Vibrio Cholerae O1 El Tor Research Articles

Vibrio cholerae O1 El Tor strains linked to global cholera show region-specific patterns by pulsed-field gel electrophoresis.

Vibrio cholerae O1 El Tor, causative agent of the ongoing seventh cholera pandemic, is native to the aquatic environment of the Ganges Delta, Bay of Bengal (GDBB). Recent studies traced pandemic strains to the GDBB and proposed global spread of cholera had occurred via intercontinental transmission. In the research presented here, NotI-digested genomic DNA extracted from V. cholerae O1 clinical and environmental strains isolated in Bangladesh during 20042014 was analyzed by pulsed-field gel electrophoresis (PFGE). Results of cluster analysis showed 94.67% of the V. cholerae strains belonged to clade A and included the majority of clinical strains of spatio-temporal origin and representing different cholera endemic foci. The rest of the strains were estuarine, all environmental strains from Mathbaria, Bangladesh, and occurred as singletons, clustered in clades B and C, or in the small clades D and E. Cluster analysis of the Bangladeshi strains and including 157 El Tor strains from thirteen countries in Asia, Africa, and the Americas revealed 85% of the total set of strains belonged to clade A, indicating all were related, yet did not form an homogeneous cluster. Overall, 15% of the global strains comprised multiple small clades or segregated as singletons. Three sub-clades could be discerned within the major clade A, reflecting distinct lineages of V. cholerae O1 El Tor associated with cholera in Asia, Africa, and the Americas. The presence in Asia and the Americas of non-pandemic V. cholerae O1 El Tor populations differing by PFGE and from strains associated with cholera globally suggests different ecotypes are resident in distant geographies.

Pre-emptive oral cholera vaccine (OCV) mass vaccination campaign in Cuamba District, Niassa Province, Mozambique: feasibility, vaccination coverage and delivery costs using CholTool

IntroductionMozambique suffers from regular floods along its principal river basins and periodic cyclones that resulted in several cholera epidemics during the last decades. Cholera outbreaks in the recent 5 years...

Molecular characterization of Vibrio cholerae O1 El Tor strains in Malaysia revealed genetically diverse variant lineages.

Vibrio cholerae O1 El Tor variants have been the major causative agents of cholera worldwide since their emergence in the 2000s. Cholera remains endemic in some regions in Malaysia. Therefore, we aimed to investigate the genetic characteristics of the V. cholerae O1 El Tor strains associated with outbreaks and sporadic cases to elucidate the molecular evolution among the strains circulating in this region. A total of 45 V. cholerae O1 El Tor strains isolated between 1991 and 2011 were examined. All strains were subjected to phenotypic characterization, and molecular characterization including detection of virulence genes and CTX prophage (CTXΦ) by Polymerase Chain Reaction (PCR) and genotyping by Pulsed-Field Gel Electrophoresis (PFGE). All strains were phenotypically confirmed as El Tor biotype and were mostly Ogawa serotype (96%). Antimicrobial susceptibility testing showed that the outbreak strains isolated in 1991 (Sabah) and 2009 (Terengganu) were all multidrug-resistant while the sporadic strains were resistant to erythromycin and furazolidone only. All strains (n=45) were resistant to erythromycin. The virulence genes ctxA, ctxB, ompW, rfb, rtxC, tcpA, tcpI, rstR, zot and hlyA were present in all strains. The outbreak strains isolated in 1991 harboured El Tor cholera toxin gene (ctxB3) while sporadic strains from 2004 to 2011 harboured classical ctxB1. Four distinctive CTXΦ arrays were identified among the El Tor variants, one of which co-occurred with El Tor strains during the 2009 outbreak in Terengganu. PFGE analysis revealed that a genetically diverse El Tor variants population persisted in Sabah. The co-existence of multiple El Tor variants together with the prototypic El Tor strains suggested a multiclonal emergence of V. cholerae O1 El Tor variants in this region.

Crystal structure of oligoribonuclease from Vibrio cholerae O1 El Tor with bound peptide.

