Treponema pallidum Immunohistochemistry is positive in human intestinal Spirochetosis

Abstract

Background: Human intestinal spirochetosis (IS) has been recognized for decades, but whether it represents commensalism or a pathogenic process remains controversial. IS is diagnosed on routine stains with confirmation by silver stains but these stains are labor intensive and slow to read. We evaluated the Treponema pallidum immunostain as a diagnostic adjunct for IS. Methods: We retrieved biopsies from 33 patients with IS for this study. Each case was tested by Warthin-Starry (WS) and T. pallidum immunohistochemistry (IHC). Species specific genotyping was performed in 3 cases. Results: Patients with IS ranged from 22 to 82 years without gender predilection. IS involved normal (n = 15), and inflamed (n = 5) mucosa and colonic polyps (n = 13). Warthin-Starry and T. pallidum IHC were positive in all cases including both species of Brachyspira. Six (18%) symptomatic patients were treated for IS, and experienced resolution. In patients diagnosed with incidental IS on cancer screening (n = 5), follow up biopsies, without therapy, were negative for IS. T. pallidum IHC required 75 min less hands-on time than WS for performance and was faster to interpret. Conclusions: T. pallidum IHC can be used to confirm the diagnosis of IS and is easier to perform and faster to interpret than WS.

The challenging diagnosis of overlapping oral primary/secondary syphilis with nonreactive serology

“…Specific tests like PCR and IHC are useful supplementary diagnostic tools, PCR test increases the sensitivity of the diagnosis of primary syphilis during the window period, 10 and IHC has shown to be a test with high sensitivity. 35,36 The strength of the present case lies in the clinical, histopathological, and serological findings, which evidence the overlap between the primary stage and secondary stage of oral syphilis in PLWH. Considering the increasing incidence of syphilis/HIV coinfection worldwide, particularly in men who have sex with men, these data could alert clinicians about the possibility of diagnosing syphilis infection, even in patients with negative serology, as well, as a contribute to improving early diagnosis, treatment, and disease management.…”

“…This case illustrates that, in the absence of serological evidence, the diagnosis of oral syphilis in HIV infection could be a challenge. Specific tests like PCR and IHC are useful supplementary diagnostic tools, PCR test increases the sensitivity of the diagnosis of primary syphilis during the window period, 10 and IHC has shown to be a test with high sensitivity 35,36 …”

Laboratory Diagnostic Tools for Syphilis: Current Status and Future Prospects

“…When serologic assays failed to detect T. pallidum antibodies, IHC is a useful complementary diagnostic tool. However, T. pallidum can cross-react with other spirochetes, including Borrelia burgdorferi and the intestinal spirochetes ( Graham et al., 2018 ). Table 2 is a summary of the direct detection tests used for syphilis diagnosis.…”

Infectious diseases of the upper gastrointestinal tract

“…50 The immunostains also reportedly cross-react with other types of spirochaete. 51 PCR-based assays are also available and are more sensitive. 52 In many cases, correlation with serological studies is necessary to confirm the diagnosis.…”

“…T. pallidum immunohistochemistry is useful to confirm the diagnosis, but stains are frequently negative, even in infected individuals 50 . The immunostains also reportedly cross‐react with other types of spirochaete 51 . PCR‐based assays are also available and are more sensitive 52 .…”