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Balakrish G Nair - One of the best experts on this subject based on the ideXlab platform.
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cholera outbreaks in the El Tor biotype era and the impact of the new El Tor variants
Current Topics in Microbiology and Immunology, 2014Co-Authors: Asish K. Mukhopadhyay, Yoshifumi Takeda, Balakrish G NairAbstract:Vibrio cholerae O1, the causative agent of the disease cholera, has two biotypes namEly the classical and El Tor. Biotype is a subspecific taxonomic classification of V. cholerae O1. Differentiation of V. cholerae strains into biotype does not alter the clinical management of cholera but is of immense public health and epidemiological importance in identifying the source and spread of infection, particularly when V. cholerae is first isolated in a country or geographic area. From recorded hisTory, till date, the world has experienced seven pandemics of cholera. Among these, the first six pandemics are bElieved to have been caused by the classical biotype whereas the ongoing seventh pandemic is caused by the El Tor biotype. In recent years, new pathogenic variants of V. cholerae have emerged and spread throughout many Asian and African countries with corresponding cryptic changes in the epidemiology of cholera. In this chapter, we describe the outbreaks during the seventh pandemic El Tor biotype era spanning more than five decades along with the recent advances in our understanding of the devElopment, evolution, spread, and impact of the new variants of El Tor strains.
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an experimental study of phage mediated bactericidal sElection emergence of the El Tor vibrio cholerae
Indian Journal of Medical Research, 2011Co-Authors: Shamim Hasan M Zahid, Balakrish G Nair, M Kamruzzaman, Zaved Waise, A N Ghosh, S Khairul A M Bashar, John J Mekalanos, Shah M. FaruqueAbstract:Background & objectives : FacTor causing the Elimination of the classical biotype of Vibrio cholerae O1, and its replacement by the El Tor biotype causing the 7 th cholera pandemic are unclear. Possible ability of the El Tor strains to adapt better than the classical strains to undefined environmental forces have been largEly implicated for the change. Here we describe an environmental bacteriophage designated JSF9 which might have contributed to the range of facTors. Methods : Competition assays were conducted in the infant mice modEl and in microcosms between representative El Tor and classical biotype strains in the absence or in the presence of JSF9 phage. Results : The JSF9 phage was found to kill classical strains and favour enrichment of El Tor strains, when mixtures containing strains of the two biotypes and JSF9 phage were subjected to alternate passage in infant mice and in samples of environmental water. Spontaneous derivatives of the classical biotype strains, as wEll as transposon mutants which devEloped resistance to JSF9 phage were found to be defective in colonization in the infant mouse modEl. Interpretation & conclusions : These results suggest that in addition to other facTors, the inherent ability of El Tor biotype strains to evade predation by JSF9 or similar phages which kill classical biotype strains, might have enhanced the emergence of El Tor strains as the predominant pandemic biotype.
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emergence and genetic diversity of El Tor vibrio cholerae o1 that possess classical biotype ctxb among travEl associated cases of cholera in japan
Journal of Medical Microbiology, 2010Co-Authors: Masatomo Morita, Eiji Arakawa, Makoto Ohnishi, Shouji Yamamoto, Balakrish G Nair, Shigeru Matsushita, Keiko Yokoyama, Akemi Kai, Kazuko Seto, Haruo WatanabeAbstract:Vibrio cholerae O1 are classified into two biotypes, classical and El Tor, each encoding a biotype-specific cholera toxin. However, El Tor strains have recently emerged with a classical cholera-toxin genotype (El Tor variant). We characterized El Tor strains of V. cholerae O1 from travEl-associated cases of cholera in Japan isolated from 1991 to 2006 by cholera toxin B subunit gene (ctxB) typing and by molecular epidemiological methods. ctxB in the biotype El Tor shifted from the El Tor-specific type to the classical-specific type around 1993, and this type fully dominated the later half of the 1990s. Based on the results of PFGE and multilocus variable-number tandem repeat analysis, strains of the classical biotype remained diverse from those of El Tor biotype. The El Tor biotype strains formed multiple minor clusters and intermingled with each other irrespective of their origins and toxin types. El Tor variant strains are widespread in Asian countries and show significant genetic diversity, indicating that their spread is a result of multiclonal expansion rather than spread from a single clone.
