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ent.otitis-externa.core.v1PRODUCTION
ent.otitis-externa.core.v1

Acute otitis externa (incl. necrotizing/malignant OE)

general_internal_medicineacutesubacuteadultpediatric
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Encounter flow

12/12 authored

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

Current phase

Frame

Detailed

Frame the external-ear-canal infection across its full severity arc: uncomplicated diffuse AOE is a TOPICAL-ONLY disease (AAO-HNS strong rec AGAINST initial systemic antimicrobials — Rosenfeld 2014); the engine's parallel job is to detect the host/exam signal of NECROTIZING (malignant) OE — Pseudomonas skull-base osteomyelitis in the diabetic/immunocompromised/elderly — which flips management entirely. Distinguish FROM acute otitis media (middle ear) and FROM referred otalgia / EAC malignancy. Skull-base-osteomyelitis source control, sepsis, and glycemic emergencies are routed OUT by engine_id, not authored here.

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Advance rule
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Advance when

OE scope confirmed; AOE-vs-necrotizing-OE dual frame established; not-this-engine concerns routed by engine_id

Patient inputs (15)

Diffuse canal edema/discharge = AOE; localized pustule = furunculosis; granulation tissue at the bony–cartilaginous junction = necrotizing-OE pivot (Rosenfeld AAO-HNS CPG 2014; Loh Otolaryngol HNS 2013)

Intact vs perforated/tube-bearing TM gates ototoxic-drop avoidance AND separates AOE from acute otitis media with perforation (Rosenfeld AAO-HNS CPG 2014 — non-ototoxic preparation if TM non-intact)

Diabetes is the dominant necrotizing-OE risk factor and the dominant modifiable substrate (microangiopathy, impaired neutrophil function, alkaline cerumen); flips management toward skull-base osteomyelitis (Long Am J Emerg Med 2020; Loh Otolaryngol HNS 2013)

HIV, transplant, chemotherapy, chronic steroids → necrotizing-OE prior elevated; also raises fungal MOE prior (Sideris Cureus 2024 — 78.7% of fungal MOE immunosuppressed)

Elderly age is an independent necrotizing-OE risk; pediatric AOE is the AAO-HNS target population (age ≥2) and changes the otomycosis/foreign-body differential weighting (Rosenfeld AAO-HNS CPG 2014; Long Am J Emerg Med 2020)

Swimming, humid climate, hearing aids, cotton-bud trauma, dermatitis macerate the canal and seed Pseudomonas/Staph — the modifiable AOE substrate (Rosenfeld AAO-HNS CPG 2014; Roland & Stroman Laryngoscope 2002)

Pain assessment is the single AAO-HNS strong-recommendation action; pain OUT of proportion to canal findings is the strongest bedside necrotizing-OE pointer (Rosenfeld AAO-HNS CPG 2014; Long Am J Emerg Med 2020)

CN VII (then IX/X/XI/XII jugular foramen, VI petrous apex) palsy signals skull-base spread and the worst-prognosis necrotizing-OE subset — mandatory neuro screen in any at-risk host (Loh Otolaryngol HNS 2013; Long Am J Emerg Med 2020)

Uncomplicated AOE is usually afebrile/non-systemic; fever + systemic features raise the necrotizing/septic prior and the disposition tier (Rosenfeld AAO-HNS CPG 2014; Long Am J Emerg Med 2020)

Canal swab/culture (and biopsy of granulation tissue) identifies Pseudomonas vs MRSA vs fungal MOE and guides systemic anti-pseudomonal therapy + excludes EAC malignancy (Roland & Stroman Laryngoscope 2002; Sideris Cureus 2024)

CT temporal bone for bony erosion; Tc-99m bone scintigraphy when CT equivocal; MRI/gallium SPECT for soft-tissue extent and treatment-response — confirms necrotizing OE and stages skull-base involvement (Haleem Am J Otolaryngol 2025; Long Am J Emerg Med 2020)

