Chapter 23, Problem 2CCS

The Case of the Lactovegetarians

Two patients—a woman and her husband, ages 23 and 22, respectively—arrive at the health clinic one morning. They report having had severe abdominal cramps, grossly bloody diarrhea, nausea, and fever for 48 hours. Cultures of stool samples grown under microaerophilic, capneic conditions contain comma- shaped, Gram-negative bacilli (see the photo). Both the patients are lactovegetarians and report being part of a “cow leasing” program at a local dairy in which patrons lease part of a cow’s milk production so they can drink natural, whole, raw milk. The couple devised the program so that they and several neighbors could circumvent state regulations prohibiting the sale of unpasteurized milk. Investigators obtained and cultured a milk sample from the dairy's bulk milk tank. The cultures contained the bacterium pictured.

1. 1. What is the pathogen?
2. 2. How did the couple become infected?
3. 3. Are the couple’s colleagues at work at risk of acquiring an infection from the couple?
4. 4. What other foods that are common sources of this bacterium can be ruled out in this case?