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39 Cards in this Set
- Front
- Back
Why is the diagnosis of septic arthritis important?
emergency? which is most dangerous and rapidly destructive joint disease? |
One of the few rheumatological emergencies (cartilage and joint destruction can occur hours/days after infection)
Nongonococcal bacterial arthritis most dangerous and rapidly destructive joint disease Distinguishing nongonococcal septic arthritis from other causes of monoarthritis is crucial Mortality rate for in-hospital nongonococcal septic arthritis ranges from 7% to 15% despite antibiotic use |
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Septic Arthritis - Classification
3 classification? Why are these classifications important? |
Classified into nongonococcal, gonococcal and prosthetic joint infections
Nongonococcal arthritis differs from gonococcal arthritis in its treatment and prognosis |
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Septic Arthritis: Pathophysiology
Name 5 possible sources? |
Hematogenous
- From a distant site: skin, teeth, respiratory, urinary tract, meninges, endocardium Contiguous spread - From a focus of osteomyelitis Lymphogenic - From an adjacent skin or soft tissue infection Iatrogenic - From an intra-articular aspiration or injection Penetrating trauma - From animal or human bites/ dirty objects |
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Septic Arthritis: Pathophysiology
Contiguous: - most common in what age group? What is different about blood vessels of infants age <1? What implication does this have on SA? What is different about the joint capsules of the hip/shoulder in infants age >1? what implication does this have on SA? |
Contiguous - most often in children
Age <1: blood vessels between the epiphysis and metaphysis communicate- focus of infection in the metaphysis can enter the joint space Age >1: joint capsules of the hip and shoulder overlie metaphysis of femur and humerus facilitating direct extension of bone infection into these joint spaces |
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Septic Arthritis: Pathophysiology
Time course? Destruction of cartilage happens how soon after onset? How should it be managed? |
Cartilage and bone loss occurs within hours of infection in experimental models
Within days of onset, septic arthritis destroys cartilage Hence it is important to aspirate the joint early and repeatedly in addition to antibiotics |
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THE NATURAL HISTORY OF BACTERIAL ARTHRITIS IN AN ANIMAL MODEL
Maximal acute arthritis symptoms seen how soon after infection? Chronic irreversible changes occur how soon after infection? |
Maximal acute arthritis symptoms = 2 days
Chronic irreversible changes = 7 days |
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Organisms in Septic Arthritis
Which is most common in both acute septic arthritis and prosthetic joint infection? Which is very common in prosthetics and not at all in acute septic arhritis? Which type of infection do gonococcal infections mostly contribute to? Which organism is common in both but less common than staph? |
Most common in both = Staph. aureus
Prosthetic infections only = Coag- staph. Gonococcal = Acute septic arthritis only Strep = common in both but less than staph aureus. |
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Septic Arthritis: isolation of organism
How often is an organism isolated? |
70% of time organism is isolated
30% no organism |
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Nongonococcal Septic Arthritis:
Risk Factors Local Factors? Systemic Factors? |
Local
- Pre-existing inflammatory arthritis, e.g. Rheumatoid arthritis - Joint trauma - Prior intra-articular steroid injection - Skin infection - Recent joint surgery - Presence of hip or knee prosthesis Systemic - Extremes of age - Diabetes mellitus - I.V. drug abuse - Hemodialysis - Immunodeficiency such as HIV infection, organ transplantation |
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Nongonococcal Septic Arthritis: Clinical Features
Tends to occur in? |
Tends to occur in
- Immunosuppressed states - Diabetes - Malignancy - IV Drug Abuse (IVDA) - Inflammatory arthritis such as Rheumatoid Arthritis |
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Nongonococcal Septic Arthritis:
T/F Fevers and chills must be present for a diagnosis |
False
Fevers and chills are common but may be absent |
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Nongonococcal Septic Arthritis:
Clinical Features Onset? Presenting joint(s)? Predominance? Knee/hip? Ankle/elbow? Wrist/shoulder? |
Abrupt onset
Single joint- hot, swollen and painful Knee>hip ~ ankle>elbow ~ wrist ~ shoulder Polyarticular - 10-20% |
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Gonococcal Septic Arthritis