ESR correlates with necrotizing-OE disease activity and is the primary treatment-response/duration marker (serial down-trend gates antibiotic cessation) (Loh Otolaryngol HNS 2013; Haleem Am J Otolaryngol 2025)

CRP tracks necrotizing-OE activity alongside ESR and trends faster; serial CRP gates IV→PO step-down and end-of-therapy decisions (Loh Otolaryngol HNS 2013)

Hyperglycemia/HbA1c quantifies the dominant necrotizing-OE driver; poor glycemic control worsens prognosis and triggers cross-engine glycemic optimization (Long Am J Emerg Med 2020; Loh Otolaryngol HNS 2013)

Renal function for systemic ciprofloxacin / ceftazidime / piperacillin-tazobactam dose adjustment in necrotizing OE (Long Am J Emerg Med 2020; Loh Otolaryngol HNS 2013)

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

Severity triggers (8)

8 need judgement
  • informationallife_threateningnecrotizing_oe_suspected
    Diabetic/immunocompromised/elderly host with severe otalgia + granulation tissue at the bony–cartilaginous junction ± otorrhea not responding to topical therapy (Long Am J Emerg Med 2020; Loh Otolaryngol HNS 2013)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationallife_threateningcranial_neuropathy_skull_base_spread
    New facial-nerve (CN VII) or lower-cranial-nerve (IX/X/XI/XII) or CN VI palsy with ear pain/discharge — skull-base osteomyelitis spread, worst-prognosis subset (Loh Otolaryngol HNS 2013)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalseverediabetic_or_immunocompromised_host_low_imaging_threshold
    Diabetes, HIV, transplant, chemotherapy, or chronic-steroid host presenting with otitis externa — elevated necrotizing/fungal-MOE prior, lowered imaging + systemic-therapy threshold (Sideris Cureus 2024 — 78.7% of fungal MOE immunosuppressed; Long Am J Emerg Med 2020)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalsevereseptic_oe_route_to_sepsis
    qSOFA ≥2, hypotension on adequate fluids, or systemic toxicity with a necrotizing-OE / skull-base source (SSC 2021; Long Am J Emerg Med 2020)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalmoderateaoe_treatment_failure_at_48_72h
    Diffuse AOE not improving on appropriate topical therapy at 48–72 h (Rosenfeld AAO-HNS CPG 2014 key-action statement)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalmoderaterefractory_granulation_exclude_eac_malignancy
    Persistent ear-canal granulation/ulceration not responding to therapy, especially without a brisk inflammatory response — external-ear-canal squamous-cell carcinoma must be excluded by biopsy (Rosenfeld AAO-HNS CPG 2014 — distinguish AOE from other causes)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalmildcanal_occlusion_needs_wick
    Ear canal occluded by edema/debris preventing topical-drop delivery (Rosenfeld AAO-HNS CPG 2014)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalmildtm_non_intact_avoid_ototoxic_drops
    Known/suspected tympanic-membrane perforation or tympanostomy tube in a patient needing topical therapy (Rosenfeld AAO-HNS CPG 2014)
    Trigger could not be auto-evaluated — needs clinician judgement.

