Diagnostic utility of cerebrospinal fluid studies in patients with clinically suspected tuberculous meningitis.

OBJECTIVE: To compare yields of cerebrospinal fluid (CSF) studies in the diagnosis of tuberculosis meningitis (TBM). DESIGN: Prospective laboratory study, Kenyatta National Hospital, Kenya. STUDY POPULATION: Consecutive patients with 1) headache, neck stiffness and altered consciousness for more than 14 days, 2) above features plus evidence of tuberculosis elsewhere in the body, and 3) on standard antimeningitic drugs for one week without response, were included. Those with contraindications to lumbar puncture, confirmed causes of meningitis (except TB) and on anti-tuberculosis treatment were excluded. METHODS: CSF cell counts, glucose and protein were assayed. CSF was stained on ZN, cultured on LJ and BACTEC and subjected to PCR and LCR for Mycobacterium tuberculosis DNA sequences. Positive tests for M. tuberculosis were classified as definite and the rest as probable TBM. RESULTS: Fifty-eight patients with a mean age of 33.0 years were recruited. Mean CSF cell count was 71/microl and CSF lymphocyte count up 67%. Mean CFS protein and glucose were 2.10 g/l and 2.05 mmol/l, respectively. BACTEC was positive in 20 cases, LJ 12, LCR eight, and PCR and ZN one each. Twenty-six patients had definite and 32 probable TBM. Patients with definite TBM had significantly higher CSF protein, lower CSF glucose, higher CSF cell count and lower CSF lymphocytes. CONCLUSION: TBM can be confirmed in half of clinically suspected cases. More sensitive tests for confirmation of TBM are required.

Under-diagnosis of smear-positive pulmonary tuberculosis in Nairobi, Kenya.

SETTING: Nairobi City Council Chest Clinic, Nairobi, Kenya. OBJECTIVE: To determine if under-reading of sputum smears is a contributing factor in the disproportionate increase in smear-negative tuberculosis in Nairobi, Kenya. METHODOLOGY: Between October 1997 and November 1998, patients fulfilling the local programme definition of smear-negative presumed pulmonary tuberculosis were enrolled in the study. Two further sputum specimens were collected for examination in a research laboratory by fluorescence microscopy. RESULTS: Of 163 adult subjects enrolled, 55% were seropositive for the human immunodeficiency virus type 1 (HIV-1). One hundred subjects had had two pre-study sputum smears assessed before recruitment and produced two further sputum specimens for re-examination in the research laboratory; of these 19 (19%) were sputum smear-positive on re-examination and a further seven (7%) became smear-positive on second re-examination. CONCLUSIONS: Of those patients with smear-negative presumed pulmonary tuberculosis by the local programme definition, 26% were smear-positive when reexamined carefully with two repeat sputum smears. This suggests that the high rates of smear-negative tuberculosis being seen may in part be due to under-reading. This is probably as a result of the overwhelming burden of tuberculosis leading to over rapid and inaccurate sputum examination. Retraining of existing technicians and training of more technicians is likely to reduce underreading and increase the yield of smear-positive tuberculosis. This finding also stresses the need for regular quality assurance.

Tuberculosis preventive therapy in HIV-infected persons: feasibility issues in developing countries.

There is now strong evidence from several randomized controlled trials for the efficacy of preventive therapy in the prevention of tuberculosis in tuberculin skin test positive persons infected with the human immunodeficiency virus (HIV). The World Health Organization and the International Union Against Tuberculosis and Lung Disease recommend preventive therapy for tuberculin skin test positive, HIV-infected persons who do not have active tuberculosis. While implementation of preventive therapy is manageable in industrialised countries because it is affordable and the infrastructure is in place to screen, treat and monitor patients on a regular basis, its implementation in developing countries presents several problems. Feasibility issues such as identification of large numbers of HIV-infected persons, exclusion of active tuberculosis, identification of those most likely to benefit, supervision of preventive therapy and monitoring of adverse drug reactions need to be resolved before tuberculosis preventive therapy can be introduced on a larger scale in developing countries. Possible sites for implementation of a tuberculosis preventive therapy service include voluntary counselling and testing centres for HIV and occupational health clinics for military personnel, hospital or company workers. Feasibility studies need to be carried out to address these issues in developing countries.