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Sinha A, SenGupta S, Guin S, Dutta S, Ghosh S, Mukherjee P, Mukhopadhyay AK, Ramamurthy T, Takeda Y, Kurakawa T, Nomoto K, Nair GB, Nandy RK. Culture-independent real-time PCR reveals extensive polymicrobial infections in hospitalized diarrhoea cases in Kolkata, India. Clin Microbiol Infect 2012; 19:173-80. [PMID: 22268636 DOI: 10.1111/j.1469-0691.2011.03746.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Culture-independent identification of diarrhoeal aetiological agents was performed using DNA harvested from diarrhoeal stool specimens with SYBR-Green-based real-time PCR targeting Vibrio cholerae, Vibrio parahaemolyticus, Campylobacter spp., Shigella spp. and three different pathotypes of diarrhoeagenic Escherichia coli. Conventional culture-dependent methods detected bacterial enteropathogens in 68 of 122 diarrhoeal stool specimens. Of 68 specimens, 59 (86.8%) had a single pathogen and the remaining nine (13.2%) had polymicrobial infections with multiple pathogens. Re-analysis of the 68 specimens by culture-independent real-time PCR methods showed that 25 (36.8%) specimens contained single pathogen and 43 (63.2%) specimens contained mixed infections with multiple pathogens. The prevalence of such high levels of polymicrobial infections would not have been detected without using real-time PCR. Culture-dependent analysis assigned 54 of the 122 selected archived specimens as 'no known aetiology'. However, re-analysis of these samples by real-time PCR showed the presence of single or multiple pathogens among 34 (63%) of these specimens. Estimation of relative pathogen load by real-time PCR in the stool specimens indicated that the inability of conventional culture-dependent methods to detect the pathogens was related to lower colony-forming units of the pathogen, as reflected by lower C(t) values. Detection of high levels of polymicrobial infection by real-time PCR indicates that in the settings like Kolkata and its surroundings, where cholera and other enteric diseases are endemic, the concept of one pathogen one disease might need to be re-evaluated.
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Abstract
Cholera is a major global health problem, causing approximately 100,000 deaths annually, about half of which occur in sub-Saharan Africa. Although early-generation parenteral cholera vaccines were abandoned as public health tools owing to their limited efficacy, newer-generation oral cholera vaccines have attractive safety and protection profiles. Both killed and live oral vaccines have been licensed, although only killed oral vaccines are currently manufactured and available. These killed oral vaccines not only provide direct protection to vaccinated individuals, but also confer herd immunity. The combination of direct vaccine protection and vaccine herd immunity effects makes these vaccines highly cost-effective and, therefore, attractive for use in developing countries. Administration of these oral vaccines does not require qualified medical personnel, which makes their use practical--even in developing countries. Although new-generation oral cholera vaccines should not be considered in isolation from other preventive approaches, especially improved water quality and sanitation, they represent important tools in the public health armamentarium to control both endemic and epidemic cholera.
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Sur D, Kanungo S, Sah B, Manna B, Ali M, Paisley AM, Niyogi SK, Park JK, Sarkar B, Puri MK, Kim DR, Deen JL, Holmgren J, Carbis R, Rao R, Thu Van N, Han SH, Attridge S, Donner A, Ganguly NK, Bhattacharya SK, Nair GB, Clemens JD, Lopez AL. Efficacy of a low-cost, inactivated whole-cell oral cholera vaccine: results from 3 years of follow-up of a randomized, controlled trial. PLoS Negl Trop Dis 2011; 5:e1289. [PMID: 22028938 PMCID: PMC3196468 DOI: 10.1371/journal.pntd.0001289] [Citation(s) in RCA: 123] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2011] [Accepted: 07/09/2011] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Killed oral cholera vaccines (OCVs) have been licensed for use in developing countries, but protection conferred by licensed OCVs beyond two years of follow-up has not been demonstrated in randomized, clinical trials. METHODS/PRINCIPAL FINDINGS We conducted a cluster-randomized, placebo-controlled trial of a two-dose regimen of a low-cost killed whole cell OCV in residents 1 year of age and older living in 3,933 clusters in Kolkata, India. The primary endpoint was culture-proven Vibrio cholerae O1 diarrhea episodes severe enough to require treatment in a health care facility. Of the 66,900 fully dosed individuals (31,932 vaccinees and 34,968 placebo recipients), 38 vaccinees and 128 placebo-recipients developed cholera during three years of follow-up (protective efficacy 66%; one-sided 95%CI lower bound = 53%, p<0.001). Vaccine protection during the third year of follow-up was 65% (one-sided 95%CI lower bound = 44%, p<0.001). Significant protection was evident in the second year of follow-up in children vaccinated at ages 1-4 years and in the third year in older age groups. CONCLUSIONS/SIGNIFICANCE The killed whole-cell OCV conferred significant protection that was evident in the second year of follow-up in young children and was sustained for at least three years in older age groups. Continued follow-up will be important to establish the vaccine's duration of protection. TRIAL REGISTRATION ClinicalTrials.gov NCT00289224.
