P. R. Narayanan

Mutations in the rpoB Gene of Multidrug-Resistant Mycobacterium tuberculosis Clinical Isolates from India

ABSTRACT Mutations in the 81-bp rifampin resistance-determining region (RRDR) of the rpoB gene were analyzed by DNA sequencing of 50 Mycobacterium tuberculosis clinical isolates (44 resistant and 6 sensitive) from various parts of India. Fifty-three mutations of 18 different kinds, 17 point mutations and one deletion, were observed in 43 of 44 resistant isolates. Three novel mutations and three new alleles within the RRDR, along with two novel mutations outside the RRDR, are reported in this study.

Regulatory role of vitamin D receptor gene variants of Bsm I, Apa I, Taq I, and Fok I polymorphisms on macrophage phagocytosis and lymphoproliferative response to mycobacterium tuberculosis antigen in pulmonary tuberculosis.

The regulatory role of vitamin D receptor (VDR) gene variants of BsmI, ApaI, TaqI, and FokI polymorphisms on vitamin D3-modulated macrophage phagocytosis with live Mycobacterium tuberculosis and lymphoproliferative response to M. tuberculosis culture filtrate antigen (CFA) was studied in patients with pulmonary tuberculosis (n = 46) and in normal healthy subjects (NHS) (n = 64). Vitamin D3 at a concentration of 1 × 10−7 M enhanced the phagocytic potential of normal subjects who had a phagocytic index of less than 20%. This increase was seen in subjects with the genotypes BB (p = 0.017), AA (p = 0.016), tt (p = 0.034), and FF (p = 0.013) and the extended genotype BBAAtt (p = 0.034). Normal subjects with BBAAtt performed better phagocytosis than individuals with bbaaTT genotype (p = 0.034). Vitamin D3 at 10−9, 10−8, and 10−7 M concentrations suppressed the lymphoproliferative response to CFA antigen in normal subjects. This decreased lymphocyte response was observed in normal individuals with the genotypes BB (p = 0.0009), tt (p = 0.016), and FF (p = 0.008) and the extended genotype BBAAtt (p = 0.02). Addition of vitamin D3 had no significant effect on macrophage phagocytosis and lymphoproliferative response to CFA in pulmonary TB patients. This may be due to the unresponsive nature of the cells to the action of vitamin D3 or the downregulated VDR expression by virtue of the disease, which renders them inactive. The genotypes BB, tt, and the extended genotype BBAAtt may be associated with increased expression of VDR which in turn regulate the action of vitamin D3 and modulate the immune functions to M. tuberculosis in NHS.

Efficacy of a 6-month versus 9-month intermittent treatment regimen in HIV-infected patients with tuberculosis a randomized clinical trial.

RATIONALE The outcome of fully intermittent thrice-weekly antituberculosis treatment of various durations in HIV-associated tuberculosis is unclear. OBJECTIVES To compare the efficacy of an intermittent 6-month regimen (Reg6M: 2EHRZ(3)/4HR(3) [ethambutol, 1,200 mg; isoniazid, 600 mg; rifampicin, 450 or 600 mg depending on body weight <60 or > or =60 kg; and pyrazinamide, 1,500 mg for 2 mo; followed by 4 mo of isoniazid and rifampicin at the same doses]) versus a 9-month regimen (Reg9M: 2EHRZ(3)/7HR(3)) in HIV/tuberculosis (TB). METHODS HIV-infected patients with newly diagnosed pulmonary or extrapulmonary TB were randomly assigned to Reg6M (n = 167) or Reg9M (n = 160) and monitored by determination of clinical, immunological, and bacteriological parameters for 36 months. Primary outcomes included favorable responses at the end of treatment and recurrences during follow-up, whereas the secondary outcome was death. Intent-to-treat and on-treatment analyses were performed. All patients were antiretroviral treatment-naive during treatment. MEASUREMENTS AND MAIN RESULTS Of the patients, 70% had culture-positive pulmonary TB; the median viral load was 155,000 copies/ml and the CD4(+) cell count was 160 cells/mm(3). Favorable response to antituberculosis treatment was similar by intent to treat (Reg6M, 83% and Reg9M, 76%; P = not significant). Bacteriological recurrences occurred significantly more often in Reg6M than in Reg9M (15 vs. 7%; P < 0.05) although overall recurrences were not significantly different (Reg6M, 19% vs. Reg9M, 13%). By 36 months, 36% of patients undergoing Reg6M and 35% undergoing Reg9M had died, with no significant difference between regimens. All 19 patients who failed treatment developed acquired rifamycin resistance (ARR), the main risk factor being baseline isoniazid resistance. CONCLUSIONS Among antiretroviral treatment-naive HIV-infected patients with TB, a 9-month regimen resulted in a similar outcome at the end of treatment but a significantly lower bacteriological recurrence rate compared with a 6-month thrice-weekly regimen. ARR was high with these intermittent regimens and neither mortality nor ARR was altered by lengthening TB treatment. Clinical Trials Registry Information: ID# NCT00376012 registered at www.clinicaltrials.gov.

Impact of HIV Infection on the Recurrence of Tuberculosis in South India

BACKGROUND There is limited information on the relative proportion of reactivation and reinfection at the time of recurrence among human immunodeficiency virus (HIV)-infected and HIV-uninfected patients who are successfully treated for tuberculosis infection in India. METHODS HIV-infected and HIV-uninfected patients with sputum culture-positive pulmonary tuberculosis were treated with short-course regimens and followed up for 36 months at the Tuberculosis Research Centre, South India. Bacteriologic recurrences were documented, and typing of strains was performed using 3 different genotypic techniques: restriction fragment length polymorphism (RFLP) by IS6110, spoligotyping, and mycobacterial interspersed repeat unit (MIRU)-variable number tandem repeat (VNTR). DNA fingerprints of paired Mycobacterium tuberculosis isolates (baseline and recurrence) were compared. RESULTS Among 44 HIV-infected and 30 HIV-uninfected patients with recurrent tuberculosis during the period July 1999 to October 2005, 25 and 23 paired isolates, respectively, were typed using all 3 methods. Recurrence was due to exogenous reinfection in 88% of HIV-infected and 9% of HIV-uninfected patients (P<.05). Among recurrent isolates, the HIV-infected patients showed more clustering, as well as a higher proportion of drug resistance, including multidrug resistance. CONCLUSIONS In India, a tuberculosis-endemic country, most recurrences after successful treatment of tuberculosis are due to exogenous reinfection in HIV-infected persons and endogenous reactivation in HIV-uninfected persons. Strategies for prevention and treatment of tuberculosis infection must take these findings into consideration.

Effect of vitamin D3 on phagocytic potential of macrophages with live Mycobacterium tuberculosis and lymphoproliferative response in pulmonary tuberculosis.

Immune responses are elicited through antigen presentation and recognition by macrophages and T-lymphocytes, respectively. The immunomodulatory effect of vitamin D3 on macrophage phagocytic potential with live Mycobacterium tuberculosis, spontaneous and M. tuberculosis culture filtrate antigen induced lymphocyte responses were studied in pulmonary tuberculosis patients (PTBPs) (n = 31) and normal healthy subjects (NHSs) (n = 43). Vitamin D3 at a concentration of 10−7 M significantly enhanced the macrophage phagocytosis of live M. tuberculosis in normal subjects with low phagocytic potential (less than 10%) (p = 0.015). No such increase was observed in PTBPs. Vitamin D3 significantly decreased the spontaneous lymphoproliferative response (p = 0.022) and increased the apoptosis of peripheral blood mononuclear cells in PTBPs (p = 0.024). In normals, vitamin D3 increased the spontaneous lymphoproliferative response. An inverse correlation between macrophage phagocytosis and spontaneous response was observed in NHSs, whereas a direct correlation was seen between vitamin D3-treated cells in normal subjects under in vitro condition. Vitamin D3 decreased the M. tuberculosis culture filtrate antigen induced lymphocyte response significantly in normal subjects (p = 0.0003), while it had no influence on the lymphocyte response in PTBPs. The present study suggests that exposure to vitamin D3 increases the phagocytic potential and spontaneous lymphoproliferative response but brings down the antigen-induced response in normals. In tuberculosis, addition of vitamin D3 has no significant effect on antigen-induced lymphoproliferative response. This may be due to the unresponsive nature of the cells to the action of vitamin D3 by virtue of the disease, which renders them inactive.

Molecular Epidemiology of Tuberculosis in a Rural Area of High Prevalence in South India: Implications for Disease Control and Prevention

ABSTRACT Molecular and conventional epidemiologic techniques were used to study the mechanisms and risk factors for tuberculosis transmission in a rural area with high prevalence in south India. Restriction fragment length polymorphism analysis with IS6110 and direct repeat probes was performed with 378 Mycobacterium tuberculosis isolates from patients. Forty-one percent of M. tuberculosis isolates harbored a single copy of IS6110. Of 378 patients, 236 had distinct strains; 142 (38%) shared a strain with other patients, indicating recent infection. Older patients, those detected by a house-to-house community survey, and those hospitalized in a sanatorium were more likely to have had a recent infection. These findings suggest that the majority of the tuberculosis cases in south India were due to reactivation; therefore, efforts to control tuberculosis should be sustained.

Evaluation of PCR Using TRC4 and IS6110 Primers in Detection of Tuberculous Meningitis

ABSTRACT We have evaluated a new set of primers (TRC4) in comparison with the IS6110 primers commonly used in PCR to detect tuberculous meningitis among children. The levels of concordance between the results of IS6110 PCR and TRC4 PCR with cerebrospinal fluid specimens from patients with clinically confirmed tuberculous meningitis were 80 and 86%, respectively. Results with the two primer sets were concordant for 55 positive and 22 negative specimens (n = 98). We conclude that the sensitivity of PCR can be increased by using both IS6110and TRC4 primers.

Randomized Clinical Trial of Thrice-Weekly 4-Month Moxifloxacin or Gatifloxacin Containing Regimens in the Treatment of New Sputum Positive Pulmonary Tuberculosis Patients

Background Shortening tuberculosis (TB) treatment duration is a research priority. This paper presents data from a prematurely terminated randomized clinical trial, of 4-month moxifloxacin or gatifloxacin regimens, in South India. Methods Newly diagnosed, sputum-positive HIV-negative pulmonary TB patients were randomly allocated to receive gatifloxacin or moxifloxacin, along with isoniazid and rifampicin for 4 months with pyrazinamide for first 2 months (G or M) or isoniazid and rifampicin for 6 months with ethambutol and pyrazinamide for first 2 months (C). All regimens were administered thrice-weekly. Clinical and bacteriological assessments were done monthly during treatment and for 24 months post-treatment. The Data and Safety Monitoring Board recommended termination of the trial due to high TB recurrence rates in the G and M regimens. Results Of 416 patients in intent-to-treat analysis, 6 (5%) of 124, 2 (2%) of 110 and 2 (2%) of 137 patients with drug-susceptible TB in the G, M and C arms respectively had unfavorable response at the end of treatment; during the next 24 months, 17 (15%) of 115, 11 (11%) of 104 and 8 (6%) of 132 patients respectively, had TB recurrence. Of 38 drug-resistant patients 1 of 8 and 3 of 26 in the G and C arms respectively had unfavourable response at the end of treatment; and TB recurrence occurred in 2 of 7 and 2 of 23 patients, respectively. The differences in TB recurrence rates between the G and C arms was statistically significant (p = 0.02). Gastro-intestinal symptoms occurred in 23%, 22% and 9% of patients in the G, M and C arms respectively, but most reactions were mild and manageable with symptomatic measures; 1% required regimen modification. Conclusions 4-month thrice-weekly regimens of gatifloxacin or moxifloxacin with isoniazid, rifampicin and pyrazinamide, were inferior to standard 6-month treatment, in patients with newly diagnosed sputum positive pulmonary TB. Trial Registration Clinical Trials Registry of India CTRI/2012/10/003060

Evaluation of the Phenol Ammonium Sulfate Sedimentation Smear Microscopy Method for Diagnosis of Pulmonary Tuberculosis

ABSTRACT We compared the sensitivity and specificity of the phenol ammonium sulfate (PhAS) sediment smear microscopy method for detection of acid-fast bacilli with those of direct smear microscopy, using culture results for Mycobacterium tuberculosis as the “gold standard.” The sensitivities of the PhAS and direct smear methods were 85% (465 of 547) and 83% (454 of 547), respectively, and the specificity of each method was 97%. The PhAS method was better accepted by the laboratory technicians and safer but necessitates an overnight sedimentation, which delays reporting of results until 1 day after sputum collection.

Effect of 1,25 dihydroxyvitamin D3 on intracellular IFN-γ and TNF-α positive T cell subsets in pulmonary tuberculosis.

We studied the immunomodulatory effect of 1,25(OH)(2)D(3) on single cell expression of IFN-gamma and TNF-alpha cytokines in T cell subsets of pulmonary tuberculosis (PTB) patients (n=22) and normal healthy subjects (n=22). Peripheral blood mononuclear cells (PBMCs) were cultured with live Mycobacterium tuberculosis (MTB) with or without 1,25(OH)(2)D(3) (10(-7)M) for 48 h. T cell subsets positive for IFN-gamma and TNF-alpha were enumerated by flow cytometry and the culture supernatants were assayed for both the cytokines using ELISA. In both NHS and PTB patients, a significantly reduced percentage of IFN-gamma and TNF-alpha expressing CD3+, CD3+CD4+ and CD3+CD8+ T cells were observed in cultures stimulated with live MTB and treated with 1,25(OH)(2)D(3) compared to cultures without 1,25(OH)(2)D(3) (NHS; CD3+ IFN-gamma+: p<0.0001; CD3+TNF-alpha+: p=0.0292 and PTB; CD3+ IFN-gamma+: p=0.0292; CD3+ TNF-alpha+: p=0.0028). The levels of IFN-gamma and TNF-alpha in the culture supernatants of 1,25(OH)(2)D(3) treated cultures were also found to be significantly decreased in both groups (NHS; IFN-gamma: p=0.0001; TNF-alpha: p<0.0001) and (PTB; IFN-gamma: p<0.0001; TNF-alpha: p<0.0001). A positive correlation was observed between IFN-gamma and TNF-alpha expressing CD3+CD8+ T cells in MTB stimulated cultures treated with or without 1,25(OH)(2)D(3) in NHS (p=0.0001; p=0.001, respectively) and PTB patients (p=0.002; p=0.005, respectively). The present study revealed the suppressive effect of 1,25(OH)(2)D(3) on single cell expression of IFN-gamma and TNF-alpha by CD3+CD4+ and CD3+CD8+ T cells in pulmonary tuberculosis. This suppressive effect of 1,25(OH)(2)D(3) on proinflammatory and Th1 cytokine positive cells might have a role in reducing inflammation at the site of infection.