High yield of culture-based diagnosis in a TB-endemic setting

BACKGROUND: In most of the world, microbiologic diagnosis of tuberculosis (TB) is limited to microscopy. Recent guidelines recommend culture-based diagnosis where feasible. METHODS: In order to evaluate the relative and absolute incremental diagnostic yield of culture-based diagnosis in a high-incidence community in Cape Town, South Africa, subjects evaluated for suspected TB had their samples processed for microscopy and culture over a 21 month period. RESULTS: For 2537 suspect episodes with 2 smears and 2 cultures done, 20.0% (508) had at least one positive smear and 29.9% (760) had at least one positive culture. One culture yielded 1.8 times more cases as 1 smear (relative yield), or an increase of 12.0% (absolute yield). Based on the latter value, the number of cultures needed to diagnose (NND) one extra case of TB was 8, compared to 19 if second specimens were submitted for microscopy. CONCLUSION: In a high-burden setting, the introduction of culture can markedly increase TB diagnosis over microscopy. The concept of number needed to diagnose can help in comparing incremental yield of diagnosis methods. Although new promising diagnostic molecular methods are being implemented, TB culture is still the gold standard

Screening of patients with diabetes mellitus for tuberculosis in India.

OBJECTIVE: To assess the feasibility, results and challenges of screening patients with diabetes mellitus (DM) for tuberculosis (TB) within the healthcare setting of six DM clinics in tertiary hospitals across India. METHOD: Agreement on how to screen, monitor and record the screening was reached in October 2011 at a national stakeholders' meeting, and training was carried out for staff in the six tertiary care facilities in December 2011. Implementation started in the first quarter of 2012, and we report on activities up to 30th September 2012. Patients with DM were screened for TB on each clinic attendance using a symptom-based enquiry, and those with positive symptoms were referred for TB investigations. RESULTS: In the three quarters, 26% of 7218, 52% of 12237 and 48% of 11691 patients with DM were screened for TB. A total of 254 patients were identified with TB, of whom 46% had smear-positive pulmonary disease. There were 18 patients newly diagnosed with TB as a result of screening and referral, with the remainder being patients already diagnosed from elsewhere. TB case rates per 100,000 patients attending the DM clinic each quarter were 859, 956 and 642. Almost 90% of patients with TB were recorded as starting or being on anti-TB treatment. Major implementation challenges related to human resources and recording systems. CONCLUSION: In India, it is feasible to screen patients with DM for TB resulting in high rates of TB detection. More attention to detail, human resource requirements and electronic medical records are needed to improve performance