Surgical Face Masks Worn by Patients with Multidrug-Resistant Tuberculosis

Abstract

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...

The epidemiology, pathogenesis, transmission, diagnosis, and management of multidrug-resistant, extensively drug-resistant, and incurable tuberculosis

“…The original Riley study 466 found that the 98% reduction in infectiousness from patients with drug-susceptible tuberculosis occurred almost immediately, since treatment was started only on hospital admission, not 2 weeks before. Since then, in South Africa, Dharmadhikari and colleagues 467 found transmission only from patients with unsuspected XDR tuberculosis who were inadequately treated with MDR drugs rather than those The Lancet Respiratory Medicine Commission patients that received effective treatment. In their study, more than a hundred patients with MDR tuberculosis just started on effective therapy were exposed to hundreds of sentinel guineapigs.…”

“…Surgical masks on patients were shown to be about 50% effective in preventing transmission of tuberculosis from people to guineapigs. 467 This risk reduction is equivalent to doubling the building ventilation, so is neither insignificant, nor completely effective.…”

Transmission and Institutional Infection Control of Tuberculosis

“…During a 4-yr period, for example, Riley estimated an average concentration of infectious quanta of 1 in 11,000 cf (311 m 3 ) and also calculated that this extremely low average concentration was sufficient to explain the rates of transmission to student nurses in hospitals during the prechemotherapy era (Riley 1957;Riley et al 1962). This same approach, using guinea pigs to quantify infectious quanta, has been used to measure the impact of such interventions as ultraviolet air disinfection, electrostatic precipitators, surgical masks on patients, and, most importantly, effective treatment as discussed below (Escombe et al 2009;Dharmadhikari et al 2012Dharmadhikari et al , 2014.…”

“…More details on respirator use and fit testing are available on line (http:// www.cdc.gov/niosh/npptl/topics/respirators/ disp_part/) (Coffey et al 2002). Surgical masks are sometimes recommended for patients who cannot cover their coughs or sneezes, they are less expensive in one study; however, they provided only a 53% reduction in infectious cough aerosol (Dharmadhikari et al 2012). This is not insignificant, the equivalent reduction to doubling room ventilation, but it does not assure that transmission will not occur.…”

Infection control in households of drug-resistant tuberculosis patients co-infected with HIV in Mumbai, India

“…2 TB infection control (IC) measures aimed at reducing the risk of TB transmission are well recognised. 3,4 Although a number of initiatives have been adopted for IC in health care settings, [5][6][7][8] limited work has been done to reduce the risk in patients' households. 9 Similar to the situation seen in health care workers in direct contact with TB patients attending health care facilities, 10 the incidence of active TB disease among household contacts of TB patients also exceeds that reported in the general population.…”