Biomedical subjects

C N Paramasivan

Publications and source records attributed to C N Paramasivan.

At least 55 records · Page 3Linked to original sources

PubMed1997

Restriction fragment length polymorphism of Mycobacterium tuberculosis strains from various regions of India, using direct repeat probe.

Intraspecies differentiation was studied on 68 M. tuberculosis strains obtained from 6 states of India by restriction fragment length polymorphism (RFLP) using a direct repeat probe (DR probe) hybridised with Alu I digest of DNA. Most strains showed polymorphism based patterns that comprised between 2 to 7 bands and were grouped into 26 RFLP types. Of the 11 strains tested from Amritsar, 8 were RFLP type 5; the remaining 3 were of type 11 and were exclusively confined to this region. The strains from other regions were more heterogeneous. We confirm that DR-associated RFLP can be an excellent tool for the differentiation of M. tuberculosis strains. Depending on their geographical origin, these strains can be differentiated to a large extent by DR fingerprinting.

DNA Fingerprinting↗

PubMed1997

Neopterin as a marker for cell-mediated immunity in patients with pulmonary tuberculosis.

SETTING: Cell-mediated immunity (CMI) involves macrophage activation and T cell proliferation. These two parameters are compared in this study. OBJECTIVE: To ascertain the role of neopterin as a biochemical marker for CMI in patients with pulmonary tuberculosis. DESIGN: We measured neopterin levels in serum and the culture supernatants of peripheral blood mononuclear cells (MNC) after stimulation with purified protein derivative (PPD) in 11 patients with pulmonary tuberculosis and 10 healthy individuals. Lymphocyte proliferative response to PPD was carried out in these two groups. RESULTS: The mean concentration of serum neopterin was significantly higher in patients than in controls (P < 0.01). The spontaneous release of neopterin was significantly higher in culture supernatants of MNC from patients when compared with those of healthy controls (P < 0.05). Release of neopterin from MNC stimulated with PPD, however, was similar in both groups. The neopterin release and the stimulation index (SI) in lymphocyte proliferation assay were not comparable, suggesting that these two parameters do not run in parallel for measuring the status of CMI. However, serum concentration of neopterin was inversely related to the SI in a large proportion of subjects (66%). CONCLUSION: Measurement of neopterin, a soluble product of immune cells (macrophage), may provide information on the state of CMI.

Adult↗

PubMed1996

Bactericidal action of ofloxacin, sulbactam-ampicillin, rifampin, and isoniazid on logarithmic- and stationary-phase cultures of Mycobacterium tuberculosis.

The bactericidal actions of ofloxacin and sulbactam-ampicillin, alone and in combination with rifampin and isoniazid, on exponential-phase and stationary-phase cultures of a drug-susceptible isolate of Mycobacterium tuberculosis were studied in vitro. In exponential-phase cultures, all drugs were bactericidal, with the higher concentrations of ofloxacin (5 micrograms/ml) and sulbactam-ampicillin (15 micrograms of ampicillin per ml) being as bactericidal as 1 microgram of isoniazid per ml or 1 microgram of rifampin per ml. In two-drug combinations, both drugs increased the levels of activity of isoniazid and rifampin and were almost as bactericidal as isoniazid-rifampin; they also appeared to increase the level of activity of isoniazid-rifampin in three-drug combinations. In contrast, ofloxacin and sulbactam-ampicillin had little bactericidal activity against stationary-phase cultures and were less active than isoniazid or rifampin alone. Furthermore, in two-drug or three-drug combinations, they did not increase the level of activity of isoniazid, rifampin, or isoniazid-rifampin. These findings suggest that ofloxacin and sulbactam-ampicillin are likely to be most useful in the early stages of treatment and in preventing the emergence of resistance to other drugs but are unlikely to be effective as sterilizing drugs helping to kill persisting lesional bacilli.

Ampicillin↗

PubMed1996

Isolation of Mycobacterium tuberculosis from cerebrospinal fluid by the centrifugation & filtration methods.

