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What is vibrio physiology and structure
all strains have LPS consisting of lipid A endotoxin, core polysaccharide, O polysaccharide.
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what is significance of O polysaccharide for vibrios
used to divide vibrio species into serogroups
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what temperature range can vibrios grow in
- broad temp range
- 14 - 40 C
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what is the pH range of vibrios
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are vibrios susceptible to stomach acid
yes
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do vibrios require salt for growth?
yes
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what are the components of LPS for vibrios
- lipid A (endotoxin)
- core (vibrio) polysaccharide: distinct from enterobacteriacae core polysach
- O polysaccharide: used to subdivide vibrio into serogroups
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V. cholerae O1 does/does not produce capsule
does produce capsule
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V. vulnificus and non -O1 V. cholera produce what kind of capsule
acid polysaccharide capsule
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what serogroup of v. cholera produces cholera toxin
O1 strains of V. cholera
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what does cholera toxin do to patients
- severe hypersecretion of water and electrolytes from intestinal by increasing cAMP levels
- adheres to mucosal layer by toxin co-regulated pilus and chemotaxis proteins
- cells that cannot adhere are unable to establish infection
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what are the toxins that can still cause significant diarrhea
- accessory cholera exotoxin
- zonula occludens toxin
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what are the virulence factors for V. parahaemolyticus
- adhesins
- thermostable direct hemolysin (TDH) AKA kanagawa hemolysin
- Type III secretion systems
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describe thermostable direct hemolysin and its function
- enterotoxin: affects intestines and digestive tract
- induces chloride ion secretion by increasing intracellular calcium
- causes B-hemolysis
- AKA kanagawa hemolysin
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what are v. vulnificus virulence factors (4)
- degrades lysine and stomach acid, producing alkaline by products
- evade host immune response by inducing macrophage apoptosis
- polysaccharide capsule
- surface proteins mediate attachment to host cells
- cytolytic toxin secretion leads to tissue necrosis
- cytolysins
- proteases
- collagenase
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where do virbios grow naturally in
- estuarine/marine environments where sea water meets fresh water
- pathogenic vibrios grow inside chitinous shellfish and form biofilms
- can be asymptomatic in humans
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how is virbio spread
- by contaminated water and food
- high inoculation
- hyperinfectiity is lost after 24 hrs
- most organism are killed by stomach acids
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what are polyclonal and monoclonal strains of v. cholerae
- polyclonal: v.cholerae strains in endemic areas without epidemic disease
- monoclonal: v. cholerae strains in epidemic waters where one highly infection
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what diseases are caused by V. parahaemolyticus
- gastroentereitis: mild to cholerae like conditions. explosive watery diarrhea, from shellfish
- wound infections: from seawater
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what are the diseases of v. vulnificus
- septicemia: sudden onset of fever and chills, vomiting, diarrhea. 50% mortality rate
- wound infection: swelling, erythema, necrosis. 20-30% mortality rate
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what is the source of infection for v. cholerae
water, food
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what is the source of infection of v. parahaemolyticus
shellfish, seawater
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what is the source of infection for v. vulnificus
shellfish, seawater
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what are the virulence factors of v. cholerae
- cholera toxin
- toxin co-regulated pilus (TCP)
- chemotaxis protein (cep)
- accessory cholera enterotoxin (ace)
- zonula occludens toxin (zot)
- neuraminidase
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what is the biological effect of cholera toxin
hypersecretion of electrolytes and water
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what is the biological effect of toxin co-regulated pilus (TCP)
- surface binding site receptor for bacteriophage CTX
- mediates bacterial adherence to intestinal mucosal cells
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what is the biological effect of accessory cholera enterotoxin (ace)
increases intestinal fluid secretion
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what is the biological effect of chemotoxis protein (cep)
adhesin factor
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what is the biological effect of neuraminidase
modifies cell surface to increase GM, binding sites for cholera toxin
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what is the biological effect of kanagawa hemolysin
enterotoxin that induces chloride ion secretion
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what is the biological effect of cytolysins, proteases, and collagenase
mediates tissue destruction
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how is virbio diagnoses
- immunoassays for cholera toxin or O1 and O139 LPS
- culturing on TCBS agar or alkaline peptone enrichment broth
- salt growth (0.5%)
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what is the treatment for v. cholerae
- fluid and electrolyte replacement
- antibiotic therapy to reduce exotoxin production (shedding)
- improve sanitation
- vaccines
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what is the treatment of v. parahaemolyticus
- fluid and electrolyte replacement
- antibiotic therapy
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what is the treatment for v. vulnificus
antibiotics
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where is aeromonas found in
ubiquitous in fresh and brackish water
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aeromonas cause what types of diseases (3)
- water diarrhea, dysenteric diarrhea, intermittent diarrhea
- wound infections
- opportunistic systemic disease
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aeromonas are G(-/+), oxygen requirement, shape
- G(-)
- facultative anaerobic
- fermentative rod
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how can aeromonas be distinguished from enterobacteriaceae
(+) oxidase
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how is aeromonas treated
fluoroquinolones
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