1. Centre for Tuberculosis, National Institute of Communicable Diseases, Johannesburg, South Africa
2. Department of Medical Microbiology, Faculty of Health Science, University of Free State, Bloemfontein, South Africa
3. DuPont Nutrition and Health, Geneva, Switzerland
4. Public Health Research Institute, Rutgers University, Newark, New Jersey, USA
5. Department of Medical Microbiology, Faculty of Health Science, University of Pretoria, Pretoria, South Africa