Spirochetes, Vibrios Flashcards
What are 6 recurring themes in Spirochetes?
- Wide variety of transmission modes
- Cross easily into bloodstream
- Primary virulence factors are for immune evasion
- Diagnosis is challenging
- Little acquired antibiotic resistance
- Jarish-Herxheimer rxn to treatment (with antibiotics, flu like symptoms, last 24 hours, then clear up – dead spirochetes are more immunogenic?)
What are two genera of spirochete pathogens that we focus on?
- Treponema (syphilis)
2. Borrelia (lyme disease)
Treponema pallidum:
- How big is it?
- Is it hardy?
- How is it transmitted?
- small
- can’t live outside the host and it is human-restricted in nature, cannot be grown in culture
- Extremely infectious sexually (acquired), one warm wet body to another, low infectious dose OR can be transmitted by blood, transplacentally (congenital) high morbidity in infants with congenital syphilis
What is unique about the immune response to T pallidum?
The host raises antibodies, specific anti-treponemal and nonspecific reagin NEITHER of which clear the infection
What is characteristic of primary syphilis?
Painless chancre at site of transmission 3-6 weeks later, highly infectious
Inflammatory infiltrate at site fails to clear organism
Chancre heals 3-12 weeks
What is characteristic of secondary syphilis?
4-10 weeks, spirochete multiplication -> systemic symptoms
Fever, malaise, myalgias, arthralgias, lymphadenopathy
Mucocutaneous lesions of variable types, condylomata lata (wart like lesions on genitals), patchy alopecia
High antibody titers - the patient is producing BULK useless antibodies
latent syphilis is the end for 2/3, organism remains, secondary symptoms resolve, may return intermittently over years.
What is characteristic of tertiary syphilis?
(3)
What is the hallmark diagnostic test for tertiary syphilis?
What is the treatment and prevention of syphilis?
Gummatous syphilis: granulomatous lesions (gummas) with rubbery, necrotic center. Primarily in liver, bons, and testes
Cardiovascular syphilis: (>10 yrs): aneurysm of ascending aorta caused by chronic inflammation of vasa vasorum
Neurosyphilis: once nerve cells are dead, they don’t regrow, won’t get function back
Argyll-Robertson pupil - one or both pupils fail to constrict in response to light but DOES constrict to focus on a near object
Penicillin and Condoms
- What is Borrelia burgdorferi?
- What is characteristic about its shape?
- How long does lyme require to transmit? What do you use to treat?
- lyme disease
- It is a motile spirochete - flat-wave shape, not spiral. Visible by standard microscopy.
- 24-48 hours - doxycycline if the patient is neither pregnant NOR allergic to tetracyclines
- After 6mo infection with Borrelia burgdorferi, what symptoms occur in the human? (stage 1)
- What happens months - year after infection? (stage 2)
- Are coinfections possible?
- What is stage 3 characterized by?
- erythema migrans rash, anti-spirochete / autoantibodies raised. Very persistent skin infection established
- Immune/neorological issues. Reinfections occur.
- Erlichia or babesioa
- Arthritis, subacute encephalopathy, chronic progressive encephalomyelitis, late axonal neuropathies, fibromyalgia
- What can you do to test for B. burgdorfi?
2. What can you do to treat B. burgdorferi?
- Serology can confirm exposure, which doesn’t mean current disease, people who received vaccine will be seropositive
- Treat 10-20 days with doxycline unless pregnant or allergic. No benefit from longer antibiotic course.
- What is characteristic of Vibrio?
- Curved, Gram (-) rods (mostly ocean-dwelling, several are halophiles
- Primarily cause fecal-oral gastroenteritis, can also infect wounds contaminated by seawater or ocean debris, also peptic ulcers
- Gastroenteritis and peptic ulcers require specialized virulence factors for survival in GI
- What is V. cholerae morphology?
- What is their relationship with oxygen?
- What are its reservoirs?
- How is V. cholerae transmitted?
- What is the infectious dose?
- What do bacteria do in the small intestine?
- curved, comma-shaped, motile Gram (-) rod
- Strains are aerobic, facultatively anaerobic
- Humans and plankton ecosystem of indian ocean
- Fecal-oral route, shed by asymptomatic carriers in incubation or convalescence AND untreated water or undercooked shellfish
- Really high. usually killed by stomach acid, people on antacids or with gastrectomy are more susceptible
- Secrete mucinase to clear path to brush border, attach and colonize
What is the enterotoxin secreted by cholera?
Choleragen, A-B subunit structure causing persistent activation of adenylate cyclase, leading to loss of water and ions. Blocks absorption by microvilli while also promoting secretion from crypt. MASSIVE WATERY DIARRHEA
Morbidity and death from dehydration and electrolyte imbalance - severe cases may kill in hours - surviving patients run the self-limited course in 7 days
- What is the diagnosis of V. cholerae?
2. How do you treat cholerae?
- Dehydration, may be difficult to catch in a child
Can tell interstitial dehydration by pinching skin - Rehydrate and rebalance electrolytes. Treat with an antibiotic to shorten course and reduce shedding
- What is the characteristic morphology of Heliobacter pylori (Vibrio)?
- What does H. Pylori cause?
- Curved Gram (-) rod, similar to campylobacter, but strongly Urease (+)
- peptic ulcer disease, associated with mucosa-associated lymphoid tissue (MALT) lymphomas, gastric lymphoma, adenocarcinoma of the stomach