Cerebrospinal fluid (CSF) samples were collected in 2 bottles each, from 112 children, examined clinically for tuberculous meningitis (TBM) One was processed by the centrifugation method and the other by the filtration method for the isolation of M. tuberculosis. Of these specimens, 11 and 13 yielded M. tuberculosis by the centrifugation method and the filtration method, respectively. In 7 specimens M. tuberculosis was isolated by both the methods; in 4, only by the centrifugation method, and in 6, only by the filtration method. Using both the methods, 17 (15.2%) of 112 specimens were culture positive for M. tuberculosis. The improvement in the rate of isolation, thus obtained, assumes importance as the confirmation of the diagnosis of TBM in all the clinically suspected cases is always desired. Moreover, the filtration method is simple and inexpensive and it can be carried out even in remote hospitals and the membranes, after filtration, can be transported to central mycobacteriology laboratory for culture of tubercle bacilli.

Bacteriological Techniques↗

PubMed1996

Immune response & modulation of immune response induced in the guinea-pigs by Mycobacterium avium complex (MAC) & M. fortuitum complex isolates from different sources in the south Indian BCG trial area.

A total of 139 guineapigs were used to study the immune response and its modulation induced by Mycobacterium avium complex (MAC) and M. fortuitum complex strains obtained from different sources in the south Indian BCG trial area. The guineapigs were divided into groups and some were directly sensitised/immunised with different MAC strains. M. fortuitum complex strain or BCG and others were sensitised with MAC or M. fortuitum complex and then immunised with BCG. The resulting delayed type hypersensitivity (DTH) response in the different groups of guineapigs was studied by skin tests using PPD-RT23 and PPD-B, and protective response was studied by challenging the guineapigs with a south Indian low virulent strain of M. tuberculosis and enumerating the bacilli in spleen at different points of time. The 3 strains of MAC induced similar low levels of DTH to PPD-RT23 but much higher and varying levels of DTH to PPD-B. MAC strains from soil and sputum induced different levels of immune modulation during subsequent immunisation with BCG on the DTH response to PPD-RT23 and PPD-B. At 2 wk after challenge, 23.8, 81 and 90.5 per cent protection was induced by the standard strain, soil isolate and sputum isolate of MAC, respectively, while 33.3 per cent protection was induced by the M. fortuitum complex strain compared to the protection induced by BCG alone. Prior exposure to MAC or M. fortuitum complex did not have any modulatory effect on the protective immunity due to BCG at this time point. However, at 6 wk after challenge, while the guineapigs immunised with BCG were protected, modulation of the protective response resulting from BCG was observed in the guineapigs sensitised with MAC and M. fortuitum from soil.

Animals↗

PubMed1995

IS6110 restriction fragment length polymorphism typing of clinical isolates of Mycobacterium tuberculosis from patients with pulmonary tuberculosis in Madras, south India.

SETTING: Madras, India. OBJECTIVE: To explore the utility of a standardized IS6110/PvuII deoxyribonucleic acid (DNA) fingerprinting restriction fragment length polymorphism (RFLP) typing method for distinguishing between isolates of Mycobacterium tuberculosis, and to assess the potential for distinguishing between relapse versus reinfection rates. DESIGN: To assess RFLP heterogeneity in the population, initial isolates, obtained from the sputum of tuberculous 98 patients in diagnosis and follow-up during short-course chemotherapy, were stored and compared. To assess the frequency of disparity between the RFLP type of the initial isolate and one obtained after successful completion of chemotherapy, either during relapse or as an isolated positive culture, 124 isolates comprising 62 such pairs were coded and compared both blind and after decoding. RESULTS: Although a wide variety of DNA band patterns (fingerprints) was present, the isolates from 39 (40%) of the patients showed a single copy of IS6110. Only 15 pairs of coded initial and follow-up isolates could be identified as having the same band pattern when isolates with zero or single bands were excluded. Nevertheless, after decoding, in a retrospective analysis that included all isolates, those isolates that bacteriologically defined a patient's relapse more often showed RFLP type identity with the initial isolate (19 of 30 comparisons) than did isolates that were obtained as isolated positive cultures (3 of 32 comparisons) (X2 P < 0.001). Tests of sensitivity to chemotherapeutic drugs, catalase activity and resistance to thiophene-2-carboxylic acid hydrazide were of minimal value in discriminating between isolates. CONCLUSIONS: Despite the high frequency of single- and zero-band isolates in this population, the discriminatory power of RFLP typing with IS6110 is sufficiently high to be useful for clinical and epidemiological studies.

