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gi.acute-gastroenteritis.core.v1PRODUCTION
gi.acute-gastroenteritis.core.v1

Acute Infectious Gastroenteritis / Acute Diarrhoea (viral, bacterial incl. invasive/inflammatory, traveller's, toxin food poisoning, C. difficile pointer) — adult + pediatric

gastroenterologyacuteadultpediatric
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12/12 authored

Canonical 12-phase frame with authored status for this dossier.

Current phase

Frame

Detailed

Establish scope — acute (≤14 d) infectious diarrhoea, adult vs pediatric; set the watery-vs-inflammatory and dehydration-severity frame; persistent (>14 d) or surgical-abdomen/IBD mimic forks to a different pathway (IDSA 2017 PMID 29053792; ACG 2016 PMID 27068718)

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acute infectious-diarrhoea context confirmed and adult/pediatric set; persistent/mimic rerouted

Patient inputs (21)

Pediatric vs adult vs elderly — weight-based ORS/zinc/antiemetic dosing; age extremes raise complicated-course and mortality risk (ESPGHAN/ESPID 2014 PMID 24739189; IDSA 2017 PMID 29053792)

Tachycardia — dehydration/hypovolaemia and sepsis screen (qSOFA/SIRS) for invasive enteric infection (IDSA 2017 PMID 29053792)

Hypotension/orthostasis → severe dehydration / hypovolaemic or septic shock route (IDSA 2017 PMID 29053792)

Fever component of the inflammatory/invasive pivot and the sepsis screen (IDSA 2017 PMID 29053792)

Acute (≤14 d) vs persistent (>14 d) — persistent routes to chronic-diarrhoea/post-infectious workup (ACG 2016 PMID 27068718)

Clinical dehydration assessment (capillary refill, mucous membranes, skin turgor, sunken eyes, mental status, % weight loss) sets severity tier and rehydration route — load-bearing pivot #2 (ESPGHAN/ESPID 2014 PMID 24739189; WHO ORS PMID 11869639)

Bloody/dysenteric stool raises invasive bacterial probability AND (if low/no fever) the STEC/HUS prior — drives stool testing and the no-empiric-antibiotic STEC anti-pattern (IDSA 2017 PMID 29053792; Wong NEJM 2000 PMID 10874060)

Pediatric ORS deficit/maintenance, zinc and ondansetron dosing; % weight loss is the pediatric dehydration metric (ESPGHAN/ESPID 2014 PMID 24739189)

Drug safety — avoid fluoroquinolones; ceftriaxone/azithromycin preferred parenteral/oral; Listeria/Salmonella considerations (ACG 2016 PMID 27068718; ISTM/IDSA 2017 PMID 28521004)

Intractable vomiting limits ORS and is an antiemetic + admission trigger (Freedman NEJM 2006 PMID 16625009)

HIV/transplant/chemo/biologic → broader pathogen spectrum, lower antibiotic threshold, prolonged course, admit (IDSA 2017 PMID 29053792)

Recent antibiotics / hospitalisation → C. difficile pivot — toxin/NAAT testing, no antimotility, route to dedicated CDI pathway (IDSA/SHEA 2021 PMID 34164674)

Travel raises ETEC/EAEC/Campylobacter/protozoal priors and enteric-fever consideration (ISTM/IDSA 2017 PMID 28521004)

Shared-meal/sick-contact/outbreak history — toxin food poisoning, public-health reportable pathogens, food-handler considerations (ACG 2016 PMID 27068718)

Significant comorbidity (CKD, cirrhosis, IBD, cardiac) raises complicated-course risk and modifies disposition + drug dosing (IDSA 2017 PMID 29053792)

Baseline + serial creatinine — volume-depletion AKI / STEC-HUS detection and renal antibiotic dose adjustment (CKD-EPI 2021)

Na/K/HCO3 — hypo/hypernatraemic dehydration, hypokalaemia, metabolic acidosis from losses guide rehydration solution choice (ESPGHAN/ESPID 2014 PMID 24739189)

