G. Balakrish Nair

Clonal Diversity among Recently Emerged Strains of Vibrio parahaemolyticus O3:K6 Associated With Pandemic Spread

Bag, Prasanta K., Nandi, Suvobroto, Bhadra, Rupak K., Ramamurthy, T., Bhattacharya, S. K., Nishibuchi, M., ...

The genomes of the O3:K6 strains of Vibrio parahaemolyticus which abruptly emerged in Calcutta, India, in February 1996 and which demonstrated an unusual potential to spread and an enhanced...

Development and Evaluation of a Phage Typing Scheme for Vibrio cholerae O139

Chakrabarti, A. K., Ghosh, A. N., Nair, G. Balakrish, Niyogi, S. K., Bhattacharya, S. K., Sarkar, B. L.

The scenario of cholera that existed previously changed in 1992 and 1993 with the emergence of toxigenic Vibrio cholerae O139 in India. The genesis of the new serogroup formed the impetus to search...

Rapid Method for Species-Specific Identification of Vibrio cholerae Using Primers Targeted to the Gene of Outer Membrane Protein OmpW

Nandi, Bisweswar, Nandy, Ranjan K., Mukhopadhyay, Sarmishtha, Nair, G. Balakrish, Shimada, Toshio, Ghose, Asoke C.

The distribution of genes for an outer membrane protein (OmpW) and a regulatory protein (ToxR) in Vibrio cholerae and other organisms was studied using respective primers and probes. PCR...

Emergence of Vibrio cholerae O1 Biotype El Tor Serotype Inaba from the Prevailing O1 Ogawa Serotype Strains in India

Garg, Pallavi, Nandy, Ranjan K., Chaudhury, Papiya, Chowdhury, Nandini Roy, De, Keya, Ramamurthy, T., ...

The toxigenic Inaba serotype of Vibrio cholerae O1 biotype El Tor reappeared in India in 1998 and 1999, almost 10 years after its last dominance in Calcutta in 1989. Extensive molecular...

Concomitant Infection of Enterotoxigenic Escherichia coli in an Outbreak of Cholera Caused by Vibrio cholerae O1 and O139 in Ahmedabad, India

Chakraborty, Subhra, Deokule, J. S., Garg, Pallavi, Bhattacharya, S. K., Nandy, R. K., Nair, G. Balakrish, ...

In Ahmedabad, a major city in the state of Gujarat, India, an outbreak of acute secretory diarrhea caused by Vibrio cholerae O1 Ogawa El Tor, V. cholerae O139, and multiple serotypes of...

Virulence Genes in Environmental Strains of Vibrio cholerae

Chakraborty, Soumen, Mukhopadhyay, Asish K., Bhadra, Rupak Kumar, Ghosh, Amar Nath, Mitra, Rupak, Shimada, Toshio, ...

The virulence of a pathogen is dependent on a discrete set of genetic determinants and their well-regulated expression. The ctxAB and tcpA genes are known to play a cardinal role in maintaining...

Distinctiveness of Genotypes of Helicobacter pylori in Calcutta, India

Mukhopadhyay, Asish K., Kersulyte, Dangeruta, Jeong, Jin-Yong, Datta, Simanti, Ito, Yoshiyuki, Chowdhury, Abhijit, ...

The genotypes of 78 strains of Helicobacter pylori from Calcutta, India (55 from ulcer patients and 23 from more-benign infections), were studied, with a focus on putative virulence genes and neutral...

Sequential Inactivation of rdxA (HP0954) and frxA (HP0642) Nitroreductase Genes Causes Moderate and High-Level Metronidazole Resistance in Helicobacter pylori

Jeong, Jin-Yong, Mukhopadhyay, Asish K., Dailidiene, Daiva, Wang, Yipeng, Velapatiño, Billie, Gilman, Robert H., ...

Helicobacter pylori is a human-pathogenic bacterial species that is subdivided geographically, with different genotypes predominating in different parts of the world. Here we test and extend an...

Cell Vacuolation, a Manifestation of the El Tor Hemolysin of Vibrio cholerae

Mitra, Rupak, Figueroa, Paula, Mukhopadhyay, Asish K., Shimada, Toshio, Takeda, Yoshifumi, Berg, Douglas E., ...

Culture supernatants of nontoxigenic nonepidemic clinical strains of Vibrio cholerae belonging to diverse serogroups were found to induce vacuolation of nonconfluent HeLa cells. The vacuoles became...

