Septic Arthritis of Native Joints

Question 1

What are mandatory non-pharm treatments for SEPTIC ARTHRITIS?

Answer 1

Prompt evacuation of the joint, either by arthcentesis at bedside, open or arthroscopic drainage in the operating room, or imaging-guided drainage in the radiology suite.

Question 2

When should patients be treated emperically for septic arthritis ?

Answer 2

if the synovial fluid white blood cell count exceeds 50,000 cells/mm3.

Question 3

What is a major cause of septic arthritis in US?

Answer 3

MRSA -

Question 4

How long are antibiotic courses for Septic arthritis?

Answer 4

Courses are around 3 to 4 weeks

Question 5

What is the usual cause of septic arthritis?

Answer 5

Occult Bacteremia

Question 6

Why is the synovium vulnerable to bacteremic seeding?

Answer 6

Because it is a vascular tissue that lacks a protective basement membrane.

Question 7

How might gram-negative septic arthritis occur?

Answer 7

may arise from bacteremia from injection drug use or loss of integrity of the gastrointestinal or urinary tracts.

Question 8

Which type of bacteria is the most common cause of septic arthritis?

Answer 8

Gram positive organisms - including S. Aureus

Question 9

How does joint damage occur in septic arthritis?

Answer 9

Joint damage occurs as a result of bacterial invasion, host inflammation and tissue ischemia. Bacterial enzymes and toxins are directly injurious to cartilage.

Question 10

What is the most robust risk factor for septic arthritis?

Answer 10

PREEXISTING JOINT DISEASE (up to 47% of patients with bacterial arthritis have prior joint problems)
Examples - rheumatoid arthritis, gout and pseudogout, osteoarthritis, lupus, trauma, recent surgery

Question 11

What are other risk factors for septic arthritis?

Answer 11

Diabetes,
IV Drug use
Cirrhosis
End-stage renal disease
Prednisone
Skin diseases
Psoriasis
Eczema
Skin ulcers
Human bite

Question 12

Why are patients with RA at high risk of bacterial arthritis?

Answer 12

Already damaged joints, immunosuppressive medications and poor skin conditions. Functional outcomes is worse and mortality is high in patients with RA and septic joints

Question 13

Which type of immunosuppresnts are associated with septic arthritis and intracellular pathogens such as listeria and salmonella?

Answer 13

Tumor necrosis factor blockers.

Question 14

How does septic arthritis present?

Answer 14

classic patient with fever, rigors, and a warm, swollen, and exquisitely painful joint.

Question 15

What are predictors of mortality in septic arthritis?

Answer 15

• Age >65,
• Confusion at presentation
• Polyarticular disease

Question 16

What joint is the principal target of bacterial septic arthritis?

Answer 16

The knee (45% of cases involve the knee)

Question 17

Describe polyarticular disease:
1. What % of patients get it?
2. Which type of bacteria cause it
3. What does it look like and how many joints are affected usually?
4. What are risk factors?

Answer 17

1. 10-20%
2. gonoccocal, pneumococcal, group B streptococcal, and gram negative septic arthritis
3. Asymmetric, and involves an average of 4 joints
4. steroid therapy, RA, lupus, and diabetes

Question 18

Which type of patient will more commonly have cartilaginous septic arthritis?

Answer 18

IV drug users

Question 19

What is the most common cause of septic arthritis?

Answer 19

Staph Aureus - 52% of cases!
Mostly MSSA

OF NOTE: Methicillin-resistant S aureus (MRSA) is increasing in importance in septic arthritis, especially in the United States. In a recent series in Boston, 25% of septic arthritis cases were caused by MRSA.All cases were associated with chronic illness, older age, and health care exposure.

Question 20

What are other potential bacterial causes of septic arthritis?

Answer 20

• Streptococci
• Gram-negative rods (Pseudomonas A. , E.Coli, Proteus species, Klebsiella

Question 21

Which types of patients may have septic arthritis from B-hepolytic streptococci?

Answer 21

elderly, especially those with diabetes, cirrhosis, and neurologic disease

Question 22

When do we typically see Coagulase-negative staphylococci?

Answer 22

Most isolates of coagulase-negative staphylococci from native joints are contaminants, but they can be true joint pathogens after arthroscopy, anterior cruciate ligament reconstruction, and other orthopedic procedures.

Question 23

HOw long do we need to treat postarthroscopic septic arthritis?

