Study tests saline as alternative to PBS for T. foetus PCR
A newly published noninferiority trial suggests 0.9% sterile saline may perform about as well as phosphate-buffered saline, or PBS, as a transport medium for Tritrichomonas foetus RT-rtPCR testing at the assay’s reported limit of detection. In the study, researchers tested 1,200 bovine preputial washing samples prepared from known negative bulls, with 300 inoculated and 300 uninoculated samples in each medium. Reported sensitivity was 70.7% for PBS and 73.3% for saline, while specificity was 99.7% for PBS and 100% for saline; the authors found no statistical difference between media, although noninferiority for sensitivity was technically inconclusive at the prespecified margin. The paper adds evidence to a practical question many field veterinarians and diagnostic labs have already been navigating as some laboratories accept saline, PBS, or other media for direct PCR workflows. (crwad.org)
Why it matters: For veterinary professionals working in bovine reproduction and regulatory testing, transport medium affects both logistics and access. PBS remains the standard in some lab guidance, including the Nebraska Veterinary Diagnostic Center’s submission requirements, but other labs already accept saline or lactated Ringer’s solution for PCR submissions, and Nevada’s animal disease lab began offering direct RT-rtPCR on samples collected in PBS or saline in February 2024. If saline is shown to be operationally equivalent in more settings, that could simplify collection in the field, reduce dependence on lab-supplied PBS tubes, and potentially lower barriers for sample submission, especially in remote or high-volume testing situations. Still, because the study evaluated performance at a very low organism concentration and did not conclusively establish noninferiority for sensitivity, veterinarians should continue following the specific collection and shipping requirements of the receiving laboratory and any state import or official-test rules. (vbms.unl.edu)
What to watch: Watch for whether diagnostic laboratories, state animal health programs, or interstate testing guidance update accepted media lists in response to these findings. (vbms.unl.edu)