Enteric Bacterial Infections 3: The Vibrios

Question 1

What are the three vibrios?

Answer 1

Vibrio cholerae, parahaemolyticus, vulnificus

Question 2

Cellular characteristics of V. cholerae?

Answer 2

• Curved
• Motile
• Gram - rod

Question 3

Two reservoirs of V. cholerae?

Answer 3

Humans and ocean

Question 4

What cell wall antigen indicates pathogenicity in V. cholerae?

Answer 4

O cell wall antigen

Question 5

What are the two V. cholerae groups that cause epidemic disease?

Answer 5

O1 and O139 groups

Question 6

V. cholerae transmission?

Answer 6

Fecal-oral

Question 7

What is a major barrier to V. cholerae infection?

Answer 7

Stomach acid

Question 8

What makes a person susceptible to V. cholerae infection?

Answer 8

Gastrectomy, antacids, or coincident H. pylori infection

Question 9

What allows the surviving V. cholerae to reach the small intestine brush border?

Answer 9

Secretion of mucinase and toxin-coregulated pilus

Question 10

What are O1 and O139 markers for?

Answer 10

Infection with the CTX bacteriophage

Question 11

Why is a high infectious dose of V. cholerae needed for infection?

Answer 11

Much of the organism is killed by gastric acid

Question 12

Describe the choleratoxin

Answer 12

• A-B subunit structure
• B binds
• A causes percistent activation of adenylate cyclase resulting in loss of water and ions from attached cells

Question 13

What is the Pavlovian Syx of V. cholerae infection?

Answer 13

Massive rice water diarrhea

Question 14

What is the cause of morbidity and mortality from V. cholerae infection?

Answer 14

Dehydration and electrolyte imbalance

Question 15

What is the typical scenario in which V. cholerae infection occurs?

Answer 15

Following travel

Question 16

What is V. cholerae’s claim to fame in the diarrhea department?

Answer 16

Most watery diarrhea of any of the infectious gastroenteritis bugs

Question 17

Typical Syx of V. cholerae infection?

Answer 17

• No fever
• No pain with diarrhea
• band hypokalemia from bicarb and K+ loss
• Hypoglycemia

Question 18

Tx for V. cholerae infection?

Answer 18

Primarily rehydration

Question 19

What is a simple test to determine the hydration status of a patient?

Answer 19

The longitudinal pinch test to assess skin turgor

Question 20

Although not commonly performed, describe the culture technique for V. cholerae

Answer 20

• Use of bile salt agar
• Acid reaction on triple-sugar-iron agar
• Oxidase positive
• Sucrose (+)

Question 21

What supportive measures are taken in the management of V. cholerae?

Answer 21

• Rehydrate and rebalance electrolytes - IV Lactated Ringer solution
• Oral Rehydration solution
• Tetracyclines if necessary

Question 22

V. cholerae preventive methods

Answer 22

• Treat water, cook food
• Killed and live vaccine but not recommended for routine use in travelers
• Prophylactic tetracyclines

Question 23

What is the typical scenario of a V. parahaemolyticus infection?

Answer 23

Typically gastroenteristis

Question 24

Cellular characteristics of V. parahaemolyticus?

Answer 24

• Oxidase (+) Gram (-), Curved motile rod
• Halophile (lives in salty areas)

Question 25

Which is more common? V. parahaemolyticus or V. vulnificus? More lethal?

Answer 25

V. p. is more common, V. h. is more lethal

Question 26

Typical scenario of a V. vulnificus infection?

Answer 26

Lethal cellulitis

Question 27

What is the leading cause of gastroenteritis in those whoe eat undercooked seafood?

Answer 27

V. parahaemolyticus

Question 28

What is a very important point to make to a person with immunocompromise?

Answer 28

No more shellfish

Question 29

What is the method to culture V. parahaemolyticus?

Answer 29

* Culture in 8% NaCl * Culture from stool on thiosulfate-citrate-bile salts-sucrose media

Question 30

Tx for parahaemolyticus?

Answer 30

Oral rehydration but if severe (high fever) doxycycline or quinolone

Question 31

Characteristics that are similar b/w the V. cholerae and non-cholerae vibrios?

Answer 31

* Possibility of dehydration * Self-limited (generally) * Efficacy of doxycyline Tx

Question 32

What is different b/w the V. cholerae and the non-cholerae vibrios?

Answer 32

* Likelihood of dehydration * Likelihood of need for doxycycline

Question 33

Cellular characteristics of V. vulnificus

Answer 33

* Oxidase (+) * Gram (-) * Halophile

Question 34

What are the virulence factors of V. vulnificus?

Answer 34

* Hemolysin * **Protease exotoxin** * Siderophores - infection exacerbated by iron overload

Question 35

What are the Pavlovian Hx characteristics?

Answer 35

Cellulitis with Hx of handling raw shellfish

Question 36

Which bug has the highest case fatality rate for a foodborne illness?

Answer 36

V. vulnificus

Question 37

Tx for V. vulnificus?

Answer 37

Early and often debridement; Ceftazidime + Doxycycline (or antipseudomonal penicillin)

Question 38

What is similar in gastroenteritis and cellulitis caused by vibrios?

Answer 38

Exotoxin production and patient RFs for complications after infection