21 – Aeromonas, Vibrio, Plesiomonas Flashcards
Microbial characteristics
- Biocontainment level 2
- Gram negative rods
o Aeromonas and Plesiomonas: straight rods
o Vibrio: curved rods - Associated with aquatic and marine environments
- Associated with ectotherms
- Enteric disease in endotherms
V. cholerea is a model toxin for
- Interfering with ion metabolism
- **can grow at high NaCl concentrations (KNOW)
Aeromonas spp. natural host or habitat
- Found in aquatic/marine environments
- Part of normal microbiome of fish
Plesiomonas shingelloides: natural host or habitat
- Aquatic organism
- NOT halophilic (perhaps in brackish but not salt water)
Vibrio spp. natural host or habitat
- Found in aquatic and marine environments
- Associated with shellfish
- Can be in intestinal tract of mammals including people
Aeromonas hydrophila virulence factors
- Type III secretion systems
- Hemolysis
- Enterotoxin
Vibrio cholerase virulence factors
- Cholera toxin
o Once inside the enterocyte, binds G proteins
o Activated G proteins turn on adenylate cyclase
o Increase intracellular cAMP
o Interferes with Na, K, and HCO3 metabolism
o Increased ions in gut lumen=increase water in lumen=diarrhea
Aeromonas hydrophilia in amphibians
- Red leg disease (bacterial septicemia: many can cause this disease)
- Seen in those malnourished OR in poor quality water
- *associated with NECROTIC STOMATITIS (mouth)in snakes
What are the clinical signs of Red leg disease? (A. hydrophilia)
- Ulcerations
- Lethargy
- Emaciation
- Petechia on legs and abdomen
Aeromonas salmonicida in a variety of fish is associated wtih
- high density aquaculture and aquarium fish
Aeromonas salmonicida in a variety of fish: disease symptoms/lesions
- ulcerative lesions
- hemorrhage
- funculosis: septicemic disease of salmonids, presence of BOILS (furuncels)
Plesiomonas shingelloides in people
- food related gastroenteritis
o unwashed foods
o undercooked shellfish - mild watery diarrhea
- immune-suppressed individuals can have cholera-like illness
- associated with tropical and sub-tropical regions in summer months
o don’t eat oysters in months without an R in it - also cause OPPORTUNISTIC INFECTIONS in fish
Vibrio cholerae in people
- not endemic in Canada
- severe, acute gastroenteritis
- *infection through ingestion
o Contaminated water or food
o Under cooked crab (Blue Crab) or raw oysters - Profuse diarrhea
- *vaccination is available
Profuse diarrhea with vibrio cholerae in people
- Can begin within hours of ingesting organism
- ‘rice water diarrhea’
- Up to 1L/hour = dehydration can be DEADLY
- *traveller: boil it, cook it, peel it OR forget it!
Vibrio cholerae vaccination
- Oral vaccine
o Reconstituted into an effervescent drink
Vibrio anguillarum in aqauculture
- Cause of haemorrhagic septicemic disease (vibriosis)
- Problematic for aquaculture industries
o Fin fish, crustaceans (shrimp), bivalves
What are the clinical signs of Vibrio anguillarum in aquaculture?
- Weight loss
- Lethargy
- Red spots
- Ophthalmic involvement (opacity followed by ulceration and exophthalmia)
Vibrio harveyi in wild and farmed marine fish and crustaceans
- *most notably shrimp
- Organism can LUMINESCE
- Treatment is challenge
o Antimicrobials have been attempted
o Bacteriophages
o Biological control: ‘probiotics’
o Dietary supplements
What the was most IDed bacteria in manatees?
- Vibrio fluvialis
Vibrio fischeri in squid
- Allow them to glow their light organ
Vibrio vulnificus in people
- Cause of serious infections
o Wounds
o Primary septicemia
o Gastroenteritis - Most develop septicemia have pre-existing conditions (ex. liver disease)
- *also reported to be pathogenic for eels
Vibrio vulnificus in people: is contracted by
- Ingestion
- Contact with water where organism is present
Specimens to collect
- Scrapings of affected tissue
- Tissue sections
- Whole animals for necropsy
Sample handling
- *prevent contamination as much as possible (environmental)
- Send samples quickly: small fish and amphibians autolyze quickly
- Do NOT freeze
Lab ID
- Culture is possible
- Inform lab of the species you are working with (need to culture at T appropriate to lifestyle of organism)
- Microscopy useful
- Fluorescent Ab test for A. salmoncida may be available
- ID based on morphology and biochemical
- PCR + sequencing for ‘unusal’ organism
Zoonotic/interspecies transmission
- Food borne illness
- Human infections can also occur following
o Exposure of open wounds to environment
o Bites/scratches/pinches by marine organisms carrying these bacteria
Treatment options
- Consult a specialty reptile/amphibian or fish medicine book=STRONGLY recommended
What is the treatment of choice for Aeromonas hydrophilia in frogs?
- Drugs with good Gram-negative spectrum
o Amionglycosides
o Fluroquinolones
What is the treatment of choice for Aeromonas salmonicida in fish?
- Can treat eggs in commercial operations
o Antimicrobial therapy based on susceptibility testing
