Molecular Detection and Typing of Treponema pallidum in Non-Ocular Samples from Patients with Ocular Syphilis

• Published in: Ocular immunology and inflammation Vol. 32; no. 8; pp. 1580 - 1584
• Main Authors: Cummings, Olivia W, Durand, Marlene L, Barshak, Miriam B, Bispo, Paulo J M
• Format: Journal Article
• Language: English
• Published: England 01-10-2024
• Subjects: Adult; Aged; Bacterial Typing Techniques; DNA, Bacterial - analysis; DNA, Bacterial - genetics; Eye Infections, Bacterial - diagnosis; Eye Infections, Bacterial - microbiology; Female; Genotype; Humans; Male; Middle Aged; Molecular Typing; Polymerase Chain Reaction; Polymorphism, Restriction Fragment Length; Sequence Analysis, DNA; Syphilis - diagnosis; Syphilis - epidemiology; Syphilis - microbiology; Treponema pallidum - genetics; Treponema pallidum - isolation & purification; syphilis; strain typing; ocular syphilis; Molecular diagnostic testing
• ISSN: 0927-3948; 1744-5078; 1744-5078
• DOI: 10.1080/09273948.2023.2263086

Ocular syphilis is a rare but potentially sight-threatening manifestation of infection with the spirochete
subspecies
. Molecular strain typing of clinical specimens obtained from patients with syphilis can provide useful epidemiological and clinical information. In this study, we assess the utility of non-ocular clinical samples in strain typing for patients with diagnosed ocular syphilis.
We collected samples of excess blood, serum, and cerebrospinal fluid (CSF) from 6 patients with ocular syphilis treated in 2013-2016. DNA was extracted, purified, and then analyzed using an enhanced molecular typing method including sequence analysis of
, number of repeats in the
gene, and restriction fragment length polymorphism of the
gene.
Molecular strain typing based on
gene sequence analysis revealed two cases of type F and two cases of type G in 3 of 6 (50%) cases with CSF samples, 1 of which was obtained after starting antibiotics. In a patient with 2 distinct episodes, the same
type (type G) was identified in both episodes using different sample types (CSF, whole blood). Serum samples were available in 6 cases, but none were successfully typed with any of the methods. Amplification of the
and
genes was unsuccessful in all cases. Overall, strain types were identified in 4 of the 7 episodes.
strain types F and G were detected in CSF or whole blood in 4 of 7 episodes in this series. We demonstrate moderate sensitivity of strain typing in ocular syphilis using non-ocular clinical specimens.