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molecular evidence favouring step wise evolution of mozambique vibrio cholerae o1 El Tor hybrid strain
Microbiology, 2010Co-Authors: Kalpataru Halder, Balakrish G Nair, Bhabatosh Das, Rupak K BhadraAbstract:The ctxAB operon, encoding cholera toxin (CT) in Vibrio cholerae, is carried by the genome of a filamentous phage, CTXΦ. Usually, specific CTXΦ infect each of the two important biotypes, classical and El Tor, of epidemic V. cholerae strains bElonging to serogroup O1, and are called CTXclassΦ and CTXETΦ, respectivEly. However, an unusual hybrid El Tor strain carrying CTXclassΦ caused the cholera epidemic in Mozambique in 2004. To understand the evolution of that strain, we have further analysed some representative hybrid El Tor strains isolated in Kolkata, India, in 1992, and the results indicate that both the Mozambique and the Indian strains are infected with a unique CTXclassΦ having only four copies of the tandem heptamer repeat sequence 5′-TTTTGAT-3′ present in the ctxAB promoter (P ctxAB ) region, like in CTXETΦ. Usually, the P ctxAB of the classical biotype contains seven to eight copies of such sequences. However, sequence analyses of the P ctxAB regions of several classical strains indicated that the copy number of heptamer repeat sequences might vary from four to eight copies, which was previously unknown. Since the hybrid strains analysed in this study carry four copies of the heptamer sequences, it may thus serve as a marker to trace the strain in future. Interestingly, while the Mozambique strain is devoid of an El Tor-specific free RS1 Element or pre-CTX prophage, the Indian hybrid strains carry such Elements. The free RS1 has been mapped, cloned and sequenced. As in pre-CTX and CTX prophages, multiple copies of free RS1 Elements were found to be integrated in tandem in the large chromosomal dif site. Since Indian hybrid El Tor strains carry either free RS1 or pre-CTX prophage in their large chromosomes, it is possible that the Mozambique hybrid El Tor strain has evolved from these progeniTor strains by step-wise dEletion of CTX genetic Elements from their large chromosomes.
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acquisition of classical ctx prophage from vibrio cholerae o141 by El Tor strains aided by lytic phages and chitin induced competence
Proceedings of the National Academy of Sciences of the United States of America, 2008Co-Authors: S Nashir M Udden, Shah M. Faruque, Balakrish G Nair, Shamim Hasan M Zahid, John J Mekalanos, Kuntal Biswas, Q S Ahmad, Alejandro CraviotoAbstract:The El Tor biotype of Vibrio cholerae O1, causing the current seventh pandemic of cholera, has replaced the classical biotype, which caused the sixth pandemic. The CTX prophages encoding cholera toxin in the two biotypes have distinct repressor (rstR) genes. Recently, new variants of El Tor strains that carry the classical type (CTXclass) prophage have emerged. These “hybrid” strains apparently originate through lateral gene transfer and recombination events. To explore possible donors of the CTXclass prophage and its mode of transfer, we tested environmental V. cholerae isolates for the presence of CTXclass prophage and mobility of the phage genome. Of the 272 environmental V. cholerae isolates tested, 6 were found to carry the CTXclass prophage; all of these bElonged to the O141 serogroup. These O141 strains were unable to produce infectious CTXclass phage or to transmit the prophage to recipient strains in the mouse modEl of infection; however, the CTXclass prophage was acquired by El Tor strains when cultured with the O141 strains in microcosms composed of filtered environmental water, a chitin substrate, and a V. cholerae O141-specific bacteriophage. The CTXclass prophage either coexisted with or replaced the resident CTXET prophage, resulting in El Tor strains with CTX genotypes similar to those of the naturally occurring hybrid strains. Our results support a modEl involving phages and natural chitin substrate in the emergence of new variants of pathogenic V. cholerae. Furthermore, the O141 strains apparently represent an alternative reservoir of the CTXclass phage genome, because the classical V. cholerae O1 strains are possibly extinct.
N A Bhuiyan - One of the best experts on this subject based on the ideXlab platform.
