Change in serotype and appearance of tetracycline resistance in V. cholerae O1 in Vellore, South India.
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Cholera↗
Biomedical subjects
M V Jesudason
Publications and source records attributed to M V Jesudason.
Culture proven cases of tuberculous meningitis: a 5 year retrospective analysis from Vellore.
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Cerebrospinal Fluid↗
Rapid identification of Burkholderia pseudomallei in blood culture supernatants by a coagglutination assay.
In total, 309 blood culture supernatants were tested for the presence of Burkholderia pseudomallei antigen using an in-house coagglutination test prepared by sensitising Cowan I staphylococcal cells with B. pseudomallei polyclonal antiserum. The coagglutination test gave a sensitivity, specificity, positive predictive value and negative predictive value of 100% in comparison with blood culture. A subset of 102 supernatants was also tested for B. pseudomallei antigen using a monoclonal antibody-based latex agglutination test. The sensitivity, specificity, positive predictive value and negative predictive values of this test were 100%, 90%, 75% and 100%, respectively.
Agglutination Tests↗
Mycobacterium fortuitum bacteraemia in an immunocompromised patient.
A case of Mycobacterium fortuitum bacteraemia in an immunocompromised patient confirmed by four positive serial blood cultures is reported here. The patient was a known case of acute lymphoblastic leukemia (ALL) on intensive chemotherapy. The source of bacteraemia was most probably a peripherally inserted vascular catheter. After initiation, of treatment with amikacin to which the strain was sensitive and clarithromycin and removal of the central line the patient's fever defervesced and repeat blood cultures were negative. This is the first time we have encountered an immunocompromised patient with M. fortuitum septicaemia in our hospital. The possibility of an infection with rapidly growing mycobacteria is important to consider when conventional organisms are not isolated in culture especially in the context of patients with malignancy.
Adult↗
Non tuberculous mycobacteria isolated from clinical specimens at a tertiary care hospital in South India.
PURPOSE: This is a retrospective analysis of the isolation rates of nontuberculous mycobacteria (NTM) from various clinical specimens and their antimicrobial susceptibility patterns. METHODS: All NTM isolated between 1999 and 2004 at Christian Medical College, Vellore, South India, were identified with various biochemical tests. Antimicrobial susceptibility test for all NTM was performed by standard methods. RESULTS: A total of 32,084 specimens were received for culture, of which 4473 (13.9%) grew acid fast bacilli (AFB). Four thousand three hundred (96.1%) of the AFB were M. tuberculosis while 173 (3.9%) were NTM. Of the 173 NTM, 115 (66.5%) were identified to the species level. Pus, biopsy specimens and sputum specimens yielded most of the NTM of which M. chelonae (46%) and M. fortuitum (41%) accounted for majority of them. M. chelonae and M. fortuitum, showed highest susceptibility to amikacin (99.2%). NTM were repeatedly isolated from seven sputum specimens, 15 biopsy and pus specimens, two CSF and two blood cultures. Six were isolated from patients with AIDS and five from post transplant patients. CONCLUSIONS: The isolation of NTM from various clinical specimens is reported in this study to highlight the associated diseases and therapeutic options in these infections.
Anti-Bacterial Agents↗
Subtype & cytokine profiles of HIV infected individuals from south India.
BACKGROUND & OBJECTIVE: The global surveillance of human immunodeficiency virus (HIV) subtypes (clades) helps understand the global distribution and incidence of different HIV subtypes. As knowledge about subtypes circulating in an area is needed for developing a candidate vaccine, prevalence of the subtypes HIV-1 and HIV-2 were studied in south India. The profile of cytokines interleukin 10 (IL10) and interferon gamma (IFNgamma) in both types of infection were also analysed as these are considered indicators of disease progression. METHODS: Patients who belonged to the 4 south Indian States i.e. Tamil Nadu, Kerala, Karnataka and Andhra Pradesh were included. HIV-1 subtyping was carried out by the heteroduplex mobility analysis (HMA) while that of HIV-2 was done by direct sequencing. The quantitation of IFNgamma and IL-10 was carried out using commercial ELISA kits. RESULTS: Among the 82 HIV-1 infected individuals subtyped, 78 (95.1%) were subtype C while all 12 HIV-2 strains were subtype A. IL-10 concentration was significantly higher among HIV infected individuals compared to normal healthy controls. IFNgamma was significantly higher among symptomatic and AIDS groups compared to asymptomatic HIV-1 infected individuals. INTERPRETATION & CONCLUSION: HIV-1 subtype C and the HIV-2 subtype A are the major subtypes circulating in south India. The study showed a trend towards a shifting of the cytokine profile from Th1 to Th2/Th0 in HIV-1, HIV-2 infections, and HIV-1 and HIV-2 dual infected individuals as the disease progresses. This trend observed is not unlike that reported from the West, despite the difference in subtype profile.
