Detection of airborne Campylobacter with three bioaerosol samplers for alarming bacteria transmission in broilers.

In an airborne transmission experiment, Campylobacter in the air was sampled by three types of bioaerosol samplers (all-glass impinger AGI-30, Andersen six-stage impactor, and OMNI-3000) in four broiler rooms. In each room, five 14-day- old broilers inoculated with Campylobacter jejuni were kept in a central cage located in the middle of the room. Another ten broilers, as susceptible animals, were kept individually in ten cages surrounding the central cage at a distance of approximately 75 cm. Air samples were taken on eight days: the day before inoculation (BI) as a negative control, and 1, 3, 6, 9, 14, 21, and 29 days post-inoculation (PI). Presence of C. jejuni was investigated with the culture method for culturable bacteria and with the PCR test for bacterial DNA. Results showed that Campylobacter infection of susceptible broilers occurred in all four rooms; however, no culturable C. jejuni could be detected in any of the air samples. This might have been the result of the low number of broilers in the room and the unfavorable conditions for Campylobacter survival, leading to Campylobacter concentrations below the detection limits of the bioaerosol samplers. The PCR test showed that DNA of C. jejuni was detected in the air samples on the first day PI, but no bacterial DNA was detected on the following days. It is concluded that the three samplers used in this study are not able to alarm Campylobacter outbreaks through an airborne route when low bacterial concentrations are present. Developments of new sampling techniques with low detection limits are required for biosecurity assessment.