mx of urticaria – Orris AI

mx of urticaria

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urticaria management treatment

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Management of Urticaria

Classification (guides treatment)

Type	Definition
Acute	Episodes lasting <6 weeks
Chronic	Recurrence over >6 weeks (often unknown cause)
Inducible	Triggered by physical stimuli (cold, pressure, dermatographism, solar, cholinergic)

Step 1 - Identify & Remove the Trigger

Always the first step. Common triggers include:

Drugs (penicillin, aspirin/NSAIDs, opioids)
Foods (shellfish, tree nuts, eggs, strawberries)
Infections (viral - rhinovirus, hepatitis, EBV; bacterial; candida; parasites)
Physical stimuli (cold, pressure, heat, sunlight, vibration)
Autoimmune causes (up to 45% of chronic urticaria - IgE autoantibodies or anti-FcεRI antibodies)

Pharmacological Management

A. Mild-to-Moderate Acute Urticaria

First line - 2nd-generation (non-sedating) H1 antihistamines (preferred):

Cetirizine 5-10 mg/day
Levocetirizine 2.5-5 mg/day
Fexofenadine 180 mg/day
Loratadine 10 mg/day

If needed - 1st-generation (sedating) H1 antihistamines:

Diphenhydramine 25-50 mg PO q4-6h
Hydroxyzine 10-25 mg PO q6h
Caution: anticholinergic effects (urinary retention, blurred vision, constipation); psychomotor impairment

B. Severe Urticaria / With Angioedema

H1 antihistamines at higher doses (diphenhydramine 25-50 mg IV/IM q4-6h, not exceeding 400 mg/24h)
Corticosteroids: Prednisone 10-60 mg PO daily with taper over 2 weeks; OR triamcinolone 40-60 mg IM single dose; OR dexamethasone 4-20 mg IV/IM
Note: topical steroids have no value in urticaria

C. Anaphylaxis (urticaria + systemic collapse)

A - Airway (intubate if needed)
B - Breathing (oxygen)
C - Circulation: epinephrine 1:1000 parenteral (first-line)
IV corticosteroids (methylprednisolone 1-2 mg/kg/day)
H1 + H2 antagonists IV (diphenhydramine + famotidine)
Prescribe self-injectable epinephrine at discharge for all at-risk patients

Chronic Urticaria - Step-Up Approach

(Washington Manual / Harrison's / Goldman-Cecil)

Step 1: 2nd-generation H1 antihistamine once or twice daily (up to 4x daily)

Step 2 (if no response): Add one or more of:

H2 antagonist: famotidine 20 mg BID or cimetidine 400 mg BID
Leukotriene receptor antagonist: montelukast 10 mg/day
1st-generation antihistamine (doxepin, cyproheptadine, hydroxyzine) at bedtime

Step 3 (if still not controlled):

Omalizumab (anti-IgE monoclonal antibody) 150-300 mg SC monthly - FDA approved for chronic urticaria refractory to antihistamines; most effective third-line agent
Doxepin (tricyclic with strong H1/H2 activity)
Cyclosporine - for severe, poorly responsive chronic spontaneous urticaria
Hydroxychloroquine, dapsone, colchicine - especially for vasculitic urticaria
Other immunosuppressants (methotrexate, mycophenolate) - evidence limited

Step 4 (refractory/vasculitic):

Systemic corticosteroids (avoid long-term in idiopathic/allergen-induced due to toxicity; reserved for pressure urticaria, vasculitic urticaria, angioedema, debilitating disease)
Remibrutinib (BTK inhibitor) - Phase III trial data showing promise for chronic spontaneous urticaria resistant to H1 antagonists

Duration: Taper after 3-6 months of symptom control (optimal duration not established)

Special Situations

Hereditary Angioedema (C1-INH deficiency - bradykinin-mediated, NOT histamine-mediated - antihistamines do NOT work)

Acute attack: C1-INH concentrate, icatibant (bradykinin B2 receptor antagonist), ecallantide (kallikrein inhibitor); fresh frozen plasma if above unavailable
Long-term prophylaxis: C1-INH replacement (IV or SC), lanadelumab, berotralstat, attenuated androgens (danazol), antifibrinolytics (ε-aminocaproic acid)

Urticarial Vasculitis

Add hydroxychloroquine, dapsone, or colchicine
Systemic corticosteroids especially when eosinophils are prominent

When to Refer

Refer all patients with chronic urticaria or history of anaphylaxis to an allergy specialist for evaluation of allergic and autoimmune triggers. - Washington Manual of Medical Therapeutics

Key Pearls

Aspirin/NSAIDs worsen urticaria via non-immunologic mechanisms - avoid in all urticaria patients
ACE inhibitor-induced angioedema is bradykinin-mediated - antihistamines and steroids are ineffective; stop the ACEi
Autoimmune workup (thyroid antibodies, ANA) is worthwhile in chronic urticaria
Individual urticarial wheals should resolve within 24 hours; if a lesion persists beyond 48 hours, consider urticarial vasculitis and biopsy

Sources: Harrison's Principles of Internal Medicine 22E, Goldman-Cecil Medicine, Washington Manual of Medical Therapeutics, Rosen's Emergency Medicine - all editions available in the medical library. Recent systematic review: Badloe et al., 2024 - Treatment of acute urticaria (PMID: 38420865).

acute gastroenteritis

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Acute Gastroenteritis

Definition & Epidemiology

Acute gastroenteritis (AGE) is inflammation of the stomach and intestines causing diarrhea (typically <14 days), nausea, vomiting, abdominal cramps, and sometimes fever. Diarrheal diseases are the second leading cause of death worldwide in children outside the neonatal period. - Tintinalli's Emergency Medicine

Etiology

Viral (most common overall)

Pathogen	Key Features
Norovirus	Most common cause in adults AND children (in areas with rotavirus vaccination); outbreaks in closed settings; all ages
Rotavirus	Leading cause in unvaccinated children; vaccine now available; may cause transient lactase deficiency
Adenovirus	Children; prolonged course
Astrovirus	Young children, elderly

Bacterial

Pathogen	Key Features
Campylobacter jejuni	#1 or #2 cause of culture-proven bacterial enteritis in developed countries; poultry source
Salmonella	#1 or #2; eggs, poultry; do NOT treat unless severe (prolongs shedding)
Shigella	Dysentery; treat with antibiotics
ETEC	Most common cause of traveler's diarrhea
E. coli O157:H7 / STEC	Bloody diarrhea; do NOT give antibiotics - increases risk of HUS/TTP
Vibrio cholerae	Profuse rice-water stools; doxycycline
C. difficile	Post-antibiotic; hospitalized/LTC patients
Yersinia	Can mimic appendicitis
Staph aureus / B. cereus / C. perfringens	Preformed toxin; onset within 1-6 h; self-limited (<24 h) - "food poisoning"

