Vibrios

Characteristics/Epidemiology

(Cell wall) O and (flagellum) H antigen present

Others

Non-cholera vibrios requires higher than usual concentration of NaCl and can survivie in 10% NaCl.

Common in coastal sea waters.

Can cause gastrointestinal illness, soft tissue infections, septicaemia, otitis media/externa.

Pathogenesis/Transmission

Pathogenic vibrios

1. Vibrio cholerae (serogroup O1 causes epidemic cholera)
2. Non-O1 V. cholerae
3. V. parahaemolyticus

Transmitted by contaminated food/water

No known animal reservoirs, no animal/insect vectors.

Cholera toxin

Noninvasive. Disease caused by enterotoxin in small intestine.

Made up of 2 units (A and B).

   * B binds to GM1 ganglioside receptors on mucosal cells

   * A2 faciliate penetration of cell membrane

   * A1 ADP-ribosylates the Gs protein in the cell membrane

   -> Gs activates adenylate cyclase

   -> Increased intracellular cAMP

   -> Secretion of ions and water into intestine.

Clinical significance

Cholera

Caused by V. cholera (other vibrios can produce similar syndrome)

Incubation - hours to few days

Watery diarrhoea (rice-water stools)

Death (from dehydration) >50% if untreated

 

Laboratory identification

A single polar flagellum allows rapid motility

Growth stimulated by NaCl

Facultative anaerobes

Cultured on blood agar or MacConkey agar

Thiosulfate-citrate-bile salts-sucrose (TCBS) enhance isolation

Oxidase positive

Treatment

Replacement of fluid and electrolytes.

First line: Doxycycline

Second line: Ciprofloxacin

Prevention/immunity

Food hygiene

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Things to revise/add later:

Bibliography:

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