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Septic Arthritis - Adult

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Topic updated on 03/31/13 8:49pm
Introduction
  • Most commonly affected joints in descending order include
    • knee > hip > elbow > ankle >stenoclavicular joint (see below)
  • Pathoanatomy
    • 3 main ways of bacterial seeding of joint
      • bacteremia
      • direct inoculation from trauma or surgery
      • contiguous spread from adjacent osteomyelitis
    • septic arthritis causes irreversible cartilage destruction in an involved joint
      • release of proteolytic enzymes from inflammatory cells (PMNs)
      • cartilage injury can occur by 8 hours
  • Most common pathogens include
    • staphylococcus species
      • staphyloccus aureus (most common, >50% cases)
      • MRSA
      • staphylococcus epidermis
    • neisseria gonorrhea
      • most common organism in otherwise healthy sexually active adolescents and young adults
      • knee most commonly involved
    • streptococcus
    • salmonella
      • seen in patients with sickle cell disease
    • pseudomonas aeruginosa
      • seen in patient with history of IV drug abuse
    • pasteurella multocida
      • seen in patients after dog or cat bite
    • eikenella corrodens
      • seen in patients after human bite
    • organism found in immunocompromised host
      • can include fungal, and candida common pathogens
  • Associated conditions
    • prosthetic implant infection topic
    • sternoclavicular joint septic arthritis
      • found in IV drug users
      • pseudomonas Aeruginosa was most common pathogen in 1980's.
      • staphylococcus aureus is now the most common pathogen in all patients, including IV drug users.
Presentation
  • Symptoms
    • pain in affected joint
    • fevers
    • may appear toxic
    • inability to bear weight
    • inability to tolerate PROM
  • Physical exam
    • involved joint will have
      • warmth, erythema, and tenderness
      • effusion
      • joint motion causes extreme pain
    • extremity tends to be in position of maximum joint volume
      • hip would be in FABER position (flexed, abducted, externally rotated)
Imaging
  • Radiographs
    • may show joint space widening or effusion
  • Ultrasound
    • may help in confirming joint effusion in large joint such as hip
      • can be used in guiding aspirations
  • MRI
    • detects joint effusion, and may detect adjacent bone involvement such as osteomyelitis
Evaluation
  • Serum
    • elevated serum WBC >10K with left shift, ESR >30, and CRP >5
      • ESR is often elevated but may be normal early in process
        • rises within 2 days of infection and can rise 3-5 days after initiation of appropriate antibiotics, and returns to normal 3-4 weeks
      • CRP is most helpful
        • best way to judge efficacy of treatment, as CRP rises within few hours of infection, and may normalize within 1 week of treatment
  • Joint fluid aspirate
    • gold standard for treatment and allows directed antiobiotic treatment
    • should be analyzed for
      • cell count with differential
      • gram stain
      • culture
      • glucose level
      • crystal analysis
    • characteristic findings
      • joint fluid appears cloudy or purulent
      • cell count with WBC > 50,000 is considered diagnostic for septic arthritis, however lower counts may still indicate infection
        • prosthetic joint with WBC >1,100 is considered septic
      • gram stains only identifies infective organism 1/3 of time
      • glucose less than 60% of serum level
  • Saline load test
    • utilized to determine if wound near a joint communicates with the joint
    • for the knee, 155 mL of saline is needed to reach 90% sensitivity 
Treatment
  • Operative
    • operative irrigation and drainage of the joint
      • indications
        • considered an orthopaedic surgical emergency
      • technique
        • may be performed open or arthroscopically
        • remove all purulent fluid and irrigate joint
        • obtain intra-operative fluid and tissue for culture
      • IV antibiotic therapy
        • initiate empiric therapy prior to definitive cultures based on patient age and or risk factors
          • young, healthy adults should be treated for staphyloccus aureus, and neisseria gonorrhea
          • immunocompromised patients should cover staphyloccus aureus, and pseudomonas aeruginosa
        • transition to organism-specific antibiotic therapy based once obtain culture sensitivities
        • treatment can be monitored by following serum CBC, ESR, and CRP levels during treatment

 

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Qbank (4 Questions)

TAG
(OBQ10.114) When performing a saline load test to evaluate for a traumatic arthrotomy of the knee, a mininum of how much saline should be utilized? Topic Review Topic

1. 30 mL
2. 50 mL
3. 75 mL
4. 100 mL
5. 155 mL

PREFERRED RESPONSE ▶
TAG
(OBQ06.63) A 20-year-old man presents with erythema, swelling, and pain at the left sternoclavicular joint shown in Figure A. His temperature is 38.9 degress Celsius, serum WBC is 14,000, and his C-reactive protein is elevated. He reports that he uses IV heroin. A coronal 3D CT scan of the left clavicle is shown in Figure B. Which of the following organisms is the most likely pathogen? Topic Review Topic
FIGURES: A   B        

1. Propionibacterium acnes
2. Staphylococcus aureus
3. Group B streptococcus
4. Neisseria gonorrhea
5. Enterococcus coli

PREFERRED RESPONSE ▶
TAG
(OBQ04.24) A 45-year-old IV drug abuser has sternoclavicular (SC) joint pain for the past 2 weeks. He is afebrile and physical exam findings include point tenderness and swelling. He most likely has septic arthritis of the sternoclavicular joint. If so, what is the most likely infecting organism? Topic Review Topic

1. Streptococcus pneumoniae
2. Staphylococcus aureus
3. Pseudomonas aeruginosa
4. Staphylococcus epidermis
5. Propionibacterium acnes

PREFERRED RESPONSE ▶




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