In this study, polymerase chain reaction (PCR) techniques were used to detect Treponema pallidum DNA in samples from patients with latent syphilis. Sixty-nine patients with latent syphilis and 18 with treated syphilis were included. Whole blood, plasma, sera and ear scrapings, totalling 235 samples from patients with latent syphilis, were obtained. Three PCR assays (47-PCR, polA-PCR and M-PCR assays) were performed. The 47-PCR yielded the highest number of positive samples -92/235 (39.1%), followed by M-PCR -90/235 (38.3%) and polA-PCR -73/235 (31.1%). Ear scrapings presented the highest number of positives (47/84 -56%), followed by plasma samples (36/84 -42.9%), whole blood (32/84 -38.1%) and sera (21/84 -25%). In conclusion, we have confirmed that T. pallidum can be found in blood of patients with latent syphilis. The 47-PCR technique was found to be the most sensitive, whereas ear lobe scrapings seem to be the best specimen for detection of T. pallidum DNA in latent syphilis.

The Treponema pallidum particle agglutination technique (TP.PA) was evaluated, in comparison with the Venereal Disease Research Laboratory (VDRL) test, microhemagglutination assay for Treponema pallidum antibodies (MHA-TP), and fluorescent treponemal antibody-ABS (FTA-Abs) test for the diagnosis of neurosyphilis. We have studied 198 cerebrospinal fluid (CSF) samples from patients with syphilis, including neurosyphilis, treated syphilis, and with other neurological manifestations than neurosyphilis. All tests were nonreactive in these last group of patients. In the neurosyphilis patients, sensitivity of the TP.PA was 100%. The performance of this test in CSF from patients with primary syphilis was as good as that of the other tests. In secondary and latent syphilis, the TP.PA results (27 reactive samples/73) were similar to those of the MHA-TP (25 reactive samples/73). In the individuals treated for syphilis, the TP.PA, FTA-Abs, and MHA-TP tests were found to be reactive in eight, six, and eight samples, respectively. In conclusion, it seems that the TP.PA can be used in CSF to diagnose neurosyphilis, although as for other serological tests, interpretation of results should be done in conjunction with other neurosyphilis parameters.

The objectives of this study were to evaluate the reproducibility of a molecular method for the subtyping of Treponema pallidum subsp. pallidum and to discriminate strains of this microorganism from strains from patients with syphilis. We studied 212 specimens from a total of 82 patients with different stages of syphilis (14 primary, 7 secondary and 61 latent syphilis). The specimens were distributed as follows: genital ulcers (n ‫؍‬ 9), skin and mucosal lesions (n ‫؍‬ 7), blood (n ‫؍‬ 82), plasma (n ‫؍‬ 82), and ear lobe scrapings (n ‫؍‬ 32). The samples were assayed by a PCR technique to amplify a segment of the polymerase gene I (polA). Positive samples were typed on the basis of the analysis of two variable genes, tpr and arp. Sixty-two of the 90 samples positive for polA yielded typeable Treponema pallidum DNA. All skin lesions in which T. pallidum was identified (six of six [100%]) were found to contain enough DNA for typing of the organism. It was also possible to type DNA from 7/9 (77.7%) genital ulcer samples, 13/22 (59.1%) blood samples, 20/32 (62.5%) plasma samples, and 16/21 (76.2%) ear lobe scrapings. The same subtype was identified in all samples from the same patient. Five molecular subtypes (subtypes 10a, 14a, 14c, 14f, and 14g) were identified, with the most frequently found subtype being subtype 14a and the least frequently found subtype being subtype 10a. In conclusion, the subtyping technique used in this study seems to have good reproducibility. To our knowledge, subtype 10a was identified for the first time. Further studies are needed to explain the presence of this subtype in Portugal, namely, its relationship to the Treponema pallidum strains circulating in the African countries where Portuguese is spoken.

Beyond some limitations of the study, which are discussed here, both PCR techniques seem to be useful for the diagnosis of neurosyphilis, although 47-PCR presents a higher sensitivity and polA-PCR a higher specificity.

To characterize the HIV-2 integrase gene polymorphisms and the pathways to resistance of HIV-2 patients failing a raltegravir-containing regimen, we studied 63 integrase strand transfer inhibitors (INSTI)-naïve patients, and 10 heavily pretreated patients exhibiting virological failure while receiving a salvage raltegravir-containing regimen. All patients were infected by HIV-2 group A. 61.4% of the integrase residues were conserved, including the catalytic motif residues. No INSTI-major resistance mutations were detected in the virus population from naïve patients, but two amino acids that are secondary resistance mutations to INSTIs in HIV-1 were observed. The 10 raltegravir-experienced patients exhibited resistance mutations via three main genetic pathways: N155H, Q148R, and eventually E92Q - T97A. The 155 pathway was preferentially used (7/10 patients). Other mutations associated to raltegravir resistance in HIV-1 were also observed in our HIV-2 population (V151I and D232N), along with several novel mutations previously unreported. Data retrieved from this study should help build a more robust HIV-2-specific algorithm for the genotypic interpretation of raltegravir resistance, and contribute to improve the clinical monitoring of HIV-2-infected patients.