Spirochetes and Vibrios

Question 1

Recurring themes of spirochetes

Answer 1

• 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

Question 2

Treponema Pallidum

Answer 2

• Syphilis
• Spirochete
• Flagellar corkscrew motion
• Not culturable
• Slow growing
• Too slender to gram stain

Question 3

Pathogenesis of T. pallidum

Answer 3

• Syphilis
• Sexual contact
• Mother-baby during birth
• Rarely, blood transfusion
• Infects endothelium of small blood vessels

Question 4

Triphasic infection of T. pallidum

Answer 4

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

Question 5

Congenital syphilis

Answer 5

Crosses the placenta, stillbirth or fetal abnormality

Question 6

Diagnosis of syphilis

Answer 6

• Exam: rash, chancre, condylomata, granulomas, CNS symptoms
• Lab: Darkfield microscopy or IF
• Serology: Reagin, specific antibodies

Question 7

Treatment of syphilis

Answer 7

Penicillin (single injection) or long term doxycycline

Should expect flu like symptoms 24 hours after starting treatment

Question 8

Borrelia burgdorferi

Answer 8

• Lyme disease!
• Spirochete
• Motile
• Visible by standard microscopy
• Tick borne
• Small (and some large) mammal reservoirs
• 24-48 hrs attachment to transmit

Question 9

Pathogenesis of lyme disease

Answer 9

• Bite site
• Blood
• Heart, joints, CNS
• Does not seem to involve toxins, primarily immune evasion

Question 10

Diagnosis of lyme disease

Answer 10

• 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

Question 11

Treatment of Lyme disease

Answer 11

• Stage 1: doxycycline of amoxicillin

- Late stage: Ceftriaxone

Question 12

Recurring themes of vibrios

Answer 12

• Curved, gram - rods
• Mostly fecal-oral gastroenteritis
• Some infection of wounds contaminated by seawater and ocean debris
• Peptic ulcers–special virulence factors for GI

Question 13

Vibrio Cholera

Answer 13

• Vibrio
• Curved, comma shaped, gram - rod
• O cell wall antigen indicates pathogenicity

Question 14

Pathogenesis of Vibrio Cholera

Answer 14

• 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

Question 15

Diagnosis of V. Cholera

Answer 15

• Watery diarrhea
• No pain, blood, or neutrophils in stool
• Acidosis and hypokalemia from loss of bicarbonate and potassium

Question 16

Treatment of V. Cholera

Answer 16

Rehydrate and rebalance electrolytes

-Tetracycline can be added to shorten course

Question 17

Helicobacter Pylori

Answer 17

• 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