Objective: To ascertain the rate of initial drug resistance and transmission patterns of Mycobacterium tuberculosis in Kampala, Uganda.
Setting: National Tuberculosis (TB) Treatment Centre, Mulago Hospital, Kampala, Uganda and Case Western Reserve University, Cleveland, Ohio, USA and McClellan Memorial Veterans Hospital, Little Rock, Arkansas, USA.
Methods: Using a radiometric BACTEC 460 TB system, susceptibility of 215 M. tuberculosis isolates from previously untreated patients from Kampala, Uganda (age range, 17-48 years, mean, 28 years; 56% males and 69% human immunodeficiency virus (HIV)-seropositive) was determined for isoniazid, rifampin, streptomycin and ethambutol. Isolates from 73 patients, selected on the basis of geographical location, were tested for strain diversity or relatedness using the IS6110 DNA fingerprinting technique.
Results: Resistance rates were as follows: isoniazid, 7.9% streptomycin, 6.1% rifampin, 1.4% and ethambutol 0.9%. Twelve per cent of the strains were resistant to at least one of the first line drugs tested and 4.7% were multiply resistant. There were no significant differences in resistance rates between patients with and without HIV infection. Using the number and size of DNA fragments containing IS6110, only three clusters of isolates with identical RFLP patterns were found out of the 73 isolates tested (8.2%). Each cluster contained two isolates. Three (4.1%) isolates had less than seven copies of IS6110.
Conclusion: This study shows that in Uganda initial drug resistance rates to anti-tuberculosis agents are low and similar to other sub-Saharan African countries and that multiple strains of M. tuberculosis have been transmitted within the community.
PIP: This study was undertaken to determine the rate of initial drug resistance and transmission patterns of Mycobacterium tuberculosis (TB) in Kampala, Uganda. Using a radiometric BACTEC 460 TB system, 215 M. tuberculosis isolates from previously untreated patients (aged 17-48 years, mean age = 28 years; 56% males and 69% HIV-seropositive) were analyzed for susceptibility to isoniazid, rifampin, streptomycin, and ethambutol. Isolates from 73 patients were examined for strain diversity or relatedness using the insertional sequence 6110 (IS6110) DNA fingerprinting technique. The study revealed the following drug resistance rates: isoniazid, 7.9%; streptomycin, 6.1%; rifampin, 1.4%; and ethambutol, 0.9%. Resistance to at least one of the first line drugs tested were developed by 12% of the strains, while 4.7% showed multiple resistance. However, no significant differences in resistance rates were found between patients with and without HIV infection. Using the number and size of DNA fragments containing IS6110, only three clusters of isolates with identical patterns were found out of the 73 isolates tested (8.2%). Each cluster contained two isolates, and three isolates had less than 7 copies of IS6110. These findings suggest that initial drug resistance to anti-tuberculosis agents in this region is low and similar to other countries in sub-Saharan Africa and that multiple strains of M. tuberculosis have been transmitted within the community.