Adolescent↗

PubMed1995

Value of bronchoalveolar lavage and gastric lavage in the diagnosis of pulmonary tuberculosis in children.

OBJECTIVE: The aim of our study was to find out if bronchoalveolar lavage (BAL) would be better than gastric lavage for the isolation of Mycobacterium tuberculosis from pediatric patients with suspected pulmonary tuberculosis. DESIGN: 50 children with suspected pulmonary tuberculosis at a mean age of 5.1 years (range 7 months to 12 years) were studied. Early morning gastric lavage was collected. Flexible bronchoscopy and bronchoalveolar lavage was performed under local anaesthesia after obtaining informed consent from the parents. The BAL fluid and gastric lavage specimens were subjected to smear examination for acid-fast bacilli (AFB) and culture for mycobacteria using established methods. RESULTS: Of the 50 cases, M. tuberculosis was grown in 6 BAL samples (12%) and 16 gastric lavage samples (32%) making a total of 17 culture proven cases (34%). Out of the 6 BAL positive cases, gastric lavage was also positive in 5 cases. CONCLUSION: We conclude that gastric lavage is better than BAL for bacteriologic confirmation of pulmonary tuberculosis in children. The overall bacteriologic yield combining both procedures was 34% while gastric lavage alone was positive in 32% of the cases.

Bronchoalveolar Lavage Fluid↗

PubMed1995

Restriction fragment length polymorphism typing of clinical isolates of Mycobacterium tuberculosis from patients with pulmonary tuberculosis in Madras, India, by use of direct-repeat probe.

Large numbers of Mycobacterium tuberculosis isolates that were obtained from patients' sputa on diagnosis and during follow-up after short-course chemotherapy in Madras, India, have either no copy or only a single copy of IS6110. This poses a limitation for DNA fingerprinting with an IS6110-based probe to determine the frequency of exogenous reinfection versus that of endogenous reactivation. In the present study, we overcame this limitation by using an alternate probe, the direct-repeat element. Comparison of pre- and posttreatment isolates by direct-repeat restriction fragment length polymorphism analysis indicated a high degree of endogenous reactivation among patients who have relapses after the successful completion of chemotherapy.

Bacterial Typing Techniques↗

PubMed1995

Isolation of tubercle bacilli from sputum samples of patients in the field studies by the cetylpyridinium chloride-sodium chloride & sodium hydroxide methods.

A total of 125 sputum specimens, collected in the field, were homogenised, aliquoted in sterile universal containers and randomly allocated to the cetylpyridinium chloride - sodium chloride (CPC-NaCl) method and sodium hydroxide (NaOH) method for culture of tubercle bacilli. After storage for 8 days at ambient temperature in the field laboratory at Thiruvallur, the aliquots were transported to the main laboratory at Madras where they were processed for culture by the respective methods. The yield of positive cultures in the CPC-NaCl (31/125) method was only marginally better than that in the NaOH method (27/125) (95% CI being-3.4 to 9.8%), while the contamination of cultures was significantly less in the CPC-NaCl method (3/125) than in the NaOH method (12/125) (95% CI being 2.2 to 12.2%). As the CPC-NaCl method has advantages over the NaOH method in reducing contamination, in augmenting the yield of positive cultures and also in its simplicity, it can be applied in field studies.

Bacteriological Techniques↗

PubMed1995

Vancomycin for controlling contamination of selective Kirchner's liquid medium in the culture of gastric lavage for tubercle bacilli.

