Longitudinal Study of the Contamination of Air and of Soil Surfaces in the
Vicinity of Pig Barns by Livestock-Associated Methicillin-Resistant
Staphylococcus aureus
During 1 year, samples were taken on 4 days, one sample in each season, from
pigs, the floor, and the air inside pig barns and from the ambient air and
soil at different distances outside six commercial livestock-associated
methicillin-resistant Staphylococcus aureus (LA-MRSA)-positive pig barns in
the north and east of Germany. LA-MRSA was isolated from animals, floor, and
air samples in the barn, showing a range of airborne LA-MRSA between 6 and
3,619 CFU/m3 (median, 151 CFU/m3). Downwind of the barns, LA-MRSA was detected
in low concentrations (11 to 14 CFU/m3) at distances of 50 and 150 m; all
upwind air samples were negative. In contrast, LA-MRSA was found on soil
surfaces at distances of 50, 150, and 300 m downwind from all barns, but no
statistical differences could be observed between the proportions of positive
soil surface samples at the three different distances. Upwind of the barns,
positive soil surface samples were found only sporadically. Significantly more
positive LA-MRSA samples were found in summer than in the other seasons both
in air and soil samples upwind and downwind of the pig barns. spa typing was
used to confirm the identity of LA-MRSA types found inside and outside the
barns. The results show that there is regular airborne LA-MRSA transmission
and deposition, which are strongly influenced by wind direction and season, of
up to at least 300 m around positive pig barns. The described boot sampling
method seems suitable to characterize the contamination of the vicinity of LA-
MRSA-positive pig barns by the airborne route