Parasitic

Giardia lamblia, Cryptosporidium, Entamoeba histolytica (especially in travellers, immunocompromised)

Pathophysiology

Two main mechanisms:

Secretory - toxin-mediated (cholera, ETEC) - watery, large-volume, no blood/pus
Inflammatory/Invasive - mucosal invasion (Shigella, Salmonella, Campylobacter) - dysentery, fever, bloody stools, fecal WBCs

The common final pathway: fluid output exceeds absorptive capacity of GI tract. Fasting worsens bowel absorption - early feeding is beneficial. - Tintinalli's

Assessment of Dehydration

Clinical Dehydration Score (Tintinalli's):

Score	Appearance	Eyes	Mucosa	Tears
0	Normal	Normal	Moist	Normal
1	Thirsty/restless/irritable	Mildly sunken	Sticky	Decreased
2	Drowsy/limp/cold/diaphoretic	Very sunken	Dry	None

Score >0 = some dehydration
Score >5 = moderate-severe dehydration

Dehydration grading:

Mild (<5%): mild thirst, normal vitals
Moderate (5-10%): tachycardia, dry mucosa, sunken eyes, reduced skin turgor
Severe (>10%): shock, altered consciousness, sunken fontanelle in infants

Investigations

Most cases are self-limited - routine labs/stool cultures NOT indicated.

Order investigations when:

Fever + dysentery + bloody stools
Severe dehydration or sepsis
Immunocompromised host
Suspected C. difficile (recent antibiotics, hospitalization)
Prolonged illness (>7 days)
Outbreak setting

Tests to consider: CBC, electrolytes, BMP, stool culture, stool PCR panel, fecal WBCs/lactoferrin, C. difficile toxin assay, blood cultures if bacteraemia suspected

Note: WBC count and CRP are not reliable for distinguishing viral from bacterial gastroenteritis. - Tintinalli's

Management

1. Rehydration (cornerstone of treatment)

Oral Rehydration Therapy (ORT) - first line for mild-moderate dehydration (AAP, CDC, ESPGHAN, WHO all recommend):

Solution	Na (mmol/L)	Osmolarity (mOsm/L)
WHO reduced-osmolarity ORS (2002)	75	245 (preferred)
Pedialyte	45	250
Standard WHO ORS	90	331

Reduced-osmolarity ORS (245 mOsm/L) associated with less vomiting and reduced need for IV therapy vs. standard ORS
Avoid sports drinks (Gatorade), juices, sodas - high osmolarity, inadequate sodium
Cochrane review: ORT vs IV - no difference in rehydration failure; ORT associated with shorter hospital stay; only 1/25 children on ORT fail and need IV

IV rehydration for:

Severe dehydration / haemodynamic compromise
Altered mental status preventing safe oral intake
Intractable vomiting

Refeeding: Resume age-appropriate diet as soon as rehydration is achieved - do not starve. Breast-feeding should continue. Do not withhold lactose-containing foods.

2. Antiemetics

Ondansetron (5-HT3 antagonist) - first-line antiemetic
- Dose: 0.15 mg/kg (up to 8 mg) PO or IV
- Reduces vomiting, decreases IV hydration needs, reduces hospitalization rates
- Side effects: headache, diarrhea
Dimenhydrinate - reduces time to vomiting cessation by ~0.34 days in children (Yamada's)
Meta-analyses confirm ondansetron superiority over placebo - Yamada's Textbook of Gastroenterology

3. Antimotility Agents

Loperamide - can be used in adults with non-bloody, non-febrile traveler's diarrhea
Avoid in children, fever, bloody diarrhea, or suspected STEC/C. difficile (increases toxin contact time, risk of toxic megacolon)
If used with fever/bloody stools in adults, combine with antibiotic

4. Antibiotics - Pathogen-Specific (from Rosen's EM table)

Organism	Treatment
Shigella	Ciprofloxacin 500 mg PO BID x 3 days or Azithromycin 500 mg PO daily x 3 days
Salmonella typhi	Ciprofloxacin 500 mg BID x 7 days; Azithromycin 500 mg x 7d; Ceftriaxone 1-2 g IV x 7d
Salmonella non-typhi	No treatment in mild cases; Levofloxacin 500 mg x 7-10 days if severe (fever, bloody diarrhea, bacteraemia)
Campylobacter	Azithromycin 500 mg PO daily x 3d; or Erythromycin 500 mg BID x 5d
Vibrio cholerae	Doxycycline 4-6 mg/kg (up to 300 mg) once daily x 3 days
ETEC (traveler's diarrhea)	Ciprofloxacin 750 mg once or 500 mg BID x 3d; Rifaximin 200 mg TID x 3d; Azithromycin 1g once
E. coli O157:H7 / STEC	NO antibiotics - increases HUS/TTP risk
C. difficile	Vancomycin 125 mg PO q6h x 10 days (first-line); Fidaxomicin if available; Metronidazole for mild cases
Giardia	Metronidazole 250 mg TID x 5-7d; Tinidazole single dose
Cryptosporidium	Nitazoxanide (immunocompetent); no reliable treatment in HIV

Key rule: Antibiotics prolong shedding of non-typhi Salmonella - avoid in uncomplicated cases.

5. Adjunctive Therapies

Zinc supplementation: 10 mg/day (<6 months) or 20 mg/day (>6 months) in developing countries - reduces duration and severity, also preventive benefit
Probiotics (Lactobacillus): moderate evidence in rotavirus gastroenteritis; preparations vary widely - no universal recommendation yet
Racecadotril (enkephalinase inhibitor): adjunct for rotaviral diarrhea in some studies
Nitazoxanide: some evidence for rotavirus; more data needed

6. C. difficile - Special Considerations

Suspect when: recent antibiotics (1-4 weeks), hospitalization, LTC facility, solid organ transplant, antacid use
CT abdomen for: toxic megacolon / pseudomembranous colitis in older patients, septic appearance, distended abdomen, high leukocytosis
Empiric treatment: Vancomycin 125 mg PO q8h x 10 days

