ranged 0.0 – 0.2, for E. coli, and the value was 0.47, for both the Ps. aeruginosa isolates. The isolated bacteria harboured a single plasmid mediating co-resistance to antibiotics and HMs. Conclusion: The current study demonstrates the occurrence of plasmid, encoding Am-Cm-Ce-Cx-Tm-Cd2+-Hg2+ and Cm-Tm-Cd2+-Hg2+ resistances, among the aquatic bacteria of Mahananda river that may potentially act as the source of dissemination of pathogenic bacteria and bacterial antibiotic resistances, requiring public awareness on the issues of misuse and/or overuse of antibiotics