Contact investigations as a means of detection and timely treatment of persons with infectious multidrug-resistant tuberculosis

SETTING: Two regions of metropolitan Lima, Peru. OBJECTIVE: To determine the outcomes of two contact investigation strategies used in therapy enrollment cohorts of patients with multidrug-resistant tuberculosis (MDR-TB). DESIGN: From 28 August 1996 to 31 December 1999, 91 index patients received individualized MDR-TB therapy (Group A), and from 1 October 1997 to 31 December 1999, another 101 index patients received a standardized MDR-TB regimen (Group B). We conducted a retrospective chart review and home visits to identify secondary cases among close contacts of both of these groups. Group A secondary cases with MDR-TB received therapy based on the drug susceptibility profile of their infecting strain, while Group B secondary cases received standard short-course therapy. RESULTS: Among 945 close contacts, 72 secondary TB cases (8%) were found. Of 42 who had drug-susceptibility testing, 35 (84 %) were MDR-TB, but only seven (17 %) had the same drug susceptibility profile as the index case. Cure exceeded 80% in Group A secondary cases, while only half of Group B secondary cases were cured (RR 1.6, 95% CI 1.1-2.2). CONCLUSION: Contact investigation protocols coupled with enrollment in MDR-TB therapy are a useful means of detecting and promptly treating persons with infectious MDR-TB. In settings with endemic MDR strains of Mycobacterium tuberculosis, effective therapy of contacts of MDR-TB patients requires knowledge of drug susceptibility for each contact with active disease.