Oligoribonuclease (Orn), a member of the DEDDh superfamily, can hydrolyse 2-5 nt nanoRNAs to mononucleotides. It is involved in maintaining the intracellular levels of RNA, c-di-GMP signalling and transcription initiation in many bacterial species. Here, the crystal structure of Orn from Vibrio cholerae O1 El Tor (VcOrn) is reported at a resolution of 1.7 Å. VcOrn, which consists ofnine α-helices and six β-strands, crystallizes with a single monomer in the asymmetric unit but forms a homodimer via crystallographic twofold symmetry. Electron density is observed in the active pocket that corresponds to an intersubunit N-terminal expression tag with sequence GPLGSHHH. The positively charged N-terminal tag binds in the negatively charged nucleotide-binding pocket with a buried surface area of ∼500 Å2. The N-terminal tag interacts with VcOrn via π-π stacking with two conserved residues involved in nucleotide binding, as well as via salt bridges and hydrogen bonds. The structure reported here reveals that the active pocket can accommodate polypeptides in addition to nucleotides, thus providing an important starting point for investigation into substrate modification and inhibitor design targeting VcOrn.

El Tor cholera at the contemporary stage of the seventh pandemia: pathogen evolution, clinical and epidemiological features, laboratory diagnostics

The phenotypic and molecular genetic properties of 133 strains of genetically modified (genovariant) Vibrio cholerae O1 El Tor biovar isolated from patients in Dagestan (1993, 1994, 1998), and compared with 246 strains of a typical toxigenic cholera vibrio El Tor biovar isolated in 1970–1990 at the Caucasus Region. It was found that 48.7% of the studied genetically modified strain variants had mixed phenotypic properties of the El Tor and classic biovars that evidences about a need to include the marker genes of the classical biovar (ctxBCl+, rtxC–) and the El Tor biovar (ctxBEl+, rtxC+) into the existing biotyping scheme. The genes of the El Tor biovar, isolated from patients in Dagestan, contain in addition to the El Tor ones, the genes of the classical biovar (ctxBCl and/or rstRCl), as well as the typical toxigenic cholera vibrios of El Tor, islands of persistence (EPI), pathogenicity (VPI-1 and VPI-2) and pandemicity (VSP-I and VSP-II). However, only the El Tor biovar genovariants were found to bear an integrative and conjugative SXT element with antibiotic polyresistance genes. Epidemic cholera outbreaks caused by the El Tor biovar genovariants that occurred in 1993–1998 at the Caucasus Region, correspond to classical (Asian) cholera based on disease severity. The epidemiological features of modern cholera were studied: the main way for transmission via fecal-oral route for typical El Tor cholera vibrio is waterborne, whereas for the El Tor gene variant — household. Primary infections upon water drinking and using domestic water from surface water bodies infected with typical El Tor vibrios occur outside the family hearth. In case of cholera caused by hybrid El Tor variants, infection is transmitted among family members via domestic factors under low sanitary level. The development of laboratory diagnostics and epidemiological surveillance of modern El Tor cholera is based on the development of PCR test systems taking into account the evolutionary genome transformations.

The Evolution of Phenotypic Properties and Molecular Genetic Organization of Genomes of Vibrio Cholerae O1 El Tor Variant Strains Isolated from Patients and Environmental Objects in the Caucasus in 1970–1998

Summary. Introduction: The formation of highly pathogenic strains of Vibrio cholerae resistant to antibiotics determines the pathogenesis, clinical picture, epidemiology, and laboratory diagnosis of cholera. It is necessary to study the structure of the genome of V. cholerae of any serological groups isolated during routine monitoring of environmental objects or patients with acute intestinal infections in order to detect toxigenic genes inherent to epidemic strains of V. cholerae O1. Our objective was to study changes in phenotypic properties and molecular genetic bases of persistence, epidemic and pathogenetic potential of El Tor variant of Vibrio cholerae O1 isolated from patients and environmental objects in the Caucasus in 1970–1998. Materials and methods: We studied phenotypic and molecular genetic characteristics of 32 V. cholerae O1 strains isolated from patients and environmental objects in the Caucasus (1970–1998) using a microbiological assay and PCR test, respectively. Results: We established that the following biotypes of V. cholerae O1 were found in the Caucasus: a) El Tor, ctxA–, and Hly+ nontoxigenic strains of V. cholerae O1, typical in their phenotypic and molecular genetic properties. Their toxigenic potential is represented by exo- and endotoxins different from the enterotoxin of toxigenic V. cholerae; b) toxigenic El Tor, ctxABEL+, rtхC+, and Hly– variant biotypes of V. cholerae O1, typical in their phenotypic, molecular and genetic properties during outbreaks of invasive cholera, producing a CT-2 enterotoxin and containing genes responsible for persistent, pathogenic and pandemic potential, and c) typical in terms of their main phenotypic characteristics but molecularly genetically altered variants (hybrids) of El Tor variant of Vibrio cholerae O1 including El Tor ctxABCL+, rtxC+, Hly–. Conclusions: The main manifestation of evolutionary changes in a typical toxigenic vibrio of the El Tor variant biotype was the replacement of the ctxBEl gene in its genome with the ctxBCL gene encoding the classical type of enterotoxin (CT-1), which significantly increased the persistent, toxic, epidemic, and pandemic potential of genetically modified variants of El Tor biotype Vibrio cholerae. The genome of these strains contains an integrative and conjugative element SXT with genes for antibiotic multiresistance.

