The Ever-Present Threat of E Coli Toxin Diarrhea: What If It Comes Here?

Guest Commentary

Events in Germany and other European countries during the past several weeks have made me queasy every time I see vegetables. The fallout of the recent Shiga toxin–producing Escherichia coli epidemic has included renal failure from hemolytic uremic syndrome and death. The potential for international spread from travelers forced me to plot an updated approach to my patients who might present with acute, presumed infectious diarrhea. A literature review provided some recent informative articles on the topic.

PRIMARY CARE WORKUP
FOR ACUTE DIARRHEA
The first article is simply titled “Infectious Diarrhea: When to Test and When to Treat.”¹ It contains practical tips for primary care clinicians—the point persons for acute diarrhea evaluation. A simple approach begins with categorizing patients with acute diarrhea into one of two groups: those with bloody diarrhea and those without.

When you are deciding on appropriate tests, historical information steers your choices. Comorbidities; recent travel; ingestion of unfiltered water; recent use of antibiotics; contact with someone who is ill; exposure to food at high risk for transmission of diarrheal pathogens, such as raw or undercooked meat, shellfish, eggs, or milk; and selected employment exposures (daycare providers, food handlers, healthcare workers, or long-term care facility employees) are associated with specific pathogens (Campylobacter from undercooked chicken and Vibrio from raw shellfish, for example). International travelers are susceptible to Shigella infection, giardiasis, cryptosporidiosis, and cyclosporiasis—diseases that are not prominent in non-travelers.²

During the physical examination, focus on signs of volume depletion. Further laboratory testing should be strongly considered for the following patients with diarrhea of greater than 1 day’s duration: those with bloody stools, fever, symptoms of sepsis or volume depletion, recent antibiotic use, or an underlying immune-compromised state. What should you test for? An algorithm included in the article¹ offers the following helpful tips:
•If nausea is prominent, consider Norovirus, Rotavirus, or Adenovirus.
•Raw shellfish ingestion should be followed by a culture for Vibrio.
•Antibiotic exposure warrants Clostridium difficile toxin testing.
•Bloody diarrhea should prompt a search for Salmonella, Shigella, Campylobacter, E coli O157, and Yersinia. The E coli responsible for the recent and previous outbreaks may be detected by the presence of a Shiga-like toxin on a special assay.
•If diarrhea lasts longer than 7 days or follows travel or a community outbreak, examination of stool for ova and parasites should be added to the tests.

Additional diagnostic features of Shiga toxin–producing E coli diarrhea are bloody diarrhea preceded by 1 to 3 days of non-bloody diarrhea, 5 stools in 24 hours, abdominal tenderness, worsening pain on defecation, afebrile presentation, and no increase in polymorphonuclear leukocytes on complete blood cell count and differential. An important caveat is that not all patients with the E coli variant have bloody diarrhea.³

WHEN ARE ANTIBIOTICS WARRANTED?
It has been known for some time that antibiotic treatment of Salmonella infection may result in chronic carriage. However, bacteremia can occur in 2% to 4% of patients with gastrointestinal Salmonella infections.¹ Therefore, antibiotics should be given to patients younger than 6 months and those older than 65 years; patients who are immune-suppressed (including those receiving corticosteroids); and patients who have inflammatory bowel disease, a prosthetic joint or vascular material, or a hemoglobinopathy, or who are receiving dialysis.

These articles primed me to perform a rational history, physical examination, and screening workup for primary care patients with acute diarrhea. They also gave me a better idea of the presentation of toxic E coli diarrhea and its complications. ■