Gastric lavage (GL) was collected for culture of tubercle bacilli from children too young to expectorate sputum. The selective Kirchner's liquid medium (SKLM), routinely used as one of the media for culture of all extrapulmonary specimens, was found to often get contaminated when cultured with GL. We have shown that vancomycin at a concentration of 10 mg/l successfully reduced the contamination from about 60 to 20 per cent, and enhanced the isolation rate of tubercle bacilli from 3 to 6 per cent. Decontamination of the liquid culture before subculture on solid medium also helped to reduce the contamination rate. Vancomycin was found to be an effective selective drug for use in the Kirchner's liquid medium for culture of tubercle bacilli.

Bacteriological Techniques↗

PubMed1995

A direct rifampicin sensitivity test for tubercle bacilli.

A direct sensitivity test for rifampicin has been standardised for early detection of resistance for the mycobacterium tuberculosis smear positive sputum samples. Indirect sensitivity tests set up from primary cultures of the same samples served as controls. The direct test showed 95 per cent agreement with the standard indirect test and as such 74 per cent and 90 per cent of the resistant strains were detected by the fourth week and fifth week, respectively, with an overall gain of 4-5 wks time. Resistance could be detected earlier for multibacillary specimens. This direct sensitivity test on Lowenstein Jensen (LJ) medium offers a feasible alternative for laboratories which lack facilities to perform drug susceptibility tests by the rapid but sophisticated and costly BACTEC method. The method is simple to perform, economic, reliable and amenable to confirmation by the indirect test, if needed.

Drug Resistance, Microbial↗

PubMed1994

Evaluation of procedures for isolation of nontuberculous mycobacteria from soil and water.

Six methods of decontamination each for the isolation of mycobacteria from soil and water were compared. On the basis of the results obtained, three of the six methods for soil and two of the six methods for water were further evaluated. For both soil and water samples, the method using 3% sodium lauryl sulfate in combination with 1% NaOH yielded more positives than the other methods.

Journal Article↗

PubMed1994

Isolation and Identification of Environmental Mycobacteria in the Mycobacterium bovis BCG Trial Area of South India.

The isolation profiles of environmental mycobacteria present in soil, water, and dust samples, and sputum samples of persons with symptoms of chest infection in the South Indian Mycobacterium bovis BCG (bacillus Calmette-Guérin) trial area were compared. Isolates belonging to the Mycobacterium avium-intracellulare-scrofulaceum complex were predominant in water, dust, and sputum samples and Mycobacterium fortuitum-complex organisms were predominant in soil samples irrespective of the season of the year.

Journal Article↗

PubMed1994

Early bactericidal action of pulsed exposure to rifampicin, ethambutol, isoniazid & pyrazinamide in pulmonary tuberculosis patients.

The bactericidal action of two therapeutic regimens on Mycobacterium tuberculosis was assessed by viable counts in serial sputum samples in 49 pulmonary tuberculosis patients being treated with rifampicin (R), ethambutol (Emb), isoniazid (I) and pyrazinamide (Z) together in a single dose thrice weekly (REmbIZ3) or with REmb and IZ on alternate days (REmb3IZ3alt). In both groups of patients, there was a significant reduction (P < or = 0.02) in the colony forming units (cfu) of M. tuberculosis per ml of sputum during the first two days of treatment itself. This early bactericidal action (EBA) as well as the reduction in counts during the subsequent days of treatment were similar (P > 0.2) for both REmbIZ3 and REmb3IZ3alt regimens indicating that splitting up REmbIZ into REmb on one day and IZ on the next day in short course chemotherapy (SCC) regimens may not affect the bactericidal action of the regimens.

Antitubercular Agents↗

PubMed1994

Protective response in guinea pigs exposed to Mycobacterium aviumintracellulare/M. scrofulaceum, BCG & south Indian isolates of M. tuberculosis.

