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S K Niyogi

Publications and source records attributed to S K Niyogi.

At least 19 recordsLinked to original sources
PubMed2006

Molecular epidemiology of human astrovirus infections in Kolkata, India.

UNLABELLED: The study is aimed to determine the seasonal distribution and clinical characteristics of astroviruses associated with acute watery diarrhoea among children in Kolkata and characterize them at the molecular level. METHOD OF STUDY: Faecal specimens of acute watery diarrhoea cases (n=857) and non-diarrhoeic samples (n=211) from the hospitals and a nearby field community were screened with IDEIA Astrovirus detection kit; astrovirus co-infections with rotavirus and/or picobirnavirus were detected by RNA-PAGE and silver staining. Further RT-PCR was carried out using specific primers, viz. Mon340 (+) and Mon348 (-) targeting a highly conserved domain of ORF1a (289 bp) of human astroviruses. RESULTS: Astrovirus infection was detected in 50 cases (50/857); astroviruses were detected mostly in children aged 6-12 months (50%); all non-diarrhoeic samples (n=211) were negative for astrovirus. In 52% of astrovirus positive cases, the virus was detected as the sole agent; mixed infections were also detected with other diarrhoeic pathogens such as rotavirus (32%), picobirnavirus (2%), rotavirus and picobirnavirus (2%), picobirnavirus and Enterotoxigenic E. coli (ETEC) (2%), rotavirus and ETEC (2%), rotavirus and Enteroaggregative E. coli (EAEC) (2%), Enteropathogenic E. coli (EPEC) (2%), Shigella flexneri type 3a (2%) and Ascaris (2%). RT-PCR and sequencing of amplicons of astroviruses from Kolkata, with specific primers targeted to the conserved domain of ORF1a (289 bp) of the astrovirus genome, showed maximum homology to the astrovirus strain ("5-158") from Seoul (98%). RESULTS AND CONCLUSIONS: Clinical characteristics of the diarrhoeic children in Kolkata indicated that astrovirus infections were detected throughout the year and were associated with varying degree of dehydration and acute watery diarrhoea. In-depth molecular epidemiological surveillance of astroviruses in Kolkata is essential for better understanding of their overall genetic nature.

Adult↗
PubMed2006

Epidemiological, microbiological & electron microscopic study of a cholera outbreak in a Kolkata slum community.

BACKGROUND & OBJECTIVE: Epidemics of cholera caused by Vibrio cholerae O1 or O139 have been reported from different parts of India. Factors such as unsafe water supply, poor environmental sanitation, indiscriminate defaecation and lack of personal hygiene are mainly responsible for continued transmission of this disease. We report here epidemiological and microbiological findings of a localized outbreak of cholera, which occurred during March and April 2004 in the eastern part of Kolkata city. METHODS: The affected slum area has a population of 4409, predominantly muslims. Patients suffering from acute watery diarrhoea attended the health outposts organized by National Institute of Cholera and Enteric Diseases, Kolkata and International Vaccine Institute, South Korea as part of a routine surveillance programme at the locality as well as the emergency medical camp organized by the Kolkata Municipal Corporation. Stool and water samples were collected and tested for diarrhoeagenic pathogens in the laboratory. Bacteriophages specific for V. cholerae were isolates and studied electron microscopically for morphology. RESULTS: A total of 89 diarrhoea cases were reported giving an attack rate of 2 per cent. V. cholerae O1 biotype ElTor, serotype Ogawa was isolated as a sole pathogen from 15 (15.8%) of 89 stool samples screened. Water samples (2 from tube wells, 3 from municipal taps and 1 from well) showed presence of coliform bacilli with high MPN (Most Probable Number) count. Bacteriophages specific to V. cholerae were isolated from 2 of 6 water samples examined. A leakage was detected in the main pipeline supplying drinking water to that area. INTERPRETATION & CONCLUSION: The outbreak was caused by V. cholerae O1 (Ogawa) biotype ElTor. The presence of phages in the water samples was an additional indicator for V. cholerae contamination in this community. Occurrences of such outbreaks support vaccination against cholera as an alternative strategy.

Bacteriophage Typing↗
PubMed2005

The burden of cholera in the slums of Kolkata, India: data from a prospective, community based study.