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Recommended regimen

Uncomplicated diffuse AOE / otomycosis — topical-first ladder (AAO-HNS CPG 2014)
axis: aoe_topical_ladderstep 1 - Step 1 — Aural toilet + analgesia + non-ototoxic-drop decision (every patient)
Selected step "Step 1 — Aural toilet + analgesia + non-ototoxic-drop decision (every patient)" — Any diffuse AOE; canal debris obstructing drop delivery; pain present; TM status determined
  • aural_toilet_microsuction_and_wick_if_canal_occluded
    first line
    procedure
    triggers: canal_debris, canal_occlusion
    Rosenfeld AAO-HNS CPG 2014 — clinicians should enhance topical delivery via aural toilet and/or a wick when the canal is obstructed; debris removal is prerequisite to topical efficacy
  • analgesia_titrated_to_pain_severity
    first line
    supportive
    triggers: otalgia
    Rosenfeld AAO-HNS CPG 2014 STRONG recommendation — assess pain and treat by severity (NSAID/acetaminophen for mild–moderate; opioid short-course for severe)
  • select_non_ototoxic_preparation_if_TM_non_intact_or_tube
    first line
    decision_gate
    triggers: tm_perforation, tympanostomy_tube
    Rosenfeld AAO-HNS CPG 2014 — prescribe a non-ototoxic preparation (fluoroquinolone-otic) when TM is known/suspected non-intact or a tube is present; AVOID aminoglycoside (neomycin/gentamicin) and acidic drops

outpatient playbook — drug actions (4)

  1. 1. ofloxacin otic (TM-safe first-line)
    rxcui 7623
    5–10 drops • otic • BID × 7 d
    trigger: Uncomplicated diffuse AOE, any TM status (non-ototoxic) (Rosenfeld AAO-HNS CPG 2014)
    Topical fluoroquinolone first-line; non-ototoxic; covers Pseudomonas + Staph (Roland & Stroman 2002)
  2. 2. ciprofloxacin+dexamethasone otic (pain/inflammation prominent)
    rxcui 2551
    4 drops • otic • BID × 7 d
    trigger: Marked canal edema/pain (Chu JAMA Netw Open 2022)
    Faster otalgia resolution (median 5.0 vs 5.9 d) vs fluoroquinolone alone
  3. 3. acetic acid 2% otic (low-cost, TM intact)
    3–4 drops • otic • TID–QID
    trigger: Early mild AOE, TM intact, cost-sensitive (Kaushik Cochrane 2010)
    Comparable at week 1, inferior beyond; never if TM non-intact
  4. 4. clotrimazole 1% (otomycosis, after aural toilet)
    rxcui 2623
    apply to canal • otic/topical • BID–TID × 2–3 wk
    trigger: Fungal elements / antibacterial-refractory (Sideris Cureus 2024)
    Switch antibacterial→antifungal for otomycosis

Auto-drafted A&P note

outpatient

Subjective

- Possible entry pathways: Acute ear pain + otorrhea + tragal/pinna tenderness with diffuse ear-canal edema/erythema (classic diffuse AOE — Rosenfeld AAO-HNS CPG 2014; Roland & Stroman Laryngoscope 2002 — Pseudomonas-predominant); Severe otalgia out of proportion to exam ± granulation tissue at the bony–cartilaginous junction of the canal floor — necrotizing OE pivot finding (Long Am J Emerg Med 2020; Loh Otolaryngol HNS 2013); Previously diagnosed otitis externa NOT responding to topical therapy at 48–72 h — mandatory reassessment trigger (Rosenfeld AAO-HNS CPG 2014 key-action statement).

Objective

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

Assessment

**Acute otitis externa (incl. necrotizing/malignant OE)** (ent.otitis-externa.core.v1).
Phenotype framing: Terminal differential with named pivots: uncomplicated diffuse AOE (diffuse canal edema + tragal tenderness + topical-responsive pivot) vs necrotizing/malignant OE (diabetic/immunocompromised host + granulation at bony–cartilaginous junction + pain out of proportion + ESR↑ pivot) vs otomycosis (itch-dominant + visible fungal hyphae/spores + topical-antibacterial failure pivot) vs furunculosis (localized pustule on a hair-bearing canal pivot) vs acute otitis media ± perforation (middle-ear pathology + bulging/perforated TM + NO canal-edema pivot — route ent.otitis-media.core.v1) vs EAC squamous-cell carcinoma / referred otalgia (refractory granulation + no inflammatory response + biopsy pivot) vs eczematous/contact dermatitis OE (chronic itch + dermatitis elsewhere pivot)
Scope: Frame the external-ear-canal infection across its full severity arc: uncomplicated diffuse AOE is a TOPICAL-ONLY disease (AAO-HNS strong rec AGAINST initial systemic antimicrobials — Rosenfeld 2014); the engine's parallel job is to detect the host/exam signal of NECROTIZING (malignant) OE — Pseudomonas skull-base osteomyelitis in the diabetic/immunocompromised/elderly — which flips management entirely. Distinguish FROM acute otitis media (middle ear) and FROM referred otalgia / EAC malignancy. Skull-base-osteomyelitis source control, sepsis, and glycemic emergencies are routed OUT by engine_id, not authored here.

