Occurrence of Antibiotic Resistance Genes and Bacterial Markers in a Tropical River Receiving Hospital and Urban Wastewaters

Abstract

The occurrence of emerging biological contaminants including antibiotic resistance genes (ARGs) and Faecal Indicator Bacteria (FIB) is still little investigated in developing countries under tropical conditions. In this study, the total bacterial load, the abundance of FIB (E. coli and Enterococcus spp. (ENT)), Pseudomonas spp. and ARGs (blaTEM, blaCTX-M, blaSHV, blaNDM and aadA) were quantified using quantitative PCR in the total DNA extracted from the sediments recovered from hospital outlet pipes (HOP) and the Cauvery River Basin (CRB), Tiruchirappalli, Tamil Nadu, India. The abundance of bacterial marker genes were 120, 104 and 89 fold higher for the E. coli, Enterococcus spp. and Pseudomonas spp., respectively at HOP when compared with CRB. The ARGs aadA and blaTEM were most frequently detected in higher concentration than other ARGs at all the sampling sites. The ARGs blaSHV and blaNDM were identified in CRB sediments contaminated by hospital and urban wastewaters. The ARGs abundance strongly correlated (r ≥ 0.36, p < 0.05, n = 45) with total bacterial load and E. coli in the sediments, indicating a common origin and extant source of contamination. Tropical aquatic ecosystems receiving wastewaters can act as reservoir of ARGs, which could potentially be transferred to susceptible bacterial pathogens at these sites.

Structural and biochemical analysis of the metallo‐β‐lactamase L1 from emerging pathogen Stenotrophomonas maltophilia revealed the subtle but distinct di‐metal scaffold for catalytic activity

“…There is a bridging water (or hydroxide) molecule binding both metals. In environmental bacteria, MBLs genes are mostly acquired through horizontal gene transfer using plasmids . These bacteria can become antibiotic‐resistant infectious agents and are getting extensive clinical attention .…”

“…In environmental bacteria, MBLs genes are mostly acquired through horizontal gene transfer using plasmids. 5,8 These bacteria can become antibiotic-resistant infectious agents and are getting extensive clinical attention. 5 B2 enzymes are resident enzymes and have a metal site formed by an asparagine or glutamine, and two histidine residues for the first metal site and cysteine, histidine and aspartic acid residues for the second site.…”

Abundance and diversity of phages, microbial taxa and antibiotic resistance genes in the sediments of the river Ganges through metagenomic approach

“…Another study Devarajan et al provide the occurrence of ARGs mainly beta-lactam ( bla NDM-1, bla SHV, bla CTX-M etc.) from the Cauvery River Basin (CRB), Tiruchirappalli, Tamil Nadu, India [50]. Likewise, Marathe et al highlighted the effect of untreated wastewater discharge on the resistome from Mutha River, Pune, India.…”

“…Various studies advocate the abundance of distinct antibiotic resistance genes (ARGs) and their reservoirs. There are several environmental sources i.e., soil [39, 40], sediments [41, 42], sewage [43], activated sludge [44], human gut microbiota [45], human feces [46], animal waste [46], drinking water [47], surface water [48, 49], river water [50], wastewater treatment plants (WWTPs) [51, 52], glaciers [53] etc. are known to have diverse type of ARGs and considered to be hotspots for same.…”

Hospital wastewater treatment reduces NDM‐positive bacteria being discharged into water bodies

“…The present study also reports the incidence of NDM‐1‐positive isolates in untreated wastewater of tertiary care hospital in Mangalore, India. NDM‐1 producing bacteria have been previously identified in hospital wastewater which becomes the main source for this pathogen (Chandran et al, ; Devarajan et al, ; Luo et al, ; Zhang et al, ; Zong & Zhang, ). NDM‐1 producing bacteria have also been reported in rivers and lakes in Vietnam (Isozumi et al, ), proving that these strains are widely distributed.…”