Leukocytosis/left-shift supports invasive bacterial disease; falling Hb + thrombocytopenia + rising creatinine = HUS (Wong NEJM 2000 PMID 10874060)

Elevated lactate flags hypoperfusion/septic shock from invasive enteric infection (Sepsis-3)

Stool culture-independent multiplex PCR (sens ≥94.5%/spec ≥97% — Buss JCM 2015 PMID 25588652) vs culture; Shiga-toxin/STEC; fecal leukocytes/lactoferrin/calprotectin; O&P selectively; C. diff toxin/NAAT — only when inflammatory/severe/immunocompromised/traveller/public-health/persistent (IDSA 2017 PMID 29053792; ACG 2016 PMID 27068718)

Oliguria flags severe dehydration and volume-depletion AKI / HUS surveillance (KDIGO; IDSA 2017 PMID 29053792)

* = hard-required. Engine cannot meaningfully run until these are filled.

Severity triggers (7)

7 need judgement
  • informationallife_threateningsevere_dehydration_hypovolemic_shock
    Severe dehydration (≥10% peds weight loss / lethargy, sunken eyes, absent tears, prolonged capillary refill, weak pulse) or hypotension/orthostatic shock (ESPGHAN/ESPID 2014 PMID 24739189; IDSA 2017 PMID 29053792)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationallife_threateningsuspected_STEC_HUS_avoid_antibiotics
    Bloody diarrhoea with little/no fever ± abdominal pain ± oliguria/pallor — suspected Shiga-toxin E. coli / evolving HUS (Wong NEJM 2000 PMID 10874060)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationallife_threateningsepsis_septic_shock_invasive_enteric
    Invasive enteric infection with qSOFA/SIRS positivity + hypotension despite fluids + lactate >2 mmol/L (Sepsis-3; IDSA 2017 PMID 29053792)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalseveredysentery_bloody_diarrhea_with_fever
    Bloody/mucoid (dysenteric) stool + high fever ± severe abdominal pain/tenesmus — invasive bacterial enteritis (IDSA 2017 PMID 29053792)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalseverevolume_depletion_aki
    Rising creatinine / oliguria from volume depletion (or STEC-HUS) during acute gastroenteritis (KDIGO; Wong NEJM 2000 PMID 10874060)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalsevereimmunocompromised_host_with_AGE
    Acute gastroenteritis in HIV/transplant/chemotherapy/biologic-immunosuppressed host (IDSA 2017 PMID 29053792)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalmoderateintractable_vomiting
    Vomiting preventing oral rehydration despite a dose of ondansetron (Freedman NEJM 2006 PMID 16625009)
    Trigger could not be auto-evaluated — needs clinician judgement.

Workflow calculators

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Recommended regimen

Acute gastroenteritis management — rehydration + selective antimicrobial + antiemetic (IDSA 2017 PMID 29053792 + ACG 2016 PMID 27068718 + ISTM/IDSA 2017 PMID 28521004 + ESPGHAN/ESPID 2014 PMID 24739189 + WHO ORS PMID 11869639)
axis: acute_gastroenteritis_managementstep 1 - Step 1 — Rehydration foundation (all patients) + early refeeding
Selected step "Step 1 — Rehydration foundation (all patients) + early refeeding" — Every acute gastroenteritis patient — rehydration is the cornerstone regardless of aetiology
  • reduced_osmolarity_oral_rehydration_salts
    first line
    oral_rehydration
    Reduced-osmolarity ORS — replace deficit (mild ~50 mL/kg, moderate ~100 mL/kg over 3-4 h) + ongoing losses (~10 mL/kg per stool) + maintenance • PO • continuous, frequent small volumes
    triggers: mild_or_moderate_dehydration, tolerating_PO
    Reduced-osmolarity ORS is the cornerstone for mild-moderate dehydration — fewer unscheduled IV infusions (OR 0.61, 95% CI 0.47-0.81), less stool output and vomiting vs standard ORS (Hahn BMJ 2001 / Cochrane CD002847 PMID 11869639; ESPGHAN/ESPID 2014 PMID 24739189). No single RxNorm CUI → non_pharm.
  • iv_isotonic_crystalloid_rehydration
    first line
    crystalloid
    Isotonic crystalloid (LR or NS); peds 20 mL/kg boluses to reverse shock then deficit + maintenance; adult 30 mL/kg if septic/shock then titrate • IV • bolus then maintenance
    triggers: severe_dehydration, hypovolemic_or_septic_shock, failed_or_unable_ORS, intractable_vomiting
    IV isotonic crystalloid for severe dehydration/shock or ORS failure (IDSA 2017 PMID 29053792; ESPGHAN/ESPID 2014 PMID 24739189)
  • early_refeeding_continue_breastfeeding
    first line
    supportive_nutrition
    Resume age-appropriate diet within 4-6 h of rehydration; continue breastfeeding throughout; no dietary dilution/restriction • PO • continuous
    triggers: rehydrated, tolerating_PO
    Early refeeding shortens illness; do NOT withhold food or interrupt breastfeeding (ESPGHAN/ESPID 2014 PMID 24739189)
  • zinc_sulfate
    add on
    micronutrient
    10 mg/day (<6 mo) or 20 mg/day (≥6 mo) PO × 10-14 days • PO • once daily
    triggers: pediatric, lmic_or_zinc_deficiency_risk
    WHO/UNICEF — zinc reduces diarrhoea duration/severity and recurrence in children in low-resource settings (ESPGHAN/ESPID 2014 PMID 24739189)
    rxcui 39954