No severity triggers fired against current inputs.

Plan

Regimen axis: **Uncomplicated diffuse AOE / otomycosis — topical-first ladder (AAO-HNS CPG 2014)** — step "Step 1 — Aural toilet + analgesia + non-ototoxic-drop decision (every patient)".
1. aural_toilet_microsuction_and_wick_if_canal_occluded (procedure, first line) — Rosenfeld AAO-HNS CPG 2014 — clinicians should enhance topical delivery via aural toilet and/or a wick when the canal is obstructed; debris removal is prerequisite to topical efficacy
2. analgesia_titrated_to_pain_severity (supportive, first line) — Rosenfeld AAO-HNS CPG 2014 STRONG recommendation — assess pain and treat by severity (NSAID/acetaminophen for mild–moderate; opioid short-course for severe)
3. select_non_ototoxic_preparation_if_TM_non_intact_or_tube (decision_gate, first line) — Rosenfeld AAO-HNS CPG 2014 — prescribe a non-ototoxic preparation (fluoroquinolone-otic) when TM is known/suspected non-intact or a tube is present; AVOID aminoglycoside (neomycin/gentamicin) and acidic drops

Setting playbook (outpatient) — Diagnose uncomplicated diffuse AOE clinically, deliver topical-first therapy + analgesia + aural toilet, AND actively screen every at-risk host for the necrotizing-OE signal before discharge (Rosenfeld AAO-HNS CPG 2014; Long Am J Emerg Med 2020)
4. ofloxacin otic (TM-safe first-line) 5–10 drops otic BID × 7 d — Uncomplicated diffuse AOE, any TM status (non-ototoxic) (Rosenfeld AAO-HNS CPG 2014) (Topical fluoroquinolone first-line; non-ototoxic; covers Pseudomonas + Staph (Roland & Stroman 2002))
5. ciprofloxacin+dexamethasone otic (pain/inflammation prominent) 4 drops otic BID × 7 d — Marked canal edema/pain (Chu JAMA Netw Open 2022) (Faster otalgia resolution (median 5.0 vs 5.9 d) vs fluoroquinolone alone)
6. acetic acid 2% otic (low-cost, TM intact) 3–4 drops otic TID–QID — Early mild AOE, TM intact, cost-sensitive (Kaushik Cochrane 2010) (Comparable at week 1, inferior beyond; never if TM non-intact)
7. clotrimazole 1% (otomycosis, after aural toilet) apply to canal otic/topical BID–TID × 2–3 wk — Fungal elements / antibacterial-refractory (Sideris Cureus 2024) (Switch antibacterial→antifungal for otomycosis)

Non-pharmacologic actions:
- Aural toilet / microsuction; place a wick if the canal is occluded (Rosenfeld AAO-HNS CPG 2014)
- Teach correct drop instillation (tragal pumping, lie affected ear up 3–5 min) (Rosenfeld AAO-HNS CPG 2014)
- Dry-ear / water-precaution counselling for prevention (Rosenfeld AAO-HNS CPG 2014)
- Explicitly document the necrotizing-OE exclusion in every diabetic/immunocompromised/elderly patient (Long Am J Emerg Med 2020)

