Data_Sheet_1_Transmission pathways of campylobacter spp. at broiler farms and their environment in Brandenburg, Germany.docx

Broiler meat is widely known as an important source of foodborne Campylobacter jejuni and Campylobacter coli infections in humans. In this study, we thoroughly investigated transmission pathways that may contribute to possible Campylobacter 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 Campylobacter 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 Campylobacter prevalence in 51/76 pooled feces (67.1%) and 49/76 boot swabs (64.5%). Average counts between 6.4 to 8.36 log10MPN/g were detected in pooled feces. In addition, levels of 4.7 and 4.1 log10MPN/g were detected in boot swabs and litter, respectively. Samples from the barn interior showed mean Campyloacter values in swabs from drinkers 2.6 log10MPN/g, walls 2.0 log10MPN/g, troughs 1.7 log10MPN/g, boards 1.6 log10MPN/g, ventilations 0.9 log10MPN/g and 0.7 log10MPN/g for air samples. However, Campylobacter was detected only in 7/456 (1.5%) of the environmental samples (water bodies, puddles or water-filled wheel tracks; average of 0.6 log10MPN/g). Furthermore, WGS showed recurring Campylobacter genotypes over several consecutive fattening periods, indicating that Campylobacter 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 Campylobacter 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 Campylobacter transmission may originate from present environmental sources (litter and water reservoirs). However, the sources of Campylobacter transmission may vary depending on the operation and farm environmental conditions.

禽肉被广泛认为是人类食源性空肠弯曲杆菌（Campylobacter jejuni）与结肠弯曲杆菌（Campylobacter coli）感染的重要传染源。本研究针对肉鸡舍内外可能导致弯曲杆菌属（Campylobacter spp.）污染的传播途径展开了全面调查。为此，本研究采用半定量培养法开展了系统性纵向采样，以识别并定量弯曲杆菌属的传播路径与储存库。2018年4月至2020年9月期间，研究人员对勃兰登堡州的3家德国肉鸡养殖场及其周边区域进行了高密度采样。研究在夏季与冬季分别对连续的肉鸡育肥周期，以及清洁消毒后的间歇空栏期开展了系统性采样。为解析肉鸡舍与环境分离株的潜在系统发育关系，本研究开展了全基因组测序（whole genome sequencing, WGS）与生物信息学分析。本研究结果显示，在76份混合粪便样本（51/76，阳性率67.1%）与76份靴拭子样本（49/76，阳性率64.5%）中，弯曲杆菌的检出率极高。混合粪便样本中的弯曲杆菌平均含量为6.4至8.36 log₁₀最大似然数（most probable number, MPN）/克。此外，靴拭子与垫料样本中的弯曲杆菌含量分别为4.7与4.1 log₁₀MPN/克。肉鸡舍内部样本的拭子检测结果显示：饮水器拭子的弯曲杆菌平均含量为2.6 log₁₀MPN/克，墙面拭子为2.0 log₁₀MPN/克，料槽拭子为1.7 log₁₀MPN/克，木板拭子为1.6 log₁₀MPN/克，通风口拭子为0.9 log₁₀MPN/克，空气样本则为0.7 log₁₀MPN/克。但在456份环境样本（包括水体、水坑或积水轮迹；平均含量0.6 log₁₀MPN/克）中，弯曲杆菌仅在7份样本中检出，阳性率为1.5%。此外，WGS结果显示，多个连续育肥周期中均出现了相同的弯曲杆菌基因型，表明空栏期内弯曲杆菌基因型可在环境中持续存在。不过，在对肉鸡舍进行清洁消毒后，研究人员未在舍内发现潜在的传染源。值得注意的是，每个育肥周期结束后均会出现不同的弯曲杆菌基因型，这也表明污染源可能来自养殖场外围更广泛的环境。因此，本研究结果表明，弯曲杆菌传播的潜在风险可能来自当前存在的环境传染源（垫料与水体储存库）。不过，弯曲杆菌的传播源可能因养殖场的运营模式与周边环境条件而异。