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Biomedical subjects

S K Bhattacharya

Publications and source records attributed to S K Bhattacharya.

At least 55 records · Page 3Linked to original sources
PubMed2005

Usefulness of the direct agglutination test in the early detection of subclinical Leishmania donovani infection: a community-based study.

The value of a direct agglutination test (DAT) in the detection of subclinical infections with Leishmania donovani has recently been investigated in the Indian state of Bihar, after the sensitivity and specificity of the test had been determined. When used to screen sera from 108 parasitologically confirmed cases of visceral leishmaniasis, 50 patients with active, non-leishmanial infection, and 641 healthy controls living close to, or distant from, an endemic area, the test was found to be 91.7% sensitive and 100% specific if a titre of 1:800 was used as the threshold for seropositivity. During a longitudinal clinical study in a rural, VL-endemic area of the Indian state of Bihar, the test was used, with 1:800 set as the threshold titre, to determine the baseline prevalence of infection with L. donovani among villagers who, though showing no symptoms of VL, had recently been febrile for at least 2 weeks. The 234 subjects of this study were either VL-case contacts [i.e. members of households in which there were active or cured VL cases (N=78)] or the members of control households with no cases or history of the disease (N=156). The results of DAT at the start of the study indicated that 49 (20.9%) of the subjects--29 (37.2%) of the VL-case contacts and 20 (12.8%) of the other subjects--were seropositive and therefore probably had subclinical infections with L. donovani. During the subsequent 9 months of follow-up, however, only eight of the subjects found seropositive at the start of the study--seven (24.1%) of the seropositive case contacts but only one (5.0%) of the other seropositives--developed symptomatic VL, all by month 6 of the follow-up. Compared with their neighbours, therefore, individuals who shared households with active or cured cases of VL appeared at greater risk not only of L. donovani infection (indicating focal transmission) but also of developing symptomatic disease once infected. Curiously, among the seropositive case contacts, those from the households that harboured active cases of VL at the baseline survey were less likely to develop symptomatic VL during the 9 months of follow-up than those from households that harboured only cured cases (18.8% v. 30.8%). The wide-spread use of DAT could allow the detection and early treatment of latent L. donovani infections and so contribute to the elimination of VL, at least as a public-health problem, from India.

Agglutination Tests↗
PubMed2005

Diagnosis & management of leishmania/HIV co-infection.

Leishmaniasis, a globally prevalent parasitic disease occurs in three forms viz., visceral, cutaneous and mucocutaneous, transmitted by the bite of infected female Phlebotomus sandflies. Visceral leishmaniasis (VL) has 100 per cent fatality rate, if left untreated. India has the largest burden of this disease. HIV infection is also increasing worldwide and several reports indicate rising trend of VL/ HIV co-infection, modifying the traditional anthroponotic pattern of VL transmission. Both VL and HIV tend to lower the cell mediated immunity (CMI) resulting in poor drug response and opportunistic infections involving gastrointestinal, cutaneous, respiratory tract and central nervous system (CNS) may occur. Diagnosis of such co-infected cases is quite difficult. However, newer tests like nested PCR, rk39 immunochromatographic test etc., can be of help. Response to different antileishmanial drugs like sodium antimony gluconate (SAG), amphotericin B is far from satisfactory. However, a new oral drug miltefosine has been found to be promising. Highly active antiretroviral therapy (HAART) need to be given for management of HIV infection along with treatment of other opportunistic infections.

HIV Infections↗
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↗
PubMed2005

Morphological variations in Phlebotomus argentipes (Diptera: Psychodidae) Annandale and Brunetti.

Morphological variations were observed in Phlebotomus argentipes, the vector for visceral leishmaniasis reported from the endemic states of Bihar, West Bengal and Uttar Pradesh. The taxonomic features distinguishing vector and nonvector species of P. argentipes were relative length of ascoid and antennal segment IV. Three morphotypes were characterized as <0.4, = 0.4 and >0.4 respectively. Other characteristics of wing width, wing length, eye, style, antennal segment III, IV, V was found statistically significant (p<0.05) and eleven other morphological measurements were not significant. This study suggests three different morphotypes of P. argentipes in these three endemic states. The genetic and reproductive isolation among such morphotypes will establish the variability in further studies.