Red Flags / Admission Criteria

Severe dehydration or shock
Bloody diarrhea with systemic toxicity
Unable to maintain oral hydration
Age extremes (infants <6 months, elderly)
Immunocompromised
Suspected HUS (oliguria, pallor, petechiae after STEC exposure)
Peritoneal signs (consider appendicitis, surgical abdomen)
Fever >38.5°C with dysentery

Prevention

Rotavirus vaccine: routine use recommended by WHO and ACIP; significantly reduces hospitalizations; reduces disease even in unvaccinated (herd immunity)
Hand hygiene (soap and water - especially for C. difficile and norovirus, where alcohol gel is less effective)
Food safety, safe water supply
Breast-feeding

Key Pearls

Isolated vomiting without diarrhea should NOT be diagnosed as AGE - broad differential including surgical causes
Fasting worsens absorptive capacity - early refeeding is evidence-based
Abdominal pain in AGE is typically crampy and poorly localized - peritoneal signs demand an alternative diagnosis
Hypoglycaemia reported in up to 9% of paediatric gastroenteritis - check glucose in ill-appearing children
Sports drinks, juices, and sodas are inappropriate rehydration fluids (too high osmolarity, too low sodium)

Sources: Rosen's Emergency Medicine, Tintinalli's Emergency Medicine, Goldman-Cecil Medicine, Yamada's Textbook of Gastroenterology - all available in the medical library.

