Rapid Impact of Effective Treatment on Transmission of Multidrug Resistant Tuberculosis
Published Date:Sep 2014
Source:Int J Tuberc Lung Dis. 18(9):1019-1025.
Pubmed Central ID:PMC4692272
Funding:R01 OH009050/OH/NIOSH CDC HHS/United States
R01OH009050/OH/NIOSH CDC HHS/United States
Effective treatment for drug susceptible tuberculosis rapidly renders patients non-infectious – long before sputum acid-fast smear or culture conversion to negative. Multidrug-resistant tuberculosis (MDR-TB) patients on treatment are currently assumed to remain infectious for months. While the resources required for prolonged hospitalization are a barrier to MDR-TB treatment scale-up, the safety of community treatment is clear.
To estimate the impact of effect treatment on MDR-TB patient infectiousness.
A series of five human-to-guinea pig tuberculosis transmission studies tested various infection control interventions. Exhaust air from a hospital ward occupied by mostly sputum smear and culture positive MDR-TB patients exposed guinea pigs in adjacent chambers. Guinea pigs were tuberculin skin tested 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 M. tuberculosis drug susceptibility relative to treatment.
Despite exposure to presumably infectious MDR-TB patients, guinea pig infection percentages ranged from 1 to 77% among the 5 experiments. In one experiment, in which 27 MDR-TB patients newly started on effective treatment exposed guinea pigs for 3 months, there was minimal transmission. In 4 other experiments with greater transmission, guinea pigs had been exposed to patients with unsuspected extensively drug resistant tuberculosis (XDR-TB) - not on effective treatment.
In this model, effective treatment appears to render MDR-TB patients rapidly non-infectious. Further prospective studies on this subject are needed.
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