Rapid impact of effective treatment on transmission of multidrug-resistant tuberculosis

• Published in: The international journal of tuberculosis and lung disease Vol. 18; no. 9; pp. 1019 - 1025
• Main Authors: Dharmadhikari, A. S., Mphahlele, M., Venter, K., Stoltz, A., Mathebula, R., Masotla, T., van der Walt, M., Pagano, M., Jensen, P., Nardell, E.
• Format: Journal Article
• Language: English
• Published: Paris International Union Against Tuberculosis and Lung Disease 01.09.2014; International Union against Tuberculosis and Lung Disease
• Subjects: Adolescent; Adult; Aged; Air Microbiology; Animals; Antitubercular Agents - therapeutic use; Bacterial diseases; Biological and medical sciences; Cross Infection - diagnosis; Cross Infection - microbiology; Cross Infection - prevention & control; Cross Infection - transmission; Extensively Drug-Resistant Tuberculosis; Extensively Drug-Resistant Tuberculosis - drug therapy; Extensively Drug-Resistant Tuberculosis - microbiology; Extensively Drug-Resistant Tuberculosis - transmission; Female; Guinea Pigs; Human bacterial diseases; Humans; Impact Of Treatment; Infection Control - methods; Infectious diseases; Male; Medical sciences; Microbial Sensitivity Tests; Middle Aged; Multidrug-Resistant Tuberculosis; Mycobacterium tuberculosis; Mycobacterium tuberculosis - drug effects; Mycobacterium tuberculosis - isolation & purification; Pneumology; Retrospective Studies; Sputum - microbiology; Time Factors; Transmission; Treatment Outcome; Tuberculin Test; Tuberculosis and atypical mycobacterial infections; Tuberculosis, Multidrug-Resistant - diagnosis; Tuberculosis, Multidrug-Resistant - drug therapy; Tuberculosis, Multidrug-Resistant - microbiology; Tuberculosis, Multidrug-Resistant - transmission; Tuberculosis, Pulmonary - diagnosis; Tuberculosis, Pulmonary - drug therapy; Tuberculosis, Pulmonary - microbiology; Tuberculosis, Pulmonary - transmission; Young Adult; Treatment resistance; Respiratory disease; Transmission; multidrug-resistant tuberculosis; Mycobacterial infection; Infection; Treatment; Tuberculosis; Mycobacterium tuberculosis; impact of treatment; Mycobacteriales; Multiple resistance; extensively drug-resistant tuberculosis; Bacteriosis; Mycobacteriaceae; Bacteria; Actinomycetes
• ISSN: 1027-3719; 1815-7920; 1815-7920
• DOI: 10.5588/ijtld.13.0834

BACKGROUND: Effective treatment for drug-susceptible tuberculosis (TB) rapidly renders patients non-infectious, long before conversion of sputum acid-fast smear or culture to negative. Multidrug-resistant TB (MDR-TB) patients on treatment are currently assumed to remain infectious for months. While the resources required for prolonged hospitalization are a barrier to the scale-up of MDR-TB treatment, the safety of community treatment is clear.OBJECTIVES: To estimate the impact of treatment on infectiousness among MDR-TB patients.METHODS: A series of five human-to-guinea pig TB transmission studies was conducted to test various interventions for infection control. Guinea pigs in adjacent chambers were exposed to exhaust air from a hospital ward occupied by mostly sputum smear- and culture-positive MDR-TB patients. The guinea pigs then underwent tuberculin skin testing for infection. Only the control groups of guinea pigs from each study (no interventions used) provide the data for this analysis. The number of guinea pigs infected in each study is reported and correlated with Mycobacterium tuberculosis drug susceptibility relative to treatment.RESULTS: Despite exposure to presumably infectious MDR-TB patients, infection percentages among guinea pigs ranged from 1% to 77% in the five experiments conducted. In one experiment in which guinea pigs were exposed to 27 MDR-TB patients newly started on effective treatment for 3 months, there was minimal transmission. In four other experiments with greater transmission, guinea pigs had been exposed to patients with unsuspected extensively drug-resistant tuberculosis who were not on effective treatment.CONCLUSIONS: In this model, effective treatment appears to render MDR-TB patients rapidly non-infectious. Further prospective studies on this subject are needed.