More than a quarter (28 percent) of patients who developed AAD stopped taking their antibiotic, and 16 percent had a follow-up health care visit because of diarrheal symptoms.

EBM Commentary

This was a small observational trial that demonstrated 26 percent of patients given IV antibiotics in the ED developed AAD. This was an absolute increase of 13 percent over those patients given oral antibiotics only and fits well into the range of 5–39 percent previously described in the literature.

The primary outcome was patient-oriented but didn’t necessarily take into account all potential confounders (history of constipation and current medications that could have affected gastrointestinal motility or the development of diarrhea/constipation).

It was unclear if the primary outcome was accurately measured to minimize bias. Patients were asked about the development of AAD with a survey four weeks after finishing antibiotic therapy. This introduces potential recall bias.

Despite its limitations, this study provides important information about potential risks of an intervention that has yet to demonstrate any benefit in a patient population well enough to go home on a course of oral antibiotics.

In addition, if 28 percent of patients who develop AAD after a dose of IV antibiotics stop taking the antibiotics early due to the side effects, this could have implications for both the patient and may contribute to the eventual development of antimicrobial resistance.

Bottom Line

Giving IV antibiotics in the ED to patients well enough to go home on oral antibiotics is not without harm. This small observational study shows IV antibiotics are associated with an increased risk of AAD in this patient population.

Case Resolution

You decide not to give a dose of IV cefazolin and send the patient home with a five-day course of cephalexin for his cellulitis as recommended by the Infectious Diseases Society of America.⁴

Thanks to Meghan Groth, the emergency medicine pharmacy specialist at the University of Vermont Medical Center, for her help with this review.

Remember to be skeptical of anything you learn, even if you learned it on The Skeptics Guide to Emergency Medicine.

References

1. Bartlett JG. Antibiotic-associated diarrhea. N Engl J Med. 2002;346(5):334-339.
2. Ghose C. Clostridium difficile infection in the twenty-first century. Emerg Microbes Infec. 2013;2(9):1-8.
3. McFarland LV. Epidemiology, risk factors and treatments for antibiotic-associated diarrhea. Dig Dis. 1998;16(5):292-307.
4. Stevens DL, Bisno AL, Chambers HF, et al. Practice guidelines for the diagnosis 
and management of skin and soft tissue infections: 2014 update by the Infectious Diseases Society of America. Clin Infect Dis. 2014;59(2):e10-52.