Detection of Streptococcus suis in Bioaerosols of Swine Confinement Buildings

Abstract

ABSTRACTStreptococcus suisis an important swine pathogen that can cause septicemia, meningitis, and pneumonia. Also recognized as an emerging zoonotic agent, it is responsible for outbreaks of human infections in Asian countries. Serotype 2 is the predominant isolate from diseased animals and humans. The aerosolization ofS. suisin the air of swine confinement buildings (SCB) was studied. The presence ofS. suisin bioaerosols was monitored in SCB where cases of infection had been reported and in healthy SCB without reported infections. Using a quantitative-PCR (qPCR) method, we determined the total number of bacteria (1 × 108to 2 × 108airborne/m3), total number ofS. suisbacteria (4 × 105to 10 × 105airborne/m3), and number ofS. suisserotype 2 and 1/2 bacteria (1 × 103to 30 × 103airborne/m3) present in the air.S. suisserotypes 2 and 1/2 were detected in the air of all growing/finishing SCB that had documented cases ofS. suisinfection and in 50% of healthy SCB. The total number of bacteria and total numbers ofS. suisandS. suisserotype 2 and 1/2 bacteria were monitored in one positive SCB during a 5-week period, and it was shown that the aerosolizedS. suisserotypes 2 and 1/2 remain airborne for a prolonged period. When the effect of aerosolization onS. suiswas observed, the percentage of intactS. suisbacteria (showing cell membrane integrity) in the air might have been up to 13%. FinallyS. suiswas found in nasal swabs from 14 out of 21 healthy finishing-SCB workers, suggesting significant exposure to the pathogen. This report provides a better understanding of the aerosolization, prevalence, and persistence ofS. suisin SCB.