Instituto de Innovación para la Producción Agropecuaria y el Desarrollo Sostenible (IPADS, INTA-CONICET), Balcarce, Buenos Aires, Argentina.
Instituto de Agrobiotecnología y Biología Molecular, Instituto Nacional de Tecnología Agropecuaria, Consejo Nacional de Investigaciones Científicas y Técnicas (IABIMO, INTA-CONICET), Hurlingham, Buenos Aires, Argentina.
Braz J Microbiol. 2023 Mar;54(1):459-467. doi: 10.1007/s42770-022-00892-1. Epub 2022 Dec 23.
Campylobacter fetus is a gram-negative motile bacterium, with two subspecies relevant to cattle health: C. fetus subsp. venerealis (Cfv) and C. fetus subsp. fetus (Cff). Both subspecies are associated with reproductive losses in cattle. In this study, we evaluated the identification of C. fetus for the diagnosis of bovine campylobacteriosis through bacteriological culture, direct immunofluorescence (DIF) and molecular tests in preputial smegma (PS) samples of three Angus bulls challenged with Cfv, Cfv biovar intermedius (Cfvi) or Cff, respectively, in an experiment imitating the natural infection. Two DNA extraction protocols were tested (in-house thermal extraction and commercial kit). Aspiration and scraping collection for PS were compared by conventional tests. Additionally, bacteremia was also evaluated in blood samples. Bulls were challenged by natural mating with heifers that had been experimentally infected with C. fetus subspecies; which led to infection. The Cfv- and Cfvi-bulls were positive for at least 9 months. Although Cff is not considered a venereal strain, in this study it was transmissible to bull from heifers experimentally infected, as evidenced by its colonization and persistence in the preputial cavity for 5 to 6 months. This finding suggests a potential risk of dissemination within herds. The results obtained by bacteriological culture or direct immunofluorescence (DIF) showed no significant differences, regardless the sampling device used (aspiration with Cassou pipette, metal and plastic scraper). C. fetus qPCR, on the other hand, yielded better results with an in-house DNA extraction method than with a commercial kit (75% vs 66.6%). Furthermore, qPCR diagnosis was more efficient than culture (66.6%) or DIF (56%). Bacteremia in whole blood samples was negative by qPCR and bacteriological culture in all samples. Altogether, this study demonstrated the transmission of Cff from heifers to bull and also showed that PCR-based methods are promising for the diagnosis of Bovine Genital Campylobacteriosis from clinical samples of PS.
胎儿弯曲菌是一种革兰氏阴性运动细菌，有两个亚种与牛的健康有关：C. fetus subsp. venerealis（Cfv）和 C. fetus subsp. fetus（Cff）。这两个亚种都与牛的生殖损失有关。在这项研究中，我们通过细菌培养、直接免疫荧光（DIF）和分子试验评估了胎儿弯曲菌的鉴定，用于诊断牛弯曲菌病，使用的是分别用 Cfv、Cfv 生物型中间型（Cfvi）或 Cff 感染的三头安格斯公牛的包皮垢（PS）样本，实验模拟了自然感染。测试了两种 DNA 提取方案（内部热提取和商业试剂盒）。通过传统试验比较了 PS 的抽吸和刮取采集。此外，还评估了血液样本中的菌血症。公牛通过与已感染胎儿弯曲菌亚种的实验感染小母牛自然交配而受到挑战；这导致了感染。Cfv 和 Cfvi 公牛至少阳性 9 个月。尽管 Cff 不被认为是一种性病菌株，但在本研究中，它可以从实验感染的小母牛传播给公牛，因为它在包皮腔内定植和持续存在 5 到 6 个月。这一发现表明了在牛群中传播的潜在风险。无论使用何种采样设备（用 Cassou 吸液管、金属和塑料刮刀抽吸），细菌培养或直接免疫荧光（DIF）的结果均无显著差异。另一方面，与商业试剂盒相比，内部 DNA 提取方法的 C. fetus qPCR 产生了更好的结果（75%比 66.6%）。此外，qPCR 诊断比培养（66.6%）或 DIF（56%）更有效。所有样本的全血 qPCR 和细菌培养均为阴性。总的来说，这项研究证明了 Cff 从小母牛传播给公牛，并且还表明基于 PCR 的方法有望从 PS 的临床样本中诊断牛生殖弯曲菌病。
