174.3 🩺 內科專科考前版

174.3.0.1 1⃣ Iron Overload Mechanism

  • Yersinia siderophore poorly developed
  • 需 host iron sources
  • Deferoxamine = iron chelator that creates ferrioxamine — usable by Y. enterocolitica
  • Deferiprone, deferasirox — different chemistry, NOT iron donor to Yersinia
  • Hemochromatosis + Yersinia bacteremia — classic association
  • β-thalassemia, sickle cell — chronic transfusion iron load

174.3.0.2 2⃣ Transfusion-Associated Bacteremia 防範

  • Donor screening (questionnaire: GI sx within 14 days)
  • Pathogen-reduction technology (PRT — psoralen + UV for plasma/platelets; emerging for RBC)
  • Cold storage doesn’t kill Yersinia
  • Detection: routine bacterial screening of platelets (mandatory); RBC less standard
  • Suspect: post-transfusion shock, hemoglobinuria, DIC → 立 send culture + start empirical

174.3.0.3 3⃣ 鑑別 Pseudoappendicitis from Real Appendicitis

項目 Yersinia Appendicitis
Onset Days, with diarrhea Hours, classic migration
Sx Fever, diarrhea, RLQ RLQ, anorexia, vomiting
WBC Variable Usually ↑
CT Ileal wall thickening, LAP, normal appendix Appendix enlarged > 6 mm
Stool cx Yersinia + (sometimes) -
Tx Self-limit / abx Appendectomy

Bedside dilemma: 10-30% of “appendicitis” surgeries find normal appendix in Yersinia patients

174.3.0.4 4⃣ Reactive Arthritis Spectrum

  • Triggers: Yersinia, Shigella, Campylobacter, Salmonella, Chlamydia trachomatis
  • HLA-B27 + (~ 50-90%)
  • Onset 1-3 wk post-infection
  • Asymmetric oligoarticular lower extremity
  • Triad classic: arthritis + urethritis + conjunctivitis (“can’t see, pee, climb”)
  • NSAID / steroid injection / sometimes DMARD if chronic

174.3.0.5 5⃣ Far East Scarlet-like Fever (Izumi Fever)

  • Y. pseudotuberculosis variant
  • Fever + 玅疹 + arthritis + GI sx
  • 鑑別: scarlet fever, Kawasaki disease, drug rxn
  • Japan + Russia outbreaks
  • Self-limit + ceftriaxone if invasive

174.3.0.6 6⃣ Yersinia Septicemia + Endocarditis / Aneurysm

  • Iron overload patients
  • Mycotic aneurysm (aorta) — like Salmonella + Campy fetus
  • IE on damaged valve
  • Treatment: 6 wk IV + surgical repair if aneurysm

174.3.0.7 7⃣ 健保 / Taiwan

  • Notifiable (Y. enterocolitica + pseudotuberculosis if cluster)
  • 健保 ceftriaxone for sepsis
  • β-thalassemia care: deferiprone (less Yersinia risk vs deferoxamine)
  • 食 safety (pork supply chain)

174.3.0.8 8⃣ ASP

  • Healthy Yersinia enteritis — NO routine antibiotic
  • High-risk patient (iron overload, immuno, severe) — empirical ceftriaxone immediately
  • AST + de-escalation