AVOID / contraindication checks:
- Avoid aminoglycoside and acidic otic drops if TM non intact or tube (Rosenfeld AAO HNS CPG 2014 — ototoxicity; use fluoroquinolone otic)
- No systemic antimicrobial for uncomplicated diffuse AOE (Rosenfeld AAO HNS CPG 2014 STRONG recommendation against initial systemic therapy)
- Do not treat otomycosis with antibacterial drops (Sideris Cureus 2024 — antibacterial drops can worsen fungal OE; switch to antifungal)
- Reassess non responder at 48 72h before extending (Rosenfeld AAO HNS CPG 2014 — exclude necrotizing OE / EAC malignancy / wrong diagnosis)

Monitoring

Regimen monitoring:
- clinical improvement expected by 48-72h (Rosenfeld AAO-HNS CPG 2014)
- symptoms typically resolve ~6 days on antibiotic steroid drops (Kaushik Cochrane 2010)
- reassess and exclude necrotizing OE if not better at 48-72h (Rosenfeld AAO-HNS CPG 2014; Long Am J Emerg Med 2020)
- recheck for otomycosis if antibacterial refractory (Sideris Cureus 2024)

Setting (outpatient) monitoring:
- Clinical improvement expected by 48–72 h; return-if-not-better safety net (Rosenfeld AAO-HNS CPG 2014)
- Symptoms typically resolve ~6 days on antibiotic/steroid drops (Kaushik Cochrane 2010)
- Reassess at 48–72 h if not better — confirm dx, exclude necrotizing OE / otomycosis / EAC malignancy / non-adherence (Rosenfeld AAO-HNS CPG 2014)

Follow-up plan: AOE recurrence prevention: dry-ear precautions, treat the eczematous/contact-dermatitis substrate, acidifying/drying drops for recurrent swimmer's ear, avoid cotton-bud trauma, hearing-aid hygiene. Necrotizing OE: long-term ENT/ID surveillance for recurrence (relapse can occur months later — re-image and re-check ESR/CRP on any symptom return), sustained glycemic optimization (route endo.dm2.core.v1 — the dominant modifiable recurrence driver), and cranial-nerve rehabilitation follow-up where deficits persist.
- Close-out criterion: AOE prevention plan documented; necrotizing OE long-term ENT/ID + glycemic-optimization surveillance plan established and routed

Monitoring phase: Uncomplicated AOE: clinical improvement expected by 48–72 h; persistence at 48–72 h mandates reassessment (confirm diagnosis, exclude necrotizing OE / otomycosis / EAC malignancy / non-ototoxic-drop need / non-adherence) NOT silent therapy extension (AAO-HNS CPG 2014 key-action statement). Necrotizing OE: serial ESR + CRP as the objective treatment-response markers gating antibiotic duration and step-down (Loh 2013 — correlate with disease activity); repeat MRI/nuclear imaging for persistent symptoms; surveillance for new cranial neuropathy or contralateral spread.

Disposition

Current setting: outpatient — Diagnose uncomplicated diffuse AOE clinically, deliver topical-first therapy + analgesia + aural toilet, AND actively screen every at-risk host for the necrotizing-OE signal before discharge (Rosenfeld AAO-HNS CPG 2014; Long Am J Emerg Med 2020)

Disposition criteria:
- Uncomplicated AOE → home on topical therapy + analgesia + 48–72 h safety net (Rosenfeld AAO-HNS CPG 2014)
- Any necrotizing modifier → do NOT discharge on topical-only; admit/urgent ENT + route id.osteomyelitis.core.v1 (Long Am J Emerg Med 2020)

Escalation triggers (move to higher acuity):
- Pain out of proportion + granulation + at-risk host → necrotizing-OE pathway, urgent ENT + imaging, route id.osteomyelitis.core.v1 (Long Am J Emerg Med 2020)
- New cranial-nerve palsy → emergent ENT, skull-base imaging, route id.osteomyelitis.core.v1 (Loh Otolaryngol HNS 2013)
- Systemic toxicity / qSOFA ≥2 → ED + route id.sepsis.core.v1 (SSC 2021)

