PULMONARY TUBERCULOSIS IN HARARE, ZIMBABWE - ANALYSIS BY SPOLIGOTYPING

Background-Over the last 10 years there has been a fourfold increase i n cases of tuberculosis in Harare, Zimbabwe. The use of molecular epid emiology to understand tuberculosis transmission in this epidemic has been hampered by the availability of suitable culture facilities. A st udy was therefore undertaken to explore the potential of spoligotyping , a polymerase chain reaction based technique that does not require tu berculosis culture. Methods-Adults attending a chest clinic with clini cal or radiological pulmonary tuberculosis and one smear positive sput um were enrolled over one month. Demographic, socioeconomic, and clini cal data were gathered using a standardised questionnaire. Molecular f ingerprinting of genomic DNA recovered from sputum was performed by sp oligotyping. Results-Sixty one subjects (median age 28 years (range 18 -73); 61% men) were recruited and 57 provided adequate sputum samples. Recent rural-urban migration or immigration was not common; 40% of su bjects lived in crowded living conditions. DNA suitable for spoligotyp ing was recovered from 28 patients and 20 different genotypes of Mycob acterrium tuberculosis were identified. Fifteen patients were infected with an M tuberculosis strain shared by one or more individuals. Pati ents infected with a shared spoligotype were not closely linked geogra phically within Harare, but were more likely to live in overcrowded co nditions (69% versus 23%; odds ratio 6.85 (95% CI 1.2 to 47), p = 0.02 6). Analysis of the patients' original rural family homes revealed two geographically related spoligotype clusters. Conclusions-Spoligotypin g may yield valuable molecular typing information in populations where tuberculosis culture is not available. This novel technique requires further development and evaluation in larger epidemiological studies.