Search PubMed⌕ Search

Biomedical subjects

B L Sarkar

Publications and source records attributed to B L Sarkar.

18 recordsLinked to original sources
PubMed2000

Development and evaluation of a phage typing scheme for Vibrio cholerae O139.

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 for O139 phages in and around the country. A total of five newly isolated phages lytic to V. cholerae O139 strains were used for the development of this phage typing scheme. These phages differed from each other and also differed from the existing O1 phages in their lytic patterns, morphologies, restriction endonuclease digestion profiles, and immunological criteria. With this scheme, 500 V. cholerae O139 strains were evaluated for their phage types, and almost all strains were found to be typeable. The strains clustered into 10 different phage types, of which type 1 (38.2%) was the dominant type, followed by type 2 (22.4%) and type 3 (18%). Additionally, a comparative study of phage types in 1993 and 1994 versus those from 1996 to 1998 for O139 strains showed a higher percentage of phage type 1 (40.5%), followed by type 3 (18.8%) during the period between 1993 and 1994, whereas phage type 2 (32. 1%) was the next major type during the period from 1996 to 1998. This scheme comprising five newly isolated phages would be another useful tool in the study of the epidemiology of cholera caused by V. cholerae O139.

Bacteriophage Typing↗
PubMed1999

Distribution of phage type of Vibrio cholerae O1 biotype ElTor in Indian scenario (1991-98).

During the period 1991-98, distribution of biotype, serotype and phage type of V. cholerae O1 strains isolated from different parts of the country and referred to the National Institute of Cholera and Enteric Diseases, Calcutta were studied. Of the 8101 strains received, 5613 (69.2%) were subjected to phage typing. All these strains belonged to the biotype ElTor and Ogawa was the predominant serotype (96.08%). The strains were clustered into only two types--types 2 and 4 and around 10 per cent strains remained untypable. However, using the new scheme, all these strains were found to be typable and 8 major types were recognized of which type number 27 was the predominant type (66.12%). The distribution of a common type throughout the country suggests that a particular clone of V. cholerae O1 is probably circulating all over India. A constant monitoring through phage typing is necessary to observe the emergence of any new clone of V. cholerae O1 in India.

Bacterial Typing Techniques↗
PubMed1999

An El Tor cholera outbreak in Maldah district, West Bengal.

An outbreak of cholera occurred in Maldah district, West Bengal during July-August 1998. Attack rate was 34/1000. Cases were more (59.3%) amongst adults (> 15 years.). V. cholerae 01 biotype E1 Tor serotype ogawa was isolated as a single pathogen from 52.9% (9/17 samples examined). All V. cholerae strains belonged to phage type 2 (Basu and Mukherjee scheme) and type 27 (new phage type scheme). The strains were resistant to co-trimoxazole, furazolidone, ampicillin, streptomycin and nalidixic acid.

Adolescent↗
PubMed1997

Isolation of Vibrio cholerae 0139 phages to develop a phage typing scheme.

Five V. cholerae 0139 phages isolated from different parts of India have been used for phage typing study. A strain isolated from Nagpur city (NPR-4) was used as the host for phage propagation. All but one of the 260 strains of V. cholerae 0139 were found to be typeable and could be clustered into 8 distinct phage types as revealed by lytic patterns. Phage type 1 was the predominant type (61.15%) followed by type 2 (18.46%). The strains isolated from Madras exhibited 7 out of 8 phage types. These newly isolated phages could be adopted for phage typing of V. cholerae 0139 strains as an epidemiological tool.

Bacteriophage Typing↗
PubMed1996

High expression of plasmid-encoded tetracycline resistance gene in E. coli causes a decrease in membrane-bound ATPase activity.

