Rationale: Drug-resistant tuberculosis transmission in hospitals threatens staff and patient health. Surgical face masks used by patients with tuberculosis (TB) are believed to reduce transmission but have not been rigorously tested. Objectives: We sought to quantify the efficacy of surgical face masks when worn by patients with multidrug-resistant TB (MDR-TB). Methods: Over 3 months, 17 patients with pulmonary MDR-TB occupied an MDR-TB ward in South Africa and wore face masks on alternate days. Ward air was exhausted to two identical chambers, each housing 90 pathogen-free guinea pigs that breathed ward air either when patients wore surgical face masks (intervention group) or when patients did not wear masks (control group). Efficacy was based on differences in guinea pig infections in each chamber. Measurements and Main Results: Sixty-nine of 90 control guinea pigs (76.6%; 95% confidence interval [CI], 68-85%) became infected, compared with 36 of 90 intervention guinea pigs (40%; 95% CI, 31-51%), representing a 56% (95% CI, 33-70.5%) decreased risk of TB transmission when patients used masks. Conclusions: Surgical face masks on patients with MDR-TB significantly reduced transmission and offer an adjunct measure for reducing TB transmission from infectious patients.Keywords: infection control; multidrug-resistant tuberculosis; transmission; surgical maskOf an estimated 9 million new cases of tuberculosis (TB) in 2008 globally (1), 440,000 were multidrug-resistant TB (MDR-TB) (2), and more than half of those are believed to have occurred in previously untreated patients, the result of transmission of already drug-resistant strains (2). Recent reports of infection with highly drug-resistant strains of Mycobacterium tuberculosis among patients and health care workers illustrate the dire consequences of nosocomial transmission, especially in areas where HIV is endemic (3, 4). Although once believed to arise primarily from unsupervised or erratic treatment of drug-susceptible TB, MDR-TB and extensively drug-resistant TB (XDR-TB) are now known to be transmissible and have emerged as important threats to patients who enter hospitals for drug-susceptible TB (reinfection) or other illnesses, to the clinical staff caring for them, and to occupants of other congregate settings, such as correctional facilities and shelters. One study in Russia found that hospitalization, rather than treatment nonadherence, conferred a sixfold greater relative risk for the acquisition of MDR-TB by patients (5), whereas another study in Latvia revealed that previous hospitalization was a highly significant risk factor for MDR-TB (odds ratio, 18.33; P , 0.002) (6). In addition, health care workers in diverse settings have been shown to be disproportionately exposed to and infected with drugsusceptible and drug-resistant TB (4, 7). TB among health care workers erodes the already limited supply of hospital personnel in many resource-constrained settings, both directly through illness and indirectly through fear of working in such high-risk envi...
To halt the global tuberculosis epidemic, transmission must be stopped to prevent new infections and new cases. Identification of individuals with tuberculosis and prompt initiation of effective treatment to rapidly render them non-infectious is crucial to this task. However, in settings of high tuberculosis burden, active case-finding is often not implemented, resulting in long delays in diagnosis and treatment. A range of strategies to find cases and ensure prompt and correct treatment have been shown to be effective in high tuberculosis-burden settings. The population-level effect of targeted active case-finding on reducing tuberculosis incidence has been shown by studies and projected by mathematical modelling. The inclusion of targeted active case-finding in a comprehensive epidemic-control strategy for tuberculosis should contribute substantially to a decrease in tuberculosis incidence.
Summary Rationale 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. Objectives To estimate the impact of effect treatment on MDR-TB patient infectiousness. Methods 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. Measurements The number of guinea pigs infected in each study is reported and correlated with M. tuberculosis drug susceptibility relative to treatment. Main Results 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. Conclusions 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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