31 VIBRIO AND AEROMONAS Flashcards
What is the common characteristic of Vibrio under the microscope?
- Shape of a curved rod.
What doe all species of vibrio require for growth?
Salt
What are the medically relevant species of Vibrio?
- V. cholera, V. parahaemolyticus, V. vulnificus
What are Vibrios suceptible to in terms of environments?
- Stomach acids, and dry environments
What do most Vibrios have structurally?
- Polar flagella (for motility)
Which strains of V. cholerae produce the cholera toxin and are associated with epidemics of cholera?
O1 and O139
What are the two biotypes of V. cholerae O1?
Classic and El Tor.
What are the 3 serotypes of of V. cholerae O1?
- Inaba, Ogawa, and Hikojima.
Which biotype of V. cholearae O1 was responsible for the sixth worldwide pandemic? Which one for the current one?
- Classical type. El Tor
What does the V. cholerae O1 doen’t have structurally?
- A capsule, so infection does not spread beyond the confines of the intestine.
How many chromosomes does V. cholerae and V. parahaemolyticus have?
- 2 circular chromosomes, each of which contains essential genes for these bacteria.
Describe the structure and mechanism of the Cholera toxin.
- A-B toxin (similar to heat-labile enterotoxin of E. coli). 5 B subunits that bind to the GM1 receptors on intestinal epithelial cells. The A subunits enters and interacts w/ G proteins that causes catabolic conversion of ATP to cAMP. Results in hypersecretion of water and electrolytes.
How is V. cholerae able to adhere to mucosal cell layer? (2)
- By means of the toxin co-regulated pili and chemotaxis proteins.
How can V. cholerae O1 still produce significant diarrhea in the absence of the cholera toxin?
- Thru the ation of the zonula occludens toxin and accessory cholera enterotoxin.
What do the most virulent strains of V. parahaemolyticus produce and how does it appear in culture?
A thermostable direct hemolysin (Kanagawa hemolysin). B-hemolytic colonies with human blood only (Kanagawa positive).