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Mutreja A, Kim DW, Thomson NR, Connor TR, Lee JH, Kariuki S, Croucher NJ, Choi SY, Harris SR, Lebens M, Niyogi SK, Kim EJ, Ramamurthy T, Chun J, Wood JLN, Clemens JD, Czerkinsky C, Nair GB, Holmgren J, Parkhill J, Dougan G. Evidence for several waves of global transmission in the seventh cholera pandemic. Nature 2011; 477:462-5. [PMID: 21866102 DOI: 10.1038/nature10392] [Citation(s) in RCA: 527] [Impact Index Per Article: 40.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2011] [Accepted: 07/26/2011] [Indexed: 11/09/2022]
Abstract
Vibrio cholerae is a globally important pathogen that is endemic in many areas of the world and causes 3-5 million reported cases of cholera every year. Historically, there have been seven acknowledged cholera pandemics; recent outbreaks in Zimbabwe and Haiti are included in the seventh and ongoing pandemic. Only isolates in serogroup O1 (consisting of two biotypes known as 'classical' and 'El Tor') and the derivative O139 can cause epidemic cholera. It is believed that the first six cholera pandemics were caused by the classical biotype, but El Tor has subsequently spread globally and replaced the classical biotype in the current pandemic. Detailed molecular epidemiological mapping of cholera has been compromised by a reliance on sub-genomic regions such as mobile elements to infer relationships, making El Tor isolates associated with the seventh pandemic seem superficially diverse. To understand the underlying phylogeny of the lineage responsible for the current pandemic, we identified high-resolution markers (single nucleotide polymorphisms; SNPs) in 154 whole-genome sequences of globally and temporally representative V. cholerae isolates. Using this phylogeny, we show here that the seventh pandemic has spread from the Bay of Bengal in at least three independent but overlapping waves with a common ancestor in the 1950s, and identify several transcontinental transmission events. Additionally, we show how the acquisition of the SXT family of antibiotic resistance elements has shaped pandemic spread, and show that this family was first acquired at least ten years before its discovery in V. cholerae.
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Sarkar BL, Bhowmick TS, Das M, Rajendran K, Nair GB. Phage Types of <i>Vibrio cholerae</i> O1 and O139 in the Past Decade in India. Jpn J Infect Dis 2011. [DOI: 10.7883/yoken.64.312] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Lindsay B, Ramamurthy T, Sen Gupta S, Takeda Y, Rajendran K, Nair GB, Stine OC. Diarrheagenic pathogens in polymicrobial infections. Emerg Infect Dis 2011. [PMID: 21470448 PMCID: PMC3377398 DOI: 10.3201/eid1704100939] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
During systematic active surveillance of the causes of diarrhea in patients admitted to the Infectious Diseases and Beliaghata General Hospital in Kolkata, India, we looked for 26 known gastrointestinal pathogens in fecal samples from 2,748 patients. Samples from about one-third (29%) of the patients contained multiple pathogens. Polymicrobial infections frequently contained Vibrio cholerae O1 and rotavirus. When these agents were present, some co-infecting agents were found significantly less often (p = 10 (-5) to 10 (-33), some were detected significantly more often (p = 10 (-5) to 10 (-26), and others were detected equally as often as when V. cholerae O1 or rotavirus was absent. When data were stratified by patient age and season, many nonrandom associations remained statistically significant. The causes and effects of these nonrandom associations remain unknown.
