In a recent study published in The Lancet Microbe, researchers determined the link between improved access to sanitation and better water quality and the human intestines' antibiotic resistance gene (ARG) frequency.
Study: Evaluating the relationship between community water and sanitation access and the global burden of antibiotic resistance: an ecological study. Image Credit: SergeyMironov/Shutterstock.com
Resistance to antibiotics is a significant population health concern, particularly in low-income and middle-income countries (LMICs).
Inadequate water, sanitation, and hygiene (WASH) infrastructure and access to water may exacerbate the spread of antibiotic resistance, as pathogenic bacteria can acquire ARGs through horizontal gene transfer.
Metagenomic sequencing has revealed the widespread prevalence of ARGs among bacteria, highlighting the challenge of preventing pathogens from acquiring them.
About the study
In the present observational ecological study, researchers assessed regional disparities in ARG frequency and investigated whether improper WASH facilities could drive antibiotic resistance.
ARG abundance in human fecal metagenomes and community-level penetration of enhanced sanitation and water quality in a 25.0 km perimeter of the metagenome coordinates.
In January 2021, the researchers obtained georeferenced family survey datasets, which stated the availability of better sanitation and sources of drinkable water from the United States (US) National Center for Biotechnology Information (NCBI) Sequence Read Archive (SRA).
The researchers selected studies from low- and middle-income countries (LMICs) and high-income countries (HICs) to represent different ages and residential locations. The latitude and longitude coordinates were acquired from the metagenomic metadata in the SRA and confirmed with the associated study publication.
Unpublished study authors from Kenya, Mozambique, and Bangladesh supplied additional human fecal metagenomes. The proportion of homes in the predefined area with better sanitation, drinking water, or both was calculated.
Antibiotic consumption estimates, GDP per capita, income categorization by nation, defined daily doses (DDDs) among every 1,000 individuals daily, and population density in 2010 were also derived.
If the geographical area and accessibility to better water supply and sanitation could not be confirmed, metagenomes were excluded. ARGs were discovered by matching reads to ARG amino acid sequences in the Comprehensive Antibiotic Resistance Database (CARD). Paired-end reads were assigned independently, with duplicate mappings deleted.
Generalized linear modeling was performed for the analysis. In addition, sensitivity analyses included radii of 50.0 km and 75.0 km.
Data from the US Agency for International Development and the UNICEF Multiple Indicator Cluster Surveys were gathered for the year closest to the study date (range of dates utilized in the analysis (2010 to 2018).
In total, 36 relevant studies were identified, including 25 LMIC studies, eight HIC studies, and three additional LMIC studies. Due to a lack of information on improved water quality for drinking and sanitation, three research investigations (one and two in Fiji and China, respectively) were removed.
Furthermore, a study conducted in Brazil was rejected because of a high proportion of non-bacterial microbes and the absence of measurable ARGs in numerous metagenomes.
A total of 1,589 metagenomes were identified from 26 nations, and increased availability of sanitation and better water quality was related to a reduction in ARG abundance, imparting resistance to trimethoprim and tetracycline antibiotics.
Africa had the greatest mean ARG abundance compared to the West Pacific, North America, and Europe. In contrast, the southeastern part of Asia had the second highest compared to North America and Europe.
Of the geographical regions investigated with variation in access to WASH, improved sanitation and water supply were related to the greatest decrease in ARGs in southeastern Asia. Tetracycline resistance was ubiquitous throughout all regions.
The link between better sanitation and water supply and ARG richness was higher in cities than in remote regions. The most abundant bacterial families among all metagenomes were Bacteroidaceae, Prevotellaceae, Oscillospiraceae (or Ruminococcaceae), Enterobacteriaceae, and Lachnospiraceae.
The subgroup analysis findings indicated a strong relationship between increased access to sanitation and drinkable water and ARG frequency in the fecal metagenomes was observed with a relatively high frequency of Enterobacteriaceae.
Africa had a greater log10-derived mean Enterobacteriaceae proportion than Europe, North America, or the Western Pacific. Notably, in Madagascar, Mozambique, Indonesia, Italy, and one Bangladesh investigation, the average Enterobacteriaceae proportion exceeded 15%. The sensitivity analysis yielded results.
Increased accessibility to sanitation and safe drinking water was associated with reducing the number of ARGs in the samples.
Of 198 ARGs identified in at least 5.0% of the samples, ermT (MLS), tetM (tetracycline resistance), blaCTX-M (beta-lactamase resistance) and qnrS (fluoroquinolone resistance) are known threats to global public health due to their presence in the genetic makeup of Staphylococcus aureus, Enterococcus faecium, Acinetobacter baumannii, Klebsiella pneumoniae, Enterobacter, and Pseudomonas aeruginosa.
Based on the study's findings, enhancing community access to sanitation and safe drinking water may reduce antibiotic resistance in LMICs.
However, further study is needed to evaluate the relationship between improved WASH and the healthcare burden of antibiotic resistance. The follow-up in future studies must also consider the time required for pre-existing ARG clearance from the human intestine.