ObjectivesUntil recently, PCR had been used to detect but not quantify Treponema pallidum. To understand infection kinetics of this uncultivable organism, a real-time PCR assay was developed to quantify 47 kDa membrane lipoprotein gene DNA (tpp47).MethodsAssay specificity was determined against DNA from humans, skin organisms and sexually transmitted pathogens. tpp47 DNA (Nichols strain) was used to construct a standard curve for T pallidum quantification. Blood and ulcer samples were obtained from 99 patients being investigated or screened for syphilis and tpp47 was quantified.ResultsThe assay was specific, not cross-reactive with other organisms tested and sensitive, with a detection limit of a single copy of tpp47 DNA. For ulcer samples, the assay was 100% sensitive and 97.14% specific. Sensitivity fell to 34.1% for blood samples but specificity remained high (100%). tpp47 DNA was more commonly detected, and at a higher copy number, in blood of patients with secondary infection (sensitivity 57.89%) compared with primary infection. Quantity of tpp47 DNA was higher in primary infection ulcers, especially in HIV-1-positive patients, than in ulcers persisting into secondary disease.ConclusionsQuantifying T pallidum provides insight into syphilis infection kinetics: Ulcers of primary disease in HIV-1-positive patients are perhaps more infectious and the presence and load of T pallidum bacteraemia is variable, with a peak in the secondary stage. Quantitative PCR has the potential to map T pallidum infection and to highlight the impact of HIV on syphilis.

eighteen patients tested reactive with the INSTI TM POCT. Of these 91 stored serum samples were available, 12 of these were false-reactive results (as identified by the initial BIORAD test). When tested with the Determine TM POCT all 12 were non reactive. Of the 79 true reactive INSTI tests, all were reactive when tested with the Determine TM POCT.As a result of this study our clinic policy changed. All patients requesting an instant HIV test are tested using the INSTI TM POCT; all individuals with a reactive result have a laboratory HIV test sent (4th generation HIV test-BIORAD) and also have a Determine TM POCT performed. If both POCTs are reactive, patients are told that it is highly likely that this represents a true HIV-positive result; however if the Determine TM test is negative patients are informed it is likely that the INSTI TM result is a false reactive one. With either circumstance patients are made aware of the laboratory result being the definitive result. Since this policy was introduced, the second HIV POCT has correctly predicted the final laboratory result in 100% of cases. Allowing false-reactive tests to be identified at 'point of contact' makes testing low-risk populations using HIV POCT more practical by reducing 'falsepositive' associated patient anxiety.Sir: In their recent report, Coyne et al. 1 reported low rates of consistent condom use and high prevalence of sexually transmitted infections (STI) among patients attending their clinic who work in the adult entertainment industry (AEI). This mirrors our own experience, with some notable differences. We present data on AEI performers attending our clinic, including some additional information, which we hope will be of interest.We performed a retrospective case note review of AEI performers attending our designated sex worker clinics. Thirty-seven performers were identified; median age 32.6 years. Fifteen were women, 14 were heterosexual men and eight were men who have sex with men (MSM). Most were either British (78%) or Eastern European (16%). Although a small number of patients, collectively they had attended for over 400 sexual health screens.In keeping with the data presented by Coyne et al., condom use on set was uncommon, although interestingly, MSM reported higher rates of consistent use than either women or heterosexual men (25% versus 0% versus 7%, respectively). However, this was not the case with regular partners (25% versus 30% versus 33%). All MSM reported anal intercourse on set, while a lower, but significant nonetheless, proportion of heterosexuals reported this (34%).We also observed high rates of STIs (see Table 1). Chlamydia was the most frequent diagnosis, but this may be due to the higher proportion of MSM in our cohort, who exhibited higher rates of Chlamydia than the other two groups. The other notable difference is the lower rate of non-specific infections observed, although this may be because urethral smears are no longer performed on asymptomatic men attending our centre.A minority of women and heterosexual men w...