MICROBIO 3.8 - SPIROCHETES

Spirochetes

• Spirochetes are bacteria with a unique spiral or corkscrew shape.
• Treponema pallidum causes syphilis.

Borrelia

• Borrelia are large, coiled spirochetes that can be microaerophilic or obligate anaerobes, and facultatively intracellular depending on the species.
• Giemsa staining and light microscopy are utilized to visualize Borrelia in blood samples.
• Virulence factors include multiple flagella and variable membrane proteins for adapting to new environments.
• Antibiotic treatment with penicillin for Borrelia infections can result in a Jarisch-Herxheimer reaction.
• The Jarisch-Herxheimer reaction tends to exacerbate symptoms, but is not usually fatal.
• Borrelia burdorferi causes Lyme disease in the US. Other Borrelia species cause Lyme disease in Europe, Central, & Eastern Asia.

Borrelia - Relapsing Fever

• Borrelia-relapsing fever is characterized by recurrent episodes of fever and septicemia, due to bacterial proliferation.
• Borrelia membrane proteins undergo antigenic variation, with changing surface antigens, resulting in cycles of bacteremia and clearance.
• Diagnosis is achieved through light microscopy of blood smears.
• Treatment involves tetracycline, with penicillin recommended for patients with CNS involvement.

Borrelia - Lyme Disease (Lyme Borreliosis)

• Lyme disease is a multi-system inflammatory disease.
• Diagnosis involves serology tests of IgM and IgG antibodies to Borrelia.
• Various species of hard ticks (black-legged Ixodes ticks) act as vectors.
• Transmission occurs through prolonged tick feeding.
• Early-stage Lyme, occurring 3-30 days post-infection, presents as localized erythema migrans, often described as a "bullseye rash."
• The bullseye rash is large, red, flat, and gradually expands, but may not always be present.
• Early-stage Lyme disease is treated with tetracyclines.
• Late-stage Lyme disease includes recurring erythema migrans, severe headache, neck stiffness, arthritis, facial palsy, Lyme carditis, CNS inflammation, and nerve pain.
• Late-stage Lyme disease is treated with intravenous penicillin or cephalosporin.

Treponema

• Treponema are spirochetes with thin cell walls and are microaerophilic (formerly believed to be obligate anaerobes).
• Gram or Giemsa stains not effective; no accessible peptidoglycan, LPS, or capsule.
• Diagnosis involves darkfield microscopy or direct antibody fluorescent methods.
• The bacteria are highly invasive due to flagellar motility.
• Tissue destruction is caused by the host inflammatory response.
• Treponema species are considered "stealth pathogens" with antigenic variation.

Treponema Pallidum

• Treponema pallidum subspecies cause syphilis (venereal), yaws, bejel, & pinta (non-venereal).
• T. carateum, another infectious species, causes pinta.

Stages of Syphilis

• Primary syphilis involves localized lesions and regional lymphadenopathy
• Secondary syphilis includes disseminated rash and generalized lymphadenopathy
• Latent syphilis is asymptomatic, but there can be a recurrence of secondary syphilis symptoms in ~25% of individuals.
• Tertiary syphilis involves coalescent granulomatous lesions (gumma lesions), cardiovascular syphilis, and late neurological complications.

Tuskegee Syphilis Experiment

• The Tuskegee Syphilis Experiment is not elaborated on in the text, its inclusion likely serves as a reference point for a well-known unethical study in medical history.

Monica Embers, PhD

• Dr. Embers found direct evidence of Borrelia burgdorferi persistence in monkeys treated with antibiotics.
• Borrelia burgdorferi persisted in monkeys treated with 28 days of antibiotics.
• Borrelia burgdorferi persisted in 8 out of 11 monkeys treated with a 90-day Klempner protocol.
• These findings lead to the concept of "Late Disseminated Lyme Disease".