Acute ge
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"acute gastroenteritis"[MeSH Terms] AND management
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I now have comprehensive information. Here is a structured clinical overview of Acute Gastroenteritis:
Acute Gastroenteritis (Acute GE)
Definition
Acute gastroenteritis (AGE) is an acute-onset illness characterized by diarrhea (≥3 loose or watery stools/day), often accompanied by nausea, vomiting, abdominal cramps, and sometimes fever. It is typically self-limiting, lasting <14 days.
Etiology
Infectious (most common)
| Category | Pathogens |
|---|---|
| Viral | Rotavirus, Norovirus (most common in post-rotavirus vaccine era), Enteric adenoviruses (types 40/41), Astrovirus, Sapovirus |
| Bacterial | Salmonella, Shigella, Campylobacter, E. coli (ETEC, STEC/O157:H7), Yersinia, Vibrio spp., C. difficile, Aeromonas hydrophila |
| Parasitic | Giardia lamblia, Entamoeba histolytica, Cryptosporidium parvum |
| Preformed toxin | S. aureus, Bacillus cereus (rapid onset, vomiting-predominant) |
Non-infectious
- Dietary (overfeeding, food allergy)
- Antibiotic-associated diarrhea
- IBD flare
- Anatomic abnormalities (intussusception, partial obstruction)
- Endocrinopathies
Clinical Features
Presentation clues by syndrome
| Predominant symptom | Likely cause |
|---|---|
| Vomiting ± minimal diarrhea | Norovirus, preformed toxin (staph) |
| Watery diarrhea, no blood | Viral, ETEC, Cryptosporidium |
| Bloody diarrhea + fever | Shigella, Campylobacter, STEC, E. coli O157:H7 |
| Traveler returning from endemic area | ETEC, Giardia, E. histolytica |
| Rice-water stools | Vibrio cholerae |
Red Flags — consider alternative diagnoses:
- Peritoneal signs → Appendicitis
- Infant with crampy pain + bloody stools + vomiting → Intussusception
- Recent antibiotics → C. difficile
- Immunocompromised host → CMV, Microsporidium, Isospora
Assessment of Dehydration
The percentage body weight lost is the gold standard, but clinical signs guide ED management:
| Severity | Features |
|---|---|
| Mild (<5%) | Thirsty, slightly dry mucous membranes, normal capillary refill |
| Moderate (5–10%) | Dry mucous membranes, decreased skin turgor, sunken eyes/fontanelle, oliguria |
| Severe (>10%) | Tachycardia, hypotension, prolonged capillary refill, altered consciousness |
A validated dehydration score correlating with length of stay and IV rehydration need is used in practice. No single variable reliably indicates severity — use a combination of history and clinical exam. (Tintinalli's Emergency Medicine)
Investigations
- Most cases: No investigations needed (viral AGE is self-limiting)
- CBC: Only if ill-appearing or bloody diarrhea (to exclude HUS: hemolytic anemia, thrombocytopenia, renal failure)
- Serum electrolytes: Selectively — severe dehydration, extremes of age, altered mental status
- Serum glucose: Essential in infants/young children (hypoglycemia in up to 9%)
- Stool culture: Bloody diarrhea, febrile dysentery, immunocompromised, travel history, outbreak
- Multiplex PCR stool panel: Increasingly used; detects viral, bacterial, and parasitic pathogens simultaneously (faster than culture, but does not yield isolates for public health surveillance)
- Parasite evaluation (O&P ×3): Suspected parasitic infection; antigen tests for Giardia and Cryptosporidium have 80–90% sensitivity
Note: WBC and CRP are not reliable for distinguishing viral from bacterial gastroenteritis. (Tintinalli's)
Treatment
1. Oral Rehydration Therapy (ORT) — First-line
The cornerstone of management. Based on Na⁺/glucose co-transporter mechanism at the intestinal brush border, which remains intact even in severe diarrhea.