Animals↗
PubMed2005

Preservation of Leishmania donovani promastigotes in blood agar slants.

Long-term cultivation of Leishmania promastigotes by weekly passage to fresh medium was reported to be disadvantageous because needs labor, risk of contamination, lowering in infectivity and virulence pattern. Cryopreservation and Lyophilization require expensive facilities which could be a burden and unaffordable to most laboratories of developing countries where the disease is endemic. These problems could be minimized by simple preservation of Leishmania donovani promastigotes in blood agar slants at 7-8 degrees C for 6-7 months. The preserved promastigotes were examined for viability up to one year at a regular interval of one month. Viable promastigotes were found and revived successfully from all the slants stored up to 7 months after that, the viability of promastigotes was found to be decreased in the slants of 8-9 month storage. No viable promastigotes were recovered from the slants stored up to 11-12 months. By this method, the promastigotes can easily be stored up to 7 months without loss of biological activity. The number of passage of promastigotes to fresh medium has been greatly reduced by this method from 30 times to 01 when compared with weekly passage in liquid medium. This simple and economical method can be recommended for short storage of Leishmania culture without loss of any activity.

Animals↗
PubMed2004

An unusually high level of quinolone resistance associated with type II topoisomerase mutations in quinolone resistance-determining regions of Aeromonas caviae isolated from diarrhoeal patients.

We examined 158 strains belonging to different Aeromonas species isolated from hospitalized acute diarrhoea cases for susceptibility to quinolones. Compared to other species, a high percentage of the A. caviae strains were resistant to ciprofloxacin and norfloxacin. Based on MIC values, 6 A. caviae strains were selected and the nucleotide sequences for the quinolone-resistant-determining regions (QRDRs) of gyrA, gyrB and parC genes were analysed. In resistant strains, double mutations (Ser(83)-->Ile and Asp(87)-->Asn) and a single mutation (Ser(80)-->Ile) were detected in the QRDR of gyrA and parC, respectively.

Aeromonas↗
PubMed2004

Molecular epidemiology of diarrhoeagenic Escherichia coli associated with sporadic cases and outbreaks of diarrhoea between 2000 and 2001 in India.

Diarrhoeal infection caused by Escherichia coli is common in India with occasional outbreaks. However, association of different pathotypes of diarrhoeagenic E. coli (DEC) with the disease and its phenotypic and genotypic characteristics are not fully demonstrated. In this study, E. coli strains from sporadic cases and outbreaks of diarrhoea during 2000-2001 were confirmed as DEC by polymerase chain reaction (PCR) targeting the specific virulence genes. DEC represented by enterotoxigenic E. coli (ETEC), enteropathogenic E. coli (EPEC) and enteroaggregative E. coli (EAggEC) were mostly belonged to O serogroups 25, 86a, 114 and 146. The gene astA was frequently detected among ETEC and EAggEC than EPEC. After initial screening of 200 DEC strains with serology and antibiotic susceptibility test, 32 strains representing ETEC, EPEC, and EAggEC isolated from different areas of India were included in the pulsed-field gel electrophoresis (PFGE) analysis. Using the PFGE results, the hierarchical representation of different linkage levels between the DEC strains were determined by unweighed pair-group arithmetic mean (UPGAMA) method. Except for few strains, clonotyping by PFGE revealed no correlation between pathotypes and serogroups as well as the place of isolation of the DEC strains. The prevailing clonal diversity among the different categories of DEC strains suggests that the pathotypes of DEC belonged to diverse clones.

Cluster Analysis↗
PubMed2004

Detection and characterization of HIV type 2 in Calcutta, India.

Since the first report of HIV/AIDS in India in 1986, continuous serosurveillance has been undertaken in all Indian states. Recently, five cases of HIV-2 infection have been detected in Calcutta, situated in the eastern part of India. The full-length envelope gene (2.5 kb) of one of the strains was amplified, cloned, and sequenced. Phylogenetic analysis of the Calcutta HIV-2 envelope revealed a close relatedness to the HIV-2 Rod sequence isolated in offshore Senegal. This strain, however, showed a genetic diversity of 13.5% to other Indian HIV-2 isolates.

Adult↗
PubMed2004

Prevalence, serotype distribution, antibiotic susceptibility and genetic profiles of mesophilic Aeromonas species isolated from hospitalized diarrhoeal cases in Kolkata, India.