Risk Factors Urban/rural? Race? Sex? Marital Status? Socioeconomic? Education? Job/hobbies? Illicit Drug use? Past medical history? |
Urban residence
Non-Caucasian race Low socioeconomic status Low educational status Female sex Unmarried Prostitution Intravenous drug abuse Previous gonococcal infection |
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Gonococcal Septic Arthritis: Clinical Features
Tends to occur in? Predisposition with? (2) Portal of entry? (3; which one is asymptomatic?) |
- Tends to occur in young, sexually active adults
- Predisposition with menstruation, pregnancy - Portal of entry- genital, less commonly pharyngeal, rectal (asymptomatic) 3-7.5% of culture positive septic arthritis |
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Gonococcal Septic Arthritis
Clinical Features Often occurs in the setting of a disseminated gonococcal infection (DGI) which takes on one of two forms: |
Arthritis- dermatitis syndrome
- 60% of the patients - Bacteremic phase of infection - Classical triad Localized septic arthritis |
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Gonococcal Septic Arthritis
Clinical Features What is the classical triad of arthritis? Which joints are commonly affected? 2/3 of patients have ______ - a major diagnostic feature |
Classical Triad of Arthritis- dermatitis syndrome: dermatitis, tenosynovitis and migratory polyarthritis
Knees and wrists Tenosynovitis - major diagnostic feature - in two- thirds of patients |
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Differential diagnosis of septic arthritis
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Mycobacterial/Funal
Viral HIV Lyme disease Reactive Arthritis Endocarditis Rheum Arthritis Gout/Pseudogout |
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Septic Arthritis: Lab Tests
What 2 tests/findings have low specificity? Synovial fluid: - often looks? - what provides the best utility in diagnosing septic arthritis? - glucose? (high or low?) - HDL (high or low?) |
Leucocytosis (low specificity)
Increased ESR (low specificity) Synovial Fluid - Appearance: turbid - WBC count: > 50 000 cells/cmm with more than 90% neutrophils – high percentage of PMNs in fluid provides the best utility in diagnosing septic arthritis - Low glucose (sensitivity 44-64%, specificity 85%) - High LDH (100% sensitivity, low specificity) Gram stain is positive in 50-80% of non gonococcal arthritis and less than 20% of gonococcal arthritis Cultures positive in 66-95% of non gonococcal arthritis and 25-50% of gonococcal arthritis |
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Septic Arthritis: Lab Tests
How do you achieve a better yield? What agar would you use for N. Gonorrhea? what medium? What do you culture when suspicious of non-gonococcal infections? What do you culture when suspicious of gonococcal infections? |
Improved yield of synovial fluid if inoculated directly into a blood culture bottle
N. Gonorrhea - fastidious organism - Chocolate agar - non contaminated areas - Thayer Martin medium- contaminated areas Look for source of infection and culture accordingly- - Non gonococcal: urine, sputum, wound, blood - Gonococcal: genital, rectal and pharyngeal - genito-urinary cultures are positive in 70-90% of patients with DGI |
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Is gram stain positive more often in non-gonococcal arthritis or in gonococcal arthritis?
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non-gonococcal arthritis
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Septic Arthritis: Diagnosis
Special Techniques: Synovial polymerase chain reaction (PCR): advantage over standard cultures in diagnosis of staph/strep joint infections? Useful for the detection of which type of organisms? including? |
Synovial polymerase chain reaction (PCR):
No advantage over standard cultures in the diagnosis of staphylococcal or streptococcal joint infections Useful for the detection of fastidious organisms like Yersinia spp, Chlamydia spp, Ureaplasma urealyticum, Neisseria gonorrheae and Borrelia burgdorferi |
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Septic Arthritis: Diagnostic Imaging
Plain X-Ray: for diagnosis? useful in excluding? CT of the joint: to detect? to guide what? MRI: useful in evaluating what? Radionuclide scans: useful in differentiating what? |
Plain X-Ray: little utility in diagnosis but useful to exclude underlying osteomyelitis
CT of the joint: for detecting effusions, to guide aspiration of poorly accessible joints MRI: in evaluation of periarticular abscesses and soft tissue infection Radionuclide scans (99m Tc and 67 Ga): differentiate bone and surrounding soft tissue inflammation- sensitive but not specific. In 111 is less sensitive but more specific |
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What radiological technique is sufficiently sensitive and specific to be diagnostically useful in suspected septic arthritis?
