Presence of Klebsiella aerogenes in Stool

Normal Intestinal Flora

The presence of K. aerogenes in stool does not automatically indicate pathogenicity or require treatment, as it can be part of the normal intestinal flora, according to the American Gastroenterological Association 1
K. aerogenes is part of the Enterobacteriaceae family, which normally composes the intestinal flora alongside other aerobes and facultative anaerobes, as stated by the European Society of Clinical Microbiology and Infectious Diseases 2

Standard stool culture protocols for infectious diarrhea target Salmonella, Shigella, Campylobacter, and Shiga toxin-producing E. coli—not K. aerogenes, as recommended by the Infectious Diseases Society of America 3
Guidelines for bacterial gastroenteritis do not list K. aerogenes as a pathogen requiring specific testing or treatment, according to the American College of Gastroenterology 3, 4
Finding K. aerogenes in stool typically represents colonization, not infection, unless there are systemic signs of illness, as noted by the American College of Physicians 4

If K. aerogenes is isolated from stool in a patient with diarrhea, consider alternative explanations for the diarrhea and look for other pathogens, as suggested by the American Gastroenterological Association 3, 4
While E. coli is a specific fecal indicator, Klebsiella species (including K. aerogenes) can be found in both fecal and non-fecal environmental sources, as reported by the Environmental Protection Agency 5