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).
What causes the V. vulnificus to produce severe, disseminated infections?
- Capsule production
What is the natural reservoir of Vibrio species?
- Estuarine and Marine environments
How is Cholera spread?
- By contaminated water and food.
How is V. cholerae and V. parahaemolyticus spread?
- Consumption of improperly cooked seafood or exposure to contaminated seawater.
Which strain of Vibrio is the most common cause of vibrio septicemia?
V. vulnificus
What are the clinical symptoms of V. cholerae?
- Asymptomatic, self-limited diarrhea or severe and rapidly fatal diarrhea. Rice-water stools from severe fluid and electrolyte loss that can come to hypovelemic shock and death.
What are the clinical symptoms of V. Parahaemolyticus?
- Watery explosive diarrhea with no eveident blood or muscus. The patient usually experiences an uneventful recovery.
What are the clinical symptoms of V. vulnificus?
- Rapidly progressive wound infection that leads to fever and chills, vomiting, diarrhea, and abdominal pain, septicemia, and intial swelling, erythema, and pain in wound site, followed by vesicles or bullae and eventual tissue necrosis.
What is the treatment recommendation for V. cholerae and V. parahaemolyticus infections?
- Fluid and electrolyte replacement. Azithromycin in severe cases.
What is the treatment for V. vulnificus?
- Prompt antibiotic treatment: minocycline w/ flouroquinolone or cefotaxime.
What are the medically relevant species of Aeromonas? (3)
- A. hydrophila, A. cavia, A. veronii biovar sobria.
What are the reservoirs for Aeromonas?
- Fresh and brackish waters
What are the disease that Aeromonas causes?
- Diarrhea, wound infection, and opportunistic systemic disease.
What is an unusual form of Aeromonas wound infection?
- Medical leeches whose gut is colonized with A. veronii biovar sobria.
What is the antibiotic of choice against Aeromonas?
- Ciprofloxacin.
