Spirochetes II Flashcards
What are spirochetes?
Spiral-shaped organisms that exhibit corkscrew motility
don’t Gram stain
Grow slowly in vitro or not at all
What are the pathogenic spirochetes?
Treponema
Borellia (can be cultured, usually fastidious and microaerophilic)
Leptospira (grown aerobically in appropriate media)
What are characteristics of Lyme disease?
Tick (Ixodes scapularis) borne infection caused by Borrelia burgdorferi
Nymphal tick stage is primarily responsible for transmission of infection
What are the clinical manifestations of Lyme disease?
Early infection (stage 1): Localized Infection
Characterized by erythema migrans at site of bitee
Early infection (stage 2): Disseminated Infection
Seconary annular skin lesions
Systemic symptoms such as:
Malaise
Fatigue
Bell’s Palsy
Early Infection (stage 3): Persistent infection
Arthritis
Meningoencephalitis
Neuropathies
How is lyme disease diagnosed?
Clinical presentation consistent with lyme disease and laboratory diagnosis:
Isoolation of B. burgdorferi
Demonstration of diagnostic levels of IgM or IgG Abs to spirochetes
Significatn increase in Ab titer between acute and convalescent serum samples
How is B. burgdorferi detected in the lab?
Direct Methods:
Culture
PCR
- -> skin and blood samples used in early stages
- synovial fluid can be used when arthritis is present
Indirect Methods:
Serologic assays: Abs to B. burgdoferi
Western blot
What is the treatment for lyme disease?
Oral antibiotics (i.e. doxycycline)
Patients with arthritis or neurological abnormalities may require IV Abx
What is Southern Tick-Associated Rash Illness (STARI)?
Rash similar to lyme disease
Associated with the bite of teh lone start tick, Amblyomma americanum
What is relapsing fever?
Disease caused by Borrelia sp. and characterized by recurrent episodes of fever separated by asymptomatic intervals
Vectors: Body louse, soft-shelled tick
What are characteristics of Louse-borne Relapsing Fever?
Borrelia recurrentis
Transmitted from person to person by lice
no animal reservoir
occurs in epidemic form
What are characteristics of Tick-borne Relapsing Fever?
Borrelia hermsii and other species
Transmitted from animals to humans by Soft-shelled ticks
Animal reservoirs (rodents)
Transovarial transmission also occurs in ticks, hence ticks can be both vector and reservoir
Occurs in endemic but not epidemic form
What is leptospirossi?
zoonotic disease caused by leptospira
wild rodents and small mammals (reservoir hosts) and domestic animals (incidental hosts) excrete Leptospira in their urine
Humans become infected by contact with infected animals or urine of those animals
What is the clinical presentation of Leptospirosis?
Acute febrile illness (accompanied by conjunctival suffusion)
May include:
Jaundice
Renal failure
and/or meningitis