outpatient playbook — drug actions (5)

  1. 1. reduced-osmolarity ORS
    Deficit (mild ~50 mL/kg / moderate ~100 mL/kg over 3-4 h) + ongoing losses + maintenance • PO • frequent small volumes
    trigger: Mild-moderate dehydration, tolerating PO
    Cornerstone — unscheduled-IV OR 0.61 (Hahn PMID 11869639)
  2. 2. early refeeding / continue breastfeeding
    Age-appropriate diet within 4-6 h; no dietary restriction • PO • continuous
    trigger: After initial rehydration
    Shortens illness; do not withhold food (ESPGHAN/ESPID 2014 PMID 24739189)
  3. 3. zinc sulfate (pediatric LMIC)
    rxcui 39954
    10 mg/day (<6 mo) or 20 mg/day (≥6 mo) × 10-14 days • PO • once daily
    trigger: Pediatric, low-resource/zinc-deficiency-risk
    Reduces duration/recurrence (WHO/UNICEF; ESPGHAN/ESPID 2014)
  4. 4. ondansetron (selective)
    rxcui 26225
    Peds 0.15 mg/kg single dose; adult 4-8 mg • PO/ODT • single dose
    trigger: Vomiting limiting ORS
    Facilitates oral rehydration (Freedman PMID 16625009); QT caution
  5. 5. azithromycin (only if moderate-severe traveller's / febrile dysentery)
    rxcui 18631
    1000 mg single dose or 500 mg daily × 3 d • PO • single/×3 d
    trigger: Moderate-severe traveller's or febrile dysentery, STEC not suspected
    Selective only — not routine viral AGE (ISTM/IDSA 2017 PMID 28521004)

Auto-drafted A&P note

outpatient

Subjective

- Possible entry pathways: Acute diarrhoea (≤14 d, usually <7) ± nausea/vomiting (IDSA 2017 PMID 29053792; ACG 2016 PMID 27068718); Bloody / mucoid (dysenteric) stool ± fever ± tenesmus — invasive/inflammatory bacterial pivot (IDSA 2017 PMID 29053792); Fever + diarrhoea — inflammatory/invasive or systemic enteric infection (IDSA 2017 PMID 29053792).

Objective

- No vitals, labs, or imaging entered for this encounter.

