Spatiotemporal distribution of antimicrobial resistant organisms in different water environments in urban and rural settings of Bangladesh

The spatial distribution of clinically important antibiotic resistant bacteria (ARB) and associated genes is important to identify the environmental distribution of contamination and ‘hotspots’ of antimicrobial resistance (AMR). We conducted an integrated survey of AMR in drinking water, wastewater and surface water (rivers and ponds) in three settings in Bangladesh: rural households, rural poultry farms, and urban food markets. Spatial mapping was conducted via geographic information system (GIS) using ArcGIS software. Samples (n = 397) were analyzed for the presence of extended-spectrum β-lactamase-producing Escherichia coli (ESBL-Ec), carbapenem-resistant E. coli (CR-Ec) and resistance genes (blaCTX-M-1, blaNDM-1). In rural households, 5% of drinking water supply samples tested positive for ESBL-Ec, and a high proportion of wastewater, pond and river water samples were positive for ESBL-Ec (90%, 76%, and 85%, respectively). In poultry farms, 10% of drinking water samples tested positive for ESBL-Ec compared to a high prevalence in wastewater, pond and river water (90%, 68%, and 85%, respectively). CR-Ec prevalence in household wastewater and pond water was relatively low (8% and 5%, respectively) compared to river water (33%). In urban areas, 38% of drinking water samples and 98% of wastewater samples from food markets tested positive for ESBL-Ec while 30% of wastewater samples tested positive for CR-Ec. Wastewaters had the highest concentrations of ESBL-Ec, CR-Ec, blaCTXM-1 and blaNDM-1 and these were significantly higher in urban compared to rural samples (p < 0.05). ESBL-Ec is ubiquitous in drinking water, wastewater and surface water bodies in both rural and urban areas of Bangladesh. CR-Ec is less widespread but found at a high prevalence in wastewater discharged from urban food markets and in rural river samples. Surveillance and monitoring of antibiotic resistant organisms and genes in waterbodies is an important first step in addressing environmental dimensions of AMR

Co-occurrence of arsenic and antibiotic resistance in extended-spectrum β-lactamase (ESBL)-producing <i>E</i>. <i>coli</i> isolates.

Co-resistance to arsenic and antibiotic resistance of ESBL E. coli isolates in A) drinking water, B) mother stool, and C) child stool samples in Hajiganj (high arsenic exposure) and Matlab (low arsenic exposure) was determined by selecting bacterial isolates that showed resistance to any of the third-generation cephalosporin antibiotics (CRO, ceftriaxone, CTX, cefotaxime; CAZ, ceftazidime; FEP, cefepime) and were arsB gene positive by PCR assays. ‘n’ indicates the number of third-generation cephalosporin-resistant bacterial isolates for each group of samples. AMP, ampicillin; TE, tetracycline; CRO, ceftriaxone, CTX, cefotaxime; CAZ, ceftazidime; FEP, cefepime; CT, colistin; CIP, ciprofloxacin; NA, nalidixic acid; AZM, azithromycin; SXT, trimethoprim-sulfamethoxazole. The asterisks indicate significance (*p <0.05).</p

Demographic characteristics of children and mothers colonized with third-generation cephalosporin-resistant (3GCr) or fluoroquinolone-resistant (FQr) <i>E</i>. <i>coli</i> in areas with and without arsenic exposure through drinking water.

Demographic characteristics of children and mothers colonized with third-generation cephalosporin-resistant (3GCr) or fluoroquinolone-resistant (FQr) E. coli in areas with and without arsenic exposure through drinking water.</p

Prevalence of <i>arsB</i> gene among <i>E</i>. <i>coli</i> isolates.