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Lindsay B, Ramamurthy T, Sen Gupta S, Takeda Y, Rajendran K, Nair GB, Stine OC. Diarrheagenic pathogens in polymicrobial infections. Emerg Infect Dis 2011; 17:606-11. [PMID: 21470448 DOI: 10.3201/eid1704.100939] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
During systematic active surveillance of the causes of diarrhea in patients admitted to the Infectious Diseases and Beliaghata General Hospital in Kolkata, India, we looked for 26 known gastrointestinal pathogens in fecal samples from 2,748 patients. Samples from about one-third (29%) of the patients contained multiple pathogens. Polymicrobial infections frequently contained Vibrio cholerae O1 and rotavirus. When these agents were present, some co-infecting agents were found significantly less often (p = 10 (-5) to 10 (-33), some were detected significantly more often (p = 10 (-5) to 10 (-26), and others were detected equally as often as when V. cholerae O1 or rotavirus was absent. When data were stratified by patient age and season, many nonrandom associations remained statistically significant. The causes and effects of these nonrandom associations remain unknown.
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Chowdhury G, Pazhani GP, Nair GB, Ghosh A, Ramamurthy T. Transferable plasmid-mediated quinolone resistance in association with extended-spectrum β-lactamases and fluoroquinolone-acetylating aminoglycoside-6'-N-acetyltransferase in clinical isolates of Vibrio fluvialis. Int J Antimicrob Agents 2011; 38:169-73. [PMID: 21683552 DOI: 10.1016/j.ijantimicag.2011.04.013] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2010] [Revised: 04/08/2011] [Accepted: 04/08/2011] [Indexed: 10/18/2022]
Abstract
Vibrio fluvialis, which causes cholera-like diarrhoea in humans, is one of the aetiological agents of acute diarrhoea in Kolkata, India, and is resistant to many antimicrobial agents. Two V. fluvialis isolates resistant to fluoroquinolones and β-lactam antimicrobials were found to have mutations in the quinolone resistance-determining regions (QRDRs) of GyrA at position 83 and of ParC at position 85 as well as carrying a 150 kb plasmid harbouring the quinolone resistance gene qnrA1, the ciprofloxacin-modifying enzyme-encoding gene aac(6')-Ib-cr and genes encoding for extended-spectrum β-lactamases such as bla(SHV) and bla(CTX-M-3). When this large plasmid was transferred to Escherichia coli by conjugation, the transconjugants showed a 10-75-fold increase in the minimum inhibitory concentrations of ciprofloxacin and norfloxacin. The qnrA1 gene was identified in a complex sul1-type integron in a plasmid of the transconjugants. Southern hybridisation and sequence analysis of qnrA1 and its flanking regions confirmed the presence of aac(6')-Ib-cr and bla(CTX-M-3) but these were not associated with the sul1-type integron. Pulsed-field gel electrophoresis (PFGE) revealed that the two V. fluvialis isolates belonged to different clones. Although the presence of many qnr alleles has been reported amongst enteric bacteria in Asian countries, this is the first report on the emergence of qnrA1 in India. qnrA1 along with aac(6')-Ib-cr and bla(CTX-M-3) genes on a mobile plasmid may spread to other bacterial species that are under the selective pressure of fluoroquinolones and β-lactam antimicrobials in this region.