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multi drug resistant vibrio cholerae o1 variant El Tor isolated in northern vietnam between 2007 and 2010
Journal of Medical Microbiology, 2012Co-Authors: Huu Dat Tran, M. Ansaruzzaman, N A Bhuiyan, Munirul Alam, Shah M Rashed, Nguyen Vu Trung, Nguyen Van Kinh, Hong Ha Nguyen, Van Ca Pham, Tuyet Trinh DaoAbstract:Since 2007, there has been a re-emergence of cholera outbreaks in northern Vietnam. To understand the molecular epidemiological rElatedness and determine the antibiotic susceptibility profiles of responsible V. cholerae O1 outbreak strains, a representative collection of 100 V. cholerae O1 strains was characterized. V. cholerae O1 strains isolated from diarrhoeal patients in northern Vietnam between 2007 and 2010 were investigated for antibiotic susceptibility and characterized by using phenotypic and genotypic tests, including PFGE analysis. Ten clinical V. cholerae O1 isolates from Bangladesh and Zimbabwe were included for comparison. The results revealed that all isolates were resistant to co-trimoxazole and nalidixic acid, 29 % were resistant to tetracycline and 1 % were resistant to azithromycin. All strains were susceptible to ampicillin–sulbactam, doxycycline, chloramphenicol and ciprofloxacin and 95 % were susceptible to azithromycin. MIC values did show reduced susceptibility to fluoroquinolones and 63 % of the strains were intermediatEly resistant to tetracycline. The isolates expressed phenotypic traits of both serogroup O1 Ogawa and El Tor and harboured an rstR El Tor and ctxB classical biotype. Among the outbreak isolates, only a single PFGE pattern was observed throughout the study period. This study shows that multi-drug resistant V. cholerae altered El Tor producing classical CT strains are now predominant in northern Vietnam.
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cholera between 1991 and 1997 in mexico was associated with infection by classical El Tor and El Tor variants of vibrio cholerae
Journal of Clinical Microbiology, 2010Co-Authors: Munirul Alam, N A Bhuiyan, Suraia Nusrin, Atiqul Islam, Niaz Rahim, Gabriela Delgado, Rosario Morales, Jose Luis Mendez, Armando Navarro, Ana I GilAbstract:Vibrio cholerae O1 biotype El Tor (ET), the cause of the current 7th pandemic, has recently been replaced in Asia and Africa by an altered ET biotype possessing cholera toxin (CTX) of the classical (CL) biotype that originally caused the first six pandemics before becoming extinct in the 1980s. Until recently, the ET prototype was the biotype circulating in Peru; a detailed understanding of the evolutionary trend of V. cholerae causing endemic cholera in Latin America is lacking. The present retrospective microbiological, molecular, and phylogenetic study of V. cholerae isolates recovered in Mexico (n 91; 1983 to 1997) shows the existence of the pre-1991 CL biotype and the ET and CL biotypes together with the altered ET biotype in both epidemic and endemic cholera between 1991 and 1997. According to sero- and biotyping data, the altered ET, which has shown predominance in Mexico since 1991, emerged locally from ET and CL progeniTors that were found coexisting until 1997. In Latin America, ET and CL variants shared a variable number of phenotypic markers, while the altered ET strains had genes encoding the CL CTX (CTX CL ) prophage, ctxB CL and rstR CL , in addition to resident rstR ET , as the underlying regional signature. The distinct regional fingerprints for ET in Mexico and Peru and their divergence from ET in Asia and Africa, as confirmed by subclustering patterns in a pulsed-fiEld gEl Electrophoresis (NotI)-based dendrogram, suggest that the Mexico epidemic in 1991 may have been a local event and not an extension of the epidemics occurring in Asia and South America. Finally, the CL biotype reservoir in Mexico is unprecedented and must have contributed to the changing epidemiology of global cholera in ways that need to be understood.
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multilocus variable number tandem repeat analysis of vibrio cholerae o1 El Tor strains harbouring classical toxin b
Journal of Medical Microbiology, 2010Co-Authors: Jehee Lee, Seon Young Choi, Hye Ri Lee, M. Ansaruzzaman, Yoonseong Jeon, Eun Jin Kim, N A BhuiyanAbstract:Atypical Vibrio cholerae O1 strains – hybrid strains (strains that cannot be classified either as El Tor or classical biotype) and altered strains (El Tor biotype strains that produce classical cholera toxin) – are currently prevalent in Asia and Africa. A total of 74 hybrid and altered strains that harboured classical cholera toxin were investigated by multilocus variable-number tandem repeat analysis (MLVA). The results showed that the hybrid/altered strains could be categorized into three groups and that they were distant from the El Tor strain responsible for the seventh cholera pandemic. Hybrid/altered strains with a tandem repeat of the classical CTX prophage on the small chromosome were divided into two MLVA groups (group I: Mozambique/Bangladesh group; group III: Vietnam group), and altered strains with the RS1–CTX prophage containing the El Tor type rstR and classical ctxB on the large chromosome were placed in two MLVA groups (group II: India/Bangladesh group; group III: India/Vietnam group).
