173.1 🎓 醫學生版

菌: Vibrio — gram - curved/comma rod, oxidase +, motile (polar flagellum), alkaline tolerant
3 主要 human species:
- V. cholerae (cholera; serogroup O1 + O139 epidemic)
- V. parahaemolyticus (seafood gastroenteritis #1 海鮮 borne)
- V. vulnificus (severe wound + bacteremia; cirrhotic / iron overload 高致死)
流行病學:
- Cholera: pandemics 7th since 1817; current 7th since 1961; outbreaks Haiti 2010, Yemen 2017-2020, Lebanon 2022, Syria 2022, Pakistan 2022 floods
- V. vulnificus: Gulf Coast USA, Asia, Mediterranean; climate change → northward spread (Baltic, NE USA)
- 暖海水 = 增 Vibrio risk
臨床:
- Cholera: 大量 rice-water diarrhea (1 L/hr), no fever, no abdominal pain, rapid dehydration → death in hours
- V. parahaemolyticus: 6-24 hr 後 raw shellfish → 水瀉 ± 血, cramping, low fever, self-limit
- V. vulnificus: 2 forms — wound (necrotizing fasciitis 後海水 exposure), primary septicemia (raw oyster + cirrhosis → bacteremia + hemorrhagic bullae + shock + > 50% mortality)
Treatment:
- Cholera: ORS (cornerstone) + doxycycline 300 mg × 1 OR azithromycin 1 g × 1
- V. parahaemolyticus: self-limit; doxy if severe
- V. vulnificus: EMERGENT — doxy + ceftriaxone IV + debridement; ICU
Vaccine (cholera): Dukoral, Shanchol, Euvichol-Plus — WHO prequalified, used outbreaks + endemic

Gram - curved rod (“comma”)
Oxidase +, motile, alkaline-preferred
TCBS (thiosulfate-citrate-bile-sucrose) selective agar — V. cholerae yellow (sucrose +), V. parahaemolyticus green
100 serogroups by O antigen; O1 (Inaba, Ogawa) + O139 = epidemic cholera
CTX phage carries cholera toxin (CT) gene

AB5 toxin
Activates Gs → adenylyl cyclase → cAMP ↑ → Cl- secretion + Na+ absorption blocked → 大量 water loss
小腸 secretion dominates

7 pandemics since 1817
現 7th pandemic (1961-) — O1 El Tor
O139 Bengal (1992 outbreak, India/Bangladesh) — first non-O1 epidemic
Risk: 食水 fecal contamination, refugee camps, post-disaster (Haiti earthquake 2010, Pakistan flood 2022)
高 ID (10^6-1011) but reduced in acid-suppressed (PPI users vulnerable to low dose)

潛伏 12 hr - 5 d
Sudden 大量 painless 水瀉, “rice-water stool” (mucus flecks)
No fever, no abdominal pain, no blood
Vomiting common 後 onset
Severe dehydration in hours: hypovolemic shock, AKI, metabolic acidosis, hypokalemia, hypoglycemia (兒童), tetany (hypocalcemia)
Mortality < 1% with proper rehydration; up to 50%+ untreated
兒童 + 老 highest risk

Severity	Approach
Mild (no signs dehydration)	ORS PO ad lib
Moderate (some skin tenting, sunken eye)	ORS PO 75 mL/kg over 4 hr
Severe (shock, lethargy, anuria)	IV LR or Ringer’s lactate 100 mL/kg in 3-6 hr → switch ORS once able

Continue ORS as long as diarrhea persists
Antibiotic (reduce volume + duration):
- Doxycycline 300 mg PO × 1 (preferred; even children, pregnancy short course OK)
- Azithromycin 1 g PO × 1
- Ciprofloxacin 1 g × 1 (some R)
Zinc supplementation (兒童) — adjunct, 加快 recovery
Antimotility (loperamide) — controversial; some use in severe to reduce stool volume

Dukoral — recombinant CTB + killed whole-cell; 2 doses (1 wk apart, ≥ 2 yr); ~ 85% efficacy 6 mo, 50% over 2 yr
Shanchol / Euvichol-Plus — killed bivalent O1/O139; 2 doses 2 wk apart; ~ 65% efficacy 5 yr
WHO stockpile for outbreaks
Routine in endemic countries pediatric program

Most lethal Vibrio; “flesh-eating Vibrio” media name
Source: warm seawater (Gulf Coast, Caribbean, Asia, Mediterranean, expanding Baltic + NE USA due climate)
High-risk hosts:
- Cirrhotic / chronic liver disease
- Hemochromatosis / iron overload (V. vulnificus 需 iron)
- HIV, immunosuppression
- Chronic kidney disease
- DM
2 临床 forms:

Raw oyster ingestion in cirrhotic → bacteremia → hemorrhagic bullae extremities + shock
12-24 hr 潛伏
High mortality > 50% (immediate empirical critical)