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Ghosh S, Pazhani GP, Chowdhury G, Guin S, Dutta S, Rajendran K, Bhattacharya MK, Takeda Y, Niyogi SK, Nair GB, Ramamurthy T. Genetic characteristics and changing antimicrobial resistance among Shigella spp. isolated from hospitalized diarrhoeal patients in Kolkata, India. J Med Microbiol 2011; 60:1460-1466. [PMID: 21659504 DOI: 10.1099/jmm.0.032920-0] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
To study the prevalence pattern and trends in the phenotypic and genetic characteristics of shigellae, we tested 212 isolates isolated from diarrhoeal patients admitted to the Infectious Diseases Hospital, Kolkata, India, from November 2007 to October 2010. Prevalence of Shigella spp. was higher in the >5 years age group (69 %) than in children in the <5 years age group (31 %). Serotypes 2a, 3a and untypable isolates of Shigella flexneri were frequently detected. An increase in the isolation of Shigella sonnei (15 %) is a novel trend in this region. Fluoroquinolone resistance among S. flexneri serotypes 2a, 3a and other serogroups of shigellae is another evolving trend. The set gene was exclusively present in S. flexneri 2a, and the sen gene was detected in all serogroups. PFGE revealed the grouping of S. flexneri isolates according to their serotypes with approximately 80-100 % similarity, whilst Shigella dysenteriae type 2 and S. sonnei were clonal in nature. There was no demarcation in the prevalence of serotypes, antimicrobial resistance or clonality between the two age groups.
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Chen Y, Stine OC, Badger JH, Gil AI, Nair GB, Nishibuchi M, Fouts DE. Comparative genomic analysis of Vibrio parahaemolyticus: serotype conversion and virulence. BMC Genomics 2011; 12:294. [PMID: 21645368 PMCID: PMC3130711 DOI: 10.1186/1471-2164-12-294] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2010] [Accepted: 06/06/2011] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Vibrio parahaemolyticus is a common cause of foodborne disease. Beginning in 1996, a more virulent strain having serotype O3:K6 caused major outbreaks in India and other parts of the world, resulting in the emergence of a pandemic. Other serovariants of this strain emerged during its dissemination and together with the original O3:K6 were termed strains of the pandemic clone. Two genomes, one of this virulent strain and one pre-pandemic strain have been sequenced. We sequenced four additional genomes of V. parahaemolyticus in this study that were isolated from different geographical regions and time points. Comparative genomic analyses of six strains of V. parahaemolyticus isolated from Asia and Peru were performed in order to advance knowledge concerning the evolution of V. parahaemolyticus; specifically, the genetic changes contributing to serotype conversion and virulence. Two pre-pandemic strains and three pandemic strains, isolated from different geographical regions, were serotype O3:K6 and either toxin profiles (tdh+, trh-) or (tdh-, trh+). The sixth pandemic strain sequenced in this study was serotype O4:K68. RESULTS Genomic analyses revealed that the trh+ and tdh+ strains had different types of pathogenicity islands and mobile elements as well as major structural differences between the tdh pathogenicity islands of the pre-pandemic and pandemic strains. In addition, the results of single nucleotide polymorphism (SNP) analysis showed that 94% of the SNPs between O3:K6 and O4:K68 pandemic isolates were within a 141 kb region surrounding the O- and K-antigen-encoding gene clusters. The "core" genes of V. parahaemolyticus were also compared to those of V. cholerae and V. vulnificus, in order to delineate differences between these three pathogenic species. Approximately one-half (49-59%) of each species' core genes were conserved in all three species, and 14-24% of the core genes were species-specific and in different functional categories. CONCLUSIONS Our data support the idea that the pandemic strains are closely related and that recent South American outbreaks of foodborne disease caused by V. parahaemolyticus are closely linked to outbreaks in India. Serotype conversion from O3:K6 to O4:K68 was likely due to a recombination event involving a region much larger than the O-antigen- and K-antigen-encoding gene clusters. Major differences between pathogenicity islands and mobile elements are also likely driving the evolution of V. parahaemolyticus. In addition, our analyses categorized genes that may be useful in differentiating pathogenic Vibrios at the species level.
