Diagnosis and Management of Acute Gastroenteritis in the Emergency Department (Pharmacology CME)

Table of Contents

 

Acute gastroenteritis is a common complaint in the ED, and we know that in 79% of the cases, a causative organism is never found. Neither patients nor emergency clinicians want unnecessary testing or antibiotics. Nonetheless, there are certain conditions and circumstances that warrant more than just reassurance and advice to drink more fluids:

Is it possible to have AGE without vomiting and/or diarrhea?

What are the high-risk criteria for AGE?

What is the most likely cause of “traveler’s diarrhea?” Are antibiotics helpful?

Even if 70% of AGE cases are caused by viruses, is there anything an emergency clinician should do?

What does blood in the stool indicate?

If a patient reports AGE, having recently eaten fish, how can you rule out ciguatera or scombroid fish poisoning?

When and why is stool testing helpful? When is it useless?

What are the special guidelines around diagnosing and treating Clostridium difficile infection?

When are antibiotics helpful? Which ones should you choose?

Do antiemetics, antimotility agents, and probiotics work? Do proton-pump inhibitors and H2-blockers increase the likelihood of infection?

1. Abstract
2. Case Presentations
3. Introduction
4. Critical Appraisal of the Literature
5. Etiology and Pathophysiology
   1. Foodborne Illness
   2. Escherichia coli Infections
   3. Traveler's Diarrhea
   4. Cryptosporidium Infection
6. Differential Diagnosis
   1. Acute Appendicitis
   2. Ciguatera Fish Poisoning
   3. Scombroid Poisoning
7. Prehospital Care
8. Emergency Department Evaluation
   1. History
   2. Physical Examination
9. Diagnostic Studies
   1. Laboratory Studies
   2. Stool Culture Testing
      1. Testing for Shiga Toxin-Producing Escherichia coli Infection
      2. Testing for Giardia
      3. Testing for Immunocompromised Patients
      4. Testing for Clostridium difficile Infection
      5. Additional Stool Testing Assays
   3. Blood Cultures and Serologic Testing
   4. Imaging
10. Treatment
    1. Initial Hydration
    2. Symptom Control
       1. Antinausea/Antiemetic Agents
          • Additional Antinausea/Antiemetic Agent Therapies
       2. Antimotility Agents
       3. Probiotics
    3. Antibiotic Use in Acute Gastroenteritis
    4. Treatment for Parasitic Infection
    5. Vaccination Status
    6. Diet
    7. Infection Precautions
11. Special Populations
12. Controversies and Cutting Edge
    1. Proton-Pump Inhibitors and H2 Blockers
    2. Postinfectious Irritable Bowel Syndrome
13. Disposition
    1. Follow-up Recommendations
14. Summary
15. Time- and Cost-Effective Strategies
16. Risk Management Pitfalls for Managing Patients with Acute Gastroenteritis in the Emergency Department
17. Case Conclusions
18. Clinical Pathway for Emergency Department Management of Acute Gastroenteritis
19. Tables and Appendix
    1. Table 1. Distinguishing Factors in the Differential Diagnosis of Acute Gastroenteritis
    2. Table 2. Key Patient History Questions for Acute Gastroenteritis in the Emergency Department
    3. Table 3. Exposure/Patient Factors Associated With Bacterial Causes Likely to be Found on Stool Culture and Shiga Toxin Testing
    4. Table 4. Antibiotics for Suspected Bacterial Acute Gastroenteritis
    5. Appendix 1. Organisms Associated With Acute Gastroenteritis in the United States
20. References

Abstract

There are approximately 178 million cases of acute gastroenteritis annually in the United States, resulting in 473,000 hospitalizations and 5000 deaths. The vast majority of these cases are of viral etiology, self-limited, and require only supportive care; nonetheless, patients at high risk due to extremes of age or immunosuppression often require specific therapy to ensure resolution of symptoms. With this common ED presentation, there are many potential decisions related to resource utilization and management. This review provides a best-evidence approach to diagnosis and management supported by recent guidelines from the American College of Gastroenterology and the Infectious Diseases Society of America.