Diminished Diarrheal Response to Vibrio cholerae Strains Carrying the Replicative Form of the CTXΦ Genome instead of CTXΦ Lysogens in Adult Rabbits

Faruque, Shah M., Rahman, M. Mostafizur, Nair, G. Balakrish, Mekalanos, John J., Sack, David A.

Toxigenic Vibrio cholerae strains are lysogens of CTXΦ, a filamentous bacteriophage which encodes cholera toxin (CT). Following infection of recipient V. cholerae cells by CTXΦ, the phage genome...

Characterization of VPI Pathogenicity Island and CTXφ Prophage in Environmental Strains of Vibrio cholerae

Mukhopadhyay, Asish K., Chakraborty, Soumen, Takeda, Yoshifumi, Nair, G. Balakrish, Berg, Douglas E.

Environmental isolates of Vibrio cholerae of eight randomly amplified polymorphic DNA (RAPD) fingerprint types from Calcutta, India, that were unusual in containing toxin-coregulated pilus or cholera...

Molecular Analysis of Non-O1, Non-O139 Vibrio cholerae Associated with an Unusual Upsurge in the Incidence of Cholera-Like Disease in Calcutta, India

Sharma, Charu, Thungapathra, M., Ghosh, A., Mukhopadhyay, Asish K., Basu, Arnab, Mitra, Rupak, ...

There was an inexplicable upsurge in the incidence of non-O1, non-O139 Vibrio cholerae among hospitalized patients admitted to the Infectious Diseases Hospital, Calcutta, India, between February and...

Molecular Evidence that a Distinct Vibrio cholerae O1 Biotype El Tor Strain in Calcutta May Have Spread to the African Continent

Sharma, Charu, Ghosh, Amit, Dalsgaard, A., Forslund, Anita, Ghosh, R. K., Bhattacharya, S. K., ...

We present molecular evidence that a distinct genotype of Vibrio cholerae O1 which appeared in Calcutta, India, in September 1993 and which is characterized by a unique ribotype that is not found in...

Molecular Epidemiology of Reemergent Vibrio cholerae O139 Bengal in India

Mukhopadhyay, Asish Kumar, Basu, Arnab, Garg, Pallavi, Bag, Prasanta K., Ghosh, Amit, Bhattacharya, S. K., ...

We report the prevalence of the O139 serogroup in Calcutta, India, after its reemergence in August 1996 and the spread of the reemerged clone to other parts of the country by using previously...

Rapid Diagnosis of Cholera Caused by Vibrio cholerae O139

Chaicumpa, Wanpen, Srimanote, Potjanee, Sakolvaree, Yuwaporn, Kalampaheti, Thareerat, Chongsa-Nguan, Manas, Tapchaisri, Pramuan, ...

Hybridomas secreting specific monoclonal antibodies (MAbs) to Vibrio cholerae serogroup O139 were produced. Six monoclones (hybridomas) secreting MAbs specific only to lipopolysaccharide of V....

Use of Monoclonal Antibodies To Identify Phospholipase C as the Enterotoxic Factor of the Bifunctional Hemolysin-Phospholipase C Molecule of Vibrio cholerae O139

Pal, Sangita, Datta, Archana, Nair, G. Balakrish, Guhathakurta, Bhakti

Two hybrid clones producing monoclonal antibodies (MAbs) raised against the purified enterotoxic hemolysin-phospholipase C (HlyPC) bifunctional molecule of a Vibrio cholerae O139 strain were used to...

Prevalence of the Pandemic Genotype of Vibrio parahaemolyticus in Dhaka, Bangladesh, and Significance of Its Distribution across Different Serotypes

Bhuiyan, N. A., Ansaruzzaman, M., Kamruzzaman, M., Alam, Khorshed, Chowdhury, N. R., Nishibuchi, M., ...

Sixty-six strains of Vibrio parahaemolyticus belonging to 14 serotypes were isolated from hospitalized patients in Dhaka, Bangladesh, from January 1998 to December 2000. Among these, 48 strains...

Virulence Genes in Helicobacter pylori Strains from West Bengal Residents with Overt H. pylori-Associated Disease and Healthy Volunteers

Chattopadhyay, Santanu, Datta, Simanti, Chowdhury, Abhijit, Chowdhury, Sujit, Mukhopadhyay, Asish K., Rajendran, K., ...

We compared putative molecular markers of virulence (vacA, cagA, and iceA) of Helicobacter pylori strains isolated from 52 adult duodenal ulcer patients from West Bengal, India, with those of H....

Escalating Association of Vibrio cholerae O139 with Cholera Outbreaks in India

Sinha, Sutapa, Chakraborty, Rupa, De, Keya, Khan, Asis, Datta, Simanti, Ramamurthy, T., ...

