Dr. Fox’s outstanding post on Infectious Diarrhea is based on The 2017 Infectious Diseases Society of America Clinical Practice Guidelines for the Diagnosis and Management of Infectious Diarrhea [PubMed Abstract] [Full Text HTML] [Full Text PDF]. Clin Infect Dis. 2017 Oct 19. doi: 10.1093/cid/cix669. [Epub ahead of print]
In addition to Dr. Fox’s post Infectious Diarrhea be sure and also review Dr. Fox’s outstanding related posts:
- Diarrhea and Dehydration May 10, 2013
- Oral Rehydration Therapy is Faster
- Guillain-Barre Syndrome (related to Campylobacter)
- Hemolytic Uremic Syndrome
- Diarrhea and the Petting Zoo June 17, 2011
- C. Diff in Kids July 24, 2015
- Salmonella Gastroenteritis APRIL 6, 2012 · UPDATED AUGUST 30, 2013
- Nonspecific diarrheal illness or HUS? OCTOBER 22, 2010 · UPDATED JULY 22, 2015
- Crohn’s Disease Red Flags JANUARY 11, 2013
- ProBiotics for AGE (Acute Gastroenteritis) Feb 8, 2013
Moral of the Morsel:
- Most childrendo NOT need empiric antibiotics for acute diarrhea.
- Stool Culture can be helpful, particularly in the setting of bloody diarrhea, but antibiotics can usually wait for results as many pathogens do not benefit from antibiotics.
- Keep your Ddx open!
Most of the time pediatric diarrhea is a self-limited disease and the family doctor’s main job is to prevent dehydration and to focus on maintaining oral rehydration. But sometimes the patient does need antibiotics. And Dr. Fox goes over these instances in his post. As noted above his post is based on the Infectious Disease Society’s 2017 Guidelines on the diagnosis and management of pediatric and adult diarrhea (references and links at the start of this post – above).
Infectious Diarrhea: Basics
- Infectious diarrhea inflicts the greatest burden on regions with inadequate sanitation and hygiene.
- Classification of diarrhea by duration:
- Acute – < 7 days
- Prolonged – 7-13 days
- Persistent – 14-29 days
- Chronic – 30+ days
- Many infectious agents are very “potent” (i.e., transmitted via low inocula).
- Since vaccination for Rotavirus, Norovirus now is the leading cause of hospitalization due to gastroenteritis.
- Most common bacterial pathogens:
- Salmonella enterica – leading bacterial cause of hospitalization due to gastroenteritis
- E. coli O157
- Some post-infectious complications to consider:
Infectious Diarrhea: IDSA Takeaway Points
The IDSA document is rather thorough, but here are some of the useful takeaway points that can help us in the acute care environments. [Shane, 2017]
- Historic points can help find patients at higher risk for infectious diarrhea in developed countries:
- Fever and/or Bloody diarrhea should catch your attention for possible enteropathogens:
- Travel to endemic areas and/or consumption of foods prepared by people with recent endemic exposure increase risk.
- Enteropathogens may present in similar clinical fashion, but can differ in their management!
- Shigella and Campylobacter may benefit from antimicrobials.
- Salmonella and Shiga Toxin producing E. Coli (STEC) do not!
- When concern for Shiga Toxin producing organisms, distinguishing between Shiga toxin 1 and Shiga toxin 2 (which is more potent) is useful.
- Considering HUS in these cases is important.
- Look for pallor and/or petechiae!
- Look for renal dysfunction, thrombocytopenia, or anemia.
- Stool studies can help determine appropriate management.
- Stool cultures and Shiga toxin assays are recommended when fever/bloody diarrhea is present.
- Obviously, stool culture results won’t guide initial management, but can affect follow-up care.
- Negative stool cultures can also raise concern for other etiologies, like Inflammatory Bowel Disease.
- Fecal leukocyte and stool lactoferrin detection should NOT be used to establish the cause of acute infectious diarrhea.
- Blood cultures should be obtained for:
- Infants < 3 months of age
- Signs of septicemia
- Immunocompromised patients
- Patients with high risk for hemolytic anemia
The routine ova and parasite examination has very poor sensitivity for 2 of the most common parasites found in the United States, G lamblia (66-79% sensitivity) and Cryptosporidium spp (< 5%). [7, 8, 9] Another method, such as an immunoassay for parasite antigen, should be used for laboratory diagnosis of these organisms.  Many labs offer an “ova and parasite screen” that consists of an immunoassay to detect only these 2 organisms. Some laboratories offer an immunoassay for E histolytica, but this test must be performed on unpreserved sample.
In regard to testing for enteric parasites please see my post: When And How To Test For Enteric Parasites (coming soon).
Now resuming the extracts from Dr. Fox:
- Empiric Therapy:
- In immunocompetent patients, empiric antibiotics while awaiting culture results are NOT recommended.
- Close family contacts that are asymptomatic do not need empiric therapy.
- Avoid antibiotics for people infected with STEC O157 and other Shiga toxin 2 producing organisms.
- Empiric therapy is recommended for:
- Ill appearing patients with documented fever and bacillary dysentery (frequent, scant bloody stools with abdominal cramping and tenesmus – presumptively due to Shigella).
- Patients who recently travelled internationally with temp >38.5C and signs of sepsis.
- Immunocompromised patients with severe illness and bloody diarrhea.
- Empiric therapy for children:
- 3rd Generation cephalosporin for infants <3 months of age and others with neurologic involvement
- Azithromycin is also an option based on local resistance patterns.