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peruvian vibrio cholerae o1 El Tor strains possess a distinct region in the vibrio seventh pandemic island ii that differentiates them from the prototype seventh pandemic El Tor strains
Journal of Medical Microbiology, 2009Co-Authors: Suraia Nusrin, Ashrafus Safa, Masahiro Asakura, N A Bhuiyan, Ana I Gil, Claudio F Lanata, Eric R Hall, Hernan Miranda, B Huapaya, Carmen G VargasAbstract:A collection of environmental and clinical strains of Vibrio cholerae O1 isolated from the beginning of the Latin American epidemic of cholera in 1991 to 2003 from multiple locations in Peru were characterized and compared with V. cholerae O1 El Tor strains of the seventh pandemic from the rest of the world (Asia, Africa, Australia and Europe) using a multilocus virulence gene profiling strategy and DNA sequencing. Peruvian strains differed from El Tor strains from the rest of the world by the failure of PCR to amplify genes VC0512, VC0513, VC0514 and VC0515 in the Vibrio seventh pandemic island-II (VSP-II) gene cluster. Sequencing of the VSP-II gene cluster and its flanking regions in one Peruvian strain (PERU-130) confirmed the PCR results, indicating that the Peruvian strain had low DNA homology (46.6 %) compared to the reference strain N16961 within the VSP-II region encompassing genes VC0511 to VC0515. Based on these differences in VSP-II, and based on the overall similarity between the pulsotypes of the Peruvian strains and the El Tor reference strain N16961, we concluded that the Peruvian, Eurasian and African strains bElonged to the same clonal complex, and that the Peruvian strains represented variants that had independently evolved for a rElativEly short time. Since these ORFs in VSP-II of Peruvian strains are unique and conserved, they could form the basis for tracking the origin of the Peruvian strains and therefore of the Latin American pandemic.
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devElopment and validation of a mismatch amplification mutation pcr assay to moniTor the dissemination of an emerging variant of vibrio cholerae o1 biotype El Tor
Microbiology and Immunology, 2008Co-Authors: Masatomo Morita, Firdausi Qadri, Hidemasa Izumiya, Eiji Arakawa, Makoto Ohnishi, N A Bhuiyan, A K Siddique, Munirul Alam, Suraia Nusrin, Balakrish G NairAbstract:A mismatch amplification mutation PCR assay was devEloped and validated for rapid detection of the biotype specific cholera toxin B subunit of V. cholerae O1. This assay will enable easy moniToring of the spread of a new emerging variant of the El Tor biotype of V. cholerae O1.
Shah M. Faruque - One of the best experts on this subject based on the ideXlab platform.
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an experimental study of phage mediated bactericidal sElection emergence of the El Tor vibrio cholerae
Indian Journal of Medical Research, 2011Co-Authors: Shamim Hasan M Zahid, Balakrish G Nair, M Kamruzzaman, Zaved Waise, A N Ghosh, S Khairul A M Bashar, John J Mekalanos, Shah M. FaruqueAbstract:Background & objectives : FacTor causing the Elimination of the classical biotype of Vibrio cholerae O1, and its replacement by the El Tor biotype causing the 7 th cholera pandemic are unclear. Possible ability of the El Tor strains to adapt better than the classical strains to undefined environmental forces have been largEly implicated for the change. Here we describe an environmental bacteriophage designated JSF9 which might have contributed to the range of facTors. Methods : Competition assays were conducted in the infant mice modEl and in microcosms between representative El Tor and classical biotype strains in the absence or in the presence of JSF9 phage. Results : The JSF9 phage was found to kill classical strains and favour enrichment of El Tor strains, when mixtures containing strains of the two biotypes and JSF9 phage were subjected to alternate passage in infant mice and in samples of environmental water. Spontaneous derivatives of the classical biotype strains, as wEll as transposon mutants which devEloped resistance to JSF9 phage were found to be defective in colonization in the infant mouse modEl. Interpretation & conclusions : These results suggest that in addition to other facTors, the inherent ability of El Tor biotype strains to evade predation by JSF9 or similar phages which kill classical biotype strains, might have enhanced the emergence of El Tor strains as the predominant pandemic biotype.
