12-phase flow (12)

1. 1FRAME
   Frame as a THREE-TIER decision: (1) is this an airway/deep-space emergency masquerading as sore throat (epiglottitis, peritonsillar/retropharyngeal/parapharyngeal abscess, Ludwig's angina, Lemierre's) — recognise & route OUT; (2) is this the ~5-15% GAS that benefits from antibiotics vs the viral majority; (3) is this a non-GAS bacterial cause or infectious mononucleosis. Most pharyngitis is viral and self-limited (Spinks Cochrane 2021 PMID 34881426 — 82% symptom-free by 1 wk untreated). Sepsis, abscess drainage, airway control, and the EBV long-tail are routed OUT, not authored here.
   advance: pharyngitis scope confirmed; emergency/EBV/sepsis concerns routed by engine_id
2. 2ENTRY
   Recognise the acute-sore-throat presentation; immediately gauge odynophagia severity and whether the patient can swallow secretions — the single fastest bedside discriminator of "simple pharyngitis" vs "deep-space/airway emergency" (Gottlieb J Emerg Med 2018 PMID 29523424)
   inputs: odynophagia_severity
   advance: entry trigger present; odynophagia severity + secretion-handling recorded
3. 3CONTEXT
   Build the Centor/McIsaac inputs (tonsillar exudate, tender anterior cervical nodes, absence of cough, fever, age band) AND the differential context: sexual-exposure history (gonococcal/HIV), immunisation status (diphtheria), fatigue/posterior-node/splenomegaly pattern (EBV). The score components are conditionally dependent — they are scored together, never multiplied as independent likelihood ratios.
   inputs: tonsillar_exudate, tender_anterior_cervical_nodes, cough_present, temperature, age_band, sexual_exposure_history, immunisation_status
   actions: workup.lymphadenopathy
   advance: Centor/McIsaac components captured + differential context assigned
4. 4RED_FLAGS
   Deep-space/airway emergency screen — trismus, drooling, muffled voice, stridor, tripod/sniffing posture, neck swelling/stiffness, unilateral tonsillar bulge with contralateral uvular deviation (peritonsillar abscess), rigors + internal-jugular tenderness + recent pharyngitis in a young adult (Lemierre), floor-of-mouth swelling/elevated tongue (Ludwig). Toxic/hypotensive → sepsis. These are recognised here and routed OUT by engine_id; do NOT instrument a compromised airway.
   inputs: airway_deep_space_red_flags, spo2_and_resp_distress, sbp
   actions: workup.airway_distress, calc.qsofa, calc.news2
   advance: airway / deep-space / sepsis red flags screened and routed by engine_id if positive
5. 5INITIAL_WORKUP
   Score-directed testing (IDSA 2012 / ACP-CDC 2016): low Centor/McIsaac (0-1) → no test, no antibiotic, symptomatic care; intermediate-high (≥2-3) → RADT ± throat culture. RADT specificity ~95%, sensitivity ~85-90% (McIsaac JAMA 2004 PMID 15069046). CBC if EBV/deep-space considered; inflammatory markers and CMP/renal as severity/dosing baseline. Do NOT test or treat asymptomatic carriers (IDSA 2012 Shulman PMID 22965026).
   inputs: rapid_strep_radt, throat_culture, cbc_with_differential
   actions: panel.cbc, panel.inflammation, panel.cmp, calc.centor
   advance: score computed; test strategy chosen and result available or deferred per score
6. 6BRANCHING_WORKUP
   Branch by finding: RADT/culture positive → confirmed GAS treatment arm; fatigue + posterior nodes + splenomegaly ± atypical lymphocytes → Monospot/EBV serology → infectious mononucleosis (avoid amoxicillin, splenic precautions, route to id.infectious-mononucleosis.core.v1); unilateral bulge/trismus → neck CT then ent.peritonsillar-abscess.core.v1; deep neck swelling/stridor → neck CT then ent.deep-neck-space-infection.core.v1 / ent.epiglottitis.core.v1; sexual exposure → gonococcal culture/NAAT; unimmunised + pseudomembrane → diphtheria notification/antitoxin.
