Pulmonary tuberculosis in Harare, Zimbabwe: analysis by spoligotyping
- R S Heydermana,
- M Goyalc,
- P Roberts,
- S Ushewokunzea,
- S Zizhoua,
- B G Marshallc,
- Robert Makombed,
- J D A Van Embdene,
- P R Masonb,
- R J Shawc
- aDepartment of Medicine, bDepartment of Medical Laboratory Technology, cMedical School, University of Zimbabwe, Zimbabwe Department of Respiratory Medicine, National Heart and Lung Institute, Imperial College School of Medicine, London, UK, dHealth Services, City of Harare, Zimbabwe, eDepartment of Bacteriology, Research Laboratory for Infectious Diseases, National Institute of Public Health and the Environment, Bilthoven, The Netherlands
- Dr R S Heyderman, Department of Infection and Tropical Medicine, Imperial College School of Medicine, Northwick Park Hospital, Harrow, Middlesex HA1 3UJ, UK.
- Received 7 April 1997
- Revision requested 17 June 1997
- Revised 17 September 1997
- Accepted 5 November 1997
Abstract
BACKGROUND Over the last 10 years there has been a fourfold increase in cases of tuberculosis in Harare, Zimbabwe. The use of molecular epidemiology to understand tuberculosis transmission in this epidemic has been hampered by the availability of suitable culture facilities. A study was therefore undertaken to explore the potential of spoligotyping, a polymerase chain reaction based technique that does not require tuberculosis culture.
METHODS Adults attending a chest clinic with clinical or radiological pulmonary tuberculosis and one smear positive sputum were enrolled over one month. Demographic, socioeconomic, and clinical data were gathered using a standardised questionnaire. Molecular fingerprinting of genomic DNA recovered from sputum was performed by spoligotyping.
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 subjects lived in crowded living conditions. DNA suitable for spoligotyping was recovered from 28 patients and 20 different genotypes of Mycobacterium tuberculosis were identified. Fifteen patients were infected with an M tuberculosis strain shared by one or more individuals. Patients infected with a shared spoligotype were not closely linked geographically within Harare, but were more likely to live in overcrowded conditions (69% versus 23%; odds ratio 6.85 (95% CI 1.2 to 47), p = 0.026). Analysis of the patients’ original rural family homes revealed two geographically related spoligotype clusters.
CONCLUSIONS Spoligotyping 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.