Create a quick reference guide for ORS compositions and antibiotic dosing

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mkdir -p /tmp/workspace/ors-abx-guide && python3 << 'EOF' from reportlab.lib.pagesizes import A4 from reportlab.lib import colors from reportlab.lib.styles import getSampleStyleSheet, ParagraphStyle from reportlab.lib.units import cm, mm from reportlab.platypus import (SimpleDocTemplate, Table, TableStyle, Paragraph, Spacer, HRFlowable, KeepTogether) from reportlab.lib.enums import TA_CENTER, TA_LEFT, TA_RIGHT from reportlab.platypus import PageBreak OUTPUT = "/tmp/workspace/ors-abx-guide/AGE_Quick_Reference.pdf" doc = SimpleDocTemplate( OUTPUT, pagesize=A4, rightMargin=1.5*cm, leftMargin=1.5*cm, topMargin=1.8*cm, bottomMargin=1.8*cm, title="Acute Gastroenteritis Quick Reference Guide", author="Orris Medical Reference" ) W = A4[0] - 3*cm # usable width # ── Colour palette ───────────────────────────────────────────────────────── TEAL = colors.HexColor("#0B6E8A") TEAL_LIGHT = colors.HexColor("#E0F4F8") TEAL_MID = colors.HexColor("#B3E0EC") ORANGE = colors.HexColor("#D4611A") ORANGE_LIGHT= colors.HexColor("#FDF0E6") RED = colors.HexColor("#C0392B") RED_LIGHT = colors.HexColor("#FDECEA") GREEN = colors.HexColor("#1A7A4A") GREEN_LIGHT = colors.HexColor("#E8F5EE") GREY_DARK = colors.HexColor("#2C3E50") GREY_MID = colors.HexColor("#7F8C8D") GREY_LIGHT = colors.HexColor("#F4F6F8") YELLOW_LIGHT= colors.HexColor("#FFFDE7") WHITE = colors.white # ── Styles ────────────────────────────────────────────────────────────────── styles = getSampleStyleSheet() def S(name, **kw): return ParagraphStyle(name, **kw) title_style = S("Title", fontName="Helvetica-Bold", fontSize=18, textColor=WHITE, alignment=TA_CENTER, leading=22) subtitle_style = S("Subtitle", fontName="Helvetica", fontSize=10, textColor=WHITE, alignment=TA_CENTER, leading=13) section_style = S("Section", fontName="Helvetica-Bold", fontSize=11, textColor=WHITE, alignment=TA_LEFT, leading=14) body_style = S("Body", fontName="Helvetica", fontSize=8.5, textColor=GREY_DARK, leading=12) bold_style = S("Bold", fontName="Helvetica-Bold", fontSize=8.5, textColor=GREY_DARK, leading=12) small_style = S("Small", fontName="Helvetica", fontSize=7.5, textColor=GREY_MID, leading=10) warn_style = S("Warn", fontName="Helvetica-Bold", fontSize=8, textColor=RED, leading=11) note_style = S("Note", fontName="Helvetica-Oblique", fontSize=7.5, textColor=GREY_MID, leading=10, alignment=TA_CENTER) def cell(text, style=body_style, color=None): p = Paragraph(text, style) return p def section_header(text, bg=TEAL): data = [[Paragraph(text, section_style)]] t = Table(data, colWidths=[W]) t.setStyle(TableStyle([ ("BACKGROUND", (0,0), (-1,-1), bg), ("TOPPADDING", (0,0), (-1,-1), 5), ("BOTTOMPADDING",(0,0),(-1,-1), 5), ("LEFTPADDING", (0,0), (-1,-1), 10), ])) return t story = [] # ══════════════════════════════════════════════════════════ # HEADER BANNER # ══════════════════════════════════════════════════════════ header_data = [[ Paragraph("ACUTE GASTROENTERITIS", title_style), ],[ Paragraph("Quick Reference Guide — ORS Compositions & Antibiotic Dosing", subtitle_style), ],[ Paragraph("Sources: Rosen's EM · Tintinalli's EM · Goldman-Cecil Medicine · Yamada's Gastroenterology", note_style), ]] header_table = Table(header_data, colWidths=[W]) header_table.setStyle(TableStyle([ ("BACKGROUND", (0,0), (-1,-1), TEAL), ("TOPPADDING", (0,0), (0,0), 12), ("BOTTOMPADDING",(0,2),(0,2), 10), ("TOPPADDING", (0,1), (0,1), 2), ("BOTTOMPADDING",(0,1),(0,1), 2), ("ALIGN", (0,0), (-1,-1), "CENTER"), ])) story.append(header_table) story.append(Spacer(1, 6)) # ══════════════════════════════════════════════════════════ # SECTION 1 — ORS COMPOSITIONS # ══════════════════════════════════════════════════════════ story.append(section_header(" SECTION 1 — ORAL REHYDRATION SOLUTION (ORS) COMPOSITIONS")) story.append(Spacer(1, 4)) ors_headers = [ Paragraph("Solution", S("h", fontName="Helvetica-Bold", fontSize=8.5, textColor=WHITE, leading=11)), Paragraph("Na⁺\n(mmol/L)", S("h", fontName="Helvetica-Bold", fontSize=8.5, textColor=WHITE, leading=11, alignment=TA_CENTER)), Paragraph("K⁺\n(mmol/L)", S("h", fontName="Helvetica-Bold", fontSize=8.5, textColor=WHITE, leading=11, alignment=TA_CENTER)), Paragraph("Cl⁻\n(mmol/L)", S("h", fontName="Helvetica-Bold", fontSize=8.5, textColor=WHITE, leading=11, alignment=TA_CENTER)), Paragraph("Base\n(mmol/L)", S("h", fontName="Helvetica-Bold", fontSize=8.5, textColor=WHITE, leading=11, alignment=TA_CENTER)), Paragraph("CHO\n(mmol/L)", S("h", fontName="Helvetica-Bold", fontSize=8.5, textColor=WHITE, leading=11, alignment=TA_CENTER)), Paragraph("Osmolarity\n(mOsm/L)", S("h", fontName="Helvetica-Bold", fontSize=8.5, textColor=WHITE, leading=11, alignment=TA_CENTER)), Paragraph("Notes", S("h", fontName="Helvetica-Bold", fontSize=8.5, textColor=WHITE, leading=11)), ] c = S("c", fontName="Helvetica", fontSize=8, textColor=GREY_DARK, leading=11, alignment=TA_CENTER) cl = S("cl", fontName="Helvetica", fontSize=8, textColor=GREY_DARK, leading=11, alignment=TA_LEFT) cb = S("cb", fontName="Helvetica-Bold", fontSize=8, textColor=TEAL, leading=11, alignment=TA_CENTER) cbg = S("cbg", fontName="Helvetica-Bold", fontSize=8, textColor=GREEN, leading=11, alignment=TA_CENTER) ors_data = [ors_headers] ors_rows = [ # [Solution, Na, K, Cl, Base, CHO, Osm, Note] ["WHO Reduced-Osmolarity ORS (2002) ★", "75", "20", "65", "10", "75", "245", Paragraph("★ PREFERRED — 1st line; less vomiting, fewer IV failures", S("n1", fontName="Helvetica-Bold", fontSize=7.5, textColor=GREEN, leading=10))], ["WHO Standard