Question

Case Study #2

A 59 year old man presents with a one day history of fever, abdominal cramps and diarrhea. His symptoms began six hours after the onset of the "runs" in two of his grandchildren and their mother all of whom had been visiting from their dairy and poultry farm in Wisconsin. The day before becoming ill all had eaten a meal consisting of Caesar salad, pasta with stir fried vegetables, bread and apples. His wife prepared her popular homemade mayonnaise.  Other than the abdominal pain and six unformed bowel movements which contained mucus, he had no complaints.

On examination the man appeared ill. Temperature was 39.3 C, pulse 100 and blood pressure 110/80 standing. He had no rash. The abdomen was tender in the periumbilical area. No pain noted otherwise. Laboratory studies presented below.

Stool culture on enteric agar

On examination the man appeared ill. Temperature was 39.3 C, pulse 100 and blood pressure 110/80 standing. He had no rash. The abdomen was tender in the periumbilical area.

WBC                              9.8 X 103 /mm3 Fecal leukocytes              Positive Fecal occult blood           Negative Stool culture is growing motile, lactose non-fermenting, gram rod that is H2S.Positive.

1. What is the likely cause of this man's diarrhea?
2. Do these organisms cause diarrhea by invasion or toxin production?
3. How did the members of the family become infected?  What is the usual route of infection with this pathogen?  
4. What is the preferred therapy for enteritis due to this organism?
5. What measures could be adopted to by this family to reduce the chance of a repeat infection later?

Answer 1

The man is infected by Salmonella species which is a Gram- negative rod of Enterobacteriaceae family. It produces symptoms within 12-72 hours of infection which includes diarrhea, fever, and abdominal cramps. Salmonella enters the body via fecal-oral route. Bacteria is present in food and water contaminated with fecal water. The family members got the infection through contaminated salad. The bacteria infects the body through toxin. Preferred therapy is oral rehydration therapy to maintain the fluid volume of the body and medications. In this either the salad vegetables are already contaminated with fecal water or may become contaminated through cross contamination by poultry. Eating raw vegetables should be avoided, storage of poultry with vegetables is to be avoided and separate chopping devices should be used for vegetables and poultry, and for raw and cooked food.