Bodyland Scroll: Cholera • H. pylori • Spirochetes • Lyme
A plain-English, exam-ready story with quick checks.
🌊 Vibrio cholerae
Gram −Comma-shapedOxidase +
Where it lives: contaminated water/seafood; likes alkaline media. acid-labile → needs high inoculum
Weapon: Cholera toxin (AB toxin) ADP-ribosylates Gs → ↑ adenylate cyclase → ↑ cAMP → pumps Cl⁻ out & water follows → rice-water diarrhea (profuse, secretory, no invasion).
Key care: Prompt aggressive oral/IV rehydration; antibiotics shorten shedding in some settings.
Quick checks
🔥 Helicobacter pylori
Curved Gram − rodCatalase +Oxidase +Urease +
Trick: Urease cloud makes ammonia → buffers acid so it can live in the mucus layer (mostly antrum).
Diseases: chronic gastritis, peptic ulcers (esp. duodenal), ↑ risk gastric cancer & MALT lymphoma.
Dx: urea breath or stool antigen (active infection).
Rx (first-line): Triple therapy = PPI + amoxicillin (metronidazole if allergic) + clarithromycin.
Quadruple (bismuth) regimen is an alternative where macrolide resistance is high.
Quick checks
🌀 Spirochetes (spiral bacteria)
BorreliaLeptospiraTreponema
Visualizing: Borrelia is Big → seen with Giemsa/Wright stain.
Treponema (e.g., T. pallidum) needs dark-field microscopy or DFA.
Leptospira has hooked ends; water/animal urine exposure.
🕷️ Lyme disease (by Borrelia burgdorferi)
Ixodes tickReservoir: mouse/deerNE U.S.
Stage 1 (early localized): flu-like + erythema migrans (bull’s-eye).
Stage 2 (early disseminated): the mnemonic FACE →
Facial nerve palsy (often bilateral), Arthritis (migratory),
Carditis (AV block), Erythema migrans at new sites + neuro Sx.
Stage 3 (late): encephalopathy, chronic arthritis.
Testing: 2-step — ELISA then Western blot (for confirmation).
Treatment: Doxycycline first-line.
If severe disease, neurologic/cardiac involvement, or pregnancy → ceftriaxone (or amoxicillin in pregnancy/children).
Quick checks
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