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Islam MS, Mahmud ZH, Uddin MH, Islam K, Yunus M, Islam MS, Nair GB, Endtz HP, Sack DA. Purification of household water using a novel mixture reduces diarrhoeal disease in Matlab, Bangladesh. Trans R Soc Trop Med Hyg 2011; 105:341-5. [PMID: 21536313 DOI: 10.1016/j.trstmh.2011.03.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2010] [Revised: 03/07/2011] [Accepted: 03/07/2011] [Indexed: 10/18/2022] Open
Abstract
In Bangladesh, one of the main causes of waterborne diseases is related to the use of contaminated surface water. This pilot study was conducted to determine the acceptability and effectiveness of a recently developed surface water purifying mixture to prevent diarrhoeal diseases in a rural community in Bangladesh. The mixture, using a combination of alum potash, bleaching powder and lime, is added to 15 l of surface water and mixed; the water becomes suitable for drinking after 30 min. A total of 420 households from 15 villages were provided with the mixture and were taught how to use it. Episodes of diarrhoeal disease from study families were determined from hospital records of the International Centre for Diarrhoeal Disease Research, Bangladesh (ICDDR,B) in Matlab and were compared with diarrhoea episodes among 1613 control families who were not provided with the mixture. A total of 83 diarrhoeal patients were treated at Matlab Hospital from 1613 control families, but only one patient was treated for diarrhoea from among the intervention families. Among the intervention families, 73 families decided to shift from using tube well water to surface water using the mixture. The mixture could be used as a cheaper, easier and simpler point-of-use water treatment strategy in Bangladesh.
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Nair GB, Takeda Y. Dr Sambhu Nath De: unsung hero. Indian J Med Res 2011; 133:127. [PMID: 21415484 PMCID: PMC3089041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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Deb AK, Kanungo S, Nair GB, Narain JP. The challenge of pneumonia & acute diarrhoea at global, regional & national levels: time to refocus on a top most priority health problem. Indian J Med Res 2011; 133:128-30. [PMID: 21415485 PMCID: PMC3089042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
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Zahid MSH, Waise Z, Kamruzzaman M, Ghosh A, Nair GB, Bashar SK, Mekalanos JJ, Faruque SM. An experimental study of phage mediated bactericidal selection & emergence of the El Tor Vibrio cholerae. Indian J Med Res 2011; 133:218-24. [PMID: 21415498 PMCID: PMC3089055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
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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Sarkar BL, Bhowmick TS, Das M, Rajendran K, Nair GB. Phage types of Vibrio cholerae O1 and O139 in the past decade in India. Jpn J Infect Dis 2011; 64:312-315. [PMID: 21788707] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Cholera has been a prevalent disease worldwide since the early 19th century. Vibrio cholerae O1 and O139 are the two serogroups that have been mainly implicated in causing cholera. This study reports the results of biotyping, serotyping and phage typing of V. cholerae O1 and O139 (1998-2007) strains received from different parts of India for the identification of the trends in the occurrence and spread of cholera in the country. However, there has been a notable steep decline in the occurrence of V. cholerae O139 strains over the past few years resulting in no strain of V. cholerae O139 being received from any part of India in 2007 and 2008. Of the total strains received, 79.1% were serotyped as Ogawa and the remaining 20.9% were found to be Inaba, which indicates that Ogawa was the predominant serotype. Almost 100% typeability was observed with the new scheme of V. cholerae O1, with type 27 being the dominant phage type and V. cholerae O139 strains were clustered into the predominant phage type T-1. From the phage typing and serotyping results, it can be concluded that V. cholerae O1 (T-27) and O139 (T-1) strains circulate throughout the country at any given time.