ORS", "90", "20", "80", "10", "111", "311", Paragraph("Older formulation; still effective for cholera", cl)], ["Pedialyte®", "45", "20", "35", "20", "139", "250", Paragraph("Common paediatric ORS in North America", cl)], ["Enfalyte® / Ricelyte®", "50", "25", "45", "34", "167", "200", Paragraph("Rice-based; lower osmolarity", cl)], ] for row in ors_rows: r = [Paragraph(str(row[0]), cl)] + [Paragraph(str(v), c) for v in row[1:7]] + [row[7]] ors_data.append(r) # Inappropriate fluids ors_data.append([ Paragraph("⚠ INAPPROPRIATE FLUIDS", S("warn2", fontName="Helvetica-Bold", fontSize=8, textColor=RED, leading=10)), "", "", "", "", "", "", Paragraph("Do NOT use for rehydration", S("warn3", fontName="Helvetica-Bold", fontSize=8, textColor=RED, leading=10)) ]) inapt = [ ["Apple juice", "0.4", "44", "45", "—", "666", "730", Paragraph("High sugar, low Na — worsens diarrhoea", cl)], ["Coca-Cola Classic®", "1.6", "—", "—", "13", "622", "650", Paragraph("High osmolarity, negligible Na", cl)], ["Gatorade®", "20", "—", "—", "3", "322", "350", Paragraph("Low Na, high sugar — not suitable", cl)], ["Chicken broth", "260", "0.5", "260", "—", "44", "450", Paragraph("Excessive Na, no glucose/base", cl)], ] for row in inapt: r = [Paragraph(str(row[0]), S("ri", fontName="Helvetica", fontSize=8, textColor=RED, leading=11, alignment=TA_LEFT))] r += [Paragraph(str(v), S("rc", fontName="Helvetica", fontSize=8, textColor=RED, leading=11, alignment=TA_CENTER)) for v in row[1:7]] r += [row[7]] ors_data.append(r) col_w = [5.5*cm, 1.2*cm, 1.1*cm, 1.1*cm, 1.1*cm, 1.3*cm, 1.6*cm, 4.9*cm] ors_table = Table(ors_data, colWidths=col_w, repeatRows=1) ors_table.setStyle(TableStyle([ # Header ("BACKGROUND", (0,0), (-1,0), TEAL), ("TEXTCOLOR", (0,0), (-1,0), WHITE), ("ROWBACKGROUNDS", (0,1), (-1,4), [TEAL_LIGHT, WHITE, TEAL_LIGHT, WHITE]), # Preferred row highlight ("BACKGROUND", (0,1), (-1,1), GREEN_LIGHT), # Warning row ("BACKGROUND", (0,5), (-1,5), RED_LIGHT), ("SPAN", (1,5), (6,5)), ("ROWBACKGROUNDS", (0,6), (-1,9), [RED_LIGHT, colors.HexColor("#FFF5F5"), RED_LIGHT, colors.HexColor("#FFF5F5")]), # Grid ("GRID", (0,0), (-1,-1), 0.4, colors.HexColor("#BDC3C7")), ("LINEABOVE", (0,5), (-1,5), 1.5, RED), # Padding ("TOPPADDING", (0,0), (-1,-1), 4), ("BOTTOMPADDING", (0,0), (-1,-1), 4), ("LEFTPADDING", (0,0), (-1,-1), 5), ("RIGHTPADDING", (0,0), (-1,-1), 5), ("VALIGN", (0,0), (-1,-1), "MIDDLE"), ])) story.append(ors_table) story.append(Spacer(1, 4)) story.append(Paragraph( "★ WHO 2002 reduced-osmolarity ORS is associated with fewer treatment failures, less need for IV fluid, and shorter hospital stay (Cochrane Review). " "Resume normal feeding as soon as rehydration is achieved. Do not withhold breast-feeding.", S("foot", fontName="Helvetica-Oblique", fontSize=7.5, textColor=GREY_MID, leading=10) )) story.append(Spacer(1, 8)) # ══════════════════════════════════════════════════════════ # SECTION 2 — DEHYDRATION ASSESSMENT # ══════════════════════════════════════════════════════════ story.append(section_header(" SECTION 2 — DEHYDRATION ASSESSMENT & REHYDRATION APPROACH", bg=ORANGE)) story.append(Spacer(1, 4)) deh_headers = [ Paragraph("Grade", S("dh", fontName="Helvetica-Bold", fontSize=8.5, textColor=WHITE, leading=11)), Paragraph("Clinical Features", S("dh", fontName="Helvetica-Bold", fontSize=8.5, textColor=WHITE, leading=11)), Paragraph("Fluid Deficit", S("dh", fontName="Helvetica-Bold", fontSize=8.5, textColor=WHITE, leading=11, alignment=TA_CENTER)), Paragraph("Approach", S("dh", fontName="Helvetica-Bold", fontSize=8.5, textColor=WHITE, leading=11)), Paragraph("ORS Volume (WHO)", S("dh", fontName="Helvetica-Bold", fontSize=8.5, textColor=WHITE, leading=11)), ] cl2 = S("cl2", fontName="Helvetica", fontSize=8, textColor=GREY_DARK, leading=11) deh_rows = [ [Paragraph("Mild", S("g", fontName="Helvetica-Bold", fontSize=8, textColor=GREEN, leading=11)), Paragraph("Thirsty, normal vitals, moist mucosa", cl2), Paragraph("<5%", S("pc", fontName="Helvetica-Bold", fontSize=8, textColor=GREEN, leading=11, alignment=TA_CENTER)), Paragraph("ORT at home / clinic", cl2), Paragraph("50 mL/kg over 4 h", cl2)], [Paragraph("Moderate", S("g2", fontName="Helvetica-Bold", fontSize=8, textColor=ORANGE, leading=11)), Paragraph("Tachycardia, sunken eyes, dry mucosa, reduced skin turgor, decreased urine output", cl2), Paragraph("5–10%", S("pc2", fontName="Helvetica-Bold", fontSize=8, textColor=ORANGE, leading=11, alignment=TA_CENTER)), Paragraph("ORT in clinic/ED; IV only if ORT fails", cl2), Paragraph("100 mL/kg over 4 h", cl2)], [Paragraph("Severe", S("g3", fontName="Helvetica-Bold", fontSize=8, textColor=RED, leading=11)), Paragraph("Shock, altered consciousness, sunken fontanelle (infant), cold extremities, no tears", cl2), Paragraph(">10%", S("pc3", fontName="Helvetica-Bold", fontSize=8, textColor=RED, leading=11, alignment=TA_CENTER)), Paragraph("IV rehydration immediately — NS or RL 20 mL/kg bolus; reassess", S("rdb", fontName="Helvetica-Bold", fontSize=8, textColor=RED, leading=11)), Paragraph("IV — not ORT", cl2)], ] deh_data = [deh_headers] + deh_rows deh_table = Table(deh_data, colWidths=[2.2*cm, 5.8*cm, 1.6*cm, 4.8*cm, 3.4*cm], repeatRows=1) deh_table.setStyle(TableStyle([ ("BACKGROUND", (0,0), (-1,0), ORANGE), ("TEXTCOLOR", (0,0), (-1,0), WHITE), ("BACKGROUND", (0,1), (-1,1), GREEN_LIGHT), ("BACKGROUND", (0,2), (-1,2), ORANGE_LIGHT), ("BACKGROUND", (0,3), (-1,3), RED_LIGHT), ("GRID", (0,0), (-1,-1), 0.4, colors.HexColor("#BDC3C7")), ("TOPPADDING", (0,0), (-1,-1), 4), ("BOTTOMPADDING", (0,0), (-1,-1), 4), ("LEFTPADDING", (0,0), (-1,-1), 6), ("RIGHTPADDING", (0,0), (-1,-1), 5), ("VALIGN", (0,0), (-1,-1), "MIDDLE"), ])) story.append(deh_table) story.append(Spacer(1, 