Spirochaetalis

Question 1

Treponema Pallidum (Syphilis)

Properties
Morphology
Epidemiology
Clinical disease
Diagnosis
Treatment

Answer 1

Properties- Outer membrane adheres to host cells.
Hyaluronidase facilitates perivascular infiltration
• Coating of fibronectin protects against phagocytosis
• Tissue destruction primarily results from host’s immune response to infection

Morphology- Spiral shaped bacteria, small (0.1–0.2 μm × 6–20 μm), tightly coiled spirochetes that are too thin to be seen by light microscopy and T. pallidum has not been cultured in the laboratory.

Epidemiology- Humans are the only host, transmitted sexually

Clinical disease- This disease develops in three stages
1. painless ulcers to the site of infection with regional lymphadenopathy(abnormal size of lymph nodes) and bacteremia (bacteria in blood)

2. flulike symtoms and generalised mucocutaneous rash and bacteremia
3. chronic inflammation and destruction of organ tissue.

Neurosyphyilis
congenital- fetal death

Diagnosis-
Darkfield or direct fluorescent antibody microscopy useful if mucosal ulcers are observed in primary or secondary stages of syphilis
• Serology is very sensitive in secondary and late stages of syphilis
• Nucleic acid amplification tests have been developed but are not widely used

Treatment-
safe sex and oxycycline or azithromycin is administered if the patient is allergic to penicillin. Vaccination not available

Question 2

Borrelia Burgdorferi 
(Lyme disease)

Properties
Morphology
Epidemiology
Clinical disease
Diagnosis
Treatment

Answer 2

Properties- immune reactivity against Lyme disease maybe responsible for the clinical disease.

Morphology- large spiral bacteria

Epidemiology- Transmitted by hard ticks from mice to humans; reservoir: mice, deer, and ticks

Clinical disease- Lyme disease develops in stages:
• Early localized disease
:small maculeor papule develops at the site of the tick bite and
then enlarges to a lesion with a flat, red border and central clearing (erythema migrans)

• Early disseminated disease: hematogenous dissemination is characterized by sys-
temic signs (severe fatigue, headache, fever, malaise), arthritis and arthralgia, myalgia,
erythematous skin lesions, and cardiac and neurologic symptoms

• Late stage manifestations include arthritis and chronic skin involvement

Diagnosis- Microscopy and culture , Nucleic acid amplification and serology

Treatment- for both early stages treatments such as moxicillin,tetracycline, or cefuroxime; late manifestations are treated with intravenous penicillin or ceftriaxone
• Reduced exposure to hard ticks through use of insecticides, application of insect repel- lents to clothing, and wearing protective clothing that reduces exposure of skin to insects
• Vaccines are not available