21 – Aeromonas, Vibrio, Plesiomonas

Question 1

Microbial characteristics

Answer 1

• 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

Question 2

V. cholerea is a model toxin for

Answer 2

• Interfering with ion metabolism
• **can grow at high NaCl concentrations (KNOW)

Question 3

Aeromonas spp. natural host or habitat

Answer 3

• Found in aquatic/marine environments
• Part of normal microbiome of fish

Question 4

Plesiomonas shingelloides: natural host or habitat

Answer 4

• Aquatic organism
• NOT halophilic (perhaps in brackish but not salt water)

Question 5

Vibrio spp. natural host or habitat

Answer 5

• Found in aquatic and marine environments
• Associated with shellfish
• Can be in intestinal tract of mammals including people

Question 6

Aeromonas hydrophila virulence factors

Answer 6

• Type III secretion systems
• Hemolysis
• Enterotoxin

Question 7

Vibrio cholerase virulence factors

Answer 7

• 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

Question 8

Aeromonas hydrophilia in amphibians

Answer 8

• 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

Question 9

What are the clinical signs of Red leg disease? (A. hydrophilia)

Answer 9

• Ulcerations
• Lethargy
• Emaciation
• Petechia on legs and abdomen

Question 10

Aeromonas salmonicida in a variety of fish is associated wtih

Answer 10

• high density aquaculture and aquarium fish

Question 11

Aeromonas salmonicida in a variety of fish: disease symptoms/lesions

Answer 11

• ulcerative lesions
• hemorrhage
• funculosis: septicemic disease of salmonids, presence of BOILS (furuncels)

Question 12

Plesiomonas shingelloides in people

Answer 12

• 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

Question 13

Vibrio cholerae in people

Answer 13

• 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

Question 14

Profuse diarrhea with vibrio cholerae in people

Answer 14

• 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!

Question 15

Vibrio cholerae vaccination

Answer 15

• Oral vaccine
  o Reconstituted into an effervescent drink

Question 16

Vibrio anguillarum in aqauculture

Answer 16

• Cause of haemorrhagic septicemic disease (vibriosis)
• Problematic for aquaculture industries
  o Fin fish, crustaceans (shrimp), bivalves

Question 17

What are the clinical signs of Vibrio anguillarum in aquaculture?

Answer 17

• Weight loss
• Lethargy
• Red spots
• Ophthalmic involvement (opacity followed by ulceration and exophthalmia)

Question 18

Vibrio harveyi in wild and farmed marine fish and crustaceans

Answer 18

• *most notably shrimp
• Organism can LUMINESCE
• Treatment is challenge
  o Antimicrobials have been attempted
  o Bacteriophages
  o Biological control: ‘probiotics’
  o Dietary supplements

Question 19

What the was most IDed bacteria in manatees?

Answer 19

• Vibrio fluvialis

Question 20

Vibrio fischeri in squid

Answer 20

• Allow them to glow their light organ

Question 21

Vibrio vulnificus in people

Answer 21

• 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

Question 22

Vibrio vulnificus in people: is contracted by

Answer 22

• Ingestion
• Contact with water where organism is present

Question 23

Specimens to collect

Answer 23

• Scrapings of affected tissue
• Tissue sections
• Whole animals for necropsy

Question 24

Sample handling

Answer 24

• *prevent contamination as much as possible (environmental)
• Send samples quickly: small fish and amphibians autolyze quickly
• Do NOT freeze

Question 25

Lab ID

Answer 25

• 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

Question 26

Zoonotic/interspecies transmission

Answer 26

• 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

Question 27

Treatment options

Answer 27

• Consult a specialty reptile/amphibian or fish medicine book=STRONGLY recommended

Question 28

What is the treatment of choice for Aeromonas hydrophilia in frogs?

Answer 28

• Drugs with good Gram-negative spectrum
  o Amionglycosides
  o Fluroquinolones

Question 29

What is the treatment of choice for Aeromonas salmonicida in fish?

Answer 29

• Can treat eggs in commercial operations
  o Antimicrobial therapy based on susceptibility testing