| ORS | Glucose (mmol/L) | Na⁺ (mEq/L) | Osmolarity |
|---|---|---|---|
| WHO Standard (1975) | 111 | 90 | 311 mOsm/L |
| WHO Reduced Osmolarity (2002) | 75 | 75 | 245 mOsm/L ✓ preferred |
| Pedialyte® | 139 | 45 | 250 mOsm/L |
- Avoid: Juices, sports drinks, tea — deficient in Na⁺, excess sugar amplifies losses
- Exception (high-income countries): In children with mild AGE and minimal dehydration, dilute apple juice followed by preferred fluids leads to fewer treatment failures than electrolyte maintenance solutions
2. IV Rehydration — Reserved for:
- Severe dehydration or hemodynamic compromise
- Inability to tolerate oral intake (persistent vomiting, severe abdominal pain)
- Medically fragile patients / altered consciousness
- Isotonic crystalloid (normal saline or Ringer's lactate) with appropriate KCl and dextrose is recommended
A Cochrane review found no difference between ORT and IV in failure to rehydrate or weight gain; ORT was associated with shorter hospital stay. (Tintinalli's)
3. Antiemetics
- Ondansetron (IV 0.15–0.3 mg/kg; oral 1.6–8 mg by weight): Reduces vomiting, IV hydration needs, and hospitalizations in children — meta-analyses confirm superiority over placebo
- Dimenhydrinate: Reduces time to cessation of vomiting by ~0.34 days in children
- Caution: ED use of ondansetron is beneficial, but post-discharge use has not demonstrated continued benefit (Yamada's)
4. Antimotility Agents
- Loperamide: Controversial — avoid in children <3 years and those with bloody diarrhea (risk of toxic megacolon, ileus). Partial efficacy in traveler's diarrhea in adults.
5. Antibiotics — Selective use only
| Indication | Choice |
|---|---|
| Traveler's diarrhea | Ciprofloxacin/Levofloxacin, Azithromycin, Rifaximin (non-invasive only) |
| Shigella | Azithromycin, fluoroquinolone, TMP-SMX |
| Severe Campylobacter | Ceftriaxone (invasive) |
| C. difficile | Metronidazole or Vancomycin (oral) |
⚠️ Do NOT give antibiotics empirically in routine AGE. Risks include: adverse effects, prolonged pathogen carriage (Salmonella), HUS development in STEC O157:H7, and selection of MDR bacteria.
6. Nutrition
- Early refeeding is encouraged — do not starve
- BRAT diet (bananas, rice, applesauce, toast) is not evidence-based; balanced diet is preferred
- Small, frequent feeds; resume normal diet as tolerated
Complications
| Complication | Notes |
|---|---|
| Dehydration | Most common; can be life-threatening in infants |
| Electrolyte disturbances | Hyponatremia, hypokalemia, metabolic acidosis |
| HUS | STEC O157:H7 — microangiopathic hemolytic anemia, thrombocytopenia, renal failure |
| Toxic megacolon | Shigella, C. difficile, rarely with loperamide |
| Bacteremia/sepsis | Salmonella in <3 months, immunocompromised |
| Reactive arthritis / Reiter's syndrome | Post-Campylobacter, Shigella, Salmonella |
| Post-infectious IBS | Altered gut microbiome and motility |
Prevention
- Vaccines: Rotavirus (universal infant vaccine), Typhoid, Cholera; norovirus vaccine in advanced development
- Hygiene: Handwashing with soap, safe food handling, clean water supply
- Traveler precautions: "Boil it, cook it, peel it, or forget it"; rifaximin for prophylaxis of non-invasive traveler's diarrhea
- Reportable pathogens must be notified to the local health department
Sources: Tintinalli's Emergency Medicine, 9th ed.; Yamada's Textbook of Gastroenterology, 7th ed.; Harriet Lane Handbook, 23rd ed.
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