Effects of chronic exposure to arsenic on the fecal carriage of antibiotic-resistant Escherichia coli among people in rural Bangladesh Original paper

What was studied?

This study explores the effects of chronic arsenic exposure on the fecal carriage of antibiotic-resistant Escherichia coli (AR-Ec) in a rural population of Bangladesh. The research focused on comparing the prevalence and resistance patterns of AR-Ec isolates in children and mothers from two distinct areas: one with high arsenic exposure (Hajiganj) and the other with low exposure (Matlab). The study sought to understand the co-selection of antibiotic resistance linked to arsenic contamination in drinking water, as arsenic is known to drive resistance mechanisms in bacteria.

Who was studied?

The study involved 50 households from each of the two regions in Bangladesh—Hajiganj, which has high arsenic exposure (>100 μg/L), and Matlab, with low arsenic exposure (<20 μg l). the participants were mothers and their children, particularly focusing on children under one year old. stool samples from both as well drinking water samples, collected for analysis. study aimed to examine how long-term arsenic exposure influences gut microbiome, carriage of antibiotic-resistant e. coli.< p>

Most important findings

The study found a significantly higher prevalence of AR-Ec in children from Hajiganj (94%) compared to those from Matlab (76%), though the prevalence in mothers did not show such a stark difference. The E. coli isolates from the high-arsenic area were more likely to be multidrug-resistant (83%) compared to those from the low-arsenic area (71%). Interestingly, co-resistance to arsenic and antibiotics, particularly third-generation cephalosporins (3GC) and fluoroquinolones (FQ), was more common in Hajiganj. The isolates from Hajiganj also demonstrated a higher frequency of resistance to multiple antibiotic classes, such as penicillin, cephalosporin, tetracycline, and macrolides, compared to those from Matlab. Furthermore, whole-genome sequencing revealed genetic diversity in the isolates, with certain virulence and antibiotic resistance genes being more prevalent in isolates from high-arsenic areas.

The study also highlighted the correlation between arsenic and antibiotic resistance, where arsenic-resistant E. coli isolates were more likely to show resistance to β-lactam antibiotics, such as ampicillin and cefotaxime. In contrast, resistance to tetracycline, trimethoprim-sulfamethoxazole, and ciprofloxacin was less frequent among arsenic-resistant isolates. The research identified several important resistance genes, such as the blaCTX-M-1 for β-lactam resistance, as well as a variety of virulence genes that were present in the isolates from high-arsenic areas.

Key implications

This study has significant implications for public health, particularly in regions with high arsenic contamination. The findings underscore the potential health risks posed by arsenic exposure, which not only affects overall health but also exacerbates the spread of antibiotic-resistant bacteria. The co-selection of arsenic and antibiotic resistance could lead to more severe infections that are harder to treat, especially in children whose gut microbiome is still developing. Additionally, the study suggests that arsenic exposure, even at lower levels through food sources like rice, could contribute to the persistence of antibiotic resistance in communities. These results call for increased monitoring of arsenic exposure in water sources and a closer look at the role of diet in arsenic-mediated resistance. Addressing both environmental and microbial factors could play a crucial role in mitigating the health risks associated with arsenic contamination.