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

Prevalence of perturbed gut microbiota in pathophysiology of arsenic-induced anxiety- and depression-like behaviour in mice

Severe toxic effects of arsenic on human physiology have been of immense concern worldwide. Arsenic causes irrevocable structural and functional disruption of tissues, leading to major diseases in chronically exposed individuals. However, it is yet to be resolved whether the effects result from direct deposition and persistence of arsenic in tissues, or via activation of indirect signaling components. Emerging evidences suggest that gut inhabitants play an active role in orchestrating various aspects of brain physiology, as the gut-brain axis maintains cognitive health, emotions, learning and memory skills. Arsenic-induced dysbiosis may consequentially evoke neurotoxicity, eventually leading to anxiety and depression. To delineate the mechanism of action, mice were exposed to different concentrations of arsenic. Enrichment of Gram-negative bacteria and compromised barrier integrity of the gut enhanced lipopolysaccharide (LPS) level in the bloodstream, which in turn elicited systemic inflammation. Subsequent alterations in neurotransmitter levels, microglial activation and histoarchitectural disruption in brain triggered onset of anxiety- and depression-like behaviour in a dose-dependent manner. Finally, to confirm whether the neurotoxic effects are specifically a consequence of modulation of gut microbiota (GM) by arsenic and not arsenic accumulation in the brain, fecal microbiota transplantations (FMT) were performed from arsenic-exposed mice to healthy recipients. 16S rRNA gene sequencing indicated major alterations in GM population in FMT mice, leading to severe structural, functional and behavioural alterations. Moreover, suppression of Toll-like receptor 4 (TLR4) using vivo-morpholino oligomers (VMO) indicated restoration of the altered parameters towards normalcy in FMT mice, confirming direct involvement of the GM in inducing neurotoxicity through the arsenic-gut-brain axis. This study accentuates the potential role of the gut microbiota in promoting neurotoxicity in arsenic-exposed mice, and has immense relevance in predicting neurotoxicity under altered conditions of the gut for designing therapeutic interventions that will target gut dysbiosis to attenuate arsenic-mediated neurotoxicity.

The zoonotic pathogen Wohlfahrtiimonas chitiniclastica - current findings from a clinical and genomic perspective

The zoonotic pathogen Wohlfahrtiimonas chitiniclastica can cause several diseases in humans, including sepsis and bacteremia. Although the pathogenesis is not fully understood, the bacterium is thought to enter traumatic skin lesions via fly larvae, resulting in severe myiasis and/or wound contamination. Infections are typically associated with, but not limited to, infestation of an open wound by fly larvae, poor sanitary conditions, cardiovascular disease, substance abuse, and osteomyelitis. W. chitiniclastica is generally sensitive to a broad spectrum of antibiotics with the exception of fosfomycin. However, increasing drug resistance has been observed and its development should be monitored with caution. In this review, we summarize the currently available knowledge and evaluate it from both a clinical and a genomic perspective.

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

[This corrects the article DOI: 10.1371/journal.ppat.1010952.].