Case Presentations

You are working in the ED on a busy morning when you meet an otherwise healthy 42-year-old man reporting 2 days with 5 to 10 watery, nonbloody, unformed stools and persistent nausea, anorexia, and 1 to 2 episodes of nonbloody emesis each day. He is mildly tachycardic, but afebrile, and is normotensive. He is alert and conversant but appears mildly uncomfortable. He has dry mucous membranes and diffuse abdominal pain, with minimal tenderness on exam. He denies any recent hospitalizations, antibiotic use, foreign travel, or sick contacts. The patient requests that you “check blood work” and provide him with IV fluids and antibiotics for his infection. You wonder how best to educate him about the best use of his time and healthcare resources for his condition…

Your next patient is a 68-year-old woman with non-insulin-dependent diabetes, hypothyroidism, and previous cholecystectomy, who resides in an assisted-living facility. She describes 1 day of diarrhea, with a fever of 38.9°C (102°F) this morning. She is tachycardic and febrile, but normotensive. She reports some generalized abdominal cramping and has a soft abdomen. She denies any recent hospitalizations, antibiotic use, or foreign travel. She tells you that she heard that one of the kitchen staff had to leave early yesterday because “he looked sick and kept vomiting.” You wonder if there is a connection between this history and the current presentation, as you ask the clerk to call the assisted-living facility…

You leave that room to see a 34-year-old man who was diagnosed with acquired immunodeficiency syndrome (AIDS) last week with a CD4 count of 180 cells/mcL. He has an appointment at the end of this week with an infectious disease specialist to start antiretroviral treatment. He tells you that he has lost 30 lb in the last 4 months, with persistent watery diarrhea for the last 2 weeks. He denies fevers but has had relatively constant nausea with a few episodes of vomiting over this time. He looks frail and cachectic, is mildly tachycardic with a blood pressure of 100/60 mm Hg, and is afebrile. His abdomen is slightly tender with no rebound. You begin generating a differential diagnosis and wonder how extensive a workup he needs in the ED…

Introduction

Acute gastroenteritis (AGE) is broadly defined as inflammation of the stomach and intestine due to an infectious cause, generally presenting with diarrhea and vomiting, fever, and abdominal pain;^1,2 however, there is no universal definition of the specific clinical criteria that correlate with this disease entity. The long-standing notion that a diagnosis of AGE requires both vomiting and diarrhea is not supported by recent literature or clinical guidelines. Over the last several decades, there has been movement toward using diarrhea as the defining characteristic of AGE, initially with the 1996 American Association of Pediatrics practice guidelines for the management of AGE in young children.³ The 2016 American College of Gastroenterology (ACG) guidelines use a definition that emphasizes diarrhea in the diagnostic criteria, but acknowledges that AGE can also be a “vomiting-predominant illness with little or no diarrhea.”⁴ The most recent guidelines from the Infectious Diseases Society of America (IDSA) adopt a similar approach.¹

In the clinical studies where specific inclusion criteria are required, we generally see more-vague criteria that allow for either a vomiting-predominant or diarrhea-predominant presentation. This is reflected in the literature, with studies classifying AGE patients as those with ≥ 1 episode of vomiting and/or ≥ 3 episodes of diarrhea in a 24-hour period, without a known chronic cause for their symptoms (such as inflammatory bowel disease).⁵ The clinical definition for diarrhea is much more standardized, being defined as the passage at least 3 unformed stools (or more than 250 g) per day.² On the basis of duration, an acute episode lasts for < 14 days, while longer courses of illness are classified as persistent (14-29 days), or chronic (> 29 days). For the purposes of an emergency department (ED) evaluation, all of the expected symptoms need not be present to make a presumptive diagnosis of AGE. Patients present at different times in their course of illness, and it may not have evolved to include all of the classic signs and symptoms. Furthermore, depending on the mechanism of disease and host factors, patients with inflammation of the stomach and intestine due to an infectious cause may not ever develop any vomiting or diarrhea.