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Patra R, Chattopadhyay S, De R, Datta S, Chowdhury A, Ramamurthy T, Nair GB, Berg DE, Mukhopadhyay AK. Intact cag pathogenicity island of Helicobacter pylori without disease association in Kolkata, India. Int J Med Microbiol 2010; 301:293-302. [PMID: 21195664 DOI: 10.1016/j.ijmm.2010.10.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2010] [Revised: 08/20/2010] [Accepted: 10/17/2010] [Indexed: 01/06/2023] Open
Abstract
Several genes including the cagA in the cag pathogenicity island (cag PAI) of Helicobacter pylori are thought to be associated with the gastroduodenal diseases and hence variation in the genetic structure of the cag PAI might be responsible for different clinical outcomes. Our study was undertaken to characterize the cag PAI of H. pylori strains from duodenal ulcer (DU) patients and asymptomatic or non-ulcer dyspepsia (NUD/AV) subjects from Kolkata, India. Strains isolated from 52 individuals (30DU and 22NUD/AV) were analyzed by PCR using 83 different primers for the entire cag PAI and also by dot-blot hybridization. Unlike H. pylori strains isolated from other parts of India, 82.6% of the strains used in this study had intact cag PAI, 9.6% had partially deleted cag PAI, and 7.7% of the strains lacked the entire cag PAI. Dot-blot hybridization yielded positive signals in 100% and 93.8% of PCR-negative strains for HP0522-523 and HP0532-HP0534 genes, respectively. An intact cagA promoter region was also detected in all cagA-positive strains. Furthermore, the expression of cagA mRNA was confirmed by RT-PCR for the representative strains from both DU and NUD/AV subjects indicating the active cagA promoter regions of these strains. A total of 66.7% of Kolkata strains produced a ∼390-bp shorter amplicon than the standard strain 26695 for the HP0527 gene, homologue of virB10. However, sequence analyses confirmed that the deletion did not alter the reading frame of the gene, and mRNA transcripts were detected by RT-PCR analysis. The strains isolated from DU and NUD/AV express CagA protein and possess a functional type IV secretion system, as revealed by Western blot analyses. Interestingly, no significant differences in cag PAI genetic structure were found between DU and NUD/AV individuals suggesting that other bacterial virulence factors, host susceptibility, and environmental determinants also influence the disease outcome at least in certain geographical locations.
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Alam M, Hasan NA, Sultana M, Nair GB, Sadique A, Faruque ASG, Endtz HP, Sack RB, Huq A, Colwell RR, Izumiya H, Morita M, Watanabe H, Cravioto A. Diagnostic limitations to accurate diagnosis of cholera. J Clin Microbiol 2010; 48:3918-22. [PMID: 20739485 PMCID: PMC3020846 DOI: 10.1128/jcm.00616-10] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2010] [Revised: 06/06/2010] [Accepted: 08/18/2010] [Indexed: 11/20/2022] Open
Abstract
The treatment regimen for diarrhea depends greatly on correct diagnosis of its etiology. Recent diarrhea outbreaks in Bangladesh showed Vibrio cholerae to be the predominant cause, although more than 40% of the suspected cases failed to show cholera etiology by conventional culture methods (CMs). In the present study, suspected cholera stools collected from every 50th patient during an acute diarrheal outbreak were analyzed extensively using different microbiological and molecular tools to determine their etiology. Of 135 stools tested, 86 (64%) produced V. cholerae O1 by CMs, while 119 (88%) tested positive for V. cholerae O1 by rapid cholera dipstick (DS) assay; all but three samples positive for V. cholerae O1 by CMs were also positive for V. cholerae O1 by DS assay. Of 49 stools that lacked CM-based cholera etiology despite most being positive for V. cholerae O1 by DS assay, 25 (51%) had coccoid V. cholerae O1 cells as confirmed by direct fluorescent antibody (DFA) assay, 36 (73%) amplified primers for the genes wbe O1 and ctxA by multiplex-PCR (M-PCR), and 31 (63%) showed El Tor-specific lytic phage on plaque assay (PA). Each of these methods allowed the cholera etiology to be confirmed for 97% of the stool samples. The results suggest that suspected cholera stools that fail to show etiology by CMs during acute diarrhea outbreaks may be due to the inactivation of V. cholerae by in vivo vibriolytic action of the phage and/or nonculturability induced as a host response.
