180.1 🎓 醫孞生版

180.1.0.1 📌 䞀頁重點

項目 Nocardia Actinomyces
Gram + filamentous beaded + filamentous
AFB (modified) + (partial AFB) -
O2 Aerobic Anaerobic (or microaerophilic)
Host Immunocompromise > healthy Healthy, mucosal breach
Source Soil inhalation Endogenous mucosal flora
Sites Lung > Brain > Skin/Soft tissue Cervico-facial (jaw, “lumpy jaw”) > thorax > abdomen > pelvis (IUD!)
“Sulfur granules” No Yes (yellow granules in pus / sinus tract)
Treatment TMP-SMX 高 dose ± imipenem/amikacin × 6-12 mo Penicillin / Amoxicillin × 6-12 mo ± surgery
Suicide vs survive O2 Yes survives No (strict anaerobe)

180.1.0.2 1⃣ Nocardia

180.1.0.2.1 Microbiology
  • Aerobic actinomycete, gram + filamentous beaded rods (易 mistake fungi)
  • Modified Ziehl-Neelsen acid-fast stain + (partial acid-fast)
  • Slow grow (1-3 wk)
  • Soil + water organism
  • Inhaled → lung primary; rare direct skin inoculation
180.1.0.2.2 Species
  • N. asteroides complex (most clinical: N. cyriacigeorgica, N. farcinica, N. nova)
  • N. brasiliensis — skin + cutaneous predominant
  • N. otitidiscaviarum, N. transvalensis — rare
180.1.0.2.3 Risk Hosts
  • Immunocompromise — solid organ transplant, HSCT, chronic steroid (≥ 20 mg pred / day), HIV (CD4 < 100), TNF-blocker, chemo, malignancy
  • Chronic lung disease (COPD, bronchiectasis)
  • Healthy 30% (inoculation cutaneous, mycetoma)
180.1.0.2.4 臚床
180.1.0.2.5 A. Pulmonary Nocardiosis (#1)
  • Subacute / chronic pneumonia
  • Cavitary, nodular, consolidative — variable imaging
  • Misdiagnosed as TB, malignancy, fungal initially
  • 圱像: 可 mass, cavity, single or multiple nodules
  • BAL / biopsy + modified AFB stain
180.1.0.2.6 B. Disseminated / CNS
  • Brain abscess — frequent dissemination from lung
  • Mortality high if missed
  • MRI: ring-enhancing lesions (mimics toxo, lymphoma, abscess)
  • Standard: lung work-up if brain abscess in immunocompromise → Nocardia consideration
180.1.0.2.7 C. Cutaneous / Soft Tissue
  • Cutaneous (N. brasiliensis common):
    • Lymphocutaneous (sporotrichoid pattern — like Sporothrix)
    • Mycetoma (chronic localized, sinus tracts, granules)
    • Cellulitis
  • Acquired direct inoculation (gardening, thorn injury)
180.1.0.2.8 D. Ocular
  • Keratitis (post-trauma / surgical)
  • Endophthalmitis
180.1.0.2.9 Diagnosis
  • Modified AFB stain of sputum / BAL / abscess pus
  • Gram stain: filamentous + branching
  • Culture aerobic, slow (incubate 3 wk)
  • MALDI-TOF for species ID
  • AST important — N. farcinica resistant to many agents (ceph, imipenem variable)
180.1.0.2.10 Treatment
  • TMP-SMX 15 mg/kg (TMP component) / day divided q6-8h IV → PO step-down
  • Combination 初始: TMP-SMX + imipenem ± amikacin (severe / disseminated / CNS)
  • Other: linezolid (intracellular activity, good for CNS), minocycline, ceftriaxone, moxifloxacin
  • Long course:
    • Pulmonary: 6 mo (immunocompetent) — 12 mo (immunocompromise)
    • CNS / disseminated: 12 mo
  • Surgical drainage of brain abscess often needed
  • AST-guided after speciation
  • N. farcinica caution — may resist imipenem, ceftriaxone

180.1.0.3 2⃣ Actinomyces

180.1.0.3.1 Microbiology
  • Anaerobic (microaerophilic) gram + filamentous + branching rods
  • AFB negative (vs Nocardia +)
  • Slow grow (1-2 wk)
  • Endogenous oral / GI / GU mucosal flora
  • Most common: Actinomyces israelii
180.1.0.3.2 臎病
  • Disease occurs after mucosal breach:
    • Dental procedure / poor oral hygiene → cervicofacial
    • Aspiration → thoracic
    • GI surgery / appendicitis perforation → abdominal
    • IUD (intrauterine device) → pelvic (long-standing)
180.1.0.3.3 臚床 — Sulfur Granules
  • Yellow “sulfur granules” in pus / sinus tract drainage = pathognomonic
  • Actually clumps of filaments, not actual sulfur
  • Histology: granules with peripheral palisading Splendore-Hoeppli reaction
180.1.0.3.4 A. Cervicofacial (“Lumpy Jaw”)
  • Most common form
  • Mass / induration mandibular angle
  • Sinus tract draining (yellow granules)
  • Slow chronic course
  • Source: dental procedure / poor oral hygiene
  • Mimics malignancy (biopsy may be needed)
180.1.0.3.5 B. Thoracic
  • Aspiration of oral flora
  • Lung consolidation, cavity, sinus tract through chest wall (rare)
  • Mimics TB, lung CA
180.1.0.3.6 C. Abdominal
  • Source: appendicitis perforation, GI surgery
  • Mass mimicking malignancy
  • Sinus tract draining
  • Often misdiagnosed; biopsy / drainage essential
180.1.0.3.7 D. Pelvic
  • IUD-associated (long-standing > 2 yr) — classic
  • Mass, pelvic pain, abnormal discharge
  • IUD removal + antibiotic
  • Recurrence common
180.1.0.3.8 E. CNS
  • Brain abscess (rare, from hematogenous / contiguous)
180.1.0.3.9 Diagnosis
  • Histology: filamentous gram + + sulfur granules
  • Anaerobic culture (often missed if not requested)
  • 16S rRNA PCR
  • Often surgical biopsy / drainage specimens
180.1.0.3.10 Treatment
  • Penicillin G IV 18-24 M U/day × 4-6 wk → PO amoxicillin × 6-12 mo
  • Alt: doxycycline, clindamycin (if PCN allergy)
  • Long course to prevent relapse (low replication, dormant phases)
  • Surgical drainage / debridement / IUD removal
  • Pelvic + IUD: remove IUD + amox 6 mo

180.1.0.4 3⃣ Whipple’s Disease (Tropheryma whipplei)

  • 非 Nocardia / Actinomyces 䜆 actinomycete-related
  • Gram +, PAS + foamy macrophages in jejunum biopsy
  • 慢 multi-system: arthralgia + 腹瀉 + weight loss + CNS + cardiac
  • Treatment: ceftriaxone × 2 wk → TMP-SMX × 1 yr