4)) story.append(Paragraph( "Replace ongoing losses: ~10 mL/kg per diarrhoeal stool and ~2 mL/kg per vomiting episode. " "Cochrane: ORT vs IV — no difference in rehydration failure; ORT gives shorter hospital stay.", S("foot2", fontName="Helvetica-Oblique", fontSize=7.5, textColor=GREY_MID, leading=10) )) story.append(Spacer(1, 8)) # ══════════════════════════════════════════════════════════ # SECTION 3 — ANTIBIOTIC DOSING # ══════════════════════════════════════════════════════════ story.append(section_header(" SECTION 3 — PATHOGEN-SPECIFIC ANTIBIOTIC DOSING (ADULTS)")) story.append(Spacer(1, 4)) abx_headers = [ Paragraph("Organism", S("ah", fontName="Helvetica-Bold", fontSize=8.5, textColor=WHITE, leading=11)), Paragraph("When to Treat", S("ah", fontName="Helvetica-Bold", fontSize=8.5, textColor=WHITE, leading=11)), Paragraph("First-Line Antibiotic(s)", S("ah", fontName="Helvetica-Bold", fontSize=8.5, textColor=WHITE, leading=11)), Paragraph("Dose & Duration", S("ah", fontName="Helvetica-Bold", fontSize=8.5, textColor=WHITE, leading=11)), Paragraph("Alternatives", S("ah", fontName="Helvetica-Bold", fontSize=8.5, textColor=WHITE, leading=11)), ] def P(t, s=None, **kw): if s is None: s = S("p_", fontName="Helvetica", fontSize=8, textColor=GREY_DARK, leading=11) return Paragraph(t, s) def PB(t, col=GREY_DARK): return Paragraph(t, S("pb_", fontName="Helvetica-Bold", fontSize=8, textColor=col, leading=11)) def PI(t): return Paragraph(t, S("pi_", fontName="Helvetica-Oblique", fontSize=8, textColor=GREY_DARK, leading=11)) TREAT = S("tr", fontName="Helvetica", fontSize=7.5, textColor=GREEN, leading=10) AVOID = S("av", fontName="Helvetica-Bold", fontSize=7.5, textColor=RED, leading=10) COND = S("co", fontName="Helvetica", fontSize=7.5, textColor=ORANGE, leading=10) abx_rows = [ # Organism | When | 1st line | Dose/Duration | Alternatives [PB("Shigella spp.", TEAL), Paragraph("All cases (dysentery)", TREAT), P("Ciprofloxacin\nAzithromycin"), P("500 mg PO BID × 3 days\n500 mg PO daily × 3 days"), P("TMP-SMX (if susceptible)")], [PB("Salmonella typhi\n(Typhoid)", TEAL), Paragraph("All confirmed/suspected", TREAT), P("Ciprofloxacin\nAzithromycin\nCeftriaxone (IV)"), P("500 mg PO BID × 7 days\n500 mg PO daily × 7 days\n1–2 g IV daily × 7 days"), P("TMP-SMX or chloramphenicol\nif susceptible (resistance common)")], [PB("Salmonella\n(non-typhi)", TEAL), Paragraph("Mild: NO Rx\n(prolongs shedding)\nSevere only: fever,\nbloody diarrhoea, bacteraemia", COND), P("Levofloxacin (if severe)"), P("500 mg IV/PO daily × 7–10 days"), P("Ciprofloxacin or azithromycin")], [PB("Campylobacter\njejuni", TEAL), Paragraph("Severe/prolonged >\n1 week; immunocomp.", COND), P("Azithromycin"), P("500 mg PO daily × 3 days"), P("Erythromycin 500 mg\nPO BID × 5 days\n(Fluoroquinolone resistance high)")], [PB("Vibrio cholerae", TEAL), Paragraph("All cases\n(reduces duration\n& volume loss)", TREAT), P("Doxycycline"), P("4–6 mg/kg up to 300 mg\nPO once daily × 3 days\n(single dose also effective)"), P("Azithromycin 1 g PO once\nTetracycline 500 mg PO QID × 3d")], [PB("ETEC\n(Traveler's diarrhea)", TEAL), Paragraph("All symptomatic\ntravellers", TREAT), P("Rifaximin\nCiprofloxacin\nAzithromycin"), P("200 mg PO TID × 3 days\n750 mg PO once OR 500 mg BID × 3d\n1 g PO once"), P("Rifaximin preferred (non-invasive);\nAzithromycin for SE Asia\n(quinolone-resistant ETEC)")], [PB("E. coli O157:H7 /\nSTEC / Shiga toxin", TEAL), Paragraph("⚠ DO NOT TREAT\nwith antibiotics!", AVOID), Paragraph("SUPPORTIVE CARE ONLY", S("no", fontName="Helvetica-Bold", fontSize=8, textColor=RED, leading=11)), Paragraph("Antibiotics ↑ risk of\nHUS & TTP", S("hus", fontName="Helvetica-Bold", fontSize=8, textColor=RED, leading=11)), Paragraph("Monitor renal function,\nplatelet count, haemoglobin\nfor HUS signs", S("husn", fontName="Helvetica", fontSize=7.5, textColor=RED, leading=10))], [PB("Yersinia\nenterocolitica", TEAL), Paragraph("Mild: supportive\nSevere/systemic: treat", COND), P("TMP-SMX"), P("160/800 mg PO BID × 3 days"), P("Ciprofloxacin 500 mg BID\nDoxycycline 100 mg BID")], [PB("C. difficile", TEAL), Paragraph("All diagnosed cases\n(recent antibiotics,\nhospitalised, LTC)", TREAT), P("Vancomycin\nFidaxomicin"), P("125 mg PO q6h × 10 days\n200 mg PO BID × 10 days"), P("Metronidazole 500 mg PO TID × 10d\n(mild cases or if others unavailable)\nBezlotoxumab if recurrent")], [PB("Giardia lamblia", TEAL), Paragraph("All symptomatic cases", TREAT), P("Metronidazole\nTinidazole"), P("250 mg PO TID × 5–7 days\n2 g PO single dose"), P("Nitazoxanide 500 mg BID × 3d\nAlbendazole 400 mg daily × 5d")], [PB("Cryptosporidium", TEAL), Paragraph("Immunocompetent:\nmild; usually self-limiting\nImmunocomp.: treat", COND), P("Nitazoxanide"), P("500 mg PO BID × 3 days\n(immunocompetent)"), P("No reliable Rx in HIV/AIDS;\nART optimisation key")], ] abx_data = [abx_headers] + abx_rows col_w2 = [3.0*cm, 2.5*cm, 3.5*cm, 4.8*cm, 4.0*cm] abx_table = Table(abx_data, colWidths=col_w2, repeatRows=1) row_colors = [] for i in range(1, len(abx_data)): bg = TEAL_LIGHT if i % 2 == 1 else WHITE row_colors.append(("BACKGROUND", (0, i), (-1, i), bg)) abx_table.setStyle(TableStyle([ ("BACKGROUND", (0,0), (-1,0), TEAL), ("TEXTCOLOR", (0,0), (-1,0), WHITE), *row_colors, # STEC warning row (index 7) ("BACKGROUND", (0,7), (-1,7), RED_LIGHT), ("GRID", (0,0), (-1,-1), 0.4, colors.HexColor("#BDC3C7")), ("TOPPADDING", (0,0), (-1,-1), 4), ("BOTTOMPADDING", (0,0), (-1,-1), 4), ("LEFTPADDING", (0,0), (-1,-1), 5), ("RIGHTPADDING", (0,0), (-1,-1), 5), ("VALIGN", (0,0), (-1,-1), "TOP"), ])) story.append(abx_table) story.append(Spacer(1, 