Vibrios

Question 1

what are the vibrios and what shape are they? and gram stain?

Answer 1

Vibrio cholera, vibrio vulnificus, vibrio parahaemolyticus

curved rods, gram negative

Question 2

what is the best way to prevent cholera?

Answer 2

good hygiene and food and water sanitation

Question 3

what is unique about the lifecycle of vibrio cholera?

Answer 3

DUAL LIFECYCLES:

• planktonic: rarely pathogenic, source of genetic diversity, mostly in primarily Indian Ocean but now seen in Gulf of Mexico
• human pathogen: this type carries the CTX bacteriophage –> enters water supply and infects–> infected feces re-enters the water supply to continue the cycle

Question 4

Vibrio cholera are _____ anaerobic and what type of motility do they have?

Answer 4

FACULTATIVE anaerobic

motile via polar flagellum

Question 5

What indicates pathogenicity in vibrio cholera?

Answer 5

O cell wall antigen; O1 and O139 (markers for infection by CTX)–> 2 biotypes: El tor and cholera
–> 3 serotypes: Ogawa, Inaba, Hikojima (diff. antigens that are distinguishable on testing)

Question 6

What does “rice water” stool indicate?

Answer 6

cholera infection

Question 7

all vibrio will grow on ________ in vitro

Answer 7

bile salts agar

Question 8

cholera pathogenesis

Answer 8

fecal-oral transmission, high Infectious Dose, colonizes small intestine w/ mucinase and toxin-coregulated pilus (TCP), secretes Choleragen exotoxin enterotoxin, AB subunit signal transduction alterer → massive watery diarrhea (“rice water stool”), both intracellular and interstitial.

Question 9

What carries the choleragen gene?

Answer 9

lysogenic bacteriophage CTX

Question 10

T/F: cholera bacteremia is common

Answer 10

FALSE: Cholera bacteremia is rare, most morbidity and mortality from dehydration and electrolyte imbalance (acidosis, loss of potassium).

Question 11

How do you diagnose interstitial dehydration in the face of GI illness like cholera?

Answer 11

skin-tenting pinch test

Question 12

How do you treat cholera?

Answer 12

treated with IV Lacted Ringer Solution. (Not just saline – acidosis.)

Question 13

Do you need abx to treat vibrio infection?

Answer 13

Short course of doxycycline helps shorten course of cholerae or parahaemolyticus, rehydration more important

Question 14

How would yo describe the course of illness caused by vibrio parahaemolyticus & vulcanis?

Answer 14

parahaemolyticus: gastroenteritis (usually self-limited)
vulcanis: rapid-progression cellulitis (life-threatening)
from eating or handling raw shellfish.

Question 15

What is the reservoir for vibrio parahaemolyticus & vulcanis?

Answer 15

Reservoir ocean water → halophiles.

Question 16

What predisposes one to complications of infection with vibrio parahaemolyticus & vulcanis? How do you treat in these situations?

Answer 16

liver disease, immunodeficiency, iron overload

–> doxycycline and IV rehydration

Question 17

How do you diagnose vibrio cellulitis?

Answer 17

exam (rapid progression, hemorrhagic bullae, seawater-exposed injury), Gram&culture, treat with dual antibiotics and surgical care.

Question 18

What is a major complication of vibrio caused cellulitis?

Answer 18

rapidly-fatal septicemia –> heorrhagic bullae in the setting of immunocompromise

Question 19

virulence factors for V. parahaemolyticus

Answer 19

T3SS

Question 20

virulence factors for V. vulnificus

Answer 20

hemolysin, protease exotoxins, siderophores

Question 21

How does cholera most commonly cause morbidity and mortality?

Answer 21

dehydration and electrolyte imbalance–> acidosis

*bacteremia is rare

Question 22

Is there a cholera vaccine?

Answer 22

yes, but it is only modestly effective and only used in epidemics