Institute of Veterinary Pathology, Vetsuisse-Faculty University Zurich, Zurich, 8057, Switzerland; Center for Clinical Studies, Vetsuisse-Faculty, University of Zurich, Zurich, 8057, Switzerland.
Institute of Veterinary Pathology, Vetsuisse-Faculty University Zurich, Zurich, 8057, Switzerland; Center for Clinical Studies, Vetsuisse-Faculty, University of Zurich, Zurich, 8057, Switzerland.
Vet Microbiol. 2021 May;256:109062. doi: 10.1016/j.vetmic.2021.109062. Epub 2021 Mar 31.
Chlamydia (C.) pecorum, an obligate intracellular bacterial species commonly found in ruminants, can also occur in pigs. However, its significance as a potential porcine pathogen, or commensal, is still unclear. In a previous study (Hoffmann et al. 2015), mixed infections of C. suis and C. pecorum were detected in 14 Swiss fattening pig farms. Using these samples, we aimed to investigate the infection dynamics of C. suis and C. pecorum mixed infections in these farms. In addition, we analyzed the genetic diversity of Swiss porcine C. pecorum strains in relation to globally circulating strains. In total, 1284 conjunctival and rectal swabs from 391 pigs, collected at the beginning and end of the fattening period, were tested during the course of this study. We determined the bacterial loads of C. suis and C. pecorum using species-specific real-time PCR (qPCR) and compared these results to already existing DNA-microarray and Chlamydiaceae qPCR data. Overall, C. suis and Chlamydiaceae copy numbers decreased in the course of the fattening period, whereas C. pecorum copy numbers increased. No association was found between clinical signs (conjunctivitis, lameness and diarrhea) and the bacterial loads. Preventive antibiotic treatment at the beginning of the fattening period significantly lowered the chlamydial load and outdoor access was associated with higher loads. Proximity to the nearest ruminants correlated with increased C. pecorum loads, indicating that C. pecorum could be transmitted from ruminants to pigs. Multi-locus sequence typing (MLST) and major outer membrane protein (ompA) genotyping revealed two novel sequence types (STs) (301, 302) and seven unique ompA genotypes (1-7) that appear to form a specific clade separate from other European C. pecorum strains.
绵羊衣原体（C.）pecorum 是一种常见于反刍动物的专性细胞内细菌物种，也可能存在于猪中。然而，其作为潜在猪病原体或共生菌的意义尚不清楚。在之前的一项研究中（Hoffmann 等人，2015 年），在 14 家瑞士育肥猪养殖场检测到猪衣原体和绵羊衣原体的混合感染。使用这些样本，我们旨在研究这些农场中猪衣原体和绵羊衣原体混合感染的感染动态。此外，我们分析了瑞士猪衣原体菌株的遗传多样性与全球流行菌株的关系。在这项研究过程中，共检测了来自 391 头猪的 1284 份结膜和直肠拭子，这些猪在育肥期开始和结束时采集。我们使用种特异性实时 PCR（qPCR）来确定猪衣原体和绵羊衣原体的细菌负荷，并将这些结果与已有的 DNA 微阵列和衣原体科 qPCR 数据进行比较。总体而言，猪衣原体和衣原体科的拷贝数在育肥期间下降，而绵羊衣原体的拷贝数增加。临床症状（结膜炎、跛行和腹泻）与细菌负荷之间没有关联。育肥期开始时的预防性抗生素治疗显著降低了衣原体的负荷，而户外活动与较高的负荷有关。与最近的反刍动物的接近程度与绵羊衣原体的负荷增加相关，表明绵羊衣原体可以从反刍动物传播给猪。多位点序列分型（MLST）和主要外膜蛋白（ompA）基因分型显示了两种新的序列类型（301、302）和七个独特的 ompA 基因型（1-7），它们似乎形成了一个与其他欧洲绵羊衣原体菌株不同的特定分支。