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Bottom line – no radiological technique is currently sufficiently sensitive or specific to be diagnostically useful in suspected septic arthritis
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Septic Arthritis: Diagnosis
What is the single most important test to diagnose SA? |
ANALYSIS OF SYNOVIAL FLUID IS THE SINGLE
MOST IMPORTANT TEST TO DIAGNOSE SEPTIC ARTHRITIS |
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Septic Arthritis:
Treatment? (3) |
Joint Drainage or Aspiration
Antibiotics Early joint mobilization |
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Septic Arthritis: Treatment
Goal of joint aspiration? When to consider, Medical (closed needle aspiration) versus surgical drainage? |
Removal of purulent material from the joint space
Medical (closed needle aspiration) versus surgical drainage - for an accessible joint where you are sure of adequacy of joint drainage, closed needle aspiration is sufficient, for a poorly accessible joint where you are not sure, a surgical drainage is appropriate Needle aspiration, in general, preferable to surgical treatment as an initial mode of treatment for septic arthritis |
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Indications for surgical drainage (4)
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Septic arthritis of the hip
Poorly accessible joints like sacro-iliac joints Suspected soft tissue extension Inadequate clinical response despite five to seven days of antibiotics |
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Septic Arthritis: Treatment
Initial antibiotic therapy based on? If negative initial results, consider use of broad spectrum antibiotics to cover _______ and ________ ? If you suspect gonococcal arthritis, you would use? |
Initial antibiotic therapy based on Gram stain
If Gram stain is negative broad spectrum parenteral antibiotics(to cover staph and strep) suspected gonococcal arthritis - Ceftriaxone or Cefotaxime |
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Septic Arthritis: Treatment
Parenteral antibiotics for how long? For gonococcal arthritis? (oral vs. IV antibiotics?) Indications for intra-articular antibiotics? |
Parenteral antibiotics for 2-4 weeks in general
Oral antibiotics (after I.V. antibiotics) in gonococcal arthritis No indication for intra-articular antibiotics- chemical synovitis |
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Septic Arthritis: Prosthetic Joint Infection
classified as either: Early? Late? |
Early (less than 12 months) versus Late (>12 months)
Annual rate of infection: Early 2%, Late 0.60% |
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Patient Profile:
Initial Presentation: Polyarticular: Recovery of Bacteria: Response to Antibiotics: |
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Septic Arthritis: Early Prosthetic Arthritis
Early Infections: how common? Often due to? What co-morbidities contribute to increased risk? What organisms are associated? Frequency decreased by? |
Early infection: more common- accounts for two thirds of all infection
Often due to intra-operative inoculation or post operative bacteremia Those at high risk: Psoriatic arthritis, RA, Prior joint infection, diabetes, steroids, prolonged operation, large bone graft Organisms: S aureus (50%), mixed (33%), Gram neg (10%) and anaerobes (5%) Frequency decreased by peri-operative antibiotics |
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Septic Arthritis: Late Prosthetic Arthritis
More/less common than early infection? What co-morbidities contribute to increased risk? What organisms are associated? |
Less common than early infection
Those at high risk: Psoriatic arthritis, RA, Prior joint infection, diabetes, steroids, prolonged operation, large bone graft Usually occurs with re implantation of a new prosthesis Organisms: Staph and Strep, E coli and anaerobic infection |
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Sequelae of prosthetic joint infection
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bone resorption
severe radiolucency scalloping fistula periosteal reaction |
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Septic Arthritis: Prosthetic joint infection
Management |
Long term antibiotics
Excision arthroplasty Arthrotomy and removal of joint prosthesis Immediate or delayed re implantation using antibiotic impregnated cement |
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Septic Arthritis: Summary
Which has a better prognosis, gonococcal or non-gonococcal arthritis? |
True medical emergency
Early joint aspiration (for diagnosis) followed by adequate joint drainage medically or surgically Antibiotics Synovial fluid cultures more often positive in non gonococcal arthritis than gonococcal arthritis Gonococcal arthritis has a better prognosis than non gonococcal arthritis |
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Case 1 Highlights:
Underlying Rheumatoid Arthritis and immunosuppression can increase risk of which type of SA? Does absence of fever rule out septic joint? Acute onset of a hot swollen knee may be secondary to what 2 things? Are elevated white count/ESR specific? What is the most diagnostic feature of SA? Management? |
Increased risk of nongonococcal septic arthritis because of underlying RA (incidence goes up from 2-10 to 30-70 per 100 000) and immunosuppression
Absence of fever does not r/o septic joint Acute onset of a hot swollen knee may be secondary to RA flare vs infection WBC count and ESR are elevated but not specific Synovial fluid WBC count of 58000/c.mm makes septic arthritis highly likely Establish adequate joint drainage and start empiric broad spectrum antibiotics pending synovial fluid Gram stain and culture results |
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Case 2 Highlights: Gout
Risk factors for SA? Fever, increased peripheral WBC count and ESR - specific? what else can they be due to? (2) Can gout and infection co-exist? What needs to be tapped for diagnosis? Management? |
Risk factors for septic arthritis – age and diabetes
Fever, increased peripheral WBC count and ESR – non-specific – can be due to gout or infection Gout and infection can co-exist Ankle needs to be tapped to establish the diagnosis As likelihood of gout higher than septic arthritis in this patient, it is reasonable to wait for results of synovial fluid analysis (cell count, crystal, Gram stain and culture) and not begin empiric antibiotics |
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Case 3 Highlights: Gonococcal Infection
Risk factors? What are classic features of disseminated gonococcal infection (DGI)? Increased peripheral WBC count and ESR - specific? Cultures obtained from which body regions should be obtained? Management? |
Risk factors for gonococcal septic arthritis – age and sexual history
Fever, rash and tenosynovitis on exam are classic for disseminated gonococcal infection Increased peripheral WBC count and ESR – non-specific Synovial fluid WBC count of 58000/c.mm makes septic arthritis highly likely Cervical, pharyngeal, rectal and blood cultures should be obtained Start empiric 3rd generation cephalosporin pending synovial fluid Gram stain and culture results |