Studies on the occurrence of antibiotic-resistant bacterial strains from agriculture-associated waters and their proteomic and genomic characterizations
The serendipitous discovery of penicillin by Alexander Fleming in 1928 marked the glorious beginning of the modem antibiotic era with an innumerable number of lives being saved every single day by the use of antibiotics. Unfortunately, emergences of antibiotic resistance are taking us back to the pre-antibiotic era. Indiscriminate uses of antibiotics for therapeutic purposes and growth promotion in cattle are the major factors for the spread of antimicrobial drug resistance. Exposure of sub lethal levels of antibiotics to pathogenic microorganisms leads to the development of resistance, which then in due course spreads to other bacterial communities via horizontal and vertical gene transfer. Natural environment acts as a centre stage for such events and act as reservoir for antibiotic resistant bacteria. Anthropogenically polluted rivers can act as one such reservoir. This thesis explores this possibility and describes the isolation characterization of multidrug resistant bacteria from the water samples of Dighty Bum. Five different strains of multidrug resistant bacteria viz. Enterobacter spp., Burkholderia cepacia, Aeromonas hydrophila, Enterobacter agglomerans, and Pseudomonas stutzeri that were resistant towards ampicillin, cotrimoxazole, novobiocin and tetracycline were successfully identified. Furthermore, the incidence of plasmid mediated and efflux pump mediated drug resistance has been proved in this work. Further studies involving proteomic and genomic analysis/comparison of environmental bacteria and their laboratory counterparts revealed the influence of the environment in conferring increased resistance and virulence in environmental strains as evidenced by marked variation in outer membrane proteins and virulence gene expression. Thus the findings of the present study point out the role of our natural ecosystems, especially rivers, in spreading multidrug resistant pathogenic bacteria and warrants further study and proactive interventions to prevent the pollution of water bodies.
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