Staphylocossus aureus (S. aureus) are Grampositive spherical bacteria which appear grape-like when viewed through a microscope. S. aureus colonizes mainly in the nasal passages, but it may regularly be found in most other anatomical locales and is a leading cause of soft tissue infections. Though normally not associated Staphylocossus aureus with influenza, in the last three pandemics (1918, 1957–58, and 1969), the addition of a S. aureus infection was an important cause of increased morbidity and mortality [Todar K. http://textbookofbacteriology.net/staph.html].

The spread of S. aureas is mainly through human-to-human contact. Each year, some 500,000 patients in American hospitals contract a staphylococcal infection. Therefore, efficacy of commonly used barrier precautions in a hospital setting is of particular interest.

Bischoff and colleagues conducted a study to test the effectiveness of scrubs, gowns, and masks, on the airborne dispersal of S. aureus. During experimental sessions, healthy nasal carriers of S. aureus sitting in an airtight test chamber wearing either street clothes, surgical scrubs, surgical scrubs plus a fluid resistant gown, or the latter plus a face mask (3MTM N95 Particulate Respirator), were exposed to common cold rhinovirus serotypes [Bischoff et al. ICAAC 2006 K1676].

Infection was determined by virus isolation in nasal washes and by measurement of homotypic serum-neutralizing antibody titers on paired acute and convalescent specimens. To assess illness, eight symptoms (sneezing, runny nose, nasal obstruction, sore or scratchy throat, cough, malaise, chills, headache) were each evaluated daily by a rating scale of 0 to 4. The total symptom score was the sum of the individual symptom ratings. A cold was defined as being present if a subject had a total symptom score > 6 and a runny nose on 3 or more days and/or the subjective impression of a cold.

Based on cold symptom score, all subjects in the study developed a symptomatic cold after the rhinovirus challenge. Compared to counts in those wearing street clothes, airborne levels of S. aureus were decreased by 75% when wearing surgical scrubs, by 80% when adding a surgical gown, and by 82% when wearing a face mask (p<0.001). Male volunteers shed S. aureus twice as frequently into the air as did female volunteers. No significant alteration of the airborne spreading patterns under different clothing conditions was found. Thus, the most efficient reduction in the airborne spread of S. aureus was obtained by changing into sterilized surgical scrubs. However, even under the most effective clothing regime 0.12 CFUs/m3/min of S. aureus were spread into the environment.

Special accommodations such as isolation procedures for S. aureus carriers suffering from these conditions appear unjustified in view of the airborne dispersal of this pathogen. However, patients and staff should be encouraged to practice basic hand washing techniques, which may include antiseptic washes and shampoos and the application of topical antibiotic ointments to the anterior nares of the nose. The use of disposable aprons and gloves by staff reduces skin-to-skin contact and may therefore further reduce the risk of transmission. The spread of S. aureus is of particular concern as it has become resistant to many commonly used antibiotics [Stucki et al. Antimicrobial Agents and Chemotherapy 2006].