Development of Hillchol®, a low-cost inactivated single strain Hikojima oral cholera vaccine

Cholera remains an important global health problem with up to 4 million cases and 140,000 deaths annually. Oral cholera vaccines (OCVs) are now a cornerstone of the WHOs “Ending Cholera – A Global Roadmap to 2030” global program for the eventual elimination of cholera. There are currently three WHO prequalified OCVs available, Dukoral®, Shanchol® and Euvichol-Plus®. These vaccines are effective but due to a multiple strain composition and two different methods of inactivation, are complex and costly to manufacture. We describe here the characterization and industrial scale development of Hillchol®; a novel, likely affordable single-component OCV for low and middle-income countries. Hillchol® consists of formalin-inactivated bacteria of a stable recombinant Vibrio cholerae O1 El Tor Hikojima serotype strain expressing approximately 50% each of Ogawa and Inaba O1 LPS antigens. The novel OCV can be manufactured on an industrial scale at a low cost. Hillchol® was well tolerated in animal toxicology studies and shown to have non-inferior oral immunogenicity in mice for both intestinal-mucosal and serological immune responses when compared with a WHO-prequalified OCV. The optimized production of this single component OCV will reduce cost of OCV production and thus substantially increase vaccine availability. Based on these results, Hillchol® has been produced at a GMP facility and used successfully for clinical phase I/II studies.

Genome Sequence of a Pathogenic Vibrio cholerae O1 El Tor Strain Defective for the Entire Vibrio Pathogenicity Island 1, Isolated in Eastern Democratic Republic of the Congo.

We report here a complete genome sequence of a Vibrio cholerae O1 El Tor (Inaba; sequence type 515 [ST515]) strain isolated from a cholera patient in North Kivu Province, Democratic Republic of the Congo (DRC), which showed a complete deletion (∼80 kb) of the Vibrio pathogenicity island 1.

Transmissive Antibiotic Resistance, Associated with the SXT Element, in Cholera Vibrios Isolated in the Territory of Russia

Aim. Detection of SXT elements in cholera vibrios O1 and nonO1/nonO139 serogroups and study of the effectiveness of their conjugative transmission to Escherichia coli cells.Materials and methods. In conjugation experiments, Vibrio cholerae O1 El Tor (3) and V. cholerae nonO1/ nonO139 (3) strains were used as donors. Donor strains, recipients, and transconjugants were tested in realtime PCR for sensitivity to antibiotics and for the presence of drug resistance genes and integrase gene (int). Electrophoresis was carried out on a 0.7% agarose gel with ethidium bromide staining.Results. Resistance to chloramphenicol, trimethoprim/sulfamethoxazole, streptomycin was transmitted in conjugation experiments with a frequency of 2.1 × 10–9–7.1 × 10–9. The genes int and dfrA1 (resistance to trimethoprim/sulfamethoxazole) were found in most V. cholerae strains, and were stably transmitted to E. coli QD Rif r cells and in reverse crosses of V. cholerae O1 El Tor 5879 Nalr .Conclusion. The detection of the SXT element in V. cholerae strains and its successful horizontal transfer emphasize the need to detect such mobile genetic elements to control the spread of antibiotic resistance in V. cholerae.

A Point Mutation in carR Is Involved in the Emergence of Polymyxin B-Sensitive Vibrio cholerae O1 El Tor Biotype by Influencing Gene Transcription.

