AUTHOR=Reichelt Benjamin , Szott Vanessa , Epping Lennard , Semmler Torsten , Merle Roswitha , Roesler Uwe , Friese Anika 

TITLE=Transmission pathways of campylobacter spp. at broiler farms and their environment in Brandenburg, Germany

JOURNAL=Frontiers in Microbiology

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2022.982693

DOI=10.3389/fmicb.2022.982693

ISSN=1664-302X

ABSTRACT=<p>Broiler meat is widely known as an important source of foodborne <italic>Campylobacter jejuni and Campylobacter coli</italic> infections in humans. In this study, we thoroughly investigated transmission pathways that may contribute to possible <italic>Campylobacter</italic> contamination inside and outside broiler houses. For this purpose we carried out a comprehensive longitudinal sampling approach, using a semi-quantitative cultivation method to identify and quantify transmissions and reservoirs of <italic>Campylobacter</italic> spp.. Three german broiler farms in Brandenburg and their surrounding areas were intensively sampled, from April 2018 until September 2020. Consecutive fattening cycles and intervening downtimes after cleaning and disinfection were systematically sampled in summer and winter. To display the potential phylogeny of barn and environmental isolates, whole genome sequencing (WGS) and bioinformatic analyses were performed. Results obtained in this study showed very high <italic>Campylobacter</italic> prevalence in 51/76 pooled feces (67.1%) and 49/76 boot swabs (64.5%). Average counts between 6.4 to 8.36 log<sub>10</sub>MPN/g were detected in pooled feces. In addition, levels of 4.7 and 4.1 log<sub>10</sub>MPN/g were detected in boot swabs and litter, respectively. Samples from the barn interior showed mean <italic>Campyloacter</italic> values in swabs from drinkers 2.6 log<sub>10</sub>MPN/g, walls 2.0 log<sub>10</sub>MPN/g, troughs 1.7 log<sub>10</sub>MPN/g, boards 1.6 log<sub>10</sub>MPN/g, ventilations 0.9 log<sub>10</sub>MPN/g and 0.7 log<sub>10</sub>MPN/g for air samples. However, <italic>Campylobacter</italic> was detected only in 7/456 (1.5%) of the environmental samples (water bodies, puddles or water-filled wheel tracks; average of 0.6 log<sub>10</sub>MPN/g). Furthermore, WGS showed recurring <italic>Campylobacter</italic> genotypes over several consecutive fattening periods, indicating that <italic>Campylobacter</italic> genotypes persist in the environment during downtime periods. However, after cleaning and disinfection of the barns, we were unable to identify potential sources in the broiler houses. Interestingly, alternating <italic>Campylobacter</italic> genotypes were observed after each fattening period, also indicating sources of contamination from the wider environment outside the farm. Therefore, the results of this study suggest that a potential risk of <italic>Campylobacter</italic> transmission may originate from present environmental sources (litter and water reservoirs). However, the sources of <italic>Campylobacter</italic> transmission may vary depending on the operation and farm environmental conditions.</p>