, 1995). Outbreaks of Mycoplasma pneumoniae among HCWs have been observed in Finland, where 44% (n = 97) of HCWs tested positive for the pathogen without detectable M. pneumoniae-specific antibody, suggesting acute infection ( Kleemola and Jokinen, 1992). Legionella has also

been described as an occupational risk factor for HCWs ( Borella et al., 2008 and Rudbeck et al., 2009). In contrast to these outbreaks, there are few prospective studies of bacterial respiratory infections or colonization and the clinical implications for HCWs. There has been Metformin recent interest in the role of medical masks and respirators in preventing respiratory infections in HCWs and the general community (MacIntyre et al., 2009, MacIntyre et al., 2011 and Macintyre

et al., 2013). Medical masks (MMs) are unfitted devices worn by an infected person, HCW, or member of the public to reduce transfer of potentially infectious body fluids between individuals. They were originally designed for surgeons in order to attenuate wound contamination, but have not been Erlotinib cell line demonstrated to have their intended efficacy (Mitchell and Hunt, 1991, Orr, 1981 and Tunevall, 1991). Of note, MMs have not been shown to clearly provide respiratory protection in the community or HCW setting (Aiello et al., 2012, Cowling et al., 2009, MacIntyre et al., 2009 and MacIntyre et al., 2011). This may be attributed to lower filtration efficiency and poorer fit than respirators which, in contrast, are specifically designed to provide respiratory protection (Balazy et al., 2006, Lawrence et al., 2006 and Weber et al., 1993). We have previously shown that a N95 respirator provides significantly better protection against clinical respiratory infection than medical masks in HCWs (MacIntyre et al., 2011 and Macintyre et al., 2013). Although our previous work tested clinical efficacy in preventing infection, the relative importance of different routes of transmission (airborne, aerosol, and direct hand-to-mouth contact) in the clinical

Parvulin efficacy of respiratory protection is unknown. That is, a mask may provide protection against more than one mode of transmission. The only bacterial infection for which respirators are considered and recommended for HCWs is tuberculosis (Chen et al., 1994 and Nicas, 1995). In this study, our aim was to determine the efficacy of respiratory protection in preventing bacterial colonization and co-infections or co-colonization in HCWs. A prospective, cluster randomized trial of N95 respirators (fit tested and non-fit tested) and medical masks compared to each other and to controls who did not routinely wear masks was conducted in frontline HCWs during the winter of 2008–2009 (December to January) in Beijing, China. The methodology and consort diagram used in the study and the primary clinical and viral infection outcomes have been previously described (MacIntyre et al., 2011).