Antimicrobial peptides play an important role in host defense against Vibrio cholerae Generally, the V. cholerae O1 classical biotype is polymyxin B (PB) sensitive and El Tor is relatively resistant. Detection of classical biotype traits like the production of classical cholera toxin and PB sensitivity in El Tor strains has been reported in recent years, including in the devastating Yemen cholera outbreak during 2016-2018. To investigate the factor(s) responsible for the shift in the trend of sensitivity to PB, we studied the two-component system encoded by carRS, regulating the lipid A modification of El Tor vibrios, and found that only carR contains a single nucleotide polymorphism (SNP) in recently emerged PB-sensitive strains. We designated the two alleles present in PB-resistant and -sensitive strains carRr and carRs alleles, respectively, and replaced the carRs allele of a sensitive strain with the carRr allele, using an allelic-exchange approach. The sensitive strain then became resistant. The PB-resistant strain N16961 was made susceptible to PB in a similar fashion. Our in silico CarR protein models suggested that the D89N substitution in the more stable CarRs protein brings the two structural domains of CarR closer, constricting the DNA binding cleft. This probably reduces the expression of the carR-regulated almEFG operon, inducing PB susceptibility. Expression of almEFG in PB-sensitive strains was found to be downregulated under natural culturing conditions. In addition, the expression of carR and almEG decreased in all strains with increased concentrations of extracellular Ca2+ but increased with a rise in pH. The downregulation of almEFG in CarRs strains confirmed that the G265A mutation is responsible for the emergence of PB-sensitive El Tor strains.

Evaluation of antibody responses to outer membrane vesicles (OMVs) and killed whole cell of Vibrio cholerae O1 El Tor in immunized mice

Cholera disease remains an important global health problem affecting 3-5 million subjects worldwide. Outer membrane vesicles (OMVs) have been found in a variety of Gram-negative bacteria and act as protective transport vesicles. The aim of this study was to evaluate Immune responses against Vibrio cholerae O1 El Tor clinical strain OMV and compare it with killed whole cell (KWC), complex of (KWC-OMV) as well as the internationally licensed oral cholera vaccine, Dukoral, in serum and intestinal secretions of mice. OMVs were prepared by using modified detergent-centrifugation procedure from V. cholerae O1 El Tor clinical strain from 2005 outbreak. The ultrastructure and content of OMVs were investigated via the Scanning Electron Microscopy (SEM) and SDS-PAGE analysis. Three doses of oral immunization were adjusted and total IgG and IgA in serum and intestinal secretion were measured by enzyme-linked immunosorbent assay (ELISA). Extracted OMVs from the V. cholerae were spherical vesicles with a size ranging from 10 to 300 nm. OMV-immunized mice showed an increased level of total IgG and IgA both in serum and intestinal secretion when compared to the negative controls. Also, there existed a higher level of secretory IgA than the total IgG, suggesting the most of protection against V. cholerae colonization provided by sIgA. Our findings revealed that oral immunization with V. cholerae OMVs might induce a long-term immunity, especially when administered in combination with KWC. This study tested the adjuvant activity of OMVs and may be useful in future nano vaccine research.

ESTIMATION OF ANTIBACTERIAL EFFECT ON VIBRIO CHOLERAE (ON THE EXAMPLE OF THE SUBSTANCE ACETYL-N- CYSTEINE–L)

We studied the effect of the substance acetyl-N-cysteine-L on cholera Vibrio. Its minimum inhibitory concentration for the strains of Vibrio cholerae El Tor O1 and O139 serogroup was 1–2.5 mg/ml in solid nutrient media - Martin's agar (pH 7.6) and LB (pH 7.2), while in Bhascaran synthetic medium, using glucose (0.1per cent) as the sole carbon source, N-acetyl-β-D-glucosamine (0.05 per cent) or colloidal chitin (0.027 per cent) it was reduced to 50–250 μg/ml. The ability of the substance acetyl-N-cysteine-L substance to suppress the activity of the purified enzyme N-acetyl-β-D-glucosaminidase (chitobiasis) was found. Antibacterial effect detected of the substance acetyl-N-cysteine-L against the strains of Vibrio cholerae El Tor O1 and O139 serogroups with different epidemic significance (presence / absence of ctxAB and tcpA genes) indicates the advisability of considering the issue on the possibility of including this substance in composition of solution components used in the rehydration therapy of diarrheal diseases cases.

