Detection of naturally aerosolized Actinobacillus pleuropneumoniae on pig farms by cyclonic air sampling and qPCR.

• Microbiological sampling of air in piggeries was optimized. • A method for detecting A. pleuropneumoniae by qPCR in air samples was developed. • Naturally aerosolised A. pleuropneumoniae was detected on a commercial farm. Respiratory infections caused by Actinobacillus pleuropneumoniae have a large impact on commercial pig farms globally. As current vaccines have limited efficacy, animal care and air hygiene are critical for disease control. Here we used a Coriolis μ cyclonic air sampler and an A. pleuropneumoniae -specific apxIV gene qPCR assay to detect the organism. Air samples were collected into a liquid medium by the Coriolis μ sampler for A. pleuropneumoniae detection by plate culture and qPCR assay. The method was validated by comparing the Coriolis μ sampler and a plate impactor (Millipore Air-T) in a specially designed aerosolization chamber. Two commercial farms, housing pigs between 3 and 21 weeks of age, were tested. On one farm, A. pleuropneumoniae was detected in low numbers (1000 organisms/m3 air) by qPCR, but not by culture, from sheds containing 8, 12, 16, and 18 weeks-old pigs. To our knowledge this is the first successful detection of naturally aerosolised A. pleuropneumoniae in commercial farms with the Coriolis μ air sampler, potentially allowing the identification of sub-clinically infected populations of pigs in the field. [ABSTRACT FROM AUTHOR]