Vibrio, Aeromonas, Plesimonas

• Major group of gram-negative, facultative anaerobic
  
• Fermentative bacilli
  
• Difference from Enterobacteriacae:
  
  • Positive oxidase
    
  • Polar flagella
    

  
  

Vibrio Species Associated with human diseases
SPECIES	SOURCE OF INFECTION	CLINICAL DISEASE
V. cholerae	Water, food	Gastroenterits
V. parahaemolyticus	Shellfish, seawater	Gastroenterits, wound infection, cellulitis
V. vulnificus	Shellfish, seawater	Bacteremia, wound infection, cellulitis
V. alginoliyticus	Seawater	Wound infection, external otitis
V. hollisae	Shellfish	Gastroenterits, wound infection, bacteremia
V.fluvialis	Seafood	Gastroenterits, wound infection, bacteremia
V. damsela	Seawater	Wound infection
others

• Vibrio choleae:
  
  • Rice-water-stools
    
• Vibrio parahaemolyticus:
  
  • Explosive diarrhea
    
  • Cellulitis after exposure to seawater
    
• Vibrio vulnificus:
  
  • Particularly virulent
    
  • Rapidly progressive wound infections(seawater contamination)
    
  • Septicemia(raw oysters)
    
  • Most severe in patients with hepatic disease, hematopoietic disease, or CKD, immunosuppressive drugs.
    

• AEROMONAS:
  
  • A. hydrophila, A. caviae, and A. veronii
    
  • Ubiquitous in fresh and brackish water
    
  • Infection by ingestion of water or food
    
  • Opportunistic systemic diseases in immunocompromised patients(liver disease, cancer)
    
  • Chronic diarrhea in healthy adults-when severe may resembles shigellosis(invasive)
    
  • Resistant to PCN, Cephalo, Erythromycins.
    
  • Effective rx: TMP/SMX, Gentamicin, and chloramphenicol
    
• PLESIOMONAS:
  
  • Gram-negative bacilli
    
  • Oxidase positive
    
  • Multiple polar flagella
    
  • Difference from Aeromonas by biochemical reactions
    
  • P. Shigelloides
    
  • Fresh water and estuarine waters
    
  • Infection by contact with fresh water, consumption of seafood, or exposure to amphibians and reptiles.
    
  • Causes gastroenteritis
    
  • RESISTANT to ampicillin, erythromycin, and many aminoglycosides.
    
  • Susceptible to cephalosporins, imipenem, TMP/SMX, fluoroquinolones