Gastrointestinal Infections

Case study: Between Thanksgiving and the winter holidays, clinic has been busier than ever with patients making last-minute appointments for sick visits. Some of your patients have been cycling in and out of clinic for weeks, toggling between upper respiratory symptoms and gastrointestinal illnesses. For example, when you last saw Mark three weeks ago, he had been sick with a fever, runny nose, and cough. At the time, he tested negative for influenza and appeared to have a viral upper respiratory infection. You recommended maintaining good hydration, Tylenol for fever, frequent hand washing, and rest. But he is back in clinic today, and you are curious why he is here. On your check-in paperwork, you see that the only symptom listed is “abdominal pain.” You knock on the door and enter the exam room. Mark is sitting on the examining table, looking miserable. He is a 45-year-old man in generally good health. He recently changed careers from IT and this is his first year teaching kindergarten. What do you want to know?

After greeting him, you ask Mark how he feels. He looks at you and says he has never been this sick in his life. He has spent the past 24 hours vomiting until there is only bile in his stomach. When he isn’t vomiting, he has been having severe diarrhea for the past 3 days, and his abdomen hurts too much for him to move. This morning, he noticed blood in his stool. Mark’s wife brought him in because she was worried that he had contracted the E. coli everyone had been reading about in the news. What do you want to do next?

On physical exam, Mark is febrile to 101.9 and has a heart rate of 112 beats per minute. His heart rate is slightly fast but rhythm is normal, breath sounds are clear bilaterally, but he does have diffuse abdominal tenderness throughout his abdomen. You look in both ears with your otoscope and do not appreciate any erythema or drainage. The patient does not have any palpable lymphadenopathy. While you are completing your physical exam, you ask him if he thinks he caught a GI bug. He tells you no. According to the news, the latest E. coli outbreak was associated with romaine lettuce, and he has been on the Paleo diet for a long time now. You ask him what that entails, and he tells you that he eats red meat, often “cooked so rare, the beef is still mooing.” At most, he had a small piece of lettuce on his hamburger last week. What additional testing do you want to perform?

You send a stool sample to the lab because the patient’s symptoms are most consistent with infectious diarrhea. In particular, the blood in the patient’s stool is most likely to be caused by Campylobacter jejuni, Salmonella, or E. coli O157:H7. You tell Mark that there are a lot of viral and bacterial gastrointestinal infections going around this time of year. You ask him about his urine output, and note that the biggest risk for him at this point is dehydration. You recommend oral rehydration fluids. Because you have not ruled out E. coli, you will not prescribe antibiotics for now. For the second time in a month, you send him home with instructions to maintain hydration, take acetaminophen for fever, and get some rest. Several hours later, the lab calls you to say that Mark tested positive for E. coli O157:H7. You call Mark back and tell him the diagnosis. You tell him that he is at risk for Hemolytic Uremic Syndrome (HUS), and to let you know if he develops decreased frequency urinating, feeling very tired, pallor, or any other concerning symptoms because HUS can lead to renal failure. You also tell him to not take any antibiotics because they have not been shown to improve symptoms of E. coli O157:H7 and may actually increase the risk of HUS.

Additional Resources

Switaj TL, Winter KJ, Christensen SR. Diagnosis and Management of Foodborne Illness. Am Fam Physician. 2015;92(5):358-65.

Dr. V. Silverstein
Durham, NC

Published on 12/12/19