Characterisation and mobilisation of IncA/C plasmid-mediated antibiotic resistance in Edwardsiella ictaluri

ABSTRACT: Objectives: Edwardsiella ictaluri is an important pathogen in farmed raised catfish. Recently, we showed that resistance to tetracycline and florfenicol in the E. ictaluri MS-17–156 strain isolated from channel catfish was facilitated by acquisition of a 135 kb plasmid (named pEIMS-171561). Methods: We described the genetic structure of pEIMS-171561. Plasmid copy number and stability within E. ictaluri strain MS-17–156 was determined. We also investigated the in vitro and in vivo transferability of pEIMS-171561 using catfish as a model for in vivo transfer. Results: pEIMS-171561 belonged to the IncA/C group and contained florfenicol efflux major facilitator superfamily (MFS) (floR), sulfonamides (sul2), and tetracycline efflux MFS (tetD) genes. The plasmid contained two conjugative transfer-associated regions and encoded six transposases and insertion sequences. In vitro conjugation experiments demonstrated that the IncA/C plasmid can transfer from E. ictaluri to Escherichia coli. The plasmid was stable in E. ictaluri without selection pressure for 33 days. We showed that pEIMS-171561 did not transfer from E. ictaluri MS-17–156 to endogenous microbiota in catfish. Moreover, we could not detect in vivo conjugal transfer of pEIMS-171561 from E. ictaluri to E. coli. Results from real-time PCR revealed upregulation of the floR gene in the intestines of catfish receiving florfenicol-medicated feed, compared with that in catfish receiving unmedicated feed. Conclusion: This study demonstrated that pEIMS-171561 did not disseminate from E. ictaluri to gut microbiota under selective pressure. This result suggests a limited role of the fish microbiota as a reservoir for this plasmid and for the spread of resistance

Vibrio cholerae Transmits Through Water Among the Household Contacts of Cholera Patients in Cholera Endemic Coastal Villages of Bangladesh, 2015–2016 (CHoBI7 Trial)

Recurrent cholera causes significant morbidity and mortality in cholera endemic estuarine areas of Bangladesh. There have been limited studies to investigate the transmission patterns of V. cholerae associated with cholera in Bangladesh. In this study, we characterized V. cholerae serogroup O1 isolated from 30 cholera patients, 76 household contacts, 119 stored drinking water samples, and 119 water source samples in Bakerganj and Mathbaria, two cholera endemic coastal regions in Bangladesh. Results of phenotypic and molecular characterization of V. cholerae isolates (n = 56) confirmed them to be toxigenic belonging to serogroup O1 biotype El Tor (ET), and possessing cholera toxin of the classical biotype (altered ET). Molecular fingerprinting of the V. cholerae O1 of clinical and water origins determined by PFGE of Not-I- digested genomic DNA showed them to be closely related, as the PFGE banding patterns were highly homogenous. Phylogenetic analysis using dendrogram of cholera patients, household contacts, and household groundwater sources showed isolates within households to be clonally linked, suggesting water as an important vehicle of transmission of cholera in the coastal villages of Bangladesh. Transmission of toxigenic V. cholerae O1 through drinking water in cholera endemic rural settings underscores the urgent need for evidence based water, sanitation, and hygiene interventions promoting safe drinking water to prevent morbidity and mortality related to cholera and other enteric infections in Bangladesh

Transmission of Infectious Vibrio cholerae Through Drinking Water among the Household Contacts of Cholera Patients (CHoBI7 Trial)

Recurrent cholera causes significant morbidity and mortality among the growing population of Dhaka, the capital city of Bangladesh. Previous studies have demonstrated that household contacts of cholera patients are at >100 times higher risk of cholera during the week after the presentation of the index patient. Our prospective study investigated the mode of transmission of Vibrio cholerae, the cause of cholera, in the households of cholera patients in Dhaka city. Of total 420 rectal swab samples analyzed from 84 household contacts and 330 water samples collected from 33 households, V. cholerae was isolated from 20%(17/84) of household contacts, 18%(6/33) of stored drinking water, and 27%(9/33) of source water samples. Phenotypic and molecular analyses results confirmed the V. cholerae isolates to be toxigenic and belonging to serogroup O1 biotype El Tor (ET) possessing cholera toxin of classical biotype (altered ET). Phylogenetic analysis by pulsed-field gel electrophoresis (PFGE) showed the V. cholerae isolates to be clonally linked, as >95% similarity was confirmed by sub-clustering patterns in the PFGE (NotI)-based dendrogram. Mapping results showed cholera patients to be widely distributed across 25 police stations with the highest incidence in households near the major rivers and polluted water bodies. The data presented on the transmission of infectious V. cholerae within the household contacts of cholera patients through drinking water underscores the need for safe water to prevent spread of cholera and related deaths in Dhaka city

