Acute Gastroenteritis- Author: Dr. Brian Geyer
Introduction:


Do both vomiting and diarrhea have to be present? No

1996 AAP guidelines, 2016 ACG guidelines, and 2017 IDSA guidelines all note diarrhea illness but may be vomiting predominant.


Studies use more vague definitions like:

> 1 episode of vomiting and/or > 3 episodes of diarrhea in 24 hours without known chronic cause like inflammatory bowel disease.
Diarrhea is at least 3 unformed stools per day.
Acute episode <14 days
Persistent episode 14-29 days
Chronic diarrhea >29 days


Patients in the ED may present with only some of these symptoms depending their time in course of illness.

Literature Review:

There is abundant literature on pediatric AGE but sparse research on AGE in adults. Therefore, many recommendations are extrapolated from the pediatric literature.

Causes:

70% of US cases are estimated to be caused by viruses, norovirus being most common.

o 26% norovirus
o 18% rotavirus


Among bacterial causes:

o 5.3% Salmonella, most common
o 5.3% Clostridium
o 3% Campylobacter
o 3% parasitic infections


Large portion, 51%, have no cause identified. (In ED patients)
Interestingly, 79% of cases never have a cause identified (not ED specific)
In ED patients, only 25% ever have a cause identified, this increases to 49% when a stool sample is obtained. (not ED specific)
Food poisoning is responsible for 5% of AGE but results in 30% of deaths. Most commonly:

Salmonella, Clostridium perfringens, and Campylobacter
Majority of foodborne illness is still viral, mostly norovirus


E Coli is normal in the gut, but two most common causes are:

Shiga toxin Ecoli (STEC) AKA enterohemorrhagic Ecoli (EHEC) - causes Hemolytic Uremic Syndrome in 5-10%
Entertoxigenic Ecoli (ETEC) - causes traveler's diarrhea
Both cause self-limited illness.



Alternate Diagnoses:

Appendicitis: In the peds literature, misdiagnosis of appendicitis as AGE leads to 47% absolute increased risk of perforation. Suggestive findings include:

Migration of pain to RLQ
RLQ tenderness on exam (initial or repeat)
Absence of diarrhea
Pain not improved with episodes of diarrhea
Negative factors include multiple ill family members, recent international travel, presence of diarrhea (as defined above).


Ciguatera Fish Poisoning

Toxin produced by algae consumed by reef fish like grouper, red snapper, sea bass and Spanish mackerel.
Symptoms begin 6-24 hours post ingestion.
Fish tastes normal.
Patients may develop neurological symptoms like paresthesias, generalized pruritis, and reversal of hot/cold sensation.
Symptoms resolve spontaneously, and treatment with mannitol is controversial.


Scombroid Poisoning

Ingesting fish in the Scombroidae family - mackerel, bonito, albacore, and skipjack - that have been stored improperly
Bacteria produce histidine decarboxylase which converts histidine to histamine
Causes abdominal cramps and diarrhea, and may cause metallic bitter or peppery taste in mouth, and facial flushing within 20-30 min of ingestion
Can be confused with allergic reaction
Symptoms resolve in 6-8 hours
Notification of health dept may prevent others from being infected.


Page 5 Table 1- Distinguishing Factors in the Differential Diagnosis of AGE

History:

Table 2, page 6 has key questions to ask.
Onset, timing, number of stools, presence of blood, fever, quality of abdominal pain and location, recent antibiotics, etc.
Extremes of age, immunosuppression, and pregnancy should be identified. Mortality is highest in the patients >65 yo.

Physical Exam:

We talked about RLQ abd pain, but what about bloody stool?
An observational study of 889 adults and 151 pediatric with AGE showed that a negative fecal occult test showed accurately excluded invasive bacterial etiology with a NPV 87% in adults and 96% in children. But PPV was only 24%.

Laboratory Testing and Imaging:

Dehydration is the biggest contributor to mortality, especially in the very young and elderly.
Lab evaluation for dehydration is recomme