PANCE Blueprint Musculoskeletal (8%)

Infectious Diseases (PEARLS)

The NCCPA™ Musculoskeletal Content Blueprint infectious diseases (PEARLS) 

Acute and chronic osteomyelitis (ReelDx) Acute or chronic infection and inflammation of bone and bone marrow – can occur as a result of hematogenous seeding, the contiguous spread of infection or direct inoculation into intact bone (trauma/surgery)

  • Fever, restriction of movement of involved extremity or refusal to bear weight

Acute osteomyelitis is most commonly seen in children with S. aureus as the most common organism

  • Sickle cell disease - Salmonella is pathognomonic

Chronic osteomyelitis is most common in adults secondary to open injury of bone and surrounding soft tissue

  • S. aureus is the most common organism (80%)
  • Staph epidermidis in prosthetic joints
  • Gram-negative pseudomonas in IVDU
  • Pasteurella seen in cases caused by cat/dog bites
  • Mycobacterium TB seen in vertebral involvement (Potts DZ)

Diagnose with bone aspiration = gold standard

  • X-ray triad: demineralization, periosteal reaction, bone destruction (lags behind symptoms 7-10 days); MRI shows changes before XR
  • Labs: CRP elevated for 4-6 weeks, WBC and ESR high in most cases
  • Definitive diagnosis = blood culture or by needle aspiration/bone biopsy

Treatment: IV antibiotics for 4-6 weeks and at least 2 weeks of IV antibiotics

  • Newborn (<4 months) - Group B Strep - nafcillin or oxacillin + 3rd gen cephalosporin
  • > 4 months S. aureus - MSSA - Nafcillin + Ancef MRSA - Vancomycin or Linezolid
  • Sickle cell - Salmonella - 3rd gen cephalosporin or FQ (Cipr)
  • Puncture wound - Pseudomonas - Cipro or levofloxacin
Septic arthritis (ReelDx) Direct bacterial invasion of joint space - most dangerous form of acute arthritis ⇒ medical emergency

  • A single, swollen, warm, painful joint that is tender to palpation + constitutional symptoms  (fever, sweats, myalgia, malaise, pain)
  • MC = knee, and hip
  • Caused by: hematogenous spread, direct inoculation, contiguous spread
  • S. aureus is most common (40-50%); N. gonorrhea in sexually active young adults, streptococci; pseudomonas in IVDU
  • Diagnose with arthrocentesis: joint fluid aspirate for definitive diagnosis (WBC > 50,000 primarily PMNs)
  • WBC > 1000 is positive in pt with prosthetic joints

Treatment is based on gram stain- 2-4 week course of antibiotics  + arthrotomy with joint drainage

  • Staph aureus = Vanco/nafcillin (Vanco or Clindamycin if PCN allergic)
  • Gonorrhea = ceftriaxone
  • IVDU = Cipro/Levaquin
Osteoarthritis (Lecture) (Prev Lesson)
(Next Lesson) Osteomyelitis (ReelDx)
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