164.1 🎓 醫孞生版

164.1.0.1 📌 䞀頁重點

  • HACEK:
    • H = Haemophilus parainfluenzae (+ H. aphrophilus reclassified)
    • A = Aggregatibacter actinomycetemcomitans + A. aphrophilus
    • C = Cardiobacterium hominis
    • E = Eikenella corrodens
    • K = Kingella kingae
  • Animal-bite pathogens:
    • Pasteurella multocida (cat/dog bite) — augmentin cover; rapid cellulitis < 24 hr
    • Capnocytophaga canimorsus (dog bite + ç„¡è„Ÿ / EtOH 高臎死 sepsis)
    • Eikenella corrodens (human bite, “fight bite”)
  • Bartonella:
    • B. henselae — cat scratch disease (regional LAP)
    • B. quintana — trench fever, urban街友
    • B. bacilliformis — Carrión’s disease (Andean)
  • Zoonoses:
    • Francisella tularensis — tularemia (rabbit, tick)
    • Yersinia pestis — plague (flea, rodent)
    • Brucella spp. — brucellosis (livestock, raw milk)
  • Capnocytophaga + ç„¡è„Ÿ = emergent — DIC + sepsis quickly

164.1.0.2 1⃣ HACEK Group (Bovine + Cardiac IE)

Species Reservoir 臚床
H. parainfluenzae Oral Native + prosthetic IE
A. actinomycetemcomitans Oral, periodontal IE, periodontitis, soft tissue
A. aphrophilus (reclassified from H.) Oral IE
C. hominis Oral IE, subacute
E. corrodens Oral IE, human bite, lung abscess
K. kingae Oral throat (children) Pediatric IE, septic arthritis (joints children 6 mo-4 yr), osteo
  • Cause ~ 1-3% IE
  • Slow-growing, fastidious
  • Modern blood cx 5-7d detect
  • Treatment: Ceftriaxone 2 g IV q24h × 4 wk (native) / 6 wk (prosthetic)
  • Alt: ampicillin-sulbactam
164.1.0.2.1 A. actinomycetemcomitans + Aggressive Periodontitis
  • 幌幎 periodontal disease
  • Soft tissue abscess
  • Can mimic actinomycosis (䜆這是 actinomyces, gram + filament)
164.1.0.2.2 Kingella kingae in Children
  • Pediatric < 4 yr — septic arthritis (knee/hip), osteomyelitis, IE
  • Pre-school 同 outbreak (saliva spread)
  • Cefazolin or ampicillin (sensitive)

164.1.0.3 2⃣ Animal Bite Pathogens

164.1.0.3.1 Pasteurella multocida
  • Gram - coccobacillus
  • Cat bite 80%+ (deep needle-like puncture), dog bite 20%
  • Rapid cellulitis < 24 hr
  • Septic arthritis (if joint involved)
  • Osteo
  • Bacteremia + abscess (immunocompromise)
  • Treatment: Amoxicillin-clavulanate (covers Pasteurella + anaerobes + S. aureus + Strep)
  • Alt: doxycycline, FQ (NOT cephalexin / dicloxacillin alone — gap on Pasteurella)
  • Tetanus prophylaxis review
164.1.0.3.2 Capnocytophaga canimorsus (DF-2)
  • Gram - fusiform rod, slow grow
  • Dog bite or scratch (cat occasional)
  • Asplenic + EtOH + immuno: fulminant sepsis + DIC + purpura + multi-organ failure within days
  • ~ 30% mortality even with treatment
  • Imune competent: mild cellulitis
  • Treatment: amox-clav, PCN G, ceftriaxone, doxycycline
  • Asplenic 接觞 dog: educate avoid bites; prophylactic abx if bitten (amox-clav 3-5d); seek care if febrile
164.1.0.3.3 Eikenella corrodens
  • Gram - rod
  • Human bite (“fight bite” — closed fist hits teeth)
  • Oral flora
  • Polymicrobial wound with strep, staph, anaerobe
  • Treatment: amox-clav (covers anaerobe), 2nd-gen ceph
  • 1st-gen ceph 䞍 cover Eikenella (gap)
164.1.0.3.4 Other Bite Pathogens
  • DF-3 (Capnocytophaga cynodegmi) — gingival sample
  • Streptobacillus moniliformis / Spirillum minus — rat bite fever (Haverhill)
  • Bartonella henselae — cat scratch

