Enterococci in river Ganga surface waters: Propensity of species distribution, dissemination of antimicrobial-resistance and virulence-markers among species along landscape

Abstract

BackgroundSurface waters quality has declined in developing countries due to rapid industrialization and population growth. The microbiological quality of river Ganga, a life-sustaining surface water resource for large population of northern India, is adversely affected by several point and non-point sources of pollution. Further, untreated surface waters are consumed for drinking and various household tasks in India making the public vulnerable to water-borne diseases and outbreaks. Enterococci, the 'indicator' of water quality, correlates best with the incidence of gastrointestinal diseases as well as prevalence of other pathogenic microorganisms. Therefore, this study aims to determine the distribution of species diversity, dissemination of antimicrobial-resistance and virulence-markers in enterococci with respect to rural-urban landscape along river Ganga in northern India.ResultsEnterococci density (χ2: 1900, df: 1; p < 0.0001) increased from up-to-down gradient sites in the landscape. Species diversity exhibit significant (χ2: 100.4, df: 20; p < 0.0001) and progressive distribution of E. faecalis, E. faecium, E. durans and E. hirae down the gradient. Statistically discernible (p: 0.0156 – < 0.0001) background pool of resistance and virulence was observed among different Enterococcus spp. recovered from five sites in the up-to-down gradient landscape. A significant correlation was observed in the distribution of multiple-antimicrobial-resistance (viz., erythromycin-rifampicin-gentamicin-methicillin and vancomycin-gentamicin-streptomycin; rs: 0.9747; p: 0.0083) and multiple-virulence-markers (viz., gelE+esp+; rs: 0.9747; p: 0.0083; gelE+efaA+; rs: 0.8944; p: 0.0417) among different Enterococcus spp.ConclusionOur observations show prevalence of multiple-antimicrobial-resistance as well as multiple-virulence traits among different Enterococcus spp. The observed high background pool of resistance and virulence in enterococci in river waters of populous countries has the potential to disseminate more alarming antimicrobial-resistant pathogenic bacteria of same or other lineage in the environment. Therefore, the presence of elevated levels of virulent enterococci with emerging vancomycin resistance in surface waters poses serious health risk in developing countries like India.

Occurrence, Genetic Diversity, and Persistence of Enterococci in a Lake Superior Watershed

“…Some species, including Enterococcus faecalis, E. faecium, E. casseliflavus, E. hirae, E. mundtii, E. gallinarum, E. durans, E. avium, and E. sulfureus, have been repeatedly isolated from sand, sediment, water, or plants (9)(10)(11)(12). In addition, evidence of the persistence of enterococci in municipal oxidation ponds and in microcosms simulating environmental conditions has been previously documented (13,14).…”

Anthropogenic Activities as a Source of High Prevalence of Antibiotic Resistant Staphylococcus Aureus in the River Ganga

“…The river and its tributaries provide 40% of water requirement of the country for various purposes including irrigation, daily use and drinking [18]. In addition mass bathing in sacred water of Ganges is an age-old ritual in India.…”

Assessing the impact of socio-economic development and climate change on faecal indicator bacteria in the Betna River, Bangladesh

“…It is therefore the most common method in use (Rochelle-Newall et al 2015). E. coli and enterococci have been used most widely as indicators of faecal contamination in water sources (Ouattara et al, 2013, Lata et al, 2009). Enterococci are a subgroup within the faecal streptococcus group and are distinguished by their ability to survive in salt water.…”

“…Microbial contamination studies are usually based on the Faecal Indicator Bacteria (FIB). E. coli and enterococci are the two most widely used indicators of microbial water quality (Lata et al, 2009). Quantitative studies on the changes in FIB concentrations in surface waters for combined scenarios have not yet been published.…”

“…[58] This study aims to analyse the fate, transport and the processes influencing the dynamic distribution of faecal contaminants in the Betna River using a coupled hydrodynamicmicrobial model (i.e. MIKE 21 FM-ECOLab).To represent the faecal contamination, we used faecal indicator bacteria (FIB) E. coli and enterococci, the two most widely used indicators of microbial water quality (Lata et al, 2009, Ouattara et al, 2013). The hydrodynamic model for Betna River was set up and validated using water temperature and salinity distribution in the river.…”