Base Sequence↗
A pilot study for serological evidence of hantavirus infection in human population in south India.
BACKGROUND AND OBJECTIVES: Hantaviruses are rodent-borne viruses of the family Bunyaviridae that have been identified as aetiological agents of two human diseases, haemorrhagic fever with renal syndrome (HFRS) and hantavirus pulmonary syndrome (HPS). There are no reports of hantavirus infections in humans from India, hence this pilot study was undertaken to provide the serological evidence of hantavirus infections in humans in south India. METHODS: Serum samples were obtained from individuals with acute febrile illness and from voluntary blood donors, majority of whom were from south India. Serum samples were tested for anti-hantavirus IgM using a commercial enzyme immunoassay (EIA). Samples found positive by the EIA were tested by an indirect immunofluorescence assay (IFA) using slides coated with Seoul virus (SEOV) infected cells as substrate. RESULTS: Of the 152 serum samples from individuals with pyrexic illness, 23 (14.7%) were positive for anti-hantavirus IgM by EIA. In contrast, only 5.7 per cent of healthy blood donors were positive by this assay. Eighteen of the 22 (82%) EIA-positive samples from patients were positive by the IFA assay. In contrast, only 2 of the 5 (40%) blood donor EIA positive samples were positive in the IFA assay. INTERPRETATION AND CONCLUSION: The finding of this study indicated the possible presence of hantavirus infections in the human population of India presenting both as asymptomatic and symptomatic infections. Further studies need to be done to confirm the findings on a larger sample using molecular techniques.
Fluorescent Antibody Technique, Indirect↗
Invasive properties of south Indian strains of Streptococcus pyogenes in a HEp-2 cell model.
The objective of this study was to consider the invasive properties of Streptococcus pyogenes in human pharyngeal epithelial cells, and to correlate these with their clinical significance. Clinical isolates of S. pyogenes obtained from blood cultures over a period of 10 years, and throat and skin isolates from a community-based study, were used in this investigation. The S. pyogenes isolates were inoculated in HEp-2 cells and subsequently treated with antibiotics to kill the extracellular bacteria. The cells were then lyzed, and a colony count was carried out to check for invasion. The throat and skin isolates had 45.7%, 25.7% and 28.5% of low, intermediate and high invasion efficiencies, respectively, while 80%, 8.6% and 11.4% of the blood isolates had low, intermediate and high invasion efficiencies. We concluded that the throat and the skin isolates from superficial infections were more invasive than the blood isolates, which is an interesting and paradoxical feature.
Colony Count, Microbial↗
A peptide enzyme linked immunosorbent assay (ELISA) for the detection of human immunodeficiency virus type-2 (HIV-2) antibodies: an evaluation on polymerase chain reaction (PCR) confirmed samples.
BACKGROUND: HIV-1 and HIV-2 infections differ in prognosis, and may also require different prevention and/or treatment approaches. Thus, estimating the true prevalence of HIV-1 and HIV-2 infections, as well as co-infections, is a critical step in controlling the disease. There are a few commercial ELISA and immunoblot kits, which can differentiate between HIV-1 and HIV-2 infections. However, some of these assays overestimate the prevalence of dual infection. Hence, it is necessary to develop assays capable of discriminating between the two infections. OBJECTIVES: To develop a synthetic HIV-2 env based peptide ELISA for the detection of HIV-2 specific antibodies and evaluate its performance on samples from HIV positive individuals previously tested by HIV-1 and HIV-2 PCR and HIV seronegative individuals. STUDY DESIGN: We studied 45 HIV seronegative and 63 HIV infected individuals, including 30 HIV-1 PCR and immunoblot positives, 19 HIV-2 PCR and immunoblot positives, five HIV-1 and two PCR and dual immunoblot positives, two PCR negative but positive for HIV-2 by immunoblot and seven dual immunoblot positives who were only positive for HIV-1 by PCR. RESULTS: All 24 HIV-2 PCR positive samples tested were positive by the peptide assay. Among 30 HIV-1 PCR and immunoblot positive samples, only one (3.3%) showed an absorbance value above the cut off level. The seven dual positive samples by immunoblot (only positive for HIV-1 by PCR) were negative by the HIV-2 peptide ELISA. There was a 100% concordance between HIV-2 PCR and peptide ELISA. The sensitivity, specificity, and the likelihood ratio for the peptide ELISA were 100,94.9, and 19.5, respectively when compared against the PCR findings. CONCLUSIONS: This ELISA, using a specific immunodominant epitope (11 amino acids) from the transmembrane (gp36) portion of the HIV-2 envelope glycoprotein showed a high concordance with PCR findings. This can be considered as a highly sensitive, specific and economically feasible assay for the discrimination of HIV-1 and HIV-2, and may serve as an alternative to HIV-2 PCR in epidemiological studies.
