Contribution of medical colleges to tuberculosis control in India under the Revised National Tuberculosis Control Programme (RNTCP): lessons learnt & challenges ahead.

Medical college faculty, who are academicians are seldom directly involved in the implementation of national public health programmes. More than a decade ago for the first time in the global history of tuberculosis (TB) control, medical colleges of India were involved in the Revised National TB Control Programme (RNTCP) of Government of India (GOI). This report documents the unique and extraordinary course of events that led to the involvement of medical colleges in the RNTCP of GOI. It also reports the contributions made by the medical colleges to TB control in India. For more than a decade, medical colleges have been providing diagnostic services (Designated Microscopy Centres), treatment [Directly Observed Treatment (DOT) Centres] referral for treatment, recording and reporting data, carrying out advocacy for RNTCP and conducting operational research relevant to RNTCP. Medical colleges are contributing to diagnosis and treatment of human immunodeficiency virus (HIV)-TB co-infection and development of laboratory infrastructure for early diagnosis of multidrug-resistant and/or extensively drug-resistant TB (M/XDR-TB) and DOTS-Plus sites for treatment of MDR-TB cases. Overall, at a national level, medical colleges have contributed to 25 per cent of TB suspects referred for diagnosis; 23 per cent of 'new smear-positives' diagnosed; 7 per cent of DOT provision within medical college; and 86 per cent treatment success rate among new smear-positive patients. As the Programme widens its scope, future challenges include sustenance of this contribution and facilitating universal access to quality TB care; greater involvement in operational research relevant to the Programme needs; and better co-ordination mechanisms between district, state, zonal and national level to encourage their involvement.

Co-expression of DevR and DevR(N)-Aph proteins is associated with hypoxic adaptation defect and virulence attenuation of Mycobacterium tuberculosis.

BACKGROUND: The DevR response regulator is implicated in both hypoxic adaptation and virulence of Mycobacterium tuberculosis (M. tb). DevR regulon genes are powerfully induced in vivo implicating them in bacterial adaptation to host control strategies. A better understanding of DevR function will illumine the way for new strategies to control and treat tuberculosis. METHODOLOGY/PRINCIPAL FINDINGS: Towards this objective, we used a combination of genetic, microbiological, biochemical, cell biological tools and a guinea pig virulence assay to compare the hypoxic adaptation and virulence properties of two novel M. tb strains, namely, a devR disruption mutant, Mut1, that expresses C-terminal truncated N-terminal domain of DevR (DevR(NTD)) as a fusion protein with AphI (DevR(N)-Kan), and its complemented strain, Comp1, that expresses intact DevR along with DevR(N)-Kan. Comp1 bacteria exhibit a defect in DevR-mediated phosphosignalling, hypoxic induction of HspX and also hypoxic survival. In addition, we find that Comp1 is attenuated in virulence in guinea pigs and shows decreased infectivity of THP-1 cells. While Mut1 bacilli are also defective in hypoxic adaptation and early growth in spleen, they exhibit an overall virulence comparable to that of wild-type bacteria. CONCLUSIONS/SIGNIFICANCE: The hypoxic defect of Comp1 is associated to a defect in DevR expression level. The demonstrated repression of DevR function by DevR(N)-Kan suggests that such a knockdown approach could be useful for evaluating the activity of DevRS and other two-component signaling pathways. Further investigation is necessary to elucidate the mechanism underlying Comp1 attenuation.

Validity of case-finding tools in a national tuberculosis programme.

For case-finding under the District Tuberculosis Programme (DTP) in India, the recommended method is sputum smear microscopy of chest symptomatics attending the health institutions on their own. It is universally followed, with a slight variation in the procedure of initial screening of outpatient attendance respectively at the District Tuberculosis Centre (DTC) and at peripheral health institutions (PHI). However it may be argued that smear microscopy of all patients with chest symptoms results in a high workload in terms of positivity rate for examinations done as well as for its comparatively lower predictive value of negativity. It would be interesting in this context to estimate validity of screening and diagnosis obtained under operational conditions. The data available from some of the field surveys and from the DTP situation have been analysed for the above purpose. Examined in the context of statistical reliability of tests, the methodology of prior X-ray screening adopted by the DTC for case-finding for tuberculosis appears to be well founded. In contrast to the DTC, the need for X-ray screening at PHIs does not arise, as the procedure of patients being subjected to screening for the presence of chest symptoms has in itself a very high specificity of about 97%. The results show that X-ray and smear microscopy should not be used indiscriminately as case-finding tools in mass case-finding programmes, as their predictive values of positivity are likely to be very low at the current case prevalence rates in the community, being 2-8 per thousand.