   inputs: monospot_ebv_serology, neck_ct_or_lateral_neck
   actions: workup.lymphadenopathy, workup.cellulitis_necfasc
   advance: GAS-positive arm OR alternative diagnosis assigned and routed by engine_id
7. 7DIFFERENTIAL
   Terminal differential with pivot findings: GAS pharyngitis (high Centor/McIsaac + RADT/culture positive + no cough/coryza pivot) vs viral pharyngitis (cough, coryza, conjunctivitis, low score pivot) vs infectious mononucleosis (marked fatigue + posterior/generalised nodes + splenomegaly + atypical lymphocytes + amoxicillin-rash pivot) vs peritonsillar abscess (trismus + unilateral bulge + uvular deviation + "hot-potato" voice pivot) vs epiglottitis (rapid toxic + drooling + stridor + minimal oropharyngeal findings pivot) vs Lemierre (recent pharyngitis + rigors + unilateral neck tenderness + septic pulmonary emboli pivot) vs gonococcal/diphtheritic/scarlet-fever/acute-retroviral pharyngitis (exposure/immunisation/rash pivots)
   advance: single best diagnosis selected; emergency mimic explicitly excluded or routed
8. 8RISK_STRATIFICATION
   Centor/McIsaac band drives test-vs-treat-vs-neither (McIsaac JAMA 2004 PMID 15069046; IDSA 2012). Layer modifiers: scarlet-fever rash (toxin-mediated GAS — treat), rheumatic-fever-risk population (lower test threshold), Fusobacterium/Lemierre-age (15-30 y, persistent/worsening — heightened deep-space vigilance), immunocompromise, pregnancy. qSOFA/NEWS2/SIRS escalate the toxic/septic picture out.
   inputs: temperature, age_band, sbp
   actions: calc.centor, calc.qsofa, calc.sirs, calc.news2
   advance: GAS-probability band + complication-risk overlay assigned
9. 9TREATMENT
   CONFIRMED GAS: penicillin V or amoxicillin first-line (amoxicillin once-daily improves pediatric adherence); benzathine penicillin G IM single dose if adherence uncertain; penicillin-allergy → cephalexin (non-anaphylactic, no severe-reaction history) OR azithromycin/clindamycin (severe/anaphylactic) (IDSA 2012 Shulman PMID 22965026). 10-day course for GAS (rheumatic-fever prevention rationale; azithromycin 5 d). VIRAL/low-score: NO antibiotic — symptomatic care (analgesia, single-dose dexamethasone for severe odynophagia — de Cassan Cochrane 2020 PMID 32356360, RR 2.4 pain resolution at 24 h). EBV suspected: AVOID amoxicillin (rash), splenic-rupture precautions. Emergencies: route to drainage/airway engines, do not antibiotic-monotherapy a drainable abscess.
   inputs: penicillin_allergy, pregnancy, rapid_strep_radt
   advance: confirmed-GAS regimen OR symptomatic-only plan started; emergency routing executed if applicable
10. 10DISPOSITION
    Most pharyngitis → discharge with symptomatic care ± GAS antibiotic and return precautions. Peritonsillar/retropharyngeal abscess, epiglottitis, Ludwig's, Lemierre, airway compromise, inability to swallow secretions, sepsis → admit and route OUT by engine_id (ent.peritonsillar-abscess.core.v1 / ent.epiglottitis.core.v1 / ent.deep-neck-space-infection.core.v1 / id.sepsis.core.v1). Infectious mononucleosis with airway-threatening tonsillar hypertrophy or splenic concern → admit / route to id.infectious-mononucleosis.core.v1.
    inputs: spo2_and_resp_distress, sbp
    advance: disposition documented; emergency cases admitted and routed
11. 11MONITORING
    Expect clinical improvement within 24-48 h of GAS therapy; antibiotics shorten symptoms only ~16 h overall (Del Mar Cochrane 2006 PMID 17054126). Counsel that most viral sore throat resolves in ~1 week regardless (Spinks Cochrane 2021 PMID 34881426). NON-RESOLUTION or worsening at 48-72 h, new trismus/neck swelling/voice change → re-evaluate for evolving peritonsillar/deep-space abscess, missed mononucleosis, Lemierre, or wrong diagnosis before extending antibiotics.
    inputs: temperature
    actions: panel.inflammation
    advance: objective improvement by 48-72 h OR re-evaluation/escalation triggered
12. 12FOLLOWUP
    GAS: complete the full 10-day course (rheumatic-fever-prevention rationale even after symptoms resolve — Spinks Cochrane 2021 PMID 34881426, ARF Peto OR 0.36). Test-of-cure NOT routine (IDSA 2012). RECURRENT TONSILLITIS: apply Paradise criteria (≥7 episodes/1 y, ≥5/y × 2 y, or ≥3/y × 3 y, each well-documented) → ENT referral for tonsillectomy candidacy. Post-streptococcal sequelae counselling (ARF, PSGN). Penicillin-allergy de-labelling referral for reported (non-verified) allergy. Recurrent GAS / household-source / carrier-state considerations per IDSA 2012.
    inputs: penicillin_allergy
    advance: course-completion + recurrence/Paradise + sequelae-counselling plan documented