Prevalence of E. coli isolates positive for arsB gene in A) total no. of E. coli isolates, B) third-generation cephalosporin-resistant E. coli isolates, and C) fluoroquinolone-resistant E. coli isolates obtained from water (WU), mother stool (MS), and child stool (CS) samples collected from the Hajiganj (RH, high arsenic exposure) and Matlab (RM, low arsenic exposure) areas in Bangladesh. Each bar represents the percentage of E. coli isolates that are positive for the arsB gene. The numbers on top of each bar indicate the number of E. coli isolates that are positive for the arsB gene and the numbers in parenthesis indicate the total number of E. coli isolates for each type of sample. The asterisks indicate significance (*p p p <0.001).</p

Prevalence of ESBL and diarrheagenic genes among <i>E</i>. <i>coli</i> isolates obtained from water, mother stool (MS), and child stool (CS) in Hajiganj and Matlab.

Prevalence of ESBL and diarrheagenic genes among E. coli isolates obtained from water, mother stool (MS), and child stool (CS) in Hajiganj and Matlab.</p

Forest plot for the odds ratios (OR) along with their 95% confidence intervals (CIs).

The black dot indicates the OR of being resistant to the corresponding antibiotics in the arsenic-resistant group of isolates compared to the arsenic-sensitive group of isolates. The whiskers are the spread of the CIs of the OR. The dotted line indicates the OR of 1 which implies no association. AMP, ampicillin; TE, tetracycline; CRO, ceftriaxone, CTX, cefotaxime; CAZ, ceftazidime; FEP, cefepime; CT, colistin; CIP, ciprofloxacin; NA, nalidixic acid; AZM, azithromycin; SXT, trimethoprim-sulfamethoxazole.</p

Neighbor-joining tree based on ribosomal MLST (rMLST) allele sequences for 30 <i>E</i>. <i>coli</i> isolates.

Sequence types (STs), ars operon, and minimum inhibitory concentration (MIC) to arsenite are shown next to the tree. Colored leaves and shaded regions indicate the phylogroups. RH and RM in isolate ID indicate if the isolate was obtained from Hajiganj (high arsenic exposure) or Matlab (low arsenic exposure) areas, respectively. WU, MS, and CS in isolate ID indicate isolates from drinking water, mother stool, and child stool, respectively.</p

The abundance of total <i>E</i>. <i>coli</i> and antibiotic-resistant <i>E</i>. <i>coli</i> in water and stool samples from mothers and children in Hajiganj and Matlab.

The number of A) total E. coli, B) third-generation cephalosporin-resistant E. coli, and C) fluoroquinolone-resistant E. coli in drinking water (WU), mother stool (MS), and child stool (CS) samples collected from the Hajiganj (RH, high arsenic exposure) and Matlab (RM, low arsenic exposure) areas were counted from the plates for each of the samples as described in the Methods section. The numbers were calculated as either CFU/100ml for water samples or CFU/g for MS and CS samples and transformed to log10 count. Each box represents the first and third quartile number of E. coli (log10 transformed) for one type of sample with the black bars representing the median count and error bars representing the minimum and maximum range of the counts, respectively. The asterisks indicate significance (***p <0.001). ‘ns’ indicates not significant.</p

Antibiotic susceptibility of <i>E</i>. <i>coli</i> isolates.

Antibiotic resistance of all E. coli isolates in A) drinking water, B) mother stool, and C) child stool samples collected from Hajiganj (high arsenic exposure) and Matlab (low arsenic exposure) was determined against 16 commercially available antibiotics as described in the Methods section. AMP, ampicillin; CN, gentamycin; TE, tetracycline; MEM, meropenem; IMP, imipenem; CRO, ceftriaxone, CTX, cefotaxime; CAZ, ceftazidime; FEP, cefepime; CT, colistin; CIP, ciprofloxacin; NA, nalidixic acid; AZM, azithromycin; SXT, trimethoprim-sulfamethoxazole; F, nitrofurantoin; C, chloramphenicol. ‘n’ indicates the number of E. coli isolates. (TIFF)</p

Arsenic concentration in water samples from Hajiganj and Matlab areas.

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