Between December 1999 and December 2000, teams from the National Institute of Cholera and Enteric Diseases, Calcutta, India, examined eight outbreaks of cholera, which occurred in different parts of...

Isolation of Shigella dysenteriae Type 1 and S. flexneri Strains from Surface Waters in Bangladesh: Comparative Molecular Analysis of Environmental Shigella Isolates versus Clinical Strains

Faruque, Shah M., Khan, Rasel, Kamruzzaman, M., Yamasaki, Shinji, Ahmad, Q. Shafi, Azim, Tasnim, ...

Bacillary dysentery caused by Shigella species is a public health problem in developing countries including Bangladesh. Although, shigellae-contaminated food and drinks are often the source of the...

Role of Active Efflux in Association with Target Gene Mutations in Fluoroquinolone Resistance in Clinical Isolates of Vibrio cholerae

Baranwal, Somesh, Dey, Keya, Ramamurthy, T., Nair, G. Balakrish, Kundu, Manikuntala

Quinolones are among the drugs of choice in the management of cholera caused by Vibrio cholerae. In this study, we demonstrate that, in addition to mutations detected in the target genes gyrA and...

RS1 Element of Vibrio cholerae Can Propagate Horizontally as a Filamentous Phage Exploiting the Morphogenesis Genes of CTXΦ

Faruque, Shah M., Kamruzzaman, M., Nandi, Ranjan K., Ghosh, A. N., Nair, G. Balakrish, ...

In toxigenic Vibrio cholerae, cholera toxin is encoded by the CTX prophage, which consists of a core region carrying ctxAB genes and genes required for CTXΦ morphogenesis, and an RS2 region encoding...

Vibrio Pathogenicity Island and Cholera Toxin Genetic Element-Associated Virulence Genes and Their Expression in Non-O1 Non-O139 Strains of Vibrio cholerae

Sarkar, Amit, Nandy, Ranjan K., Nair, G. Balakrish, Ghose, Asoke C.

A non-O1 non-O139 Vibrio cholerae strain, 10259, belonging to the serogroup O53 was shown to harbor genes related to the vibrio pathogenicity island (VPI) and a cholera toxin (CT) genetic element...

New Variants of Vibrio cholerae O1 Biotype El Tor with Attributes of the Classical Biotype from Hospitalized Patients with Acute Diarrhea in Bangladesh

Nair, G. Balakrish, Faruque, Shah M., Bhuiyan, N. A., Kamruzzaman, M., Siddique, A. K., Sack, David A.

The sixth pandemic of cholera and, presumably, the earlier pandemics were caused by the classical biotype of Vibrio cholerae O1, which was progressively replaced by the El Tor biotype representing...

Antibiotic Resistance, Virulence Gene, and Molecular Profiles of Shiga Toxin-Producing Escherichia coli Isolates from Diverse Sources in Calcutta, India

Khan, Asis, Das, S. C., Ramamurthy, T., Sikdar, A., Khanam, J., Yamasaki, S., ...

Antibiotic resistance, virulence gene, and molecular profiles of Shiga toxin-producing Escherichia coli (STEC) non-O157 strains isolated from human stool samples, cow stool samples, and beef samples...

Cloning and Characterization of Genes Encoding Homologues of the B Subunit of Cholera Toxin and the Escherichia coli Heat-Labile Enterotoxin from Clinical Isolates of Citrobacter freundii and E. coli

Karasawa, Tadahiro, Ito, Hideaki, Tsukamoto, Teizo, Yamasaki, Shinji, Kurazono, Hisao, Faruque, Shah M., ...

We identified and characterized a gene encoding a homologue of the B subunits of cholera toxin (CTB) and heat-labile enterotoxin (LTB) of Escherichia coli from a clinical isolate of Citrobacter...

Pathogenic Potential of Environmental Vibrio cholerae Strains Carrying Genetic Variants of the Toxin-Coregulated Pilus Pathogenicity Island

Faruque, Shah M., Kamruzzaman, M., Meraj, Ismail M., Chowdhury, Nityananda, Nair, G. Balakrish, Sack, R. Bradley, ...

The major virulence factors of toxigenic Vibrio cholerae are cholera toxin (CT), which is encoded by a lysogenic bacteriophage (CTXΦ), and toxin-coregulated pilus (TCP), an essential colonization...

DNA-Level Characterization of Helicobacter pylori Strains from Patients with Overt Disease and with Benign Infections in Bangladesh

Rahman, Motiur, Mukhopadhyay, Asish K., Nahar, Shamsun, Datta, Simanti, Mashhud Ahmad, Milan, Sarker, Safique, ...

