Detection of a substantial rate of multidrug-resistant tuberculosis in an HIV-infected population in South Africa by active monitoring of sputum samples.

BACKGROUND

Tuberculosis (TB) coinfection with human immunodeficiency virus (HIV) is a substantial problem in South Africa. There has been a presumption that drug-resistant strains of TB are common in South Africa, but few studies have documented this impression.

METHODS

In Phidisa, a joint observational and randomized HIV treatment study for South African National Defence Force members and dependents, an initiative was launched to test subjects (by use of microbiologic TB test) who appeared to be at high risk. We report results for HIV-infected subjects.

RESULTS

TB was identified by culture in 116 (19.9%) of 584 patients selected for sputum examination on the basis of suggestive symptoms. Smear was an insensitive technique for confirming the diagnosis: only 33% of culture-positive patients were identified by smear, with a 0.2% false-positive rate. Of the 107 culture-positive individuals with susceptibility testing, 22 (20.6%) were identified to be multidrug resistant (MDR), and 4 (3.7%) were identified to be extensively drug resistant. Culture-positive cases with a history of TB treatment had more than twice the rate of MDR than those without (27.1% vs 11.9%; P = .05).

CONCLUSIONS

TB is common in this cohort of HIV-infected patients. Smear was not a sensitive technique for identifying culture-positive cases in this health system. Drug susceptibility testing is essential to proper patient management because MDR was present in 20.6% of culture-positive patients. Better management strategies are needed to reduce the development of MDR TB, because so many of these patients had received prior antituberculous therapy that was presumably not curative.