Randomized Controlled Trial of Hospital-Based Hygiene and Water Treatment Intervention (CHoBI7) to Reduce Cholera

The risk for cholera infection is >100 times higher for household contacts of cholera patients during the week after the index patient seeks hospital care than it is for the general population. To initiate a standard of care for this high-risk population, we developed Cholera-Hospital-Based-Intervention-for-7-Days (CHoBI7), which promotes hand washing with soap and treatment of water. To test CHoBI7, we conducted a randomized controlled trial among 219 intervention household contacts of 82 cholera patients and 220 control contacts of 83 cholera patients in Dhaka, Bangladesh, during 2013–2014. Intervention contacts had significantly fewer symptomatic Vibrio cholerae infections than did control contacts and 47% fewer overall V. cholerae infections. Intervention households had no stored drinking water with V. cholerae and 14 times higher odds of hand washing with soap at key events during structured observation on surveillance days 5, 6, or 7. CHoBI7 presents a promising approach for controlling cholera among highly susceptible household contacts of cholera patients

Additional file 2: Table S2. of Genetic relatedness of Vibrio cholerae isolates within and between households during outbreaks in Dhaka, Bangladesh

SNP List of Chromosomes and Genes using reference 300,043. (XLSX 19 kb

A prospective cohort study comparing household contact and water <i>Vibrio cholerae</i> isolates in households of cholera patients in rural Bangladesh

<div><p>Background</p><p>Household contacts of cholera patients are at a 100 times higher risk of developing cholera than the general population. The objective of this study was to examine the incidence of <i>V</i>. <i>cholerae</i> infections among household contacts of cholera patients in a rural setting in Bangladesh, to identify risk factors for <i>V</i>. <i>cholerae</i> infections among this population, and to investigate transmission pathways of <i>V</i>. <i>cholerae</i> using multilocus variable-number tandem-repeat analysis (MLVA).</p><p>Methodology/Principal findings</p><p>Stool from household contacts, source water and stored water samples were collected from cholera patient households on Day 1, 3, 5, and 7 after the presentation of the index patient at a health facility. Two hundred thirty clinical and water <i>V. cholerae</i> isolates were analyzed by MLVA. Thirty seven percent of households had at least one household contact with a <i>V</i>. <i>cholerae</i> infection. Thirteen percent of households had <i>V</i>. <i>cholerae</i> in their water source, and 27% had <i>V</i>. <i>cholerae</i> in stored household drinking water. Household contacts with <i>V</i>. <i>cholerae</i> in their water source had a significantly higher odds of symptomatic cholera (Odds Ratio (OR): 5.49, 95% Confidence Interval (CI): 1.07, 28.08). Contacts consuming street vended food had a significantly higher odds of a <i>V</i>. <i>cholerae</i> infection (OR: 9.45, 95% CI: 2.14, 41.72). Older age was significantly associated with a lower odds of a <i>V</i>. <i>cholerae</i> infection (OR: 0.96, 95% CI: 0.93, 0.99). Households with both water and clinical <i>V</i>. <i>cholerae</i>-positive samples all had isolates that were closely related by MLVA.</p><p>Conclusions/Significance</p><p>These findings emphasize the need for interventions targeting water treatment and food hygiene to reduce <i>V</i>. <i>cholerae</i> infections.</p></div

Household and individual level <i>V</i>. <i>cholerae</i> infection characteristics (visits 1–4), rural Bangladesh.

<p>Household and individual level <i>V</i>. <i>cholerae</i> infection characteristics (visits 1–4), rural Bangladesh.</p