Enzyme-Linked Immunosorbent Assay↗
Correlation of CD4(+) T-Cell counts estimated by an immunocapture technique (Capcellia) with viral loads in human immunodeficiency virus-seropositive individuals.
As antiretroviral therapy becomes more affordable, valid, reliable, and inexpensive laboratory tests are also needed to monitor the progression of disease in people with human immunodeficiency virus (HIV) infection. The CD4(+) T-cell counts estimated by Capcellia, an immunocapture method, and flow cytometry were compared and were correlated with HIV type 1 (HIV-1) load. There was a significant negative correlation between the HIV-1 load and CD4(+) T-cell counts estimated by flow cytometry (r = -0.63, P = <0.001) as well as between the HIV-1 load and CD4(+) T-cell counts estimated by Capcellia (r = -0.61, P = <0.001). Capcellia is a cost-effective, user-friendly assay that correlated well with HIV-1 load determinations for individuals both with and without treatment.
Adult↗
An indirect ELISA for the diagnosis of melioidosis.
BACKGROUND & OBJECTIVES: Very little information is available on melioidosis in India. This disease caused by Burkholderia pseudomallei is not often considered as a differential diagnosis and patients are not usually investigated for it. Thus we are unaware of its prevalence in India. This study was undertaken to detect the presence of melioidosis in patients presenting with pyrexia of unknown origin (PUO) using an indirect ELISA. METHODS: The well established ELISA technique was adapted to detect melioidosis in patients attending the Christian Medical College and Hospital, Vellore and to provide a serological test using reagents with a reasonable shelf-life. The ELISA is designed to detect IgG antibodies to B. pseudomallei in serum samples. RESULTS: A cut-off optical density (OD) of 0.36 (mean +/- 2 SD of healthy controls) was chosen as diagnostic criterion for the diseased group. The mean OD values in the sera of patients with culture proven melioidosis was significantly (P < 0.001) higher than that of healthy controls. INTERPRETATION & CONCLUSION: The indirect ELISA was simple to perform and may be recommended as a diagnostic serological test when melioidosis is considered as a differential diagnosis.
Adolescent↗
A study on some phenotypic virulence markers of enteropathogenic Escherichia coli.
BACKGROUND & OBJECTIVES: The problem of enteropathogenic Escherichia coli (EPEC) causing diarrhoea in infants exists in India. But often the enteropathogenic status is not based on adequate characterization. Hence there is a need for evaluating the serotyping being used to identify EPEC for its validity in the light of recent knowledge on phenotypic markers of virulence. This study was done to evaluate the EPEC isolates for two potential virulence factors namely entero-adhesiveness with subsequent actin accumulation and verotoxin production. METHODS: Fifty consecutive EPEC strains identified by serotyping from stool samples of children with diarrhoea during January 1997 to June 1999 were studied for HEp-2 cell adherence, the fluorescent actin staining (FAS) characteristics of Hep-2 cells and vero cytotoxin production. RESULTS: Serotypes O55, O125 and O126 accounted for most of the isolates. In the Hep-2 assay, 72 per cent of the strains showed localised pattern of adherence and 22 per cent showed a mixed pattern of localised and diffuse adherence. In the FAS test 96 per cent strains showed typical staining while none of the strains produced verotoxin. INTERPRETATION & CONCLUSION: 'O' serogrouping appears to be still the simplest and an useful test for presumptive identification of EPEC. The FAS test for confirmation of EPEC was found to be very consistent in indicating EPEC.
Animals↗
Per-exposure rate of transmission of HIV-1, HIV-1/2, and HIV-2 from women to men may be higher in India.
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Disease Transmission, Infectious↗
Peripheral CD4+/CD8+ T-lymphocyte counts estimated by an immunocapture method in the normal healthy south Indian adults and HIV seropositive individuals.