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Basu S, Singh AK, Nair GB. Emerging carbapenem resistance in the context of a new metallo-beta-lactamase (NDM-1). THE NATIONAL MEDICAL JOURNAL OF INDIA 2010; 23:261-262. [PMID: 21250578] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
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Senoh M, Ghosh-Banerjee J, Ramamurthy T, Hamabata T, Kurakawa T, Takeda M, Colwell RR, Nair GB, Takeda Y. Conversion of viable but nonculturable Vibrio cholerae to the culturable state by co-culture with eukaryotic cells. Microbiol Immunol 2010; 54:502-7. [DOI: 10.1111/j.1348-0421.2010.00245.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Nair GB, Narain JP. From endotoxin to exotoxin: De's rich legacy to cholera. Bull World Health Organ 2010; 88:237-40. [PMID: 20428396 DOI: 10.2471/blt.09.072504] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Between 1951 and 1959, Sambhu Nath De made crucial discoveries on the pathogenesis of cholera that changed the course of our understanding of the disease. The discovery that cholera is caused by a potent exotoxin (cholera enterotoxin) affecting intestinal permeability, the demonstration that bacteria-free culture filtrates of Vibrio cholerae were enterotoxic, and the development of a reproducible animal model for the disease are considered milestones in the history of the fight against cholera. In this commentary, a classic article by De & Chatterje published in 1953 and its public health and research impact are highlighted.
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Mukherjee P, Ghosh S, Ramamurthy T, Bhattacharya MK, Nandy RK, Takeda Y, Nair GB, Mukhopadhyay AK. Evaluation of a Rapid Immunochromatographic Dipstick Kit for Diagnosis of Cholera Emphasizes Its Outbreak Utility. Jpn J Infect Dis 2010. [DOI: 10.7883/yoken.63.234] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Mukherjee P, Ghosh S, Ramamurthy T, Bhattacharya MK, Nandy RK, Takeda Y, Nair GB, Mukhopadhyay AK. Evaluation of a rapid immunochromatographic dipstick kit for diagnosis of cholera emphasizes its outbreak utility. Jpn J Infect Dis 2010; 63:234-238. [PMID: 20657061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
We evaluated the Crystal VC, a commercially produced dipstick, for the rapid detection of Vibrio cholerae serotypes O1 and O139 directly from the stool samples of hospitalized diarrheal patients using the conventional bacteriological method as gold standard. The sensitivity and specificity of the dipsticks were about 92 and 73%, respectively. Introduction of the PCR-based method along with the classical bacteriological method as the gold standard for the evaluation of a kit may improve the sensitivity and specificity of the assay. The dipstick method requires minimal technical skill, and the test can be read in about 10 min. This dipstick test has the potential to act as an early warning system for cholera in many developing countries, especially during the start of an outbreak, which would ultimately lead to a decrease in the spread of the disease as well as the case fatality rate. Furthermore, the use of a rapid detection test will improve surveillance and thus reduce the burden of disease estimates, especially in remote settings.
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Morita M, Ohnishi M, Arakawa E, Yamamoto S, Nair GB, Matsushita S, Yokoyama K, Kai A, Seto K, Watanabe H, Izumiya H. Emergence and genetic diversity of El Tor Vibrio cholerae O1 that possess classical biotype ctxB among travel-associated cases of cholera in Japan. J Med Microbiol 2010; 59:708-712. [DOI: 10.1099/jmm.0.017624-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