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El Tor cholera with severe disease a new threat to asia and beyond
Epidemiology and Infection, 2010Co-Authors: A K Siddique, David A. Sack, G. Balakrish Nair, Firdausi Qadri, Shah M. Faruque, Munirul Alam, A Huq, Azhar Nizam, Ira M Longini, Rita R ColwellAbstract:During epidemics of cholera in two rural sites (Bakerganj and Mathbaria), a much higher proportion of patients came for treatment with severe dehydration than was seen in previous years. V. cholerae O1 isolated from these patients was found to be El Tor in its phenotype, but its cholera toxin (CT) was determined to be that of classical biotype. Whether the observed higher proportion of severe dehydration produced by the El Tor biotype was due to a shift from El Tor to classical CT or due to other facTors is not clear. However, if cholera due to strains with increased severity spread to other areas where treatment facilities are limited, there are likEly to be many more cholera deaths.
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acquisition of classical ctx prophage from vibrio cholerae o141 by El Tor strains aided by lytic phages and chitin induced competence
Proceedings of the National Academy of Sciences of the United States of America, 2008Co-Authors: S Nashir M Udden, Shah M. Faruque, Balakrish G Nair, Shamim Hasan M Zahid, John J Mekalanos, Kuntal Biswas, Q S Ahmad, Alejandro CraviotoAbstract:The El Tor biotype of Vibrio cholerae O1, causing the current seventh pandemic of cholera, has replaced the classical biotype, which caused the sixth pandemic. The CTX prophages encoding cholera toxin in the two biotypes have distinct repressor (rstR) genes. Recently, new variants of El Tor strains that carry the classical type (CTXclass) prophage have emerged. These “hybrid” strains apparently originate through lateral gene transfer and recombination events. To explore possible donors of the CTXclass prophage and its mode of transfer, we tested environmental V. cholerae isolates for the presence of CTXclass prophage and mobility of the phage genome. Of the 272 environmental V. cholerae isolates tested, 6 were found to carry the CTXclass prophage; all of these bElonged to the O141 serogroup. These O141 strains were unable to produce infectious CTXclass phage or to transmit the prophage to recipient strains in the mouse modEl of infection; however, the CTXclass prophage was acquired by El Tor strains when cultured with the O141 strains in microcosms composed of filtered environmental water, a chitin substrate, and a V. cholerae O141-specific bacteriophage. The CTXclass prophage either coexisted with or replaced the resident CTXET prophage, resulting in El Tor strains with CTX genotypes similar to those of the naturally occurring hybrid strains. Our results support a modEl involving phages and natural chitin substrate in the emergence of new variants of pathogenic V. cholerae. Furthermore, the O141 strains apparently represent an alternative reservoir of the CTXclass phage genome, because the classical V. cholerae O1 strains are possibly extinct.
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genomic analysis of the mozambique strain of vibrio cholerae o1 reveals the origin of El Tor strains carrying classical ctx prophage
Proceedings of the National Academy of Sciences of the United States of America, 2007Co-Authors: Shah M. Faruque, John D Clemens, John J Mekalanos, Nityananda Chowdhury, Vincent C Tam, Pornphan Diraphat, Michelle Dziejman, John F Heidelberg, Balakrish G NairAbstract:Cholera outbreaks in subSaharan African countries are caused by strains of the El Tor biotype of toxigenic Vibrio cholerae O1. The El Tor biotype is the causative agent of the current seventh cholera pandemic, whereas the classical biotype, which was associated with the sixth pandemic, is now extinct. Besides other genetic differences the CTX prophages encoding cholera toxin in the two biotypes of V. cholerae O1 have distinct repressor (rstR) genes. However, recent incidences of cholera in Mozambique were caused by an El Tor biotype V. cholerae O1 strain that, unusually, carries a classical type (CTXclass) prophage. We conducted genomic anal- ysis of the Mozambique strain and its CTX prophage together with chromosomal phage integration sites to understand the origin of this atypical strain and its evolutionary rElationship with the true seventh pandemic strain. These analyses showed that the Mozam- bique strain carries two copies of CTXclass prophage located on the small chromosome in a tandem array that allows excision of the prophage, but the excised phage genome was deficient in repli- cation and did not produce CTXclass virion. Comparative genomic microarray analysis revealed that the strain shares most of its genes with the typical El Tor strain N16961 but did not carry the TLC gene cluster, and RS1 sequence, adjacent to the CTX prophage. Our data are consistent with the Mozambique strain's having evolved from a progeniTor similar to the seventh pandemic strain, involving multiple recombination events and suggest a modEl for origination of El Tor strains carrying the classical CTX prophage. cholera CTX phage TLC Element evolution
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Cholera due to altered El Tor strains of Vibrio cholerae O1 in Bangladesh.