The complex relation between the genotype of Helicobacter pylori and its association with clinical outcome is not well understood. Studies in the West have showed that strains expressing certain...

Environmental Isolates of Aeromonas spp. Harboring the cagA-Like Gene of Helicobacter pylori

Datta, Simanti, Khan, Asis, Nandy, Ranjan K., Rehman, Motiur, Sinha, Sutapa, Chattopadhyay, Santanu, ...

We investigated the presence of cagA-like gene of Helicobacter pylori in environmental isolates of Aeromonas spp. from different water samples of Calcutta, India, by colony hybridization using a...

Association of Cytolethal Distending Toxin Locus cdtB with Enteropathogenic Escherichia coli Isolated from Patients with Acute Diarrhea in Calcutta, India

Pandey, Mritunjay, Khan, Asis, Das, Suresh C., Sarkar, Bhaswati, Kahali, Soumen, Chakraborty, Subhra, ...

Among Escherichia coli strains isolated from stool specimens from patients with acute diarrhea, 1.4% were found to harbor cdtB by use of enrichment cytolethal distending toxin (CDT) PCR. These...

CTXΦ-independent production of the RS1 satellite phage by Vibrio cholerae

Faruque, Shah M., Kamruzzaman, M., Sack, David A., Mekalanos, John J., Nair, G. Balakrish

The cholera toxin genes of Vibrio cholerae are encoded by the filamentous phage, CTXΦ. Chromosomal CTXΦ prophage DNA is often found flanked by copies of a related genetic element designated RS1,...

Emergence and evolution of Vibrio cholerae O139

Faruque, Shah M., Sack, David A., Sack, R. Bradley, Colwell, Rita R., Takeda, Yoshifumi, Nair, G. Balakrish

The emergence of Vibrio cholerae O139 Bengal during 1992–1993 was associated with large epidemics of cholera in India and Bangladesh and, initially, with a total displacement of the existing V....

Shigella dysenteriae Type 1-Specific Bacteriophage from Environmental Waters in Bangladesh

Faruque, Shah M., Chowdhury, Nityananda, Khan, Rasel, Hasan, M. Rubayet, Nahar, Jebun, Islam, M. Johirul, ...

Shigella dysenteriae type 1 is the causative agent of the most severe form of bacillary dysentery, which occurs as epidemics in many developing countries. We isolated a bacteriophage from surface...

Genetic diversity and virulence potential of environmental Vibrio cholerae population in a cholera-endemic area

Faruque, Shah M., Chowdhury, Nityananda, Kamruzzaman, M., Dziejman, Michelle, Rahman, M. Hasibur, Sack, David A., ...

To understand the evolutionary events and possible selection mechanisms involved in the emergence of pathogenic Vibrio cholerae, we analyzed diverse strains of V. cholerae isolated from environmental...

Multiplex PCR Assay for Rapid Detection and Genotyping of Helicobacter pylori Directly from Biopsy Specimens

Chattopadhyay, Santanu, Patra, Rajashree, Ramamurthy, T., Chowdhury, Abhijit, Santra, Amal, Dhali, G. K., ...

We developed and evaluated a simple, novel multiplex PCR assay for rapid detection of Helicobacter pylori infection and for the determination of vacA and cagA genotypes directly from gastric biopsy...

Antimicrobial Susceptibility of Helicobacter pylori Strains Isolated in Bangladesh

Nahar, Shamsun, Mukhopadhyay, Asish K., Khan, Rasel, Ahmad, Mian Mashhud, Datta, Simanti, Chattopadhyay, Santanu, ...

Antimicrobial susceptibility of 120 Helicobacter pylori isolates to metronidazole, tetracycline, clarithromycin, and amoxicillin was determined, and 77.5, 15, 10, and 6.6% of the isolates,...

Diverse CTX Phages among Toxigenic Vibrio cholerae O1 and O139 Strains Isolated between 1994 and 2002 in an Area Where Cholera is Endemic in Bangladesh

Nusrin, Suraia, Khan, G. Yeahia, Bhuiyan, N. A., Ansaruzzaman, M., Hossain, M. A., Safa, Ashrafus, ...

PCR surveillance of the rstR genes of CTX phages in Vibrio cholerae O1 and O139 showed no relationship between the incidence of disease and changes in the rstR but showed variations in their presence...

Seasonal epidemics of cholera inversely correlate with the prevalence of environmental cholera phages

Faruque, Shah M., Naser, Iftekhar Bin, Islam, M. Johirul, Faruque, A. S. G., Ghosh, A. N., Nair, G. Balakrish, ...

