A negative RPR for syphilis refers to a negative serologic test for a non-specific antigen of the syphilis spirochete, RPR specifically refers to the Rapid Plasma Reactin Ring Card Test. A negative result indicates that a person is most likely free of syphilis infection. After syphilis infection, this result can be positive and become a 1:2, 1:4, 1:8, etc. result. But this negative result is not 100% certain, because after syphilis spirochete infection, if treated, this RPR test can gradually decline from 1:16, 1:8, etc., down to a negative level. So if a syphilis patient is treated and cured, he or she can also appear to be RPR negative. At this time, the particle agglutination test for syphilis spirochetes, or TPPA, will also show a positive result, so the TPPA results should be checked further.