Which serogroups of Vibrio cholerae are associated with cholera epidemics?
- O1 and O139
- Note: O1 does not have a capsule and does not spread past the intestine
What are the five virulence factors of V. cholerae O1 and O139? **need to know!!**
- Cholera toxin: hypersecretion of electrolytes and water
- Toxin co-regulated pilus: adherence to intestinal mucosal cells – binding site for CTX
- Accessory cholera enterotoxin: increases intestinal fluid secretion
- Zonnula occludens toxin: increases small intestinal permeability
- Neuraminidase: modifies cell surface to increase GM1 – better binding
How does Vibrio cholerae acquire virulence?
- Bacteriophage CTX binds to toxin-co-regulated pilus (tcp) and enters bacterium to become integrated into bacterial genome
- These are the following genes transferred by the bacteriophage
- ctxA and ctxB: cholera toxin subunits
- ace: accessory cholera enterotoxin gene
- zot: Zonnula occludens toxin gene
- These are coordinated by ToxR regulator
How does cholera toxin work? What toxin is it similar to?
- It is similar to the LT of E. Coli
- Five B subunits bind GM1
- A subunit enters cell and activates adenylyl cyclase
- ATP -> cAMP resulting in hypersecretion of electrolytes
What virulence factor is associated with Vibrio parahaemolyticus?
Thermostable direct hemolysin (Kanagawa hemolysin) what it does is increase intracellular calcium which induces chloride secretion in epithelial cells, it also produces beta hemolysis on human blood agar
What virulence factors are associated with Vibrio vulnificus?
- Antiphagocytic polysaccharide capsule
What are the sources of infection and disease caused by vibrio cholerae, parahaemolyticus, and vulnificus?
- Vibrio cholerae: water/food -> Gastroenteritis
- Vibrio parahaemolyticus: shellfish/seawater -> Gastroenteritis, wound infection, bacteremia
- Vibrio vulnificus: shellfish/seawater -> bacteremia, wound infection, cellulitis
What culture mediums are specific for Vibrio?
- Thiosulfate citrate bile salts sucrose (TCBS)
- Cary-Blair transport medium for delayed samples
What treatment is there for Vibrio Cholera, parahaemolyticus, and vulnificus?
- Vibrio cholera: first fluids, then doxycycline or tetracycline for adults, furazolidone for pregnant women, and trimethoprim-sulfamethoxazole for children *O139 is resistant to furazolidone and sulfa-trimethoprim*
- Vibrio parahaemolyticus: fluids; antibiotics in extreme cases
- Vibrio vulnificus: minocycline plus fluoroquinolone or cefotaxime
Describe the diarrhea associated with Campylobacter
- Greenish watery, foul smelling
- May be followed by bloody diarrhea
- Severe abdominal pain and fever are associated
What organism infection is associated with Guillain-Barre syndrome?
- Campylobacter jejuni
- Specifically serotype O:19
How do you grow campylobacter?
- Have to use Campylobacter selective agar
- Very little air/oxygen
- 42 degrees
How do you treat Campylobacter infections?
- GI: fluids
- Septicemia or severe GI: Erythromycin or azithromycin, also can use tetracyclines or fluoroquinolones
- Resistant to penicillins, cephs, and sulfonamides
Classify Helicobacter pylori (Shape, gram, motility, oxidase, urease)
- Gram negative rods
- Highly motile
- Oxidase positive
- Urease positive * urease deficient mutants don’t colonize stomach or cause pathology*
What do you use to treat Helicobacter?
Tetracycline, metronidazole, omeprazole, Bismuth salts
What do you use to treat Aeromonas hydrophila?
- Acute diarrhea: nothing
- Chronic diarrhea or systemic infection: Cipro, aminoglycosides, trimethoprim
- *resistant to beta lactam and erythromycin