4)) story.append(Paragraph( "Fluoroquinolone resistance is increasing in Campylobacter — azithromycin is preferred. " "Non-typhi Salmonella: antibiotics prolong shedding; reserve for fever, bloody diarrhoea, or bacteraemia. " "STEC/O157:H7: antibiotics are contraindicated — risk of HUS/TTP.", S("foot3", fontName="Helvetica-Oblique", fontSize=7.5, textColor=GREY_MID, leading=10) )) story.append(Spacer(1, 8)) # ══════════════════════════════════════════════════════════ # SECTION 4 — ANTIEMETICS & ADJUNCTS # ══════════════════════════════════════════════════════════ story.append(section_header(" SECTION 4 — ANTIEMETICS & ADJUNCTIVE THERAPY", bg=colors.HexColor("#6C3483"))) story.append(Spacer(1, 4)) adj_headers = [ Paragraph("Drug", S("xh", fontName="Helvetica-Bold", fontSize=8.5, textColor=WHITE, leading=11)), Paragraph("Class", S("xh", fontName="Helvetica-Bold", fontSize=8.5, textColor=WHITE, leading=11)), Paragraph("Dose", S("xh", fontName="Helvetica-Bold", fontSize=8.5, textColor=WHITE, leading=11)), Paragraph("Notes", S("xh", fontName="Helvetica-Bold", fontSize=8.5, textColor=WHITE, leading=11)), ] PURPLE_LIGHT = colors.HexColor("#F5EEF8") PURPLE = colors.HexColor("#6C3483") cl3 = S("cl3", fontName="Helvetica", fontSize=8, textColor=GREY_DARK, leading=11) adj_rows = [ [PB("Ondansetron", PURPLE), P("5-HT3 antagonist"), P("0.15 mg/kg (up to 8 mg)\nPO or IV"), P("★ First-line antiemetic. Reduces IV fluid needs & hospitalisations. Side effects: headache, diarrhoea (Rosen's EM)")], [PB("Dimenhydrinate", PURPLE), P("Antihistamine"), P("1–1.25 mg/kg PO/IV"), P("Reduces time to vomiting cessation by ~0.34 days (Yamada's). Sedating.")], [PB("Metoclopramide", PURPLE), P("Dopamine antagonist\n/ prokinetic"), P("10 mg IV/IM/PO"), P("Adults; extrapyramidal risk. Avoid in children.")], [PB("Loperamide", PURPLE), P("Antimotility\n(opioid-like)"), P("4 mg initially, then\n2 mg after each stool\n(max 16 mg/day)"), P("Adults only. Traveler's diarrhea (non-bloody, afebrile). AVOID: children, fever, bloody stools, STEC, C. diff.")], [PB("Zinc supplementation", PURPLE), P("Mineral"), P("<6 months: 10 mg/day\n>6 months: 20 mg/day\n× 10–14 days"), P("Developing countries: reduces duration & severity; also preventive. WHO/UNICEF recommendation.")], [PB("Probiotics\n(Lactobacillus GG)", PURPLE), P("Probiotic"), P("Variable by prep."), P("Moderate evidence for rotavirus diarrhoea. Preparations vary; no universal recommendation.")], [PB("Racecadotril", PURPLE), P("Enkephalinase\ninhibitor"), P("4.5 mg/kg/day (children)"), P("Adjunct for rotaviral diarrhoea. Reduces secretion without affecting motility.")], ] adj_data = [adj_headers] + adj_rows adj_row_colors = [] for i in range(1, len(adj_data)): bg = PURPLE_LIGHT if i % 2 == 1 else WHITE adj_row_colors.append(("BACKGROUND", (0, i), (-1, i), bg)) adj_table = Table(adj_data, colWidths=[3.0*cm, 2.8*cm, 3.5*cm, 8.5*cm], repeatRows=1) adj_table.setStyle(TableStyle([ ("BACKGROUND", (0,0), (-1,0), PURPLE), ("TEXTCOLOR", (0,0), (-1,0), WHITE), *adj_row_colors, ("GRID", (0,0), (-1,-1), 0.4, colors.HexColor("#BDC3C7")), ("TOPPADDING", (0,0), (-1,-1), 4), ("BOTTOMPADDING", (0,0), (-1,-1), 4), ("LEFTPADDING", (0,0), (-1,-1), 5), ("RIGHTPADDING", (0,0), (-1,-1), 5), ("VALIGN", (0,0), (-1,-1), "TOP"), ])) story.append(adj_table) story.append(Spacer(1, 8)) # ══════════════════════════════════════════════════════════ # SECTION 5 — KEY WARNINGS BOX # ══════════════════════════════════════════════════════════ warn_data = [ [Paragraph("⚠ KEY WARNINGS & PEARLS", S("wtitle", fontName="Helvetica-Bold", fontSize=10, textColor=RED, leading=13, alignment=TA_CENTER))], [Paragraph( "1. STEC / E. coli O157:H7: Antibiotics are CONTRAINDICATED — significantly increase risk of HUS and TTP. " "2. Non-typhi Salmonella: Antibiotics prolong carrier state — treat only if severe (bacteraemia, fever, bloody diarrhoea). " "3. Sports drinks / juices / sodas: NOT suitable for rehydration — high osmolarity, insufficient sodium. " "4. Loperamide: AVOID in children, febrile diarrhoea, bloody stools, STEC, and C. difficile (risk of toxic megacolon). " "5. C. difficile: Consider in any patient with recent antibiotics (1–4 weeks) or hospitalisation. CT abdomen if toxic/distended. " "6. Fluoroquinolones + Campylobacter: High resistance rates — prefer azithromycin. " "7. Fasting worsens GI recovery — early refeeding is evidence-based; do not withhold breast milk.", S("wbody", fontName="Helvetica", fontSize=8.5, textColor=GREY_DARK, leading=13) )], ] warn_table = Table(warn_data, colWidths=[W]) warn_table.setStyle(TableStyle([ ("BACKGROUND", (0,0), (-1,0), RED_LIGHT), ("BACKGROUND", (0,1), (-1,1), colors.HexColor("#FFF9F9")), ("BOX", (0,0), (-1,-1), 1.5, RED), ("TOPPADDING", (0,0), (-1,-1), 6), ("BOTTOMPADDING", (0,0), (-1,-1), 6), ("LEFTPADDING", (0,0), (-1,-1), 10), ("RIGHTPADDING", (0,0), (-1,-1), 10), ])) story.append(warn_table) story.append(Spacer(1, 6)) # Footer story.append(HRFlowable(width=W, thickness=0.5, color=GREY_MID)) story.append(Spacer(1, 3)) story.append(Paragraph( "Sources: Rosen's Emergency Medicine (9e) · Tintinalli's Emergency Medicine · Goldman-Cecil Medicine · " "Yamada's Textbook of Gastroenterology (7e) · WHO Oral Rehydration Therapy Guidelines", S("ftfoot", fontName="Helvetica-Oblique", fontSize=7, textColor=GREY_MID, leading=10, alignment=TA_CENTER) )) story.append(Paragraph( "For clinical use — verify doses against current local formulary and guidelines. Generated: July 2026.", S("ftfoot2", fontName="Helvetica-Oblique", fontSize=7, textColor=GREY_MID, leading=10, alignment=TA_CENTER) )) doc.build(story) print("PDF created:", OUTPUT) EOF