Assessment

**Acute Infectious Gastroenteritis / Acute Diarrhoea (viral, bacterial incl. invasive/inflammatory, traveller's, toxin food poisoning, C. difficile pointer) — adult + pediatric** (gi.acute-gastroenteritis.core.v1).
Phenotype framing: Viral AGE (commonest) vs inflammatory bacterial (Salmonella/Shigella/Campylobacter/STEC/Yersinia/Vibrio) vs preformed-toxin food poisoning vs traveller's (ETEC/EAEC/protozoal) vs C. difficile vs non-infectious mimics (early IBD/UC flare, ischaemic colitis, appendicitis with diarrhoea, DKA/thyrotoxicosis, medication/laxative, overflow, HUS/TTP) (IDSA 2017 PMID 29053792; ACG 2016 PMID 27068718)
Scope: Establish scope — acute (≤14 d) infectious diarrhoea, adult vs pediatric; set the watery-vs-inflammatory and dehydration-severity frame; persistent (>14 d) or surgical-abdomen/IBD mimic forks to a different pathway (IDSA 2017 PMID 29053792; ACG 2016 PMID 27068718)

No severity triggers fired against current inputs.

Plan

Regimen axis: **Acute gastroenteritis management — rehydration + selective antimicrobial + antiemetic (IDSA 2017 PMID 29053792 + ACG 2016 PMID 27068718 + ISTM/IDSA 2017 PMID 28521004 + ESPGHAN/ESPID 2014 PMID 24739189 + WHO ORS PMID 11869639)** — step "Step 1 — Rehydration foundation (all patients) + early refeeding".
1. reduced_osmolarity_oral_rehydration_salts Reduced-osmolarity ORS — replace deficit (mild ~50 mL/kg, moderate ~100 mL/kg over 3-4 h) + ongoing losses (~10 mL/kg per stool) + maintenance PO continuous, frequent small volumes (oral_rehydration, first line) — Reduced-osmolarity ORS is the cornerstone for mild-moderate dehydration — fewer unscheduled IV infusions (OR 0.61, 95% CI 0.47-0.81), less stool output and vomiting vs standard ORS (Hahn BMJ 2001 / Cochrane CD002847 PMID 11869639; ESPGHAN/ESPID 2014 PMID 24739189). No single RxNorm CUI → non_pharm.
2. iv_isotonic_crystalloid_rehydration Isotonic crystalloid (LR or NS); peds 20 mL/kg boluses to reverse shock then deficit + maintenance; adult 30 mL/kg if septic/shock then titrate IV bolus then maintenance (crystalloid, first line) — IV isotonic crystalloid for severe dehydration/shock or ORS failure (IDSA 2017 PMID 29053792; ESPGHAN/ESPID 2014 PMID 24739189)
3. early_refeeding_continue_breastfeeding Resume age-appropriate diet within 4-6 h of rehydration; continue breastfeeding throughout; no dietary dilution/restriction PO continuous (supportive_nutrition, first line) — Early refeeding shortens illness; do NOT withhold food or interrupt breastfeeding (ESPGHAN/ESPID 2014 PMID 24739189)
4. zinc_sulfate 10 mg/day (<6 mo) or 20 mg/day (≥6 mo) PO × 10-14 days PO once daily (micronutrient, add on) — WHO/UNICEF — zinc reduces diarrhoea duration/severity and recurrence in children in low-resource settings (ESPGHAN/ESPID 2014 PMID 24739189)

Setting playbook (outpatient) — Mild-moderate acute gastroenteritis, no red flag — reduced-osmolarity ORS + early refeeding + return precautions; NO routine stool testing or antibiotics (ACG 2016 PMID 27068718; ESPGHAN/ESPID 2014 PMID 24739189)
5. reduced-osmolarity ORS Deficit (mild ~50 mL/kg / moderate ~100 mL/kg over 3-4 h) + ongoing losses + maintenance PO frequent small volumes — Mild-moderate dehydration, tolerating PO (Cornerstone — unscheduled-IV OR 0.61 (Hahn PMID 11869639))
6. early refeeding / continue breastfeeding Age-appropriate diet within 4-6 h; no dietary restriction PO continuous — After initial rehydration (Shortens illness; do not withhold food (ESPGHAN/ESPID 2014 PMID 24739189))
7. zinc sulfate (pediatric LMIC) 10 mg/day (<6 mo) or 20 mg/day (≥6 mo) × 10-14 days PO once daily — Pediatric, low-resource/zinc-deficiency-risk (Reduces duration/recurrence (WHO/UNICEF; ESPGHAN/ESPID 2014))
8. ondansetron (selective) Peds 0.15 mg/kg single dose; adult 4-8 mg PO/ODT single dose — Vomiting limiting ORS (Facilitates oral rehydration (Freedman PMID 16625009); QT caution)
9. azithromycin (only if moderate-severe traveller's / febrile dysentery) 1000 mg single dose or 500 mg daily × 3 d PO single/×3 d — Moderate-severe traveller's or febrile dysentery, STEC not suspected (Selective only — not routine viral AGE (ISTM/IDSA 2017 PMID 28521004))

