Table 2. Characteristics of 9 syphilis patients without signs or symptoms of syphilis who had PCR detection of Treponema pallidum from oral, anal, or vaginal sites in retrospective study of men and women who visited the Melbourne Sexual Health Centre, Melbourne, Victoria, Australia, during November 2018–March 2020*.

Group by sexual practice	HIV/PrEP status	Signs on examination	Mucosal PCR sites (value if positive†)				Serologic test results		Previous serologic test results (RPR titer if reactive)	Staging of syphilis
			Oral cavity	Vagina	Anal		Current RPR titer	Previous syphilis serologic test
Woman‡	Neg	No	–	+ (31)	ND		1:8	8 y	Negative	Primary
Woman§	Neg	ND	–	+ (36)	ND		1:2	None	NA	Primary
Woman‡	Neg	No	+ (33)	ND	ND		1:128¶	None	NA	Primary
Woman‡	Neg	ND	+ (32)	+ (37)	ND		1:16	None	NA	Early latent
Bisexual man	Neg	ND	–	NA	+ (35)		Nonreactive#	8 mo	Negative	Early latent
MSM	Neg	No	–	NA	+ (26)		1:32	12 mo	Negative	Early latent
MSM	HIV	No	+ (30)	NA	–		1:256¶	10 mo	+ (1:8)	Primary
MSM	HIV	No	+ (36)	NA	–		1:128¶	10 mo	Negative	Primary
MSM	PrEP	No	+ (36)	NA	+ (32)		1:32	2 mo	Nonreactive	Primary

*MSM, men who have sex with men; NA, not applicable; ND, not done; neg, HIV-negative and not taking PrEP; PrEP, preexposure prophylaxis for HIV; RPR, rapid plasma reagin; woman, heterosexual woman; –, negative by T. pallidum PCR; +, positive by T. pallidum PCR. †Cycle threshold value of T. pallidum PCR. ‡The regular partners (of >1 year duration) had early syphilis (primary and secondary) diagnosed. §The casual partner had secondary syphilis diagnosed. ¶These 3 patients had high RPR titers with oral PCR detection. We attribute oral PCR detection to shedding after dissemination of T. pallidum on the basis of the high RPR titer, although this finding could be attributable to occult lesions in the oral cavity. #Positive T. pallidum–specific antibodies and nonreactive RPR with negative T. pallidum–specific antibodies 8 months prior.