The aim of this study was to assess to what extent patients with 
meticillin-resistant Staphylococcus aureus (MRSA) at respiratory sites shed 
viable MRSA into the air of hospital rooms. We also evaluated whether the 
distance from the patient could influence the level of contamination. Air 
sampling was performed directly onto MRSA-selective agar in 24 hospital rooms 
containing patients with MRSA colonization or infection of the respiratory 
tract. Samplings were performed in duplicate at 0.5, 1 and 2-3 m from the 
patients' heads. Clinical and environmental isolates were compared using 
antimicrobial resistance patterns and pulsed-field gel electrophoresis. MRSA 
strains were isolated from 21 out of 24 rooms, in quantities varying from 
between 1 and 78 cfu/m3. In each of the 21 rooms, at least one of the 
environmental isolates was identical to a clinical isolate from the patient in 
that room. There was no significant difference in MRSA counts between the 
distance from the patient's head and the sampler. This study demonstrates that 
most patients with MRSA infection or colonisation of the respiratory tract shed 
viable MRSA into the air of their room. The results emphasise the need to study 
MRSA in air in more detail in order to improve infection control 
recommendations.