Abstract
Every year millions of people die due to fatal waterborne diseases around the world especially in developing countries like India. Sikkim, a northeastern state of India, greatly depends on natural water sources. About 80% of the population of Sikkim depends on natural spring water for domestic as well as agricultural use. Recent waterborne disease outbreaks in the state raises a concerning question on water quality. In this study, we analyzed water quality especially for the detection of Enterobacteriaceae members from four districts of the state. Isolation with selective culture media techniques and taxonomic characterization of Enterobacteriaceae bacteria with 16S rRNA gene showed the prevalence of Escherichia coli (37.50%), Escherichia fergusonii (29.41%), Klebsiella oxytoca (36.93%), Citrobacter freundii (37.92%), Citrobacter amalonaticus (43.82%), Enterobacter sp. (43.82%), Morganella morganii (43.82%), Hafnia alvei (32.42%), Hafnia paralvei (38.74%), and Shigella flexneri (30.47%) in the spring water of Sikkim. Antibiotic susceptibility test (AST) showed resistance of the isolates to common antibiotics like ampicillin, amoxicillin as well as to third generation antibiotics like ceftazidime and carbapenem. None of the isolates showed resistance to chloramphenicol. E. coli isolated from spring water of Sikkim showed presence of different virulence genes such as stx1 (81.81%), elt (86.66%), and eae (66.66%) along with resistance gene for ampicillin (CITM) (80%), quinolones (qnrB) (44.44%), tetracycline (tetO) (66.66%), and streptomycin (aadA1) (66.66%). The data indicates a high incidence rate of multiple antibiotic resistant enteric bacteria in the spring water of Sikkim. Additionally, the presence of enteric bacteria in the water samples indicates widespread fecal contamination of the spring water.
Highlights
Water is important for every facet of life (Mishra et al, 2018)
Among the 400 clinically important bacteria isolated from different districts, Citrobacter amalonaticus [18.18%, p > 0.05, (p = 0.92)], Enterobacter sp. [18.18%, p > 0.05, (p = 0.92)], and Morganella morganii [18.18%, p > 0.05, (p = 0.92)] were predominant followed by Escherichia fergusonii [13.79%, p > 0.05, (p = 0.92)] and Hafnia alvei [13.79%, p > 0.05, (p = 0.92)]
District wise bacterial diversity showed that East Sikkim was mainly dominated by Hafnia alvei [13.79, p > 0.05, (p = 0.92)] and Escherichia fergusonii [13.79, p > 0.05, (p = 0.0001)] whereas South Sikkim was dominated by Shigella flexneri [10%, p < 0.05, (p = 0.92)]
Summary
Surface water acts as a natural source of freshwater and is important for drinking, cooking as well as other household purposes (Vaz-Moreira et al, 2013). Contaminated water can cause several illnesses including dysentery, cholera, diarrhea, typhoid, and in chronic cases leading to loss of life on a normal basis especially in developing countries. Due to lack of quality health care systems and insufficiency in the supply of pure potable water, developing countries are on the alarming list of waterborne disease outbreaks (World Health Organisation, 2018). Diarrhea alone is the cause of 8,42,000 deaths every year and by 2025 half of the world is expected to be living in the water stressed areas increasing the risks of dying from waterborne diseases (World Health Organisation, 2018)
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