A comprehensive study was performed to examine incidence, species distribution, drugs sensitivity, virulence genes and molecular fingerprints of Aeromonas species isolated from patients with acute diarrhoea over a period of 2 years in Kolkata, India. Following the Aerokey II scheme, more than 95 % of strains were identified to species level. Seven different species were encountered in this study, with Aeromonas caviae being dominant, followed by Aeromonas hydrophila and Aeromonas veronii biovar sobria. Thirty different serotypes were encountered, with O16, O83 and O85 being dominant, but no serotype was associated specifically with a single species. The majority of Aeromonas strains exhibited multidrug resistance. The alt and act genes, which encode heat-labile cytotonic and cytotoxic enterotoxins, were respectively found in 71.9 and 20.1 % of strains examined. Only 2.4 % of strains carried the heat-stable cytotonic enterotoxin (ast) gene. The hlyA gene was found in 28 % of Aeromonas strains. With few exceptions, genomic diversity of Aeromonas strains belonging to the same serotype was observed by random amplification of polymorphic DNA PCR and ribotyping. Different species of Aeromonas and different clones of Aeromonas species seem to be associated with hospitalized cases of diarrhoea in Kolkata, India.

Aeromonas↗
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↗
PubMed2004

Multiplex PCR assay for rapid detection and genotyping of Helicobacter pylori directly from biopsy specimens.

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 specimens. This assay did not require culturing of strains or extraction of DNA from biopsy samples. This multiplex PCR assay would be of particularly great value for laboratories in developing countries.

Antigens, Bacterial↗
PubMed2004

Virulence characteristics and molecular epidemiology of enteroaggregative Escherichia coli isolates from hospitalized diarrheal patients in Kolkata, India.

Enteroaggregative Escherichia coli (EAEC) is an important diarrheal enteropathogen defined by aggregative adherence to cultured epithelial cells. We have detected EAEC from 121 (6.6%) of 1,826 hospitalized patients admitted with diarrhea to the Infectious Diseases Hospital in Kolkata, India. Watery diarrhea was recorded significantly (P = 0.0142) more often in children. The majority of the EAEC isolates were not serotypeable (62%) and showed resistance to five or more antibiotics (76%). We studied different virulence genes and the molecular epidemiology of 121 EAEC isolates recovered from diarrheal patients. A PCR assay for detection of virulence genes, an assay for determination of clump formation in liquid culture, and a HeLa cell adherence assay were carried out to characterize the EAEC isolates. Investigations were also conducted to correlate the virulence gene profiles with diarrheal symptoms and molecular epidemiology by pulsed-field gel electrophoresis (PFGE). Two or more virulence genes were detected in 109 (90.1%) EAEC isolates. In the cluster analysis, some isolates with specific gene profiles and phenotypes formed a group or subcluster. This study highlights the comparative distributions of three fimbrial adhesins and other virulence genes among EAEC isolates. The diverse virulence gene and PFGE profiles, along with the existence of diverse serotypes and antibiograms, suggests that the EAEC isolates are genetically heterogeneous in Kolkata.

Base Sequence↗
PubMed2004

Evaluation of cholinesterase level in an endemic population exposed to malathion suspension formulation as a vector control measure.

The manuscript describes a study on the blood cholinesterase (ChE) level in an exposed population at different interval of time after spraying with malathion suspension (SRES) use for kala-azar vector control in an endemic area of Bihar, India. The toxicity of a 5% malathion formulation in the form of a slow release emulsified suspension (SRES) was assessed by measuring serum ChE levels in spraymen and in the exposed population. The study showed a significant decrease in ChE levels in the spraymen (p < 0.01) after one week of spraying and in exposed population one week and one month after of spraying (p < 0.01), but was still within the normal range of ChE concentration, one year after spraying, the ChE concentration in the exposed population was the same as prior to spraying (p > 0.01). On no occasion was the decrease in ChE level alarming. A parallel examination of the clinical status also showed the absence of any over toxicity or any behavioural changes in the exposed population. Hence, it may be concluded that 5% malathion slow release formulation, SRES, is a safe insecticide for use as a vector control measure in endemic areas of kala-azar in Bihar, India so long as good personal protection for spraymen is provided to minimize absorption and it can substitute the presently used traditional DDT spray.

Animals↗