Cohort study of HIV-positive and HIV-negative tuberculosis, Nairobi, Kenya: comparison of bacteriological results.

We have set up a cohort of human immunodeficiency virus (HIV) positive and negative patients with tuberculosis in order to address the problems associated with HIV-related tuberculosis. We present here the results of sputum smear microscopy, culture, mycobacterial identification tests and drug susceptibility assays from specimens taken at presentation. In this selected population of largely pulmonary tuberculosis cases, HIV infection is not associated with significant differences in sputum smear positivity rate, culture positivity rate or initial drug resistance. No atypical mycobacteria were found. Direct sputum smear examination remains specific for the diagnosis of tuberculosis in Kenya in spite of the presence of HIV. HIV infection was not associated with an increase in the proportion of pulmonary cases still culture-positive at 6 months. However a significant increase in the proportion of cases still culture-positive at 6 months was seen in those with initially resistant strains and also in those treated with standard regimen (streptomycin, thiacetazone and isoniazid for 1 month followed by thiacetazone and isoniazid for 11 months, 1STH/11TH) rather than a short-course, rifampicin-containing regimen (rifampicin, pyrazinamide and isoniazid for 2 months, together with streptomycin for the first month and followed by 6 months of thiacetazone and isoniazid, SHRZ/6TH).

PIP: A study of HIV-related tuberculosis (TB) in Kenya was conducted by analyzing all cases of new suspected TB presenting from April 1989 through May 1990 at the Infectious Disease Hospital and the Ngaira Avenue Chest Clinic. There were 355 cases, 117 of whom were HIV+. No atypical mycobacteria were isolated. There were no significant differences between HIV+ and HIV-patients as to colony counts, grading of sputum smears or prevalence of drug-resistant strains initially. HIV infection was not associated with a significantly increased proportion of pulmonary TB cases still culture positive at 6 months. However, there was a significant increase in the proportion of cases still culture-positive at 6 months among those who initially had drug resistant strains and who were treated with the standard drug regimen (streptomycin, thiacetazone and isoniazid for 1 month, then thiacetazone and isoniazid for 11 months). The discussion enumerated several factors potentially effecting selection of the high proportion of pulmonary TB patients in this series. Direct sputum smear remains specific for diagnosis of TB in Kenya in spite of HIV. These results still suggest that HIV+ pulmonary TB responds well to standard anti-TB therapy.

Cross-sectional survey of HIV infection among patients with tuberculosis in Nairobi, Kenya.

Evidence from many countries suggests an association of human immunodeficiency virus (HIV) infection and tuberculosis of major public health significance. In order to begin assessing the impact of HIV on tuberculosis in Kenya, we have determined the HIV-1 seroprevalence among tuberculosis patients and compared the clinical characteristics of tuberculosis in HIV-positive and HIV-negative patients in two cross-sectional studies at the Infectious Disease Hospital (IDH) and the Ngaira Avenue Chest Clinic (NACC), Nairobi, Kenya. The diagnosis in 92% of all patients with pulmonary tuberculosis was confirmed by culture. The remainder were diagnosed on histological, clinical or radiological grounds. HIV seroprevalence among tuberculosis patients at IDH was 26.5% (52/196) compared to 9.2% (18/195) at NACC (P less than 0.001). There was no association between numbers of streptomycin injections in the previous 5 years and HIV infection. Positive sputum smear rates in HIV-positive patients were slightly lower than in HIV-negative patients at both study sites (71% vs 83% at IDH and 73% vs 82% at NACC) but the difference was not significant. Only Mycobacterium tuberculosis was isolated. Miliary disease was not associated with HIV infection. Persistent diarrhoea, oral candidiasis, generalized itchy rash, herpes zoster and generalized lymphadenopathy were all associated with HIV infection, but 46% (95% CI:38-54%) of all HIV-positive patients had none of the clinical features listed in the WHO Clinical Criteria for the Diagnosis of AIDS, apart from fever, cough and weight loss. Stevens-Johnson Syndrome was reported in 7/52 (13%) patients with HIV infection, and in 4/144 (3%) patients without (RR 4.85, 95% CI: 1.45-15.88).(ABSTRACT TRUNCATED AT 250 WORDS)

Quality control in the laboratory diagnosis of tuberculosis.

The study was conducted in 4 hospital laboratories to assess the value of smear re-examination, duplicate smear and culture in quality control in the diagnosis of pulmonary tuberculosis. In each hospital 1 to 3 sputum specimens were collected from each suspect and examined by the Ziehl-Neelsen method. Smears along with corresponding specimens were sent to the reference laboratory for re-examination and examination of fresh duplicate smears and culture. A total of 994 specimens plus 23 known negative and 23 known positive controls were analysed. For each assessment method, both over-diagnosis and underdiagnosis were indicated with under-diagnosis being a more common problem in the four hospital laboratories. The limitations of these assessment methods are presented.