Journal of Clinical Microbiology, 2006Co-Authors: G. Balakrish Nair, Firdausi Qadri, Jan Holmgren, Ann-mari Svennerholm, Ashrafus Safa, Nurul A. Bhuiyan, Q. Shafi Ahmad, Shah M. Faruque, Abu Syed Golam Faruque, Yoshifumi TakedaAbstract:We determined the types of cholera toxin (CT) produced by a collection of 185 Vibrio cholerae O1 strains isolated in Bangladesh over the past 45 years. All of the El Tor strains of V. cholerae O1 isolated since 2001 produced CT of the classical biotype, while those isolated before 2001 produced CT of the El Tor biotype.
Biao Kan - One of the best experts on this subject based on the ideXlab platform.
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the resistance of vibrio cholerae o1 El Tor strains to the typing phage 919tp a member of k139 phage family
Frontiers in Microbiology, 2016Co-Authors: Xiaona Shen, Jingyun Zhang, Bo Pang, Biao KanAbstract:Bacteriophage 919TP is a temperate phage of Vibrio cholerae serogroup O1 El Tor and is used as a subtyping phage in the phage-biotyping scheme in cholera surveillance in China. In this study, sequencing of the 919TP genome showed that it bElonged to the Vibrio phage K139 family. The mechanisms conferring resistance to 919TP infection of El Tor strains were explored to hElp understand the subtyping basis of phage 919TP and mutations rElated to 919TP resistance. Among the test strains resistant to phage 919TP, most contained the temperate 919TP phage genome, which facilitated superinfection exclusion to 919TP. Our data suggested that this immunity to Vibrio phage 919TP occurred after absorption of the phage onto the bacteria. Other strains contained LPS recepTor synthesis gene mutations that disable adsorption of phage 919TP. Several strains resistant to 919TP infection possessed unknown resistance mechanisms, since they did not contain LPS recepTor mutations or temperate K139 phage genome. Further research is required to Elucidate the phage infection steps involved in the resistance of these strains to phage infection.
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variations in sxt Elements in epidemic vibrio cholerae o1 El Tor strains in china
Scientific Reports, 2016Co-Authors: Ruibai Wang, Junjie Yue, Biao KanAbstract:Vibrio cholerae O1 El Tor biotype strains are responsible for three multiyear epidemics of cholera in China during the seventh ongoing pandemic. The presence of the integrative conjugative Element SXT is strongly corrElated with resistance to nalidixic acid, tetracycline, and trimethoprim-sulfamethoxazole in these strains. Here, we sequenced the conserved genes of the SXT Element, including eex, setR, and int, from 59 V. cholerae O1 El Tor strains and extracted and assembled the intact SXT sequences from the 11 genome sequenced strains. These Elements had characteristics distinct from those of previously reported integrative conjugative Elements (ICEs). They could be clearly divided into two types based on the clustering of conserved genes and gene structures of the Elements, showing their possibly independent derivation and evolution. These two types were present before and after 2005, respectivEly, demonstrating the type substitution that occurred in 2005. Four to six antibiotic-resistant genes were found on the SXT Elements, including genes resistant to tetracycline, trimethoprim-sulfamethoxazole, and multiple drugs. In summary, our findings demonstrated the roles of the SXT Element in the emergence of multidrug resistance in epidemic O1 El Tor V. cholerae strains in China.
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Outer Membrane Protein OmpW Is the RecepTor for Typing Phage VP5 in the Vibrio cholerae O1 El Tor Biotype
Journal of Virology, 2014Co-Authors: Jingyun Zhang, Jie Liu, Haijian Zhou, Lijuan Zhang, Jun Zhu, Biao KanAbstract:Phage typing is used for the subtyping of clones of epidemic bacteria. In this study, we identified the outer membrane protein OmpW as the recepTor for phage VP5, one of the typing phages for the Vibrio cholerae O1 El Tor biotype. A characteristic 11-bp dEletion in ompW was observed in all epidemic strains resistant to VP5, suggesting that this mutation event can be used as a tracing marker in cholera surveillance.
