Syphilis: Treponema pallidum infection

Causative agent: spirochete Treponema pallidum. Extremely fastidious, and fragile; sensitive to disinfectant, heat, and drying. Treponema pallidum is a chemoheterotrophic, secretes the enzyme hyaluronidase. Transmission: sexual, blood transfusion, transplacental.

Pathogenesis and tissue damage: Stages of syphilis: Primary stage: after 3 weeks of incubation. Secondary stage. Latent stage. Tertiary stage (complications). Congenital.

Primary syphilis: The bacterium enters the body through a break in the skin, or by penetrating the mucous membranes of the genitalia. Tissue destruction in primary syphilis: The microbial virulence: Microbial hyaluronidase destroy the polysaccharide (hyaluronic acid; glycosaminoglycan) that holds host cells together in the extracellular matrix. The cellular immune defenses: (Neutrophils, lymphocytes, and macrophage) against replicating Treponema and tissues. This results in an ulcer formation (chancer).

N After three weeks of inoculation, syphilitic chancre appears on the site of entry (usually the genitalia). Chancre is a single, painless, non-itchy skin ulcer with a clean base and sharp borders between 0.3 and 3.0 cm in size. Chancre heals spontaneously within 3-6 weeks but the microbe continues to spread via the lymph and blood in asymptomatic period lasting 2- 24 weeks.

Red-maculopapular rash on almost any part of the body. Secondary Syphilis: Characterized by: Red-maculopapular rash on almost any part of the body. Condylomata lata: Wart like lesions on the anogenital region. Hepatitis, glomerulonephritis and meningitis. Secondary syphilis resolve within weeks to months. (A macule is a change in skin color, without elevation or depression. A papule is a circular, solid elevation of skin with no fluid)

moth-eaten alopecia

Latent syphilis stage : In two-thirds of individuals who acquire syphilis. After healing of secondary syphilis, the microbe enters a latency period that can last 3-30 years. In one-half of this group, tertiary syphilis is established. Asymptomatic period but serologic tests show positive results. N

Occur three to 15 years after the initial infection. Tertiary syphilis: Occur three to 15 years after the initial infection. Divided into three different forms: Gummatous syphilis: granulomatous lesions in the liver, skin, and bones (15%). Neurosyphilis (6.5%): infection of the brain parenchyma and dorsal column of spinal cord. Cardiovascular syphilis (10%): Vasculitis and aortic valve insufficiency. N

Dilatation of the aorta

Congenital syphilis is associated with: The microbe can be transmitted to the fetus from infected mother (transplacentally) after the first ten to fifteen weeks of pregnancy. Congenital syphilis is associated with: Intrauterine growth retardation. Hepatosplenomegaly. CNS infection: hydrocephalus, optic atrophy, and seizures. Mucocutaneous lesions. lymphadenopathy. Appropriate treatment of early congenital syphilis within the first three months of life prevents some, but not all, of the late manifestations of congenital syphilis

Saber shins Hutchinson teeth Saddle nose Saber shins= curved sowrd

Diagnosis of Syphilis: Clinical specimens: Exudate (pus), tissue biopsy, and serum specimens. Direct: Microscopy in microbiology laboratory and histopathology laboratory. Culture: animal inoculation. Indirect: Serology: specific and non specific tests.

In Microbiology Lab: A- Dark field microscopy: Rotary corkscrew-like motility with 90˚ angulation. B- Immunofluorescent microscopy: staining of microbe by anti-treponemal antibodies. In Histopathology Lab: Bright-field microscopy: modified Steiner silver stain.

Cultivation of Treponema pallidium: -The bacterium do not grow on conventional culture media. -Animal inoculation can be used for cultivation of microbe.

Non treponemal tests (non-specific): Indirect diagnosis: Serology: Non treponemal tests (non-specific): Anti cardiolipin antibodies by Venereal Disease Research Laboratory (VDRL) or rapid plasma reagin (RPR) test. Treponemal test (specific): Detection of anti treponemal antibodies by T. pallidum haemagglutination test (TPHA) or fluorescent treponemal antibodies absorption (FTA-Abs). Treatment: All species are sensitive to penicillin. Alternate therapy: tetracycline and erythromycin. N

FTA-Abs TPHA RBCs + treponemal antigens