Concerning imported cases of cholera in the city of Almaty, Kazakhstan, 2017

In 2017, from October 15 to November 21, 5 cholera cases imported from India – 3 patients and 2 carriers of V. cholerae – were recorded in Almaty. The patients recovered from the disease. Objective of the study was to characterize the imported cases of cholera and investigate the properties of cholera vibrio strains isolated from patients and carriers of V. cholerae. Materials and methods. Revised were the medical records; blood sera, feces from patients and contact persons were assayed. Studied were sensitivity spectrum to antibacterial preparations of isolated V. cholerae strains according to the “Methodological guidelines on laboratory diagnosis of cholera”, dated September 27, 2010; No 252. Epidemiological, microbiological, immunological and molecular-genetic methods were applied for investigation. Results and conclusions. Consequently to molecular genetic studies, genes of specificity, wbeN and toxicity (epidemic significance), ctxA, tcpA were detected in samples from 3 patients and 2 contact persons. The isolated strains were identified as Vibrio cholerae O1 Eltor Inaba in two cases, and in one case – as Vibrio cholerae O1 Eltor Hykoshima, Heiberg group I, toxigenic, hemolysis negative in Greig test, virulent, highly sensitive to ciprofloxacin, doxycilin, erythromycin, tetracycline and moderately sensitive to levomycetin. It was established that the country of export in all the cases was India. Relevant anti-epidemic and preventive measures were undertaken to localize and eradicate the foci in order to prevent possible threat of epidemic spread of infections among the population.

Vibrio cholerae accessory colonisation factor AcfC: a chemotactic protein with a role in hyperinfectivity

Vibrio cholerae O1 El Tor is an aquatic Gram-negative bacterium responsible for the current seventh pandemic of the diarrheal disease, cholera. A previous whole-genome analysis on V. cholerae O1 El Tor strains from the 2010 epidemic in Pakistan showed that all strains contained the V. cholerae pathogenicity island-1 and the accessory colonisation gene acfC (VC_0841). Here we show that acfC possess an open reading frame of 770 bp encoding a protein with a predicted size of 28 kDa, which shares high amino acid similarity with two adhesion proteins found in other enteropathogens, including Paa in serotype O45 porcine enteropathogenic Escherichia coli and PEB3 in Campylobacter jejuni. Using a defined acfC deletion mutant, we studied the specific role of AcfC in V. cholerae O1 El Tor environmental survival, colonisation and virulence in two infection model systems (Galleria mellonella and infant rabbits). Our results indicate that AcfC might be a periplasmic sulfate-binding protein that affects chemotaxis towards mucin and bacterial infectivity in the infant rabbit model of cholera. Overall, our findings suggest that AcfC contributes to the chemotactic response of WT V. cholerae and plays an important role in defining the overall distribution of the organism within the intestine.

THE EFFECT OF N-ACETYL-L-CYSTEINE ON BIOFILM OF VIBRIO CHOLERAE

Aim. To study the effect of N-acetyl-L-cysteine on biofilm of V. cholerae of different sero-groups isolated from various sources and with different epidemiological significance (the presence/ absence of the ctx AB genes and tcpA). Materials and methods. Bacterial eiiltiire of Vibrio cholerae El Tor O1 and O139 serogroups were grown as biolms. We have estimated the influence of the drug N-acetyl-L-cysteine at a concentration of 0.5 - 4 mg/ml on the formation, of the formed biofilm and in planktonic form. Results. Discovered antibacterial activity of N-acetyl-L-cysteine. Noted that it was influenced as in the formation, of the already formed biofilm and the planktonic form, the representatives of the Vibrio cholerae El Tor O1 and O139 serogroups in concentrations of 2 - 4 mg/ml, showing an antibacterial effect regardless of the presence/absence of genes ctx and tcpA AB. Conclusion. Identified the antibacterial action of the drug N-acetyl-L-cysteine against biofilm of V. cholerae indicates the desirability of considering the possibility of using drug therapy in cases variety of diseases caused by causative agents II - IV groups pathogenicity.

Analysis of Vibrio seventh pandemic island II and novel genomic islands in relation to attachment sequences among a wide variety of Vibrio cholerae strains.