The protective immunity resulting from exposure to nontuberculous mycobacteria (NTM), BCG and virulent mycobacteria in different sequences was studied in the guinea pig model employing strains prevalent in the south Indian BCG trial area and time kinetics to observe the immuno-modulation. The findings suggest that during the early course of challenge infection in guinea pigs there was no interference with the immunity due to BCG, by prior exposure to NTM. In the animals sensitised with M. avium intracellulare before immunisation, the challenge infection was localised and confined to the site of inoculation, and only a few organisms reached the spleen. However, at the later stages of the infection, as seen by the spleen viable counts at 12 wk, it appeared that the barrier at the localised site of infection may not be intact in the animals with prior exposure to NTM, and a few organisms disseminate to the spleen.

Animals↗

PubMed1993

Critical assessment of smear-positive pulmonary tuberculosis patients after chemotherapy under the district tuberculosis programme.

This is a status report of a retrospectively assembled cohort of 3357 smear-positive patients initiated on anti-tuberculosis chemotherapy in the North Arcot district between April 1986 and March 1988. The patients were contacted once at their homes between November 1988 and June 1989 (6 and 36 months after start of treatment), and information on their status, including death, could be obtained from 76% of them. Regimens were selected by the patients. 2306 (69%) had accepted short course regimens (SCC) and 1051 (31%) had been started on standard chemotherapy (non-SCC), 43% and 35% in SCC and non-SCC respectively had completed 80% or more of their treatment. Overall mortality was 28%. Of those remaining, 31% had active disease and were excreting bacilli, among which 65% of the cultures were resistant to isoniazid and 12% to rifampicin. Combined resistance to isoniazid and rifampicin was seen in 4% and to isoniazid and streptomycin was seen in 19%. A significant finding was that even among those who had taken less than 50% of their treatment, 56% were bacteriologically negative. However, inadequate or irregular chemotherapy resulted in over four times the mortality and about twice the rate of smear positivity as compared with those taking adequate chemotherapy. No comparisons are made between patients on short-course and standard regimens as the patients selected their treatment and the groups are not comparable.

Adolescent↗

PubMed1993

Bacteriological investigations for short-course chemotherapy under the tuberculosis programme in two districts of India.

To examine the bacteriological profile and the prevalence of drug resistance among patients attending the health facilities where the District Tuberculosis Programme (DTP) was in operation with short-course chemotherapy (SCC) regimens, sputum specimens were collected on admission and the end of treatment in North Arcot district and Pondicherry region. In North Arcot district, rifampicin, isoniazid and pyrazinamide were given twice weekly for the first 2 months followed by rifampicin and isoniazid twice a week for the next 4 months under fully supervised administration. In Pondicherry, rifampicin, isoniazid and pyrazinamide were given daily for the first 2 months followed by rifampicin and isoniazid twice weekly for the next 4 months. Of the patients who had received 80% or more of the drugs, 80% from North Arcot and 92% from Pondicherry were rendered culture-negative for Mycobacterium tuberculosis at the end of treatment. Even among patients with initially resistant bacilli, a high proportion had a favourable response. Before start of treatment, of the 2779 patients from North Arcot, 25% had resistance to one or more drugs including 2% with resistance to rifampicin. In Pondicherry, 13% of the patients had initial resistance to one or more drugs. Initial resistance to rifampicin was observed in 0.9%. None of the initially drug-sensitive patients had acquired resistance to rifampicin at the end of treatment.

Adolescent↗

PubMed1993

Bactericidal action of pulsed exposure to rifampicin, ethambutol, isoniazid & pyrazinamide on Mycobacterium tuberculosis in vitro.

The bactericidal action of pulsed exposure to rifampicin (R), ethambutol (Emb), isoniazid (I) and pyrazinamide (Z) together on alternate days (REmbIZ) and as REmb and IZ separately on alternate days (REmb/IZ) on M.tuberculosis H37Rv, two isolates of M.tuberculosis sensitive to these drugs, as well as four isolates resistant to one or more drugs, was studied using an in vitro method. The experimental duration was 6 days. REmbIZ and REmb/IZ appeared to have equally good bactericidal action on M.tuberculosis strains in the in vitro system. The results suggest that splitting REmbIZ into REmb and IZ on alternate days in short course chemotherapy regimens for tuberculosis may not affect the bactericidal action of the regimens.

Antitubercular Agents↗