There are 178.8 million cases of acute gastroenteritis annually in the United States, resulting in 473,000 hospitalizations (0.26%) and 5000 deaths (0.0028%). In approximately 79% of these cases, a causative organism is never identified.⁶ Among ED patients with AGE, a causative organism is identified in only 25% of all cases; in cases where a stool sample is obtained and analyzed, 49% reveal a causative organism.⁵

Many common exposures increase the risk of developing AGE, such as domestic or international travel to areas with poor sanitation practices; antibiotic use; exposure to zoonoses; and time spent in healthcare settings, long-term care facilities, and childcare settings. Host features also play a significant role, particularly immunosuppression (due to medication or primary disease) and vaccination status. A careful history is essential to risk stratify patients.

This issue of Emergency Medicine Practice focuses on the evaluation and management of patients with AGE who present to the ED. Current literature and relevant subspecialty guidelines are evaluated to show where there is strong agreement regarding diagnosis and treatment, as well as where there are gaps in the literature. After completing this review, the reader should be able to rapidly and accurately evaluate and risk stratify ED patients with AGE and formulate a safe and comprehensive treatment plan and disposition.

Critical Appraisal of the Literature

A literature search was performed on PubMed for English language articles published from 1984 to 2018 using the search terms: diarrhea, emergency department (412 articles); acute gastroenteritis, emergency department (133 articles); Clostridium difficile, emergency department (30 articles); acute gastroenteritis clinical trials only (130 articles); ondansetron, gastroenteritis clinical trials only (13 articles); and antiemetic, gastroenteritis clinical trials only (119 articles). Pertinent articles returned from this search were examined for citations that would be relevant to this review. A review of leading emergency medicine texts as well as United States Centers for Disease Control and Prevention (CDC) guidelines, the 2017 IDSA guidelines,¹ and the 2016 ACG clinical guidelines⁴ were also evaluated for additional relevant citations.

There appears to be a discordance between the frequency of AGE in the United States and the number of publications investigating this disease. The literature is sparse in many key areas, such as indications for diagnostic testing and empiric antibiotic treatment. This paucity of data is reflected in subspecialty guidelines that lack specific recommendations for ED management of AGE. A notable contrast to this is the relative abundance of United States studies that guide evaluation and treatment of pediatric ED patients with AGE. As a consequence, many recommendations in this review for adult patients are extrapolated from the pediatric literature.

Risk Management Pitfalls for Managing Patients with Acute Gastroenteritis in the Emergency Department

3. “My patient just returned from the Democratic Republic of the Congo, and has been having large volumes of watery diarrhea. I decided to treat him for traveler’s diarrhea with empiric antibiotics and discharge him. He should be better in a few days.”

A patient with diarrhea returning from a low-resource country may have traveler’s diarrhea, but consideration should be given to other more severe causes of AGE. This is particularly true when the patient is returning from a nation where cholera epidemics are common.

5. “This healthy young man has had fever, vomiting, and grossly bloody diarrhea for the last day. He’s looking and feeling better after some oral medications and oral fluids. He probably has viral gastroenteritis, so there's no need to do any workup.”

Patients with grossly bloody stools are a minority of AGE patients seen in the ED, and they are significantly more likely to have bacterial infection. Withholding empiric antibiotics is acceptable in patients with a documented improvement in the ED and no high-risk features, but at a minimum, laboratory studies and a stool culture should be sent to guide therapy in case the patient does not continue to improve at home.

10. “He has had nausea, diarrhea, and abdominal cramping for the last 3 weeks. That sounds like a severe infection. I will treat him for bacterial gastroenteritis with azithromycin and send him home. No need to send any testing.”

Persistent diarrhea (> 14 days) has a differential diagnosis beyond bacterial AGE, including parasitic causes. Be sure to obtain a complete history, including a travel history, and send the appropriate laboratory and stool studies to make the correct diagnosis.

Tables and Appendix

References

Evidence-based medicine requires a critical appraisal of the literature based upon study methodology and number of subjects. Not all references are equally robust. The findings of a large, prospective, randomized, and blinded trial should carry more weight than a case report.

To help the reader judge the strength of each reference, pertinent information about the study, such as the type of study and the number of patients in the study is included in bold type following the references, where available. In addition, the most informative references cited in this paper, as determined by the author, are highlighted.

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