Septic arthritis
Background
- Def: inflammation of a synovial membrane with purulent effusion into the joint capsule
- usually affects monoarticular joints (the knee is most commonly affected in adults and the hip in children)
- Relatively rare disease however because it can quickly destroy the joint or lead to osteomyelitis, fibrous ankylosis, sepsis, or even death it is important to catch and treat promptly
- Frequency is ~20,000 cases in USA/year (may be higher in pts with immunologic disorders (RA, SLE))
- M>F predominance, usually in patients >65 years
- Etiology is usually bacterial, divided into gonococcal or nongonococcal groups
- staph and strep are most common nongonococcal causes
- consider different organisms in children, IV drug users, and those with prosthetic joints
Diagnosis
- may be difficult to diagnose in early stages
- patient typically presents with fever and a warm, red, painful, swollen joint with decreased range of motion even passively
- confirm diagnosis with work up
Work-Up
- CBC
- ESR
- Blood Cultures
- Gonorrhea culture (urethral/cervical/pharyngeal/rectal)
- Arthrocentesis with synovial fluid analysis
- Plain films (often normal but may show widening of joint space or evidence of osteomyelitis)
- Ultrasound (can show joint effusion, extent of disease, and may help differentiate from other conditions)
DDx
- toxic synovitis
- abscess
- cellulitis
- primary rheumatologic disorder (i.e. vasculitis)
- iatrogenic
- reactive arthritis (post infectious)
Gonococcal Arthritis
Healthy, young sexually active adults
Women > men
Suppurative monoarthritis (may be preceded by polyarthralgias)
Knee, wrist, ankle
Arthritis-Dermatitis Syndrome
Diagnosis
-Triad: dermatitis, tenosynovitis, migratory polyarthritis (hematogenous spread of bacteria and immune complexes)
-Skