Constitutive expression of SMAR1 confers susceptibility to Mycobacterium tuberculosis infection in a transgenic mouse model.

Background & objectives: Studies involving animal models of experimental tuberculosis have elucidated the predominant role of cytokines secreted by T cells and macrophages to be an essential component of the immune response against Mycobacterium tuberculosis infection. The immune activities of CD4+ T cells are mediated in part by Th1 cytokine interferon gamma (IFN-γ) which is produced primarily by T cells and natural killer (NK) cells and critical for initiating the immune response against intracellular pathogen such as M. tuberculosis. Nuclear matrix protein SMAR1 plays an important role in V(D)J recombination, T helper cell differentiation and inflammatory diseases. In this study a transgenic mouse model was used to study the role of SMAR1 in M. tuberculosis infection. Methods: Wild type BALB/c, C57BL/6, BALB/c-EGFP-SMAR1 and C57BL/6-SMAR1 transgenic mice were infected with M. tuberculosis (H37Rv). A dose of 100 bacilli was used for infection via respiratory route. Bacterial load in lung and spleen of infected mice was determined at 2, 4, 6 and 8 wk post-infection. Gene expression analysis for Th1 cytokines and inducible nitric oxide synthase (iNOS) was performed in infected lung tissues by quantitative reverse transcription (RT)-PCR. Results: SMAR1 transgenic mice from both BALB/c and C57BL/6 genetic background displayed higher bacillary load and susceptibility to M. tuberculosis infection compared to wild type mice. This susceptibility was attributed due to compromised of Th1 response exhibited by transgenic mice. Interpretation & conclusions: SMAR1 transgenic mice exhibited susceptibility to M. tuberculosis infection in vivo irrespective of genetic background. This susceptibility was attributed to downregulation of Th1 response and its hallmark cytokine IFN-γ. Hence, SMAR1 plays an important role in modulating host immune response after M. tuberculosis infection.

Mycobacterium indicus pranii as stand-alone or adjunct immunotherapeutic in treatment of experimental animal tuberculosis.

Background & objectives: Mycobacterium w (M.w) is a saprophytic cultivable mycobacterium and shares several antigens with M. tuberculosis. It has shown good immunomodulation in leprosy patients. Hence in the present study, the efficacy of M.w immunotherapy, alone or in combination with multi drug chemotherapeutic regimens was investigated against drug sensitive M. tuberculosis H37Rv and three clinical isolates with variable degree of drug resistance in mice. Methods: BALB/c mice were infected with M. tuberculosis H37Rv (susceptible to all first and second line drugs) and three clinical isolates taken from the epository of the Institute. The dose of 200 bacilli was used for infection via respiratory route in an aerosol chamber. Chemotherapy (5 days/wk) was given one month after infection and the vaccinated group was given a dose of 1×107 bacilli by subcutaneous route. Bacterial load was measured at 4 and 6 wk after initiation of chemotherapy. Results: M.w when given along with chemotherapy (4 and 6 wk) led to a greater reduction in the bacterial load in lungs and other organs of TB infected animals compared to. However, the reduction was significantly (P<0.05) more in terms of colony forming units (cfu) in both organs (lungs and spleen). Conclusion: M.w (as immunomodulator) has beneficial therapeutic effect as an adjunct to chemotherapy.

In vitro effect of fl uoroquinolones against Mycobacterium tuberculosis isolates from Agra & Kanpur region of north India.