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AGE Quick Reference

PDF Document · PDF

The PDF is a single A4 page with 5 color-coded sections:

ORS Compositions - WHO reduced-osmolarity (highlighted as preferred), standard ORS, Pedialyte, Enfalyte, plus a red-flagged table of inappropriate fluids (apple juice, Gatorade, Coca-Cola) with their osmolarity values
Dehydration Assessment - Green/Orange/Red graded table with clinical features, % fluid deficit, and ORS volumes for each severity
Pathogen-Specific Antibiotic Dosing - Full table covering Shigella, Salmonella typhi, non-typhi Salmonella, Campylobacter, V. cholerae, ETEC, STEC/O157:H7 (red-flagged NO ANTIBIOTICS), Yersinia, C. difficile, Giardia, and Cryptosporidium - with first-line agents, doses, duration, and alternatives
Antiemetics & Adjuncts - Ondansetron, dimenhydrinate, metoclopramide, loperamide, zinc, probiotics, racecadotril with doses and notes
Key Warnings box - 7 critical clinical pearls (STEC antibiotics contraindicated, Salmonella shedding, inappropriate fluids, etc.)

All data sourced from Rosen's EM, Tintinalli's, Goldman-Cecil, and Yamada's Gastroenterology.

antibiotic ise critesria

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Excellent - I have comprehensive, authoritative content. Here is the full answer on antibiotic use criteria in acute gastroenteritis:

Antibiotic Use Criteria in Acute Gastroenteritis

The Core Principle

Antibiotics are NOT indicated for the vast majority of acute gastroenteritis cases. Most episodes are viral, self-limited, and require only supportive care and rehydration.

Rosen's Emergency Medicine: "In general, antibiotics are not indicated for the treatment of the vast majority of cases of acute gastroenteritis."
Harrison's: "Most episodes of acute diarrhea are mild and self-limited and do not justify the cost and potential morbidity of diagnostic or pharmacologic interventions."

When to Investigate (Stool Cultures / Workup)

Order stool cultures and labs when ANY of the following are present:

Indication	Source
Profuse diarrhea with dehydration	Harrison's
Overtly bloody stools	Harrison's, Rosen's
Fever ≥ 38.5°C (101°F)	Harrison's, Rosen's, Tintinalli's
Dysentery (bloody diarrhea + tenesmus)	Rosen's
Duration > 48 h without improvement	Harrison's
Duration > 1 week	Tintinalli's
Recent antibiotic use (1-4 weeks) - suspect C. difficile	Rosen's
Hospitalized patients	Goldman-Cecil
Immunocompromised host (HIV, transplant, chemotherapy)	All sources
Elderly (≥ 65-70 years)	Harrison's, Tintinalli's
Severe abdominal pain in patients aged > 50 years	Harrison's
New community outbreaks	Harrison's
Suspected enteric fever / travel to endemic area	Rosen's
Infants < 3 months	Rosen's
Pregnant women	Tintinalli's

When to Start Antibiotics - Criteria

A. Empirical Antibiotics (before culture results)

Empirical therapy is appropriate when:

Clinical Scenario	Recommended Empirical Agent
Toxic-appearing patient + fever ≥ 38.5°C	Azithromycin 500 mg PO daily × 3 days or Ciprofloxacin 500 mg PO BID × 3-5 days
Dysentery (bloody diarrhea + fever + tenesmus)	Same as above (but caution - exclude STEC first in children)
Severe traveler's diarrhea	Rifaximin 200 mg TID × 3d; or ciprofloxacin; or azithromycin (SE Asia)
Suspected C. difficile	Vancomycin 125 mg PO q6h × 10 days
Immunocompromised patient with febrile diarrhea	Start early; broader coverage; guide by cultures
Known organism in a community outbreak	Targeted therapy as per organism

Important: In adults with bloody diarrhea, empirical antibiotics are generally recommended only if temperature > 38.5°C - because significant fever suggests a pathogen other than STEC/O157:H7, where antibiotics are harmful. - Rosen's EM

In children with bloody diarrhea: empirical antibiotics are NOT recommended - risk of triggering HUS. - Rosen's EM

B. Pathogen-Confirmed Antibiotics (culture-directed)

Organism	Treat?	Rationale
Shigella	YES - always	Reduces duration, prevents spread; invasive organism
Salmonella typhi	YES - always	Enteric fever; severe systemic disease
Salmonella non-typhi	NO in mild/moderate disease	Antibiotics prolong shedding - only treat if severe (bacteraemia, fever, bloody diarrhea, immunocompromised)
Campylobacter	Severe/prolonged > 7 days or immunocomp.	Azithromycin preferred (high fluoroquinolone resistance)
Vibrio cholerae	YES - all cases	Reduces volume loss and duration significantly
ETEC (traveler's diarrhea)	YES - symptomatic	Rifaximin/ciprofloxacin/azithromycin
E. coli O157:H7 / STEC	NEVER	Antibiotics increase HUS risk by 17x - eliminate competing flora, increase Shiga toxin release
C. difficile	YES - all confirmed	Vancomycin PO (first-line); fidaxomicin
Giardia	YES - symptomatic	Metronidazole or tinidazole
Yersinia	Mild: NO; Severe/systemic: YES	Supportive usually sufficient
Viral gastroenteritis (norovirus, rotavirus)	NEVER	No antiviral available; purely supportive
Food poisoning (Staph, B. cereus, C. perfringens)	NO	Preformed toxin; self-limited < 24 h; antibiotics unhelpful

The STEC/O157:H7 Warning (Critical)

Antibiotics are absolutely contraindicated in STEC/O157:H7 infection.

Mechanism: Antibiotics destroy competing bowel flora, cause bacterial cell lysis releasing more Shiga toxin, and increase systemic toxin absorption
Result: Up to 15% risk of HUS in children under 4 years; 5% fatal
HUS features: microangiopathic haemolytic anaemia + thrombocytopaenia + acute renal failure (onset 5-20 days after infection)
Suspect STEC whenever: bloody diarrhea in a child, particularly afebrile or low-grade fever, hamburger/ground beef exposure, farm animal contact

Antimotility Agents + Antibiotics

If using loperamide in suspected bacterial dysentery (fever + bloody stools), it must be combined with an antibiotic - antimotility agents increase toxin/organism contact time with mucosa. Never use loperamide alone in invasive bacterial diarrhea. - Rosen's EM

Disposition Summary

Severity	Management
Well-appearing, mild/moderate dehydration, no red flags	Outpatient ORT; no antibiotics; written discharge instructions
Fever + dysentery + toxic appearance	Cultures + empirical antibiotics
Bloody diarrhea in child	Cultures; NO empirical antibiotics; exclude STEC
Immunocompromised	Lower threshold for cultures, antibiotics, and admission
Severe dehydration, cannot tolerate oral fluids, electrolyte disturbance	Admit for IV rehydration
C. difficile + toxic/distended abdomen	CT abdomen; vancomycin PO; ID consult

Key takeaway: The decision to use antibiotics in AGE is based on host factors (age, immune status), clinical features (fever, dysentery, toxicity), pathogen (when known), and critically - excluding STEC before treating bloody diarrhea in children.

Sources: Rosen's Emergency Medicine (9e), Harrison's Principles of Internal Medicine (22e, 2025), Goldman-Cecil Medicine, Tintinalli's Emergency Medicine, Sleisenger & Fordtran's GI and Liver Disease

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