Expression of the plasmid pBR322-encoded tetracycline-resistant gene (tet) is known to cause other pleiotropic effects in addition to mediating the efflux of tetracycline from bacterial host cells. We have recently reported that expression of the tet gene in plasmid pKH47, a high-copy-number derivative of pBR322, causes growth inhibition of Escherichia coli cells harboring this plasmid. In this paper we report that reduced membrane-bound ATPase activity is found in E. coli cells containing plasmid pKH47. This effect is dependent on the presence of an intact tet gene and reduces the ability of the cells to grow in a minimum medium containing succinate as the sole carbon source. The same effect is more dramatically observed in cells containing an unrelated plasmid in which tet gene expression is under the control of the tac promoter.

Adenosine Triphosphatases↗
PubMed1996

Biological activity & interaction of Vibrio cholerae bacteriophages in rabbit ileal loop.

A set of ten V. cholerae EITor phages is in routine use for phage typing of V. cholerae O1 biotype EITor strains. These phages were used in rabbit ileal loop experiment to investigate whether these phages have any prophylactic value as regards their lytic capability on V. cholerae strains. The phages were found to have no prophylactic use as they were unable to lyse the standard bacterial strain V. cholerae MAK 757.

Animals↗
PubMed1994

Outbreak of cholera due to Vibrio cholerae 01 in Orissa state.

During May-June 1993, an outbreak of acute diarrhoea resulting in deaths primarily in adults was reported in two districts of Orissa state. Epidemiological and microbiological investigations revealed that this outbreak was caused by V. cholerae 01 biotype EITor. V. cholerae 01 strains were uniformly resistant to furazolidone.

Adult↗
PubMed1994

Validity of new phage typing scheme against Vibrio cholerae 01 biotype ElTor strains.

A total of 538 strains of V. cholerae 01 biotype ElTor were phage typed by the conventional Basu and Mukerjee and also the new typing scheme developed at the National Institute of Cholera and Enteric Diseases, Calcutta. The strains could be clustered into seven types by the new scheme as against only two by the conventional method. The results provide conclusive evidence on the validity of the new scheme for phage typing of V. cholerae strains.

Bacteriophage Typing↗
PubMed1993

New phage typing scheme for Vibrio cholerae O1 biotype El Tor strains.

The conventional phage typing scheme proposed by S. Basu and S. Mukerjee (Experientia 24:299-300, 1968) has been used routinely for identification of the strains at the Vibrio Phage Reference Laboratory since 1968. However, because of limitations of this scheme, a new phage typing scheme using five newly isolated phages was incorporated into the conventional scheme. A different definition of routine test dilution (almost confluent lysis) was found to be more useful than the one previously used (confluent lysis). The 1,000 strains tested could be clustered into 27 types with the five new phages. With the new scheme of 10 phages (5 new phages and 5 phages of Basu and Mukerjee), the 1,000 strains could be grouped into 146 types. The new phages were different from each other and also from those of Basu and Mukerjee, as revealed by lytic pattern, electron microscopy, restriction endonuclease digestion, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and antiphage antiserum studies. With the new typing scheme, 99.6% of the strains were typeable. Phage type 115 was the most common and includes 119 (11.9%) of the 1,000 strains tested. Next most common were phage types 142 (9.4%), 143 (7.0%), 104 and 116 (both 5.4%), 3 (5.3%), 5 (4.1%), 4 (3.9%), 24 (2.1%), and 100 (1.7%). The larger number of types would be useful for further classification of the strains for epidemiological purposes. This newly developed scheme is highly applicable to, and could be widely adopted for, phage typing of Vibrio cholerae O1 biotype El Tor strains.

Antibodies, Viral↗
PubMed1993

An outbreak of acute diarrhoeal disease amongst tribal population in Tripura.

A massive outbreak of acute diarrhoeal diseases occurred during March-April, 1992 in the north district of Tripura. Investigation of the outbreak revealed Vibrio cholerae 01 biotype ElT or as the main etiologic agent in 50 per cent of patients. The outbreak which started amongst the tribal population might have spread due to prevailing illiteracy, poverty, low personal and domestic hygiene and vulnerable water sources (chhara water).

Adult↗
PubMed1987

Hemolytic activity of and lethal toxin production by environmental strains of Vibrio parahaemolyticus.

