BACTERIAL AND FUNGAL FLORA OF DUST DEPOSITS IN A PIG BUILDING

Objectives-The purpose of the study was to investigate the bacterial a nd fungal flora of dust deposits in a newly built pig grower finisher building. Viable bacterial counts and microbial species found in a bar n which had never housed pigs were compared with those in a barn housi ng 144 pigs. Methods-The quantitative streak plate method was used to measure viable bacterial counts on nutrient agar or sheep blood agar. Viable bacterial counts of the dust deposits were expressed as the num ber of colony forming units (CFUs)/mg of dust. Gram positive cocci and Gram negative bacilli were identified by an automated system. Identif ications with a confidence interval > 90% were accepted at the species level. Fungi were identified to the genus level with slide culture pr eparations on cereal agar. Results-The lowest viable bacterial count ( 4.8 x 10(4)/mg of dust) was found in the barn with no pigs. In the bar n with pigs the highest viable bacterial count (2.1 x 10(4)/mg of dust ) was in dust from the top of a partition close to gig activity. Six s pecies of bacteria or fungi were found in dust from the room with no p igs, whereas 22 different microorganisms were detected in dust from th e room with pigs. With the exception of Enterobacter agglomerans no ot her species of the family Enterobacteriaceae was found in dust deposit s in this new pig building. Twelve species of Gram positive bacteria w ere found in the room housing pigs. Conclusions-The pig is not only a source but also a disperser of airborne bacteria in pig buildings. Spe ciation of the microbial flora in dust from the pig building suggests that many of the microorganisms were either of human or environmental origin. Nevertheless as some of these microorganisms are known opportu nistic pathogens or allergens and because of the documented increased incidence of chronic respiratory symptoms in pig workers, precautions to reduce inhalation of microbial or dust particles by pig workers see m prudent.