Earlier-Return Triggers

Return-precaution thresholds (watch for):
- [LIFE_THREATENING] Diabetic/immunocompromised/elderly host with severe otalgia + granulation tissue at the bony–cartilaginous junction ± otorrhea not responding to topical therapy (Long Am J Emerg Med 2020; Loh Otolaryngol HNS 2013)
- [LIFE_THREATENING] New facial-nerve (CN VII) or lower-cranial-nerve (IX/X/XI/XII) or CN VI palsy with ear pain/discharge — skull-base osteomyelitis spread, worst-prognosis subset (Loh Otolaryngol HNS 2013)
- [SEVERE] Diabetes, HIV, transplant, chemotherapy, or chronic-steroid host presenting with otitis externa — elevated necrotizing/fungal-MOE prior, lowered imaging + systemic-therapy threshold (Sideris Cureus 2024 — 78.7% of fungal MOE immunosuppressed; Long Am J Emerg Med 2020)

Citations

- AAO-HNS Clinical Practice Guideline: Acute Otitis Externa (Rosenfeld et al, Otolaryngol Head Neck Surg 2014; PMID 24491310; executive summary PMID 24492208) — current US authority, replaced the 2006 guideline (PMID 16638473), not superseded as of 2026-05-17. Supplemented by Kaushik Cochrane "Interventions for acute otitis externa" 2010 (PMID 20091565), Roland & Stroman microbiology of AOE 2002 (PMID 12169893), and the necrotizing-OE literature: Loh Otolaryngol HNS 2013 (PMID 23558287 — ESR/CRP markers, ceftazidime+fluoroquinolone), Long Am J Emerg Med 2020 (PMID 32505469 — EM red-flag framing), Haleem Am J Otolaryngol 2025 (PMID 40344787 — diagnostic algorithm + nuclear imaging), Sideris Cureus 2024 (PMID 39534824 — fungal MOE systematic review) [PMID:24491310](https://pubmed.ncbi.nlm.nih.gov/24491310/)
- Cited evidence (PMID 24492208) [PMID:24492208](https://pubmed.ncbi.nlm.nih.gov/24492208/)
- Cited evidence (PMID 16638473) [PMID:16638473](https://pubmed.ncbi.nlm.nih.gov/16638473/)
- Cited evidence (PMID 20091565) [PMID:20091565](https://pubmed.ncbi.nlm.nih.gov/20091565/)
- Cited evidence (PMID 12169893) [PMID:12169893](https://pubmed.ncbi.nlm.nih.gov/12169893/)

Last reconciled with current guidelines: 2026-05-17.
References
  • AAO-HNS Clinical Practice Guideline: Acute Otitis Externa (Rosenfeld et al, Otolaryngol Head Neck Surg 2014; PMID 24491310; executive summary PMID 24492208) — current US authority, replaced the 2006 guideline (PMID 16638473), not superseded as of 2026-05-17. Supplemented by Kaushik Cochrane "Interventions for acute otitis externa" 2010 (PMID 20091565), Roland & Stroman microbiology of AOE 2002 (PMID 12169893), and the necrotizing-OE literature: Loh Otolaryngol HNS 2013 (PMID 23558287 — ESR/CRP markers, ceftazidime+fluoroquinolone), Long Am J Emerg Med 2020 (PMID 32505469 — EM red-flag framing), Haleem Am J Otolaryngol 2025 (PMID 40344787 — diagnostic algorithm + nuclear imaging), Sideris Cureus 2024 (PMID 39534824 — fungal MOE systematic review) — PMID:24491310
  • Cited evidence (PMID 24492208) — PMID:24492208
  • Cited evidence (PMID 16638473) — PMID:16638473
  • Cited evidence (PMID 20091565) — PMID:20091565
  • Cited evidence (PMID 12169893) — PMID:12169893