Vibrio & Aeromonas Flashcards
name the Three strains of Vibrio which are pathogenic to humans ?
V. cholerae
V. parahaemolyticus
V. vulnificus
Describe the appearance of a Cholera patient?
Profuse watery diarrhea;
Rice water stools – (Rice= flecks of intestinal mucosa)
Severe Dehydration -
loss of skin turgor
sunken eyes
Vomiting
Leg cramps
hypovolemic shock
what are the two cholera serotypes associated with cholera Epidemics?
O1 and O139
Virulence factors (CT and Toxin Co-Regulated Pilus) are exclusively on these two serotypes
Epidemiology of Cholera:
- how is it tranismitted?
- What is its environemntal reservoir?
- what condition leads to increased severity of disease ?
- where does cholera colonize in humans?
- Fecal/Oral transmission;
- Low stomach acid leads to increased severity of disease
–Brackish water reservoirs
- colonizes in the small intestine
What are the virulence factors of Cholera? describe their mechanisms
1) Cholera Toxin – AB Toxin
- B binds to GMI Gangliosides
- A subunit: ADP ribosylating of G- alpha-s –> AC –> cAMP –> opening of CFTR channels + closure or Na absorption channels
Water follows = Diarrhea
2) Toxin Coregulated Pilus – Type 4 pilus critical for colonization of the small intestine. Regulated by ToxR. ToxR is upregulated in In Vivo conditions
Once a cell is infected, it stays intoxicated until is sloughed off
Where does cholera colonize?
The small intestine
Treatment and Prevention of Cholera
Treatment:
1) Rehydration: Replenishment of the fluids and electrolytes
2) Abx: Tetracycline (but always with rehydration therpay)
Prevention: Vaccine
- Mutated organism missing the A toxin, but still has the immunogenic B toxin
• V. parahaemolyticus
- what are outbreaks associated with?
- what is the environmental reservoir ?
Leading bacterial cause of seafood associated gastroenteritis;
outbreaks in coastal states associated with eating sea foods (crabs, oysters, shrimp)
Reservoir: estuary environments
• V. parahaemolyticus
- Describe the (2) disease manifestations?
Diarrhea: watery, self-limited diarrhea, Cramps, nausea, vomting
Wound: Some wound infections after exposure to warm seawater
• V. parahaemolyticus
what are it’s virulence factors?
what is unique about its generation time?
Enterotoxin – thermal stable hemolysin.
Rapidly growing – generation time 9 minutes
V. vulnificus
- what are the disease manifestations?
- who is at risk for the more severe version of the disease?
1) Wound infections:
occurs after exposure of wound to warm seawater (eg a patient lacerated hand while cleaning crabs)
wound infxn -> cellulitis -> bullae -> necrosis.
2) Primary Sepsis:
ingestion of raw seafood –> bacteremia –> sepsis, fever, chills, hypotension,
secondary skin lesions –> vessilces/blullae –>necrotic ulcers
for the later group, these patients usually have pre-existing or chronic disease (HIV, cirrhosis, immunosuppressed)
90% of these cases in males
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What are the virulence factors of V. vulnificus?
polysaccharide Capsule
Endotoxin
Degradative enzymes: protease, elastase; –
treatment of V. vulnificus?
Aggressive treatment: debridement, amputation,
tetracycline plus ciprofloxacin or cefotaxime
Prevention is best (i.e., no raw seafood for anyone with pre-disposing condition)
• Aeromonas
what is the most common of the pathogenic species?
where does it reside?
• Aeromonas hydrophila
Soil and water
what are the disease manifestations of • Aeromonas hydrophila ?
Wound infections — cellulitis related to water/soil exposure
Medicinal leech exposure
Bacteremia – usually associated with hepatic/pancreatic/biliary disease/malignancy
Some implications to diarrhea
