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Antibiotic resistance in Vibrio cholerae: Understanding the ecology of resistance genes and mechanisms
Bhabatosh Das | Jyoti Verma | Pawan Kumar | Amit Ghosh | Thandavarayan Ramamurthy
Date of Publication:
February 29, 2020
The unique genetic makeup and remarkable competency of Vibrio cholerae are the key factors that help the cholera pathogen adapt rapidly to adverse environmental conditions and resist the detrimental effect of antimicrobial agents. In the last few decades, V. cholerae that causes acute watery diarrhoeal disease cholera has emerged as a notorious multidrug resistant enteric pathogen. Although chromosomal mutations can contribute to antimicrobial resistance (AMR), the frequent acquisition of extrachromosomal mobile genetic elements from closely/distantly related bacterial species are major players in V. cholerae drug resistance. Whole genome sequence analysis of clinical and environmental V. cholerae strains revealed that the genome of most of the recent isolates harbour integrating conjugative elements, plasmids, superintegron, transposable elements and insertion sequences, which are the key carriers of genetic traits encoding antimicrobial resistance function. Different antimicrobial resistance genes identified in V. cholerae can contribute in antibiotic resistance by facilitating one of the following three mechanisms; reduced permeability or active efflux of the antibiotics, (alteration of the antibiotic targets by introducing post-transcriptional/translational modifications and (hydrolysis or chemical modification of antibiotics. We present an overview of the present insights on the emergence and mechanisms of AMR in V. cholerae.
A Metagenomic Approach to Evaluating Surface Water Quality in Haiti
Monika A. Roy | Jean M. Arnaud | Paul M. Jasmin | Steve Hamner | Nur A. Hasan | Rita R. Colwell | Timothy E. Ford
Date of Publication:
International Journal of Environmental Research and Public Health
The cholera epidemic that occurred in Haiti post-earthquake in 2010 has resulted in over 9000 deaths during the past eight years. Currently, morbidity and mortality rates for cholera have declined, but cholera cases still occur on a daily basis. One continuing issue is an inability to accurately predict and identify when cholera outbreaks might occur. To explore this surveillance gap, a metagenomic approach employing environmental samples was taken. In this study, surface water samples were collected at two time points from several sites near the original epicenter of the cholera outbreak in the Central Plateau of Haiti. These samples underwent whole genome sequencing and subsequent metagenomic analysis to characterize the microbial community of bacteria, fungi, protists, and viruses, and to identify antibiotic resistance and virulence associated genes. Replicates from sites were analyzed by principle components analysis, and distinct genomic profiles were obtained for each site. Cholera toxin converting phage was detected at one site, and Shiga toxin converting phages at several sites. Members of the Acinetobacter family were frequently detected in samples, including members implicated in waterborne diseases. These results indicate a metagenomic approach to evaluating water samples can be useful for source tracking and the surveillance of pathogens such as Vibrio cholerae over time, as well as for monitoring virulence factors such as cholera toxin.
Environmental bacteriophages active on biofilms and planktonic forms of toxigenic Vibrio cholerae: Potential relevance in cholera epidemiology
Iftekhar Bin Naser | M. Mozammel Hoque | Ahmed Abdullah | S. M. Nayeemul Bari | Amar N. Ghosh | Shah M. Faruque
Date of Publication:
In cholera-endemic areas, toxigenic Vibrio cholerae persist in the aquatic ecosystem mostly in a biofilm-associated state in which the bacteria remain embedded in an exopolysaccharide matrix. The biofilm-associated cells often enter into a dormant form referred to as conditionally viable environmental cells, which resist cultivation on routine bacteriological media. However, these cells can naturally resuscitate into the active planktonic form through various mechanisms, multiply, and cause epidemics of cholera. This study was conducted to study possible effects of environmental bacteriophages on the prevalence and distribution of the pathogen between the biofilm associated state, and the planktonic form. Besides potential applicability in phage-mediated control of cholera, our results have relevance in appreciating possible intricate role of diverse environmental phages in the epidemiology of the disease, since both biofilms and phages influence the prevalence and infectivity of V. cholerae in a variety of ways.