Study Explores qPCR Campylobacter Monitoring in Fecal, Air Samples on Poultry Farms
A longitudinal study of commercial broiler farms has demonstrated the value of monitoring both fecal and airborne samples for Campylobacter, with targeted quantitative polymerase chain reaction (qPCR) providing the most sensitive detection method across sample types.
Published in Microbiology Research, the study investigated the occurrence and temporal dynamics of Campylobacter across three consecutive production cycles at two commercial broiler farms in Portugal. The researchers also compared culture-based methods, qPCR, and 16S rRNA gene amplicon sequencing for detecting the pathogen.
The two farms shared broiler genetics, chick sources, and comparable feeding programs but differed in historical productive performance. Farm 1 had a history of suboptimal growth performance, while Farm 2 had historically performed optimally.
Across the study, researchers collected 24 fecal and 24 air samples. Sampling during the first production cycle occurred at days 0, 7, 14, 21, 28, and 35; subsequent cycles were sampled at days 0, 14, and 35.
Campylobacter Colonization Emerged Mid-Cycle
At Farm 1, Campylobacter was consistently detected in fecal samples from day 14 onward during all three production cycles using culture and qPCR. During the first cycle, both approaches showed sustained high loads between days 21 and 35.
In contrast, no Campylobacter was detected in fecal samples from Farm 2 during its first monitored cycle by any of the three methods. In the second cycle, qPCR detected low levels at day 14, but colonization was not confirmed by both culture and qPCR until day 35. During the third cycle, fecal colonization was detected beginning at day 14, with counts increasing by day 35.
qPCR Air Monitoring Detected Campylobacter DNA
Culture-based methods did not recover Campylobacter from any air samples at either farm. In comparison, qPCR intermittently detected airborne Campylobacter DNA, sometimes before or independently of fecal detection.
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Notably, at Farm 2, qPCR detected Campylobacter DNA in air samples at day 14 of the second cycle and as early as day 0 of the third cycle. The researchers said early airborne detection suggested the possibility of environmental carryover between flocks, but stressed that qPCR cannot distinguish between viable cells, nonviable cells, or extracellular DNA. Therefore, the signals could have reflected residual DNA, contaminated dust or manure particles, bedding, or external environmental sources, among other possibilities.
qPCR was Most Sensitive, Consistent Test Method
Across both fecal and air samples, qPCR was the most sensitive and consistent detection approach. Culture provided information about viable bacterial loads in feces but showed limited sensitivity for low-biomass environmental samples. Meanwhile, microbiome sequencing detected Campylobacter less consistently and generally at low relative abundances.
Agreement between qPCR and culture for fecal samples was high. In air samples, however, agreement was low because qPCR frequently produced positive results when culture remained negative.
The researchers concluded that integrating multiple sampling matrices and detection methods could improve understanding of Campylobacter occurrence in commercial broiler production and support preharvest surveillance. They called for larger studies involving more farms and production cycles, more frequent sampling, and greater consideration of management, environmental, and antimicrobial use factors.
