Mawhinney Ian, Davis Nicky, Carson Therese, Torrens Nicholas, Wales Andrew
APHA Veterinary Investigation Centre, Rougham Hill, Bury St Edmunds, Suffolk, UK.
APHA Veterinary Investigation Centre, Rougham Hill, Bury St Edmunds, Suffolk, UK.
J Equine Vet Sci. 2022 Dec;119:104138. doi: 10.1016/j.jevs.2022.104138. Epub 2022 Oct 13.
The study examined and compared the sensitivity of culture and a quantitative PCR assay for screening equine semen for the presence of Taylorella equigenitalis (CEMO). Chilled semen samples, both raw and treated with extender, from two stallions were spiked with the organism at seven or 23 days postejaculation and prepared in serial dilutions. Culture of the 7-day raw semen readily detected CEMO at all dilutions, but extended semen yielded counts that were two log cycles lower at equivalent dilutions, with the organism being nearly undetectable at the maximal dilutions. By contrast, PCR sensitivity was not affected by extender, but for 7-day-old raw semen, PCR detection declined abruptly three log dilutions earlier than detection by culture. The more aged 23-day-old semen proved less satisfactory for spiking, with detection of CEMO by culture failing in three of the four samples due to overgrowth with commensal organisms. However, PCR performance was similar in both the 23- and 7-day spiking series. The detection limit by PCR is estimated at between 10 and 10 cfu/mL. Typical CEMO concentrations in the semen of colonized stallions are not widely reported but where natural semen contamination has been investigated, the organism was present at this order of magnitude. The reliability of detecting CEMO infection using semen samples by either method is discussed.
本研究检测并比较了培养法和定量聚合酶链反应（PCR）检测法筛查马精液中马泰勒氏菌（CEMO）的敏感性。对来自两匹种公马的冷冻精液样本（包括未稀释的原液和经稀释液处理的样本）在射精后7天或23天接种该菌，并进行系列稀释。7天龄的未稀释精液培养在所有稀释度下均能轻易检测到CEMO，但稀释精液在相同稀释度下的菌落计数低两个对数周期，在最大稀释度下几乎检测不到该菌。相比之下，PCR敏感性不受稀释液影响，但对于7天龄的未稀释精液，PCR检测比培养法早三个对数稀释度时就突然下降。23天龄的陈旧精液接种效果较差，四个样本中有三个样本因共生菌过度生长而导致培养法未能检测到CEMO。然而，在23天和7天接种系列中，PCR性能相似。PCR的检测限估计在10至10 cfu/mL之间。关于定植种公马精液中典型的CEMO浓度，报道并不广泛，但在对自然精液污染进行调查的情况下，该菌的存在数量级与此相当。本文还讨论了使用这两种方法通过精液样本检测CEMO感染的可靠性。
