Spirochetes and Vibrios Flashcards
Recurring themes of spirochetes
- Wide variety of transmission methods (sexual, vector, environmental)
- Cross easily into bloodstream
- Primary virulence factors are for immune evasion (little inflammation, few exotoxins, no vaccines)
- Diagnosis is challenging (variety of symptoms, phases, eye exam can be useful)
- Generally simple treatment once diagnosed
- Jarisch-Herxheimer reaction to treatment
Treponema Pallidum
- Syphilis
- Spirochete
- Flagellar corkscrew motion
- Not culturable
- Slow growing
- Too slender to gram stain
Pathogenesis of T. pallidum
- Syphilis
- Sexual contact
- Mother-baby during birth
- Rarely, blood transfusion
- Infects endothelium of small blood vessels
Triphasic infection of T. pallidum
1) Primary syphilis (weeks)–forms an ulcer at site of infection (chancre), initiates bacteremia
2) Secondary syphilis (months)–macropapular rash on palms and soles, patch alopecia
3) 1/3 will resolve, 1/3 will enter latency (years)–symptoms come and go, patients remain infectious, later they are no longer infectious
4) Remaining 1/3 enter tertiary syphilis–granulomas (gummas) and CNS involvement
Congenital syphilis
Crosses the placenta, stillbirth or fetal abnormality
Diagnosis of syphilis
- Exam: rash, chancre, condylomata, granulomas, CNS symptoms
- Lab: Darkfield microscopy or IF
- Serology: Reagin, specific antibodies
Treatment of syphilis
Penicillin (single injection) or long term doxycycline
Should expect flu like symptoms 24 hours after starting treatment
Borrelia burgdorferi
- Lyme disease!
- Spirochete
- Motile
- Visible by standard microscopy
- Tick borne
- Small (and some large) mammal reservoirs
- 24-48 hrs attachment to transmit
Pathogenesis of lyme disease
- Bite site
- Blood
- Heart, joints, CNS
- Does not seem to involve toxins, primarily immune evasion
Diagnosis of lyme disease
- Stage 1: Expanding macular rash with bullseye appearance, possibly flu like symptoms
- Stage 2 (months): cardiac and neurologic involvement, myocarditis, heart block, aseptic meningitis, bilateral facial nerve palsy
- Stage 3 (months): arthritis in large joints, chronic progressive CNS disease
In lab: serology (ELISA or IF), confirm with western blot or PCR
Treatment of Lyme disease
- Stage 1: doxycycline of amoxicillin
- Late stage: Ceftriaxone
Recurring themes of vibrios
- Curved, gram - rods
- Mostly fecal-oral gastroenteritis
- Some infection of wounds contaminated by seawater and ocean debris
- Peptic ulcers–special virulence factors for GI
Vibrio Cholera
- Vibrio
- Curved, comma shaped, gram - rod
- O cell wall antigen indicates pathogenicity
Pathogenesis of Vibrio Cholera
- Transmitted by fecal-oral route
- Travels to untreated water or undercooked shellfish
- Usually killed by stomach acid (high ID)
- Surviving bacteria reach small intestine, secrete mucinase to clear path, attach and colonize
- Growing bacteria secrete cholera toxin: choleragen (A-B) subunit structure
- Massive watery diarrhea
- Death from dehydration and electrolyte imbalance possible
Diagnosis of V. Cholera
- Watery diarrhea
- No pain, blood, or neutrophils in stool
- Acidosis and hypokalemia from loss of bicarbonate and potassium
Treatment of V. Cholera
Rehydrate and rebalance electrolytes
-Tetracycline can be added to shorten course
Helicobacter Pylori
- Vibrio
- Curved gram - rod
- Strongly urease +
- Gastritis, peptic ulcer
- Recurrent pain and bleeding into GI
- Antigen present in stool, igG in serum, urea breath
- Normalize pH with bismuth salts
- Kill bacteria with metronidazole plus amox or tetra