AIMS: To conduct a prospective, community based study in an impoverished urban site in Kolkata (formerly Calcutta) in order to measure the burden of cholera, describe its epidemiology, and search for potential risk factors that could be addressed by public health strategies. METHODS: The study population was enumerated at the beginning and end of the study period. Surveillance through five field outposts and two referral hospitals for acute, watery, non-bloody diarrhoea was conducted from 1 May 2003 to 30 April 2004. Data and a stool sample for culture of Vibrio cholerae were collected from each patient. Treatment was provided in accordance with national guidelines. RESULTS: From 62 329 individuals under surveillance, 3284 diarrhoea episodes were detected, of which 3276 (99%) had a stool sample collected and 126 (4%) were culture confirmed cholera. Nineteen (15%) were children less than 2 years of age, 29 (23%) had severe dehydration, and 48 (38%) were hospitalised. Risk factors for cholera included a household member with cholera during the period of surveillance, young age, and lower educational level. CONCLUSIONS: There was a substantial burden of cholera in Kolkata with risk factors not easily amenable to intervention. Young children bear the brunt not only of diarrhoeal diseases in general, but of cholera as well. Mass vaccination could be a potentially useful tool to prevent and control seasonal cholera in this community.

Adolescent↗
PubMed2005

Species diversity and antimicrobial resistance of Shigella spp. isolated between 2001 and 2004 from hospitalized children with diarrhoea in Kolkata (Calcutta), India.

The incidence, phenotypic characteristics and antimicrobial resistance patterns of 193 Shigella strains isolated from 2489 hospitalized children with acute diarrhoea were studied during January 2001 to August 2004. S. flexneri (60%) was the most prevalent serogroup, followed by S. sonnei (23.8%), S. dysenteriae (9.8%) and S. boydii (5.7%). Since 2002, S. flexneri 2a was the most dominant serotype. Almost all S. flexneri strains exhibited resistance to ampicillin, co-trimoxazole, tetracycline, nalidixic acid and fluoroquinolones. After a lapse of almost 14 years, S. dysenteriae type 1 strains reemerged for the first time during 2002 and these strains were resistant to more than two antibiotics (multidrug resistance), including fluoroquinolones. An upsurge of similar resistance patterns was also noted among S. flexneri type 2a since December 2003. Resistance to fluoroquinolone increased year on year among S. dysenteriae type 1 and S. flexneri, but not in S. boydii or S. sonnei. Monitoring of antimicrobial susceptibility through a surveillance programme is recommended to select appropriate antibiotics for the effective treatment of shigellosis in this region.

Anti-Bacterial Agents↗
PubMed2005

Epidemiology of HIV infection among brothel-based sex workers in Kolkata, India.

A cross-sectional study was carried out during January-June 2004 to assess the status of HIV infection among brothel-based sex workers in Kolkata city, India. Six hundred and twenty-two sex workers, selected from six brothels, were included in the study to assess their HIV status, and 362 sex workers, a subset of the above population, were interviewed to study their risk behaviour and practices. Blood samples were collected from each sex worker for testing HIV by an unlinked anonymous method. The prevalence of HIV infection was 9.6%, but was much higher among younger sex workers aged 20 years or less (27.7%) compared to the older age group (8.4%). This difference was statistically significant, indicating an association of younger ages with HIV infection [p = 0.006 and odds ratio (OR) = 4.18; (95% confidence interval (CI) 1.2-13.8)]. HIV was not associated with duration of sex work, average number of clients entertained per day, condom use, practice of sex during menstruation, pre-coital examination of penis for visible ulcer/discharge, suffering from sexually transmitted infections, and entertaining clients outside the brothel. There was a big gap between the reported and the evaluated condom use by sex workers. The results suggest that there is a need to develop suitable HIV intervention strategies, considering the socioeconomic and cultural aspects of city sex workers, with a provision for continuous monitoring and evaluation.

Adolescent↗
PubMed2004

Genetic relatedness of ciprofloxacin-resistant Shigella dysenteriae type 1 strains isolated in south Asia.