164.1.0.4 3⃣ Bartonella

164.1.0.4.1 B. henselae — Cat Scratch Disease
  • Cat (especially kitten + flea-infested) scratch / lick / bite
  • Regional tender LAP 1-2 wk after; resolves spontaneous 2-6 mo
  • Papule at site (often missed)
  • Atypical: hepatosplenic granulomata, encephalitis, neuroretinitis (macular star, vision loss), endocarditis (culture-neg)
  • Treatment:
    • Mild LAP: 可䞍治療 (self-limited)
    • Symptomatic / severe: Azithromycin 500 mg × 1 → 250 qd × 4d
    • Hepato-splenic / neuro: doxy + rifampin
    • IE: doxy + rifampin × 4-6 wk + gent
164.1.0.4.2 B. quintana — Trench Fever
  • Body louse → 街友, refugee
  • Recurrent fever, headache, leg pain, splenomegaly
  • Bacillary angiomatosis (HIV/immuno): vasoproliferative skin lesions (mimic Kaposi)
  • IE in 街友 (homeless)
  • Treatment: doxycycline + gentamicin
164.1.0.4.3 B. bacilliformis — Carrión’s Disease
  • Andean S. America, sand fly
  • Acute: Oroya fever (severe hemolytic anemia, sepsis)
  • Chronic: verruga peruana (skin warts)
  • Doxy or ceftriaxone or chloramphenicol

164.1.0.5 4⃣ Tularemia (Francisella tularensis)

  • Gram - fastidious
  • Bioterror category A (highly infectious)
  • Rabbit, beaver, hare, deer tick (Dermacentor) vector
  • 6 clinical forms:
    1. Ulceroglandular (#1): skin ulcer + tender regional LAP
    2. Glandular: LAP only
    3. Oculoglandular: conjunctivitis + LAP
    4. Oropharyngeal: ingestion → tonsillitis + LAP
    5. Pneumonic: 吞入 → severe pneumonia
    6. Typhoidal: GI + sepsis
  • Treatment: streptomycin or gentamicin IM × 10d; doxy / cipro alt
  • 通報 (notifiable)

164.1.0.6 5⃣ Plague (Yersinia pestis)

  • Gram - bipolar staining (“safety pin”)
  • Bioterror category A
  • Flea bite (rodent reservoir; Rat → 飛 to human via Xenopsylla cheopis), aerosol (pneumonic)
  • 3 forms:
    1. Bubonic (#1): tender LAP (bubo) + fever
    2. Septicemic (no bubo, just sepsis)
    3. Pneumonic (most contagious — human-to-human via droplet)
  • Treatment: Streptomycin or gentamicin IM 10d; doxy, cipro, levofloxacin alt
  • Isolation (pneumonic)
  • 通報

164.1.0.7 6⃣ Brucellosis (Brucella spp.)

  • Gram - coccobacillus, intracellular
  • B. melitensis (goat, sheep) — most virulent
  • B. abortus (cattle), B. suis (pig), B. canis (dog)
  • Unpasteurized milk / cheese, occupational contact (farmer, vet, lab worker, butcher)
  • “Undulant fever” + sweats + arthralgia + hepatosplenomegaly + spondylitis + epididymo-orchitis + endocarditis
  • Chronic + relapse common
  • Treatment: Doxycycline 100 mg PO bid × 6 wk + rifampin 600-900 PO qd × 6 wk (WHO)
  • Alt: doxy + streptomycin IM × 2-3 wk + doxy continue
  • Spondylitis / IE: 添加 gentamicin or ceftriaxone + longer