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o antigen is the recepTor of vibrio cholerae serogroup o1 El Tor typing phage vp4
Journal of Bacteriology, 2013Co-Authors: Jingyun Zhang, Lijuan Zhang, Weili Liang, Biao KanAbstract:Bacteriophage VP4 is a lytic phage of the Vibrio cholerae serogroup O1, and it is used in phage subtyping of V. cholerae biotype El Tor. Studies of phage infection mechanisms will promote the understanding of the basis of phage subtyping as wEll as the genetic differences between sensitive and resistant strains. In this study, we investigated the recepTor that phage VP4 uses to bind to El Tor strains of V. cholerae and found that it infects strains through adsorbing the O antigen of V. cholerae O1. In some natural isolates that are resistant to VP4 infection, mutations were identified in the wb* cluster (O-antigen gene cluster), which is responsible for the biosynthesis of O antigen. Mutations in the manB, wbeE, and wbeU genes caused failure of adsorption of VP4 to these strains, whereas the observed amino acid residue mutations within wbeW and manC have no effect on VP4 infection. Additionally, although mutations in two resistant strains were found only in manB and wbeW, complementing both genes did not resTore sensitivity to VP4 infection, suggesting that other resistance mechanisms may exist. Therefore, the mechanism of VP4 infection may provide a basis for subtyping the phage. Elaborate mutations of the O antigen may imbue V. cholerae strains with resistance to phage infection.
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antibiotic resistance of vibrio cholerae o1 El Tor strains from the seventh pandemic in china 1961 2010
International Journal of Antimicrobial Agents, 2012Co-Authors: Ruibai Wang, Lijuan Zhang, Jie Liu, Jing Lou, Biao KanAbstract:Antibiotic resistance is observed with increasing frequency among epidemic Vibrio cholerae strains in some countries. In this study, the antibiotic resistance profiles of V. cholerae O1 El Tor strains isolated in China from 1961 to 2010 were analysed. The frequency of antibiotic resistance among the seventh pandemic El Tor isolates from China remained low, except for resistance to nalidixic acid (45.9%), tetracycline (11%) and trimethoprim/sulfamethoxazole (38.5%). All test strains in the first multiyear epidemic in the 1960s were sensitive to all test antibiotics, whereas strains from the 1990s and later showed a rapid increase in the prevalence of resistance. The class I integron was present primarily among strains isolated between 1993 and 1998, and the prevalence of the SXT Element was much greater among strains isolated after 1993. This study determined the regional resistance characteristics of epidemic clones in China and serves as a warning of the rapid dissemination of resistance in the past 20 years.
Asish K. Mukhopadhyay - One of the best experts on this subject based on the ideXlab platform.
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unique clones of vibrio cholerae o1 El Tor with haitian type ctxb allEle implicated in the recent cholera epidemics from nigeria africa
PLOS ONE, 2016Co-Authors: Akinsinde Kehinde Adewale, Asish K. Mukhopadhyay, Gururaja P Pazhani, Iwalokun Bamidele Abiodun, Oluwadun Afolabi, Olukoya Daniel Kolawole, Thanadarayan RamamurthyAbstract:The antimicrobial susceptibility patterns and genetic characteristics of Vibrio cholerae O1, which is responsible for several cholera epidemics in Nigeria, are not reported in detail since 2007. In this study, we screened V. cholerae O1 El Tor biotype isolates from cholera cases and water samples from different states to investigate their phenotypic and genetic attributes with special reference to their clonality.All the V. cholerae O1 biotype El Tor isolates isolated during 2007-2013 were susceptible to fluoroquinolones and tetracycline, the drugs currently used in the treatment of cholera cases in Nigeria. Emergence of CT genotype 7 (Haitian type of ctxB allEle) was predominantly seen among Ogawa serotype and the CT genotype 1 (classical ctxB allEle) was mostly found in Inaba serotype. Overall, V. cholerae O1 from clinical and water samples were found to be closEly rElated as determined by the pulsed-fiEld gEl Electrophoresis. V. cholerae isolates from Abia, Kano and Bauchi were found to be genetically distinct from the other states of Nigeria.Fecal contamination of the water sources may be the possible source of the cholera infection. Combined prevalence of Haitian and classical ctxB allEles were detected in Ogawa and Inaba serotypes, respectivEly. This study further demonstrated that V. cholerae O1 with the ctxB has been emerged similar to the isolates reported in Haiti. Our findings suggest that the use of fluoroquinolones or tetracycline/doxycycline may hElp in the effective management of acute cholera in the affected Nigerian states. In addition, strengthening the existing surveillance in the hospitals of all the states and supply of clean drinking water may control cholera outbreaks in the future.