OBJECTIVES: The aim of the present study was to determine the clonal relationships of ciprofloxacin-resistant Shigella dysenteriae type 1 strains isolated from south Asia, and S. dysenteriae 1 strains associated with epidemics in 1978, 1984 and 1994. METHODS: The antimicrobial susceptibilities were examined by NCCLS methods. Molecular epidemiological characterization was performed by plasmid profiling, pulsed-field gel electrophoresis (PFGE) and mutation analysis of the quinolone resistance-determining region (QRDR) of gyrA by sequencing. RESULTS: Plasmid patterns of the current ciprofloxacin-resistant strains from India, Nepal and Bangladesh were very similar to those of the 1978, 1984 and 1994 epidemic isolates of S. dysenteriae 1, except for the presence of a new plasmid of approximately 2.6 MDa, which was found in one recent ciprofloxacin-resistant strain isolated in Bangladesh. PFGE analysis showed that the ciprofloxacin-resistant strains isolated in Bangladesh, India and Nepal belonged to a PFGE type (type A), which was possibly related to that of the 1984 and 1994 clone of S. dysenteriae 1, but different from 1978 epidemic strains. The current ciprofloxacin-resistant strains belong to five subtypes (A3-A7), all of which were found in India, but in Bangladesh and Nepal, only A3 existed. Mutation analysis of the QRDR of gyrA revealed that amino acid substitutions at positions 83 and 87 of ciprofloxacin-resistant strains isolated in Bangladesh were similar to those of the strains isolated in Nepal, but different (at position 87) from ciprofloxacin-resistant strains isolated in India. CONCLUSIONS: PFGE and mutation analysis of gyrA showed differences between the current ciprofloxacin-resistant S. dysenteriae 1 strains isolated in south Asia and those associated with epidemics in 1978, 1984 and 1994.

Amino Acid Substitution↗
PubMed2004

Prevalence of the sat, set and sen genes among diverse serotypes of Shigella flexneri strains isolated from patients with acute diarrhoea.

New virulence factors associated with the genus Shigella have been described recently. These comprise enterotoxins ShET-1 and ShET-2, encoded by the set and sen genes, respectively, and the secreted autotransporter toxin Sat, encoded by the sat gene. The present study aimed to determine the prevalence of genes encoding these toxins among a collection of Shigella flexneri clinical isolates belonging to different serotypes. While the set gene was detected only in S. flexneri serotypes 2a and 2b, the sen and sat genes were present in diverse serotypes of S. flexneri.

Acute Disease↗
PubMed2004

Clonal multidrug-resistant Shigella dysenteriae type 1 strains associated with epidemic and sporadic dysenteries in eastern India.

Multidrug-resistant strains of Shigella dysenteriae type 1 were implicated in three outbreaks and sporadic cases of dysentery in eastern India in 2002 and 2003. After a hiatus of 14 years, this pathogen reemerged with an altered antibiotic resistance pattern. In addition to ampicillin, co-trimoxazole, tetracycline, chloramphenicol, and nalidixic acid, all the recent strains were resistant to norfloxacin, lomefloxacin, pefloxacin, and ofloxacin and showed reduced susceptibility to ciprofloxacin. Pulsed-field gel electrophoresis identified a new clone of S. dysenteriae type 1 that was associated with the recent outbreaks and sporadic cases. Based on the spatial and temporal spread of multidrug-resistant S. dysenteriae type 1, we predict that this clonal type may spread further in this region.

DNA Fingerprinting↗
PubMed2002

Decreasing trend in the occurrence of Salmonella enterica serotype Typhi amongst hospitalised children in Kolkata, India during 1990-2000.

In a prospective hospital based surveillance, 1454 children clinically diagnosed as typhoid fever were enrolled during the period between 1990 to 2000. Of them 336 (23.1%) children were positive for Salmonella enterica serotype Typhi by blood culture. A declining trend of hospitalization and identification of the pathogen was observed from 1992 to 2000 as compared to 1990-1991. A declining trend of resistance to the commonly used anti-typhoid drugs was seen in the S. enterica serotype Typhi isolates. Recently in 2000, nine strains were detected as ciprofloxacin resistant. Misuse and overuse of ciprofloxacin for the treatment of typhoid fever influenced the development of ciprofloxacin resistant strains of S. enterica serotype Typhi in and around Kolkata.

Child↗
PubMed2001

Double blind, randomised controlled clinical trial of hypo-osmolar oral rehydration salt solution in dehydrating acute diarrhoea in severely malnourished (marasmic) children.