Non-pharmacologic actions:
- Return precautions: bloody stool, high fever, lethargy, no urine 8-12 h, unable to keep fluids down, signs of severe dehydration → ED
- Hand hygiene / food-safety counselling; exclude from work/school per local rules
- NO antimotility if bloody/febrile, C. diff suspected, or pediatric bloody stool (anti-pattern)
- NO antibiotics if suspected STEC (bloody stool, low/no fever) — supportive only + HUS surveillance

AVOID / contraindication checks:
- No_empiric_antibiotics_for_routine_viral_AGE (ACG 2016 PMID 27068718; IDSA 2017 PMID 29053792)
- No_empiric_antibiotics_in_suspected_STEC_EHEC_O157_HUS_risk (Wong NEJM 2000 PMID 10874060)
- No_antimotility_in_dysentery_Cdiff_or_pediatric_bloody_diarrhea (IDSA 2017 PMID 29053792; ACG 2016 PMID 27068718)
- Antibiotics_for_travelers_diarrhea_only_moderate_to_severe (ISTM/IDSA 2017 PMID 28521004)
- Avoid_fluoroquinolones_in_pregnancy_and_pediatric (ACG 2016 PMID 27068718)
- Fluoroquinolone_rising_campylobacter_resistance_prefer_azithromycin (ISTM/IDSA 2017 PMID 28521004)
- Ondansetron_QT_prolongation_caution_avoid_congenital_longQT_or_QT_drugs (Freedman NEJM 2006 PMID 16625009)
- Bismuth_subsalicylate_avoid_pediatric_viral_Reye_renal_impairment_salicylate_allergy_pregnancy (ISTM/IDSA 2017 PMID 28521004)
- Renal_dose_adjust_fluoroquinolone_ceftriaxone_vancomycin (CKD EPI 2021; KDIGO)
- Reduced_osmolarity_ORS_preferred_over_standard_WHO_ORS (Hahn PMID 11869639; ESPGHAN/ESPID 2014 PMID 24739189)

Monitoring

Regimen monitoring:
- hydration status urine output weight q4 to 6h until improving (ESPGHAN/ESPID 2014 PMID 24739189)
- electrolytes and renal function if severe or on renal dosed abx (CKD-EPI 2021)
- HUS surveillance CBC smear creatinine if STEC suspected (Wong NEJM 2000 PMID 10874060)
- clinical response at 48 to 72h with antimicrobial de escalation (IDSA 2017 PMID 29053792)
- ondansetron QT if repeated dosing or QT risk (Freedman NEJM 2006 PMID 16625009)
- antibiotic stewardship stop if viral or self limited (ACG 2016 PMID 27068718)

Setting (outpatient) monitoring:
- Caregiver-monitored hydration: oral intake, urine output, alertness; expect improvement over days
- Return for reassessment if not improving at 48-72 h or any red flag

Follow-up plan: Most: complete recovery, return precautions, hygiene/food-safety counselling, no routine test-of-cure; public-health reporting + food-handler clearance for reportable pathogens; persistent/post-infectious symptoms → reassess (post-infectious IBS — gi.ibs.core.v1; persistent → chronic-diarrhoea workup); rotavirus-vaccine context (pediatric) (IDSA 2017 PMID 29053792; ACG 2016 PMID 27068718)
- Close-out criterion: recovery confirmed or persistent/post-infectious pathway routed, public-health/food-handler addressed, follow-up scheduled