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sensitivity to polymyxin b in El Tor vibrio cholerae o1 strain kolkata india
Emerging Infectious Diseases, 2015Co-Authors: Prosenjit Samanta, Thandavarayan Ramamurthy, Priyanka Ghosh, Goutam Chowdhury, Asish K. MukhopadhyayAbstract:To the EdiTor: The epidemiology of cholera, especially in Africa and Asia, has periodically changed in subtle ways (1). The recent cholera epidemic in Haiti, a Caribbean country with no cholera cases in decades, affected >500,000 persons, caused ≈8,000 deaths, and brought this illness to the forefront of Haitian public health concerns (2,3). This life-threatening disease is caused by Vibrio cholerae, a waterborne bacterium with >200 serogroups, 2 of which, O1 and O139, cause epidemic or pandemic cholera. V. cholerae O1 is categorized as classical and El Tor biotypes, which differ biochemically and have different levEls of virulence. Classical strains typically cause more severe illness than El Tor strains, which result in mild or moderate and sometimes asymptomatic cases. However, El Tor strains have replaced classical strains as the cause of cholera; the classical biotype is bElieved to be extinct, and El Tor strains currently prevail. However, the genetic traits specific to classical strains are still present in environmental and clinical V. cholerae isolates. Currently, all clinical strains of V. cholerae in Kolkata produce classical cholera toxin. Such phenotypic and genetic changes in V. cholerae are being moniTored worldwide.
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cholera outbreaks in the El Tor biotype era and the impact of the new El Tor variants
Current Topics in Microbiology and Immunology, 2014Co-Authors: Asish K. Mukhopadhyay, Yoshifumi Takeda, Balakrish G NairAbstract:Vibrio cholerae O1, the causative agent of the disease cholera, has two biotypes namEly the classical and El Tor. Biotype is a subspecific taxonomic classification of V. cholerae O1. Differentiation of V. cholerae strains into biotype does not alter the clinical management of cholera but is of immense public health and epidemiological importance in identifying the source and spread of infection, particularly when V. cholerae is first isolated in a country or geographic area. From recorded hisTory, till date, the world has experienced seven pandemics of cholera. Among these, the first six pandemics are bElieved to have been caused by the classical biotype whereas the ongoing seventh pandemic is caused by the El Tor biotype. In recent years, new pathogenic variants of V. cholerae have emerged and spread throughout many Asian and African countries with corresponding cryptic changes in the epidemiology of cholera. In this chapter, we describe the outbreaks during the seventh pandemic El Tor biotype era spanning more than five decades along with the recent advances in our understanding of the devElopment, evolution, spread, and impact of the new variants of El Tor strains.
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outbreak of cholera caused by vibrio cholerae o1 El Tor variant strain in bihar india
Japanese Journal of Infectious Diseases, 2014Co-Authors: Hemanta Koley, Asish K. Mukhopadhyay, Thandavarayan Ramamurthy, Soumik Barman, Goutam Chowdhury, Nivedita Ray, Soma Mitra, Bibhuti Sarkar, Rakesh Katyal, Pradeep DasAbstract:An outbreak of cholera struck Bihar, an Indian state, in August 2008 following a massive flood. Here we report the phenotypic and genotypic characteristics of Vibrio cholerae strains isolated from patients with diarrhea. Rectal swabs were obtained from patients with diarrhea who were admitted to medical camps or the hospital, and the strains were biochemically and serologically characterized. V. cholerae was isolated from 21 (65.6%) of 32 rectal swabs. Serological studies revealed that all the 21 isolates bElonged to V. cholerae O1 Ogawa. Mismatch amplification mutation assay (MAMA)-PCR showed that the isolates bElonged to El Tor variant group, and pulsed-fiEld gEl Electrophoresis (PFGE) proved that these isolates were of a different lineage than the conventional El Tor variant strains. These isolates were resistant to several drugs, including ampicillin, streptomycin, tetracycline, nalidixic acid, and furazolidone. The uniqueness of the current report arises from the fact that records of cholera in Bihar are availiable for the early 1960s but not for the next 4 decades. Moreover, the present study is the first to report a cholera outbreak in Bihar that was caused by an El Tor variant strain.
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Cholera Toxin Production by the El Tor Variant of Vibrio cholerae O1 Compared to Prototype El Tor and Classical Biotypes
Journal of Clinical Microbiology, 2010Co-Authors: Jayeeta Ghosh-banerjee, Asish K. Mukhopadhyay, Thandavarayan Ramamurthy, Mitsutoshi Senoh, Takashi Takahashi, Takashi Hamabata, Soumik Barman, Hemanta Koley, Shruti Chatterjee, Masahiro AsakuraAbstract:Vibrio cholerae O1 El Tor variant strains produced much more cholera toxin than did prototype El Tor strains. The amount of cholera toxin produced by El Tor variant strains both in vitro and in vivo was more or less equivalent to that produced by classical strains.