AIMS: To compare the clinical efficacy of hypo-osmolar oral rehydration salt (ORS) solution (224 mmol/l) and standard ORS solution (311 mmol/l) in severely malnourished (marasmic) children having less than 60% Harvard standard weight for age with dehydrating acute watery diarrhoea. METHODS: In a double blind, randomised, controlled trial, 64 children aged 6-48 months were randomly assigned standard (n = 32) or hypo-osmolar ORS (n = 32). RESULTS: Stool output (52.3 v 96.6 g/kg/day), duration of diarrhoea (41.5 v 66.4 hours), intake of ORS (111.5 v 168.9 ml/kg/day), and fluid intake (214.6 v 278.3 ml/kg/day) were significantly less in the hypo-osmolar group than in the standard ORS group. Percentage of weight gain on recovery in the hypo-osmolar group was also significantly less (4.3 v 5.4% of admission weight) than in the standard ORS group. A total of 29 (91%) children in the standard ORS group and 32 (100%) children in the hypo-osmolar group recovered within five days of initiation of therapy. Mean serum sodium and potassium concentrations on recovery were within the normal range in both groups. CONCLUSION: Our findings suggest that hypo-osmolar ORS has beneficial effects on the clinical course of dehydrating acute watery diarrhoea in severely malnourished (marasmic) children. Furthermore, children did not become hyponatraemic after receiving hypo-osmolar ORS.

Child, Preschool↗
PubMed2001

Rise in free intracellular calcium in HeLa cells infected with aggregative Klebsiella pneumoniae strains isolated from cases of diarrhoea.

BACKGROUND & OBJECTIVES: Klebsiella pneumoniae strains occasionally cause diarrhoea in humans. This study was done to determine the involvement of calcium in the pathogenesis of aggregative K. pneumoniae strains. METHODS: A total of nine strains of K. pneumoniae were tested for adherence assay in HeLa cell line. A representative strain CO-1215 was used for [Ca2+]i study using Fura-2 fluorescence. RESULTS: Infection of cultured HeLa cells with aggregative K. pneumoniae strain resulted in five-fold elevation of intracellular level of free calcium ([Ca2+]i) with maximum Ca2+ influx at 3 h after bacterial infection. Chelation of extracellular Ca2+ with [ethylenebis(oxyethylenenitrile)] tetraacetic acid and suspension of cells in Ca2+ free buffer suggested that the rise of Ca2+ in aggregative K. pneumoniae infected HeLa cells was due to influx of Ca2+ from extracellular medium. INTERPRETATION & CONCLUSIONS: This study showed aggregative adherence in HeLa cells and this adherence leads to influx of extracellular Ca2+. The unrestricted passage of calcium ions across cell membranes could cause phosphorylation of proteins involved in ion transport across the membrane, which could result in secretory diarrhoea. Further work is in progress to study the enterotoxicity of these strains in an in vitro rabbit intestinal model.

Calcium↗
PubMed2000

Impact of zinc supplementation in malnourished children with acute watery diarrhoea.

A double-blind, randomized, controlled clinical trial was conducted on 80 malnourished children with acute dehydrating diarrhoea to evaluate the efficacy of oral supplementation of zinc as an adjunct therapy to oral rehydration solution (ORS). After decoding it was observed that 44 children received zinc sulphate (177 mg/kg/day in three divided doses equivalent to 40 mg elemental zinc) in a syrup form and 36 children received only syrup placebo. Clinical parameters and microbiological findings of stool samples were comparable in the two groups at the time of enrollment. All the children (100 per cent) in the zinc supplemented group and 32 (89 per cent) children in the placebo group recovered within 5 days of hospitalization (p = 0.04). The zinc supplemented group had a significantly shorter duration of diarrhoea (70.4 +/- 10.0 vs. 103.4 +/- 17.1 h; p = 0.0001), passed less liquid stool (1.5 +/- 0.7 vs. 2.4 +/- 0.7kg; p=0.0001), consumed less oral rehydration solution (2.5 +/- 1.0 vs. 3.6 +/- 0.8 litre; p = 0.0001) and other liquids (867.0 +/- 466.1 vs. 1354.7 +/- 675.6 ml; p = 0.0001) as compared to the placebo group. Our findings suggest that zinc supplementation as an adjunct therapy to ORS has beneficial effects on the clinical course of dehydrating acute diarrhoea.

Acute Disease↗
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↗