Background & objectives: Fluoroquinolones (FQs) are important drugs used for treatment of drug resistant tuberculosis and are also now being considered as fi rst line drugs to shorten the duration of treatment of tuberculosis (TB). In order to fi nd out useful FQs for treatment of tuberculosis, the comparative effi cacy of fi ve FQs, namely, ofl oxacin (OFL), ciprofl oxacin (CIP), sparfl oxacin (SPX), gatifl oxacin (GAT) and levofl oxacin (LEVX) was studied against Mycobacterium tuberculosis (MTB) isolates obtained from both treated and untreated patients from Agra and Kanpur regions of north India. Methods: A total of 162 MTB isolates [including 110 MTB isolates obtained from untreated patients (Cat-I) and 52 isolates from treated patients (Cat-II)] were tested for their susceptibilities to FQs using standard minimum inhibitory concentration (MIC) method on Löwenstein-Jensen medium. Results: Keeping in view the therapeutically achievable drug levels, it was found that in Cat-I 97.2 per cent (107/110) isolates were sensitive to GAT, 89 per cent (98/110) to LEVX at 1 μg/ml whereas 92.7 per cent (102/110) isolates were inhibited by OFL at 2 μg/ml and 73.6 per cent (81/110) to SPX at 0.5 μg/ml. Only 63.6 per cent (70/110) isolates were found to be sensitive to CIP at 2 μg/ml which increased to 89 per cent (98/110) at 4 μg/ml (higher than achievable peak serum level). On the other hand, among 52 isolates for Cat-II, 37 (71.2%) were found to be sensitive to GAT and 33 (63.5%) to LEVX at 1 μg/ml concentration, 28 (53.8%) to SPX at 0.5 μg/ml whereas 33 (63.5%) and 24 (46.2%) isolates were found to be sensitive to OFL and CIP at 2 μg/ml, respectively. Interpretation & conclusions: It appears that GAT has higher activity against MTB isolates followed by OFL, LEVX and SPX whereas CIP showed the lowest activity. GAT was also found to be the most effective FQ against multi-drug resistant (MDR) isolates both from Cat-I and Cat-II patients. Thus, except CIP, other FQs showed potential to be included in the treatment regimens of tuberculosis including MDR-TB.

Simultaneous ethambutol & isoniazid resistance in clinical isolates of Mycobacterium tuberculosis.

BACKGROUND & OBJECTIVE: There is a need to understand the nature of drug resistance patterns and predictors of emergence of drug resistance in Mycobacterium tuberculosis. There could be common factors/mechanisms for resistance to the drugs, isoniazid and ethambutol, both acting on cell wall. The present study was conducted to analyze the antimycobacterial susceptibility patterns of M. tuberculosis isolates to determine the minimum inhibitory concentrations (MICs) of ethambutol for M. tuberculosis; and to find out possible association of ethambutol resistance with isoniazid resistance. METHODS: A total of 380 M. tuberculosis isolates were tested for their susceptibilities to ethambutol at 2, 4, 6 microg/ml, isoniazid at 1 microg/ml and rifampicin at 64 microg/ml using MIC method. RESULTS: 44.21, 24.73 and 14.21 per cent isolates were resistant to ethambutol at concentrations of 2, 4 and 6 microg/ml respectively. At 6 microg/ml of ethambutol concentration, 85.18 per cent ethambutol resistant isolates were resistant to isoniazid also. At the same ethambutol concentration a fraction of 28.75 per cent isoniazid resistant isolates were ethambutol resistant. INTERPRETATION & CONCLUSION: Ethambutol resistance was accompanied with isoniazid resistance in a large percentage of isolates whereas ethambutol resistance was weakly linked with multidrug resistance. On the other hand, association between isoniazid and ethambutol resistance was weak showing one way linkage.

Risk taking behavior and Sexually Transmitted Diseases: a study among men.

Sexually Transmitted Diseases (STDs) among men not only jeopardize their own health but also increase sexual morbidities among their spouses. STDs are primarily attributed to high-risk sexual behavior. The study was carried out among male patients attending the OPD of a Government dispensary. Risk taking behavior was assessed using a structured, pre-tested questionnaire and STDs were diagnosed using syndromic approach supported by laboratory investigations. Three hundred two men were selected by systemic random sampling for inclusion in the study. 39% had pre-marital sexual relationship, 20% had sex with Commercial Sex Workers. 12% of the married men had extramarital sex mostly with CSWs. 27% had more than one sex partner ever. Only 3.6% used condoms consistently. Thirteen per cent respondents had history of symptoms suggestive of STDs. Prevalence of syphilis, gonorrhea and other STDs among study subjects were 3.6%, 0.7% and 0.7% respectively. High risk sexual behavior is widely prevalent and STDs are also common. Behavior change communication and early diagnosis and prompt treatment of STDs will reduce the burden significantly.