A 32-year-old woman goes to an emergency depament because she has developed severe, watery diarrhea. About 36 hours later, she developed vomiting and an abrupt, painless, watery diarrhea. The volume of diarrhea has been copious, and she has subsequently developed intense thirst, oliguria, muscle cramps, and weakness. At the time of being seen in the emergency depament, she is noted to have marked loss of tissue turgor, sunken eyes, and wrinkling of the skin of her fingers. Laboratory studies demonstrate hemoconcentration and severe metabolic acidosis with potassium depletion. An organism cultured from the patient's stool is subsequently characterized as an oxidase-positive, gram-negative curved rod with polar flagella that shows "shooting star" mobility and grows best on TCBS medium. Which of the following is the most likely pathogen?
High-Yield Explanation
The features noted are those of Vibrio cholerae, the causative organism of the severe diarrheal disease, cholera. The diarrhea is the result of the action of the cholera enterotoxin, which acts by ADP-ribosylating adenylate cyclase, leading to increased cyclic AMP with secondary increased efflux of Cl- and H2O. World-wide, cholera is usually spread by fecally contaminated water. Pseudomonas is an oxidase-positive, gram-negative rod that characteristically produces the blue pigment, pyocyanin. Salmonella is a motile, gram-negative rod that is a non-lactose fermenter that produces H2S. Shigella are non-motile gram-negative rods.