The effect of sneezing and clothing on the airborne spread of Staphylococcus aureus.

摘要

Background. Staphylococcus aureus (SA) is among the most important pathogens in today's hospital setting.;Objective. The aims were to investigate the effects of histamine-induced sneezing and the efficacy of commonly used barrier precautions on airborne dispersal of SA in volunteers with and without experimentally induced common colds.;Design. Prospective non-randomized experiment.;Setting. Wake Forest University, Winston-Salem, NC.;Participants. 21 nasal SA carriers.;Interventions/measurements. Airborne dispersal of SA was studied in volunteers in chamber sessions using volumetric air samplers. After pre-exposure measurements (2 or 4 days), volunteers were inoculated with a rhinovirus and followed for a total of 16 days. Ten volunteers underwent daily sneezing and non-sneezing sessions, and 11 participated in the following clothing conditions: street clothes (SC), surgical scrubs (SS), surgical scrubs plus gown (SG), and the latter plus mask (SM) (N95). Daily quantitative nasal and skin cultures for bacteria and nasal cultures for rhinovirus were obtained, cold symptoms were assessed, and volunteer activities recorded during sessions.;Results. All participants developed cold symptoms. Sneezing caused a 4.71-fold increase in airborne dispersal of SA (p0.001) releasing an additional 2.83 colony forming units/m3/min SA per sneeze. The cold did not change sneezing frequency or airborne dispersal. Respiratory allergies increased the spread of SA by 3.75-fold (p0.001). Incidence risk ratios (IRR) indicated a 75% reduction of SA from SC to SS, 80% reduction from SC to SG, and 82% reduction from SC to SM (p0.001). Adding a mask was not effective in reducing SA dispersal (8% reduction, p>0.05). Male volunteers shed twice as much SA than females (IRR: 2.04, p=0.013). The cold did not alter the efficacy of barrier precautions.;Conclusion. Nasal carriers of SA expel a significant amount of SA into the air by sneezing. A cold does not affect bacterial dispersal patterns, but respiratory allergies multiply the effect of sneezing SA. Dressing in scrubs and gowns reduces the airborne dispersal of SA independent of a cold. A mask does not further reduce airborne SA. This emphasizes the need for a better understanding of the potential risk by sneezing and in the utilization of masks for prevention of SA transmission.