The relationship among (i) the local incidence of cholera, (ii) the prevalence in the aquatic environment of Vibrio cholerae, and (iii) bacterial viruses that attack potentially virulent O1 and O139...

Genomic Relatedness of the New Matlab Variants of Vibrio cholerae O1 to the Classical and El Tor Biotypes as Determined by Pulsed-Field Gel Electrophoresis

Safa, Ashrafus, Bhuiyan, Nurul Amin, Alam, Munirul, Sack, David A., Nair, G. Balakrish

The genomes of the recently described Matlab variants of Vibrio cholerae O1 that are hybrids between classical and El Tor biotypes were compared with those of El Tor and classical biotypes by the use...

Self-limiting nature of seasonal cholera epidemics: Role of host-mediated amplification of phage

Faruque, Shah M., Islam, M. Johirul, Ahmad, Qazi Shafi, Faruque, A. S. G., Sack, David A., Nair, G. Balakrish, ...

Phage predation of Vibrio cholerae has recently been reported to be a factor that influences seasonal epidemics of cholera in Bangladesh. To understand more about this phenomenon, we studied the...

Pandemic Serovars (O3:K6 and O4:K68) of Vibrio parahaemolyticus Associated with Diarrhea in Mozambique: Spread of the Pandemic into the African Continent

Ansaruzzaman, M., Lucas, Marcelino, Deen, Jacqueline L., Bhuiyan, N. A., Wang, Xuan-Yi, Safa, Ashrafus, ...

Forty-two episodes of Vibrio parahaemolyticus infections were detected in Beira, Mozambique, from January to May 2004. The majority of the isolates (81%) belonged to the pandemic serovars (O3:K6 and...

Critical Factors Influencing the Occurrence of Vibrio cholerae in the Environment of Bangladesh

Huq, Anwar, Sack, R. Bradley, Nizam, Azhar, Longini, Ira M., Nair, G. Balakrish, Ali, Afsar, ...

The occurrence of outbreaks of cholera in Africa in 1970 and in Latin America in 1991, mainly in coastal communities, and the appearance of the new serotype Vibrio cholerae O139 in India and...

Reduction in Capsular Content and Enhanced Bacterial Susceptibility to Serum Killing of Vibrio cholerae O139 Associated with the 2002 Cholera Epidemic in Bangladesh

Qadri, Firdausi, Svennerholm, Ann-Mari, Shamsuzzaman, Sohel, Bhuiyan, Taufiqur Rahman, Harris, Jason B., Ghosh, A. N., ...

Vibrio cholerae O139 emerged in 1992 as a major cause of epidemic cholera. However, the incidence of disease due to this new serogroup subsequently decreased for almost a decade. In April 2002, there...

Effect of Transport at Ambient Temperature on Detection and Isolation of Vibrio cholerae from Environmental Samples

Alam, Munirul, Sadique, Abdus, Bhuiyan, Nurul A., Nair, G. Balakrish, Siddique, A. K., ...

It has long been assumed that prolonged holding of environmental samples at the ambient air temperature prior to bacteriological analysis is detrimental to isolation and detection of Vibrio cholerae,...

Toxigenic Vibrio cholerae in the Aquatic Environment of Mathbaria, Bangladesh

Alam, Munirul, Sultana, Marzia, Nair, G. Balakrish, Sack, R. Bradley, Sack, David A., Siddique, A. K., ...

Toxigenic Vibrio cholerae, rarely isolated from the aquatic environment between cholera epidemics, can be detected in what is now understood to be a dormant stage, i.e., viable but nonculturable when...

Transmissibility of cholera: In vivo-formed biofilms and their relationship to infectivity and persistence in the environment

Faruque, Shah M., Biswas, Kuntal, Udden, S. M. Nashir, Ahmad, Qazi Shafi, Sack, David A., Nair, G. Balakrish, ...

The factors that enhance the waterborne spread of bacterial epidemics and sustain the epidemic strain in nature are unclear. Although the epidemic diarrheal disease cholera is known to be transmitted...

Seasonal Cholera Caused by Vibrio cholerae Serogroups O1 and O139 in the Coastal Aquatic Environment of Bangladesh

Alam, Munirul, Hasan, Nur A., Sadique, Abdus, Bhuiyan, N. A., Ahmed, Kabir U., Nusrin, Suraia, ...

Since Vibrio cholerae O139 first appeared in 1992, both O1 El Tor and O139 have been recognized as the epidemic serogroups, although their geographic distribution, endemicity, and reservoir are not...