Answer 23

Two weeks of parenteral antibiotics are usually curative for postarthroscopic septic arthritis

Question 24

Where would a brucellosis infection causing septic arthritis be seen commonly?

Answer 24

Brucella species are a common cause of subacute or chronic arthritis in countries in which livestock are not vaccinated and unpasteurized dairy products are consumed.

The highest cure rates were reported with the combination of doxycycline for 45 days and streptomycin for 14 days.
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Question 25

What types of pathogens are implicated in human and animal bites?

Answer 25

Human bites cause polymicrobial infection, involving aerobic bacteria, such as staphylococci; α- and β-hemolytic streptococci; oral gram-negative rods, such as Eikenella corrodens; and oral anaerobes, including Prevotella, Fusobacterium, and Peptostreptococcus species.
Animal bites have a similar bacteriology, with Pasteurella multocida as an important additional pathogen.

Question 26

What is Whipple disease?
How is it treated?

Answer 26

The multisystem disorder, Whipple disease, is caused by the fastidious actinomycete Tropheryma whippelii. In 63% of cases, a migratory, nondestructive, peripheral arthritis is the initial manifestation, preceding the onset of abdominal pain, diarrhea, malabsorption, and weight loss by a mean of 8 years in 1 series.

Two weeks of parenteral ceftriaxone is recommended as initial therapy, followed by oral trimethoprim-sulfamethoxazole for at least 1 year.
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Question 27

What type of bacteria do we see involved in hypogammaglublinemia or organ transplant?

Answer 27

mycoplasmas and ureaplasmas - These are very rare type of septic arthritis!

Question 28

What is the most common pathogenic cause of septic arthritis in IV drug users?

Answer 28

Pseudomonas aeruginosa

Question 29

The bacteria Kingella Kingae is recognized as an important cause of septic arthritis, osteomyelitis and intervetebral diskitis in what age?

Answer 29

Children <2 years old

Question 30

What type of diagnostic tests should be done in patients with suspected septic arthritis?

Answer 30

1. Blood cultures

Question 31

What are possible explanations for the fact that 20% of cases of suspected arthritis have negative cultures of synovial fluid on solid media?

Answer 31

• diagnosis is mistaken
• Synovial fluid was obtained after the initiation of antibiotics
• Small numbers of bateria were present
• The quantity of synovial fluid was inadequate.

Question 32

What is the threshold for starting antibiotics low in synovial fluid tests?

Answer 32

Because these tests lack precision! Also
septic arthritis is so rapidly destructive, broad-spectrum antibiotics are usually warranted until culture data are available.

Question 33

What are emperic therapy options for suspected septic arthritis of native joints if:
1. High prevalence area of MRSA
2. Low prevalence area for MRSA

Answer 33

1. Vancomycin 1g IV every 12 hours
2. Cefazolin 2g IV every 8 hours

Question 34

What are antibiotics of choice for the following situations:
1. Gram-negative cocci on gram stain of synovial fluid OR clinical syndrome suggestive of disseminated gonococcal infection?
2. Gram-negative rods on gram stain of synovial fluid
3. No organisms seen on gram stain?

Answer 34

1. Ceftriaxone 1 g IV every 24 hours PLUS Azithromycin 1 g orally (single dose)
2. Cefepime 2g IV every 8 hours or pip/taz 4.5g IV every 6 hours
3. Vancomycin 1 g IV every 12 hours (cefazolin may be used in areas of low MRSA prevalence)

In the elderly, immunocompromised, critically ill, or intravenous drug users, add an antipseudomonal beta-lactam, such as cefepime or piperacillin-tazobactam

Question 35

How long should treatment be for septic arthritis in adults?

Answer 35

Data on duration of therapy are scanty. In general, septic arthritis in adults should be treated for at least 3 weeks, which may include a period of step-down oral therapy. In children with uncomplicated septic arthritis, as few as 10 days of antibiotic therapy may suffice.

Gonococcal septic arthritis can be treated with 2 weeks of ceftriaxone.

Question 36

What is an important adjunct procedure for septic arthritis?

Answer 36

Joint drainage!
There is general agreement that surgical drainage is indicated for septic arthritis of the hip, failure to respond after 5 to 7 days of antibiotics and arthrocentesis, and soft tissue extension of infection. The shoulder joint should be drained either surgically or under radiologic guidance.