ABSTRACT Vibrio cholerae O1 El Tor, the pathogen responsible for the current cholera pandemic, became pathogenic by acquiring virulent factors including Vibrio seventh pandemic islands (VSP)‐I and −II. Diversity of VSP‐II is well recognized; however, studies addressing attachment sequence left (attL) sequences of VSP‐II are few. In this report, a wide variety of V. cholerae strains were analyzed for the structure and distribution of VSP‐II in relation to their attachment sequences. Of 188 V. cholerae strains analyzed, 81% (153/188) strains carried VSP‐II; of these, typical VSP‐II, and a short variant was found in 36% (55/153), and 63% (96/153), respectively. A novel VSP‐II was found in two V. cholerae non‐O1/non‐O139 strains. In addition to the typical 14‐bp attL, six new attL‐like sequences were identified. The 14‐bp attL was associated with VSP‐II in 91% (139/153), whereas the remaining six types were found in 9.2% (14/153) of V. cholerae strains. Of note, six distinct types of the attL‐like sequence were found in the seventh pandemic wave 1 strains; however, only one or two types were found in the wave 2 or 3 strains. Interestingly, 86% (24/28) of V. cholerae seventh pandemic strains harboring a 13‐bp attL‐like sequence were devoid of VSP‐II. Six novel genomic islands using two unique insertion sites to those of VSP‐II were identified in 11 V. cholerae strains in this study. Four of those shared similar gene clusters with VSP‐II, except integrase gene.

Visualizing a Vibrio cholerae O1 El Tor typing bacteriophage belonging to the Myoviridae group and the packaging of its genomic ends inside the phage capsid

Phage D10, an O1 El Tor tying vibriophage, has been successfully employed to tract the outspread of cholera epidemic. Using Transmission Electron Microscopy and computational image analysis, we have determined the structures of the capsid, head-to-tail connector, the contractile helical tail, the baseplate and combined them to form the complete three-dimensional (3D) D10 phage structure. Using partial denaturation experiments on the genome and using the computed 3D structure of the phage, we have established the packing of the genome ends inside the capsid together with the release styles during the phage infection, respectively. Finally, using the 3D density maps of the different components of the D10 phage, we have presented a simplified picture of morphogenesis of the D10 vibriophage. Using the complete assembled structure of the D10 phage, we have traced the path of the phage genome during the infection process, all the way from the phage head down the tail tube of the tail to the top of the baseplate. To the best of our knowledge, this is first structural study for a long-tailed vibriophage. We have tabulated the structural features of the different components of the phages belonging to the Myoviridae and Siphoviridae. The comparative study suggested the possibility of a common origin of the bacteriophages, irrespective of belonging to different groups and species.

Antibiotics resistance in El Tor Vibrio cholerae 01 isolated during cholera outbreaks in Mozambique from 2012 to 2015.

RationaleMozambique has recorded cyclically epidemic outbreaks of cholera. Antibiotic therapy is recommended in specific situations for management and control of cholera outbreaks. However, an increase in resistance rates to antibiotics by Vibrio cholerae has been reported in several epidemic outbreaks worldwide. On the other hand, there are few recent records of continuous surveillance of antibiotics susceptibility pattern of V. cholerae in Mozambique.GoalsThe purpose of this study was to evaluate antibiotics resistance pattern of Vibrio cholerae O1 Ogawa isolated during Cholera outbreaks in Mozambique to commonly used antibiotics.MethodologyWe analyzed data from samples received in the context of surveillance and response to Cholera outbreaks in the National Reference Laboratory of Microbiology from the National Institute of Health of Mozambique, 159 samples suspected of cholera from cholera treatment centers of, Metangula (09), Memba (01), Tete City (08), Moatize (01), Morrumbala (01) districts, City of Quelimane (01), Lichinga (06) and Nampula (86) districts, from 2012 to 2015. Laboratory culture and standard biochemical tests were employed to isolate and identify Vibrio cholerae; serotypes were determined by antisera agglutination reaction in blade. Biotype and presence of important virulence factors analysis was done by PCR. Antibiotics susceptibility pattern was detected by disk diffusion method Kirby Bauer. Antibiotic susceptibility and results were interpreted by following as per recommendations of CLSI (Clinical and Laboratory Standards Institute) 2014. All samples were collected and tested in the context of Africhol Project, approved by the National Bioethics Committee for Health.ResultsAmong isolates from of Vibrio cholerae O1 El Tor Ogawa resistance to Sulphamethoxazole-trimethropim was 100% (53/53) to Trimethoprim-, being 100% (54/54) for Ampicillin, 99% (72/74) for Nalidixic Acid, 97% (64/66) to Chloramphenicol, 95% (42/44) for Nitrofurantoin and (19/20) Cotrimoxazole, 83% (80/97) Tetracycline, 56% (5/13) Doxycycline, 56% (39/70) Azithromycin and 0% (0/101) for Ciprofloxacin. PCR analysis suggested strains of V. cholerae O1 being descendants of the current seventh pandemic V. cholerae O1 CIRS 101 hybrid variant. The V. cholerae O1 currently causing cholera epidemics in north and central Mozambique confirmed a CTXΦ genotype and a molecular arrangement similar to the V. cholerae O1 CIRS 101.ConclusionAlthough V. cholerae infections in Mozambique are generally not treated with antibiotics circulating strains of the bacteria showed high frequency of in vitro resistance to available antibiotics. Continuous monitoring of antibiotic resistance pattern of epidemic strains is therefore crucial since the appearance of antibiotic resistance can influence cholera control strategies.

