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...

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.

Background Tuberculosis remains a global health challenge, with early diagnosis key to its reduction. Face-mask sampling detects exhaled Mycobacterium tuberculosis. We aimed to investigate bacillary output from patients with pulmonary tuberculosis and to assess the potential of face-mask sampling as a diagnostic method in active casefinding. MethodsWe did a 24-h longitudinal study in patients from three hospitals in Pretoria, South Africa, with microbiologically confirmed pulmonary tuberculosis. Patients underwent 1 h of face-mask sampling eight times over a 24-h period, with contemporaneous sputum sampling. M tuberculosis was detected by quantitative PCR. We also did an active case-finding pilot study in inhabitants of an informal settlement near Pretoria. We enrolled individuals with symptoms of tuberculosis on the WHO screening questionnaire. Participants provided sputum and face-mask samples that were tested with the molecular assay Xpert MTB/RIF Ultra. Sputum-negative and face-mask-positive individuals were followed up prospectively for 20 weeks by bronchoscopy, PET-CT, and further sputum analysis to validate the diagnosis.

Upper room germicidal UV air disinfection with air mixing was highly effective in reducing tuberculosis transmission under hospital conditions. These data support using either a total fixture output (rather than electrical or UV lamp wattage) of 15-20 mW/m(3) total room volume, or an average whole-room UV irradiance (fluence rate) of 5-7 μW/cm(2), calculated by a lighting computer-assisted design program modified for UV use.

Recognition of conserved pathogen-associated molecular patterns constitutes a crucial step in the initiation of innate immune responses. We studied the contribution to the host-pathogen interaction of mycolic acid (MA), a major lipid component of the cell envelope of the macrophage intracellular pathogen Mycobacterium tuberculosis and other mycobacteria. MA administered to the peritoneal cavity or to the airways induced a unique macrophage morphotype, similar to the foamy macrophage derivatives observed in tuberculous granulomas and characterized by intracellular accumulation of neutral lipids and entry into mitosis. When assayed for production of inflammatory mediators, a conditioning rather than a direct activation of the MA-elicited foamy macrophages was observed. MA enabled production of IFN-c and myeloperoxidase, enhanced TNF-a production and suppressed IL-10 upon renewed exposure to innate triggers. Intratracheal instillation of MA mimicked additional features of the airway response to M. tuberculosis infection, namely a rapid but transient neutrophil influx and IL-6 production and a chronic IL-12 production. These MA-elicited cellular innate defenses and the accompanying formation of foamy macrophages identify for the first time the foamy macrophage morphotype as part of the host response to a pathogenassociated structure. Furthermore, these results characterize MA as a direct trigger of innate immunity, distinct from Toll-like receptor ligands.