• Shuffle
    Toggle On
    Toggle Off
  • Alphabetize
    Toggle On
    Toggle Off
  • Front First
    Toggle On
    Toggle Off
  • Both Sides
    Toggle On
    Toggle Off
  • Read
    Toggle On
    Toggle Off
Reading...
Front

Card Range To Study

through

image

Play button

image

Play button

image

Progress

1/39

Click to flip

Use LEFT and RIGHT arrow keys to navigate between flashcards;

Use UP and DOWN arrow keys to flip the card;

H to show hint;

A reads text to speech;

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
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
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
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
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
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
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.
Septic Arthritis: isolation of organism

How often is an organism isolated?
70% of time organism is isolated
30% no organism
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
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
Nongonococcal Septic Arthritis:

T/F
Fevers and chills must be present for a diagnosis
False

Fevers and chills are common but may be absent
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%
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
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
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
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
Differential diagnosis of septic arthritis
Mycobacterial/Funal
Viral
HIV
Lyme disease
Reactive Arthritis
Endocarditis
Rheum Arthritis
Gout/Pseudogout
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
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
Is gram stain positive more often in non-gonococcal arthritis or in gonococcal arthritis?
non-gonococcal arthritis
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
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
What radiological technique is sufficiently sensitive and specific to be diagnostically useful in suspected septic arthritis?
Bottom line – no radiological technique is currently sufficiently sensitive or specific to be diagnostically useful in suspected septic arthritis
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
Septic Arthritis:

Treatment? (3)
Joint Drainage or Aspiration

Antibiotics

Early joint mobilization
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
Indications for surgical drainage (4)
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
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
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
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%
Patient Profile:

Initial Presentation:

Polyarticular:

Recovery of Bacteria:

Response to Antibiotics:
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
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
Sequelae of prosthetic joint infection
bone resorption
severe radiolucency
scalloping
fistula
periosteal reaction
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
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
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
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
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