Comparative study of survival of altered and hybrid Vibrio cholerae O1 El Tor in association with Anabaena variabilis in fresh and brackish water microcosms

AbstractThe survival of altered and hybrid Vibrio cholerae O1 El Tor in association with a cyanobacterium, Anabaena variabilis in pond (fresh) and brackish water microcosms was investigated. Survival of culturable bacteria was monitored on taurocholate tellurite gelatine agar plate. Viable but nonculturable (VBNC) bacteria were examined using fluorescent antibody (FA) technique. In pond water, altered and hybrid El Tor survived with cyanobacteria 10 and 18 days respectively and in control water 6 and 12 days respectively in culturable state. In pond water VBNC state altered and hybrid El Tor were found to persist 48 and 53 days respectively but in brackish water 65 and 70 days respectively in association with cyanobacteria. Brackish water was found to be a better habitat than pond water for the survival of these strains. Hybrid El Tor survived longer inside the mucilaginous sheath of A. variabilis than altered El Tor both in pond and brackish water microcosms.

A prolonged, community-wide cholera outbreak associated with drinking water contaminated by sewage in Kasese District, western Uganda

BackgroundIn May 2015, a cholera outbreak that had lasted 3 months and infected over 100 people was reported in Kasese District, Uganda, where multiple cholera outbreaks had occurred previously. We conducted an investigation to identify the mode of transmission to guide control measures.MethodsWe defined a suspected case as onset of acute watery diarrhoea from 1 February 2015 onwards in a Kasese resident. A confirmed case was a suspected case with Vibrio cholerae O1 El Tor, serotype Inaba cultured from a stool sample. We reviewed medical records to find cases. We conducted a case-control study to compare exposures among confirmed case-persons and asymptomatic controls, matched by village and age-group. We conducted environmental assessments. We tested water samples from the most affected area for total coliforms using the Most Probable Number (MPN) method.ResultsWe identified 183 suspected cases including 61 confirmed cases of Vibrio cholerae 01; serotype Inaba, with onset between February and July 2015. 2 case-persons died of cholera. The outbreak occurred in 80 villages and affected all age groups; the highest attack rate occurred in the 5–14 year age group (4.1/10,000). The outbreak started in Bwera Sub-County bordering the Democratic Republic of Congo and spread eastward through sustained community transmission. The first case-persons were involved in cross-border trading. The case-control study, which involved 49 confirmed cases and 201 controls, showed that 94% (46/49) of case-persons compared with 79% (160/201) of control-persons drank water without boiling or treatment (ORM-H=4.8, 95% CI: 1.3–18). Water collected from the two main sources, i.e., public pipes (consumed by 39% of case-persons and 38% of control-persons) or streams (consumed by 29% of case-persons and 24% control-persons) had high coliform counts, a marker of faecal contamination. Environmental assessment revealed evidence of open defecation along the streams. No food items were significantly associated with illness.ConclusionsThis prolonged, community-wide cholera outbreak was associated with drinking water contaminated by faecal matter and cross-border trading. We recommended rigorous disposal of patients’ faeces, chlorination of piped water, and boiling or treatment of drinking water. The outbreak stopped 6 weeks after these recommendations were implemented.