Validation of Treponema pallidum haemoagglutination test compared with Treponema pallidum particle agglutination test

Treponema pallidum (T. pallidum) is the bacteria that causes syphilis, which is a sexually transmitted disease that might give the carrier a multisystemic infection. A combination of serological tests is needed to put a diagnosis of T. pallidum infection, because the bacteria cannot be cultured in vitro. Serological tests categorize intro nontreponemal test and treponemal test, which both are needed for a correct diagnosis. The principle of a nontreponemal test is the measure of antibodies directed towards lipoid antigens, whereas the principle of a treponemal test is the measure of antibodies directed towards specific T. pallidum antigens. One kind of a treponemal test that are used are treponemal antibody test which is a manual agglutination test. At Sundsvall County hospital TP-PA was used for detection of antibodies, this kit is no longer available for purchase which means that a new kit must be validated to take its place. The purpose of this study was to evaluate the possible replacing kit, TP-HA. To validate TP-HA, ten positive serum samples were analyzed and compared with the two kits. A positive kit-control were also used to confirm the results of this study. The results showed that TP-PA was more sensitive than TP-HA according to a Wilxocon ranking test (p<0.05). Because TP-PA has to be replaced due to stricter in vitro diagnostic regulation (IVD-R laws), TP-HA will be taking its place even though it differs in sensitivity. This might effect tests with a lower titre, they might give a negative result even though the test has a low concentration of antibodies which needs to be further evaluated.