BACKGROUND: Flow cytometry is the standard method for the estimation of CD4/CD8 counts, but the high initial investment for this instrument and costly reagents make it unaffordable to most of the centers in a developing country like India. OBJECTIVES: To evaluate the feasibility of an alternate system for the estimation of CD4 and CD8 counts in normal south Indian adults and validate the usefulness of this assay to monitor the counts in HIV seropositive individuals. STUDY DESIGN: Forty-six normal healthy adults and 68 HIV seropositive individuals both belonging to south Indian linguistic groups were enrolled in this cross-sectional study. The HIV seropositive individuals included 54 HIV-1, 9 HIV-2 and 5 HIV 1&2 infected individuals serologically confirmed by one of the commercial Immunoblot kits. The Capcellia CD4/CD8 whole blood assay, an immuno-capture ELISA based kit from Sanofi DIAGNOSTICS Pasteur, (France) was used with a few modifications in the procedure to measure the CD4 and CD8 counts. RESULTS: The mean CD4 cell counts were 1048 (central 95 centile only), 746 and 424 for the normal healthy adults, asymptomatic HIV seropositives and symptomatic HIV patients, respectively, and the mean CD8 counts were 595, 889 and 732, respectively. Statistically significant differences were observed in the CD4 cell counts between HIV seronegative healthy adults and asymptomatic (P < 0.001) as well as asymptomatic and symptomatic (P < 0.05) HIV infected individuals. The mean CD4 counts of asymptomatic HIV-2 infected individuals was significantly higher than the counts of asymptomatic HIV-1 infected individuals (P < 0.05). CONCLUSIONS: This is an user friendly test and can be an alternate to flow cytometry for the estimation of peripheral T-lymphocyte subsets in developing countries. The assay system has certain limitations inherent to ELISA techniques.
Adult↗
Ecological study of Vibrio cholerae in Vellore.
Vellore is endemic for cholera due to Vibrio cholerae O1 and O139. In a previous study the prevalence of Vibrio cholerae in drinking water, lakes and sewage outfalls in a single 2-months period in Vellore, India was determined. In addition water samples from three sites were also tested for the presence of V. cholerae O1 and O139 by fluorescent antibody staining. This follow on study has examined how the environmental distribution of V. cholerae at the same sites alters over a 12-month period and the relationship to the clinical pattern of cholera in Vellore. Samples of water were collected from fixed sites at three water bodies each month between April 1997 and March 1998. Bacteria isolated from samples were identified by standard biochemical tests and isolated strains of V. cholerae tested for their ability to agglutinate O1 and O139 antisera. Samples were also tested for the presence of V. cholerae O1 and O139 by fluorescent antibody staining. The clinical isolation rate of V. cholerae in Vellore, maximum temperature and rainfall were also studied. The results demonstrate the presence in the environment of viable but non-cultivable (VNC) V. cholerae in 10 of 12 months of the study year as well as their viability. Their prevalence in the environment also correlated with the isolation of these pathogens from clinical samples over the same study period.
Cholera↗
Molecular confirmation of human immunodeficiency virus (HIV) type 2 in HIV-seropositive subjects in south India.
Nested PCRs for human immunodeficiency virus type 1 (HIV-1) and HIV-2 were compared with immunoblot test results. Twelve of 13 immunoblot-positive HIV-2 samples were positive by PCR. There were five INNO-LIA (Innogenetics, Zwijnaarde, Belgium) and/or HIVBLOT 2.2 (Genelabs, Singapore) samples that tested positive for dual infection. HIV-1 PCR was positive in all samples, while HIV-2 PCR was positive in two and RIBA (Chiron Corporation, San Diego, Calif.) was positive for HIV-2 in three samples. Thus the prevalence of HIV-2 is accurately estimated by the use of immunoblotting, but that of HIV-1 and -2 dual infection may be overestimated.
Female↗
A simplified procedure for rapid screening of vibrios for cholera toxin production.
Conventional methods for the detection of cholera toxin (CT) production by vibrios are not readily available to most laboratories. A modification is described here of a simplified method standardised earlier and based on the degradation of nicotinamide adenine dinucleotide (NAD) by CT; this is simple and can be carried out in small laboratories also. It is also easy to perform, and gives reproducible results.
Cholera Toxin↗
Systemic bacterial infections in bone marrow transplant patients.
The clinical microbiology department at CMC&H, Vellore in conjunction with the haematology department carries out routine surveillance of patients admitted to the hematology department. Since 1994 in a sample population of 55 patients with various underlying clinical conditions who have had bone marrow transplant, sepsis was observed in 16 patients (29%). The predominant Gram negatives associated with sepsis were non-fermenting Gram negative bacilli and all the 5 Gram positives were coagulase negative staphylococci. These organisms were susceptible to most of the routinely used antimicrobial agents. Continued surveillance is needed to determine changing trends with respect to organisms causing systemic infections and their susceptibility to antimicrobials.
Adolescent↗