Secondary Syphilis in Cali, Colombia: New Concepts in Disease Pathogenesis

Abstract

Venereal syphilis is a multi-stage, sexually transmitted disease caused by the spirochetal bacterium Treponema pallidum (Tp). Herein we describe a cohort of 57 patients (age 18–68 years) with secondary syphilis (SS) identified through a network of public sector primary health care providers in Cali, Colombia. To be eligible for participation, study subjects were required to have cutaneous lesions consistent with SS, a reactive Rapid Plasma Reagin test (RPR-titer ≥1∶4), and a confirmatory treponemal test (Fluorescent Treponemal Antibody Absorption test- FTA-ABS). Most subjects enrolled were women (64.9%), predominantly Afro-Colombian (38.6%) or mestizo (56.1%), and all were of low socio-economic status. Three (5.3%) subjects were newly diagnosed with HIV infection at study entry. The duration of signs and symptoms in most patients (53.6%) was less than 30 days; however, some patients reported being symptomatic for several months (range 5–240 days). The typical palmar and plantar exanthem of SS was the most common dermal manifestation (63%), followed by diffuse hypo- or hyperpigmented macules and papules on the trunk, abdomen and extremities. Three patients had patchy alopecia. Whole blood (WB) samples and punch biopsy material from a subset of SS patients were assayed for the presence of Tp DNA polymerase I gene (polA) target by real-time qualitative and quantitative PCR methods. Twelve (46%) of the 26 WB samples studied had quantifiable Tp DNA (ranging between 194.9 and 1954.2 Tp polA copies/ml blood) and seven (64%) were positive when WB DNA was extracted within 24 hours of collection. Tp DNA was also present in 8/12 (66%) skin biopsies available for testing. Strain typing analysis was attempted in all skin and WB samples with detectable Tp DNA. Using arp repeat size analysis and tpr RFLP patterns four different strain types were identified (14d, 16d, 13d and 22a). None of the WB samples had sufficient DNA for typing. The clinical and microbiologic observations presented herein, together with recent Cali syphilis seroprevalence data, provide additional evidence that venereal syphilis is highly endemic in this region of Colombia, thus underscoring the need for health care providers in the region to be acutely aware of the clinical manifestations of SS. This study also provides, for the first time, quantitative evidence that a significant proportion of untreated SS patients have substantial numbers of circulating spirochetes. How Tp is able to persist in the blood and skin of SS patients, despite the known presence of circulating treponemal opsonizing antibodies and the robust pro-inflammatory cellular immune responses characteristic of this stage of the disease, is not fully understood and requires further study.

Evaluation of a PCR Test for Detection of Treponema pallidum in Swabs and Blood

“…Our results suggest that the use of the whole-blood fraction would be more effective for the detection of T. pallidum in cases of secondary syphilis (38%), although the results for this fraction were not significantly different from those for the PBMC fraction (31%). Previous studies on rabbit models of syphilis infection reported that whole blood was the best sample for spirochete detection (36) and that T. pallidum was detected in 46% of the whole-blood samples obtained from 57 patients with secondary syphilis (9). This difference in sensitivity may result from the use of a different target gene (tpp47 versus polA) and the conditions in which whole blood was stored, as it has been shown that the freezing of samples may affect sensitivity (9).…”

“…However, DFM is highly operator dependent and cannot be used for blood or for oral chancres, as it can give false-positive results due to the presence of saprophytic spirochetes in the oral cavity. New detection strategies have been developed during the last 15 years that are based on advances in our knowledge of the sequence of the T. pallidum genome (13 (2,3,6,15,17,18,23,30,31,32,34,39), and others, such as polA, being involved in genome duplication (9,27,28,35). Recent comparisons of the results for the detection of T. pallidum DNA obtained by the amplification of the tpp47, bmp, polA, and 23S rRNA genes showed that these tests give concordant results (29).…”

A Homology Model Reveals Novel Structural Features and an Immunodominant Surface Loop/Opsonic Target in the Treponema pallidum BamA Ortholog TP_0326

“…MT35060CI). Deidentified, banked sera from HIV-negative patients with secondary syphilis were from two distinct geographic sources: (i) Dallas, TX (approved for use by the Institutional Review Board of the University of Connecticut Health Center [UCHC]), and (ii) Cali, Colombia, collected after we obtained informed consent under protocols approved by the human subject boards at the Connecticut Children's Medical Center (CCMC), UCHC, and the CIDEIM (43,44).…”

“…After obtaining informed consent, we took two punch biopsy specimens from the affected skin of two different patients with untreated secondary syphilis (designated Cali-77 and Cali-84) seen at our Cali, Colombia, study site (43,44) according to protocols approved by the human subject boards at CCMC, UCHC, and CIDEIM (43,44). DNA was extracted using the QIAamp DNA minikit (Qiagen) according to procedures recommended by the manufacturer, eluted in 100 l of elution buffer at 70°C, and stored at Ϫ80°C.…”

Syphilis: using modern approaches to understand an old disease

“…T. pallidum can be identified by PCR in the bloodstream of patients with all stages of syphilis, and the quantity of treponemes in blood is highest during early syphilis (2,3). Individuals with lesions of early syphilis are most likely to transmit T. pallidum.…”