Monitoring phase: Hydration status / urine output / weight (pediatric), electrolytes + renal function (AKI, antibiotic dosing), clinical course/response, antibiotic stewardship + QT with ondansetron, HUS surveillance (CBC/smear/creatinine) if STEC, response to de-escalation (IDSA 2017 PMID 29053792; Wong NEJM 2000 PMID 10874060)

Disposition

Current setting: outpatient — Mild-moderate acute gastroenteritis, no red flag — reduced-osmolarity ORS + early refeeding + return precautions; NO routine stool testing or antibiotics (ACG 2016 PMID 27068718; ESPGHAN/ESPID 2014 PMID 24739189)

Disposition criteria:
- Continue outpatient ORS if improving and tolerating PO
- Escalate to ED/inpatient if any escalation trigger met

Escalation triggers (move to higher acuity):
- Severe dehydration / shock / lethargy → ED for IV resuscitation
- Bloody diarrhoea + high fever / dysentery → ED + stool studies
- Suspected STEC (bloody, low/no fever, decreasing urine, pallor) → ED + HUS workup (avoid abx/antimotility)
- Intractable vomiting unresponsive to a dose of ondansetron → ED

Earlier-Return Triggers

Return-precaution thresholds (watch for):
- [LIFE_THREATENING] Severe dehydration (≥10% peds weight loss / lethargy, sunken eyes, absent tears, prolonged capillary refill, weak pulse) or hypotension/orthostatic shock (ESPGHAN/ESPID 2014 PMID 24739189; IDSA 2017 PMID 29053792)
- [LIFE_THREATENING] Bloody diarrhoea with little/no fever ± abdominal pain ± oliguria/pallor — suspected Shiga-toxin E. coli / evolving HUS (Wong NEJM 2000 PMID 10874060)
- [LIFE_THREATENING] Invasive enteric infection with qSOFA/SIRS positivity + hypotension despite fluids + lactate >2 mmol/L (Sepsis-3; IDSA 2017 PMID 29053792)

Citations

- IDSA 2017 Clinical Practice Guidelines for the Diagnosis and Management of Infectious Diarrhea (Shane, Clin Infect Dis 2017) + ACG 2016 Acute Diarrheal Infections in Adults (Riddle, Am J Gastroenterol 2016) + ISTM/IDSA 2017 Travelers' Diarrhea graded expert panel (Riddle, J Travel Med 2017) + ESPGHAN/ESPID 2014 pediatric AGE (Guarino, JPGN 2014) + WHO/UNICEF reduced-osmolarity ORS + zinc [PMID:29053792](https://pubmed.ncbi.nlm.nih.gov/29053792/)
- Cited evidence (PMID 27068718) [PMID:27068718](https://pubmed.ncbi.nlm.nih.gov/27068718/)
- Cited evidence (PMID 28521004) [PMID:28521004](https://pubmed.ncbi.nlm.nih.gov/28521004/)
- Cited evidence (PMID 24739189) [PMID:24739189](https://pubmed.ncbi.nlm.nih.gov/24739189/)
- Cited evidence (PMID 11869639) [PMID:11869639](https://pubmed.ncbi.nlm.nih.gov/11869639/)

Last reconciled with current guidelines: 2026-05-22.
References
  • IDSA 2017 Clinical Practice Guidelines for the Diagnosis and Management of Infectious Diarrhea (Shane, Clin Infect Dis 2017) + ACG 2016 Acute Diarrheal Infections in Adults (Riddle, Am J Gastroenterol 2016) + ISTM/IDSA 2017 Travelers' Diarrhea graded expert panel (Riddle, J Travel Med 2017) + ESPGHAN/ESPID 2014 pediatric AGE (Guarino, JPGN 2014) + WHO/UNICEF reduced-osmolarity ORS + zinc — PMID:29053792
  • Cited evidence (PMID 27068718) — PMID:27068718
  • Cited evidence (PMID 28521004) — PMID:28521004
  • Cited evidence (PMID 24739189) — PMID:24739189
  • Cited evidence (PMID 11869639) — PMID:11869639