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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Gleick PH, Adams RM, Amasino RM, Anders E, Anderson DJ, Anderson WW, Anselin LE, Arroyo MK, Asfaw B, Ayala FJ, Bax A, Bebbington AJ, Bell G, Bennett MVL, Bennetzen JL, Berenbaum MR, Berlin OB, Bjorkman PJ, Blackburn E, Blamont JE, Botchan MR, Boyer JS, Boyle EA, Branton D, Briggs SP, Briggs WR, Brill WJ, Britten RJ, Broecker WS, Brown JH, Brown PO, Brunger AT, Cairns J, Canfield DE, Carpenter SR, Carrington JC, Cashmore AR, Castilla JC, Cazenave A, Chapin FS, Ciechanover AJ, Clapham DE, Clark WC, Clayton RN, Coe MD, Conwell EM, Cowling EB, Cowling RM, Cox CS, Croteau RB, Crothers DM, Crutzen PJ, Daily GC, Dalrymple GB, Dangl JL, Darst SA, Davies DR, Davis MB, De Camilli PV, Dean C, DeFries RS, Deisenhofer J, Delmer DP, DeLong EF, DeRosier DJ, Diener TO, Dirzo R, Dixon JE, Donoghue MJ, Doolittle RF, Dunne T, Ehrlich PR, Eisenstadt SN, Eisner T, Emanuel KA, Englander SW, Ernst WG, Falkowski PG, Feher G, Ferejohn JA, Fersht A, Fischer EH, Fischer R, Flannery KV, Frank J, Frey PA, Fridovich I, Frieden C, Futuyma DJ, Gardner WR, Garrett CJR, Gilbert W, Goldberg RB, Goodenough WH, Goodman CS, Goodman M, Greengard P, Hake S, Hammel G, Hanson S, Harrison SC, Hart SR, Hartl DL, Haselkorn R, Hawkes K, Hayes JM, Hille B, Hökfelt T, House JS, Hout M, Hunten DM, Izquierdo IA, Jagendorf AT, Janzen DH, Jeanloz R, Jencks CS, Jury WA, Kaback HR, Kailath T, Kay P, Kay SA, Kennedy D, Kerr A, Kessler RC, Khush GS, Kieffer SW, Kirch PV, Kirk K, Kivelson MG, Klinman JP, Klug A, Knopoff L, Kornberg H, Kutzbach JE, Lagarias JC, Lambeck K, Landy A, Langmuir CH, Larkins BA, Le Pichon XT, Lenski RE, Leopold EB, Levin SA, Levitt M, Likens GE, Lippincott-Schwartz J, Lorand L, Lovejoy CO, Lynch M, Mabogunje AL, Malone TF, Manabe S, Marcus J, Massey DS, McWilliams JC, Medina E, Melosh HJ, Meltzer DJ, Michener CD, Miles EL, Mooney HA, Moore PB, Morel FMM, Mosley-Thompson ES, Moss B, Munk WH, Myers N, Nair GB, Nathans J, Nester EW, Nicoll RA, Novick RP, O'Connell JF, Olsen PE, Opdyke ND, Oster GF, Ostrom E, Pace NR, Paine RT, Palmiter RD, Pedlosky J, Petsko GA, Pettengill GH, Philander SG, Piperno DR, Pollard TD, Price PB, Reichard PA, Reskin BF, Ricklefs RE, Rivest RL, Roberts JD, Romney AK, Rossmann MG, Russell DW, Rutter WJ, Sabloff JA, Sagdeev RZ, Sahlins MD, Salmond A, Sanes JR, Schekman R, Schellnhuber J, Schindler DW, Schmitt J, Schneider SH, Schramm VL, Sederoff RR, Shatz CJ, Sherman F, Sidman RL, Sieh K, Simons EL, Singer BH, Singer MF, Skyrms B, Sleep NH, Smith BD, Snyder SH, Sokal RR, Spencer CS, Steitz TA, Strier KB, Südhof TC, Taylor SS, Terborgh J, Thomas DH, Thompson LG, Tjian RT, Turner MG, Uyeda S, Valentine JW, Valentine JS, Van Etten JL, van Holde KE, Vaughan M, Verba S, von Hippel PH, Wake DB, Walker A, Walker JE, Watson EB, Watson PJ, Weigel D, Wessler SR, West-Eberhard MJ, White TD, Wilson WJ, Wolfenden RV, Wood JA, Woodwell GM, Wright HE, Wu C, Wunsch C, Zoback ML. Climate change and the integrity of science. Science 2010; 328:689-90. [PMID: 20448167 DOI: 10.1126/science.328.5979.689] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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Choi SY, Lee JH, Jeon YS, Lee HR, Kim EJ, Ansaruzzaman M, Bhuiyan NA, Endtz HP, Niyogi SK, Sarkar BL, Nair GB, Nguyen BM, Hien NT, Czerkinsky C, Clemens JD, Chun J, Kim DW. Multilocus variable-number tandem repeat analysis of Vibrio cholerae O1 El Tor strains harbouring classical toxin B. J Med Microbiol 2010; 59:763-769. [PMID: 20299504 DOI: 10.1099/jmm.0.017939-0] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
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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