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. 2022 Aug 22:13:894014.
doi: 10.3389/fmicb.2022.894014. eCollection 2022.

Prevalence of antibiotic resistance genes in drinking and environmental water sources of the Kathmandu Valley, Nepal

Mohan Amarasiri  1 , Tsubasa Takezawa  1 , Bikash Malla  2 , Takashi Furukawa  1 , Jeevan B Sherchand  3 , Eiji Haramoto  2 , Kazunari Sei  1
Affiliations

Prevalence of antibiotic resistance genes in drinking and environmental water sources of the Kathmandu Valley, Nepal

Mohan Amarasiri et al. Front Microbiol. .

Abstract

Antibiotic-resistant bacteria-associated infections are responsible for more than 1.2 million annual deaths worldwide. In low- and middle-income countries (LMICs), the consumption of antibiotics for human and veterinary uses is not regulated effectively. Overused and misused antibiotics can end up in aquatic environments, which may act as a conduit for antibiotic resistance dissemination. However, data on the prevalence of antibiotic resistance determinants in aquatic environments are still limited for LMICs. In this study, we evaluated the prevalence and concentration of antibiotic resistance genes (ARGs) in different drinking and environmental water sources collected from the Kathmandu Valley, Nepal, using droplet digital polymerase chain reaction to understand the current situation of ARG contamination. River water and shallow dug well water sources were the most contaminated with ARGs. Almost all samples contained sul1 (94%), and intI1 and tet(A) were detected in 83 and 60% of the samples, respectively. Maximum ARG concentration varied between 4.2 log10 copies/100 ml for mecA and 9.3 log10 copies/100 ml for sul1. Significant positive correlations were found between ARGs (r > 0.5, p < 0.01), except for mecA, qnrS, and vanA. As sul1 and intI1 were detected in almost all samples, the presence of these genes in a given sample may need to be considered as background antibiotic resistance in LMICs. Therefore, monitoring of ARGs, such as β-lactam ARGs, quinolone resistance genes, and vancomycin resistance genes, may provide a better picture of the antibiotic resistance determinants in aquatic environments of LMICs.

Keywords: Kathmandu Valley; antibiotic resistance genes; aquatic environments; ddPCR; drinking water.

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Conflict of interest statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Figures

FIGURE 1
FIGURE 1
Concentration of antibiotic resistance genes (ARGs) in different drinking and environmental water sources.
FIGURE 2
FIGURE 2
Relative abundance of antibiotic resistance genes (ARGs) in different drinking and environmental water sources.
FIGURE 3
FIGURE 3
Correlation analysis of antibiotic resistance genes (ARGs) and fecal indicator bacteria. Correlation coefficient is shown in the pie, while non-significant correlations (p > 0.01) are kept blank.
FIGURE 4
FIGURE 4
Non-metric multidimensional scaling (NMDS) plot of samples grouped by source type (stress = 0.088).
See this image and copyright information in PMC

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