Repeated subculturing of Kanagawa-negative strains of Vibrio parahaemolyticus on Wagatsuma agar induced the production of a hemolysin which was not the thermostable direct hemolysin. Crude hemolysin exhibited a 30 to 40% lethal toxicity in mice after intraperitoneal injection. A 21-kilodalton protein band was observed with all the environmental isolates in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Results suggested that a certain percentage of environmental strains of V. parahaemolyticus is responsible for pathogenesis.

Animals↗
PubMed1987

Observation on a 65-kilodalton protein isolated from kanagawa positive strains of Vibrio parahaemolyticus.

Crude hemolysin from four KP+ strains of Vibrio parahaemolyticus belonging to serotype 02:K3 exhibited a major protein band (molecular weight, 65 kilodaltons (kDa] in addition to a previously known thermostable direct hemolysin band (molecular weight, 21 kDa) in SDS - polyacrylamide slab gel electrophoresis. These strains showed maximum virulence leading to 100% mouse lethality within 2-6 h. It is hypothesized that this 65-kDa protein may play a vital role in the pathogenesis of the disease caused by V. parahaemolyticus.

Bacterial Proteins↗
PubMed1985

Seasonal distribution of Vibrio parahaemolyticus in freshwater environs and in association with freshwater fishes in Calcutta.

The seasonal distribution of Vibrio parahaemolyticus in freshwater environs and in association with freshwater fishes was studied in 1982 and 1983. The occurrence of this organism in water and sediments at the three sites studied was very infrequent and was restricted to the summer months, although it was not always isolated during these months. The association of V. parahaemolyticus with plankton was chiefly confined to the summer months and progressively declined with the onset of monsoons, remaining below detectable levels during the postmonsoon and winter months. The incidence and counts of V. parahaemolyticus were consistently higher in association with plankton than with water and sediment samples. V. parahaemolyticus could be recovered throughout the period of investigation from freshly caught and market samples of freshwater fishes. The highest recovery rate of this halophile from fishes was invariably from fecal samples. Most of the strains isolated in this study were untypable, and those which could be typed were predominantly serotypes encountered in the environment. All the isolates were Kanagawa negative. From this study, it could be concluded that the survival of V. parahaemolyticus in freshwater ecosystems is transient and dependent on a biological host.

Animals↗
PubMed1985

Serotypes of Vibrio parahaemolyticus isolates from hydrobiologically dissimilar aquatic environments.

Serological analysis of the O and K antigens was performed on 324 isolates of Vibrio parahaemolyticus obtained from three hydrobiologically dissimilar aquatic environments. Only 50.9% of the strains could be serotyped. The largest number of untypable strains and the lowest serological diversity were observed from the freshwater collection. Three serotypes, O2:K28, O5:K17, and O2:K3, dominated among all biotopes. There appears to be some distinction between serotypes of environmental and clinical origins.

Fresh Water↗
PubMed1985

Comparison of the modified Elek test and Wagatsuma agar for determination of the Kanagawa phenomenon of Vibrio parahaemolyticus.

The modified Elek test and Wagatsuma agar were compared for their ability to detect the Kanagawa activity of 142 strains of Vibrio parahaemolyticus. The performance of the modified Elek test was on a par with that of the Wagatsuma agar as far as positivity was concerned, and the test was far superior to Wagatsuma agar in eliminating doubtful results. The results of the modified Elek test were not unduly influenced by the different types of agar used.

Bacteriological Techniques↗
PubMed1983

Incidence and level of Vibrio parahaemolyticus associated with freshwater plankton.

We isolated Vibrio parahaemolyticus from plankton samples collected from different freshwater areas in the vicinity of Calcutta, India. Levels of this organism in association with freshwater plankton were low (less than 90 organisms per g). All of the 16 strains of V. parahaemolyticus isolated in this study were Kanagawa negative, and all except 1 were untypable. The occurrence of V. parahaemolyticus in association with freshwater plankton suggests that adsorption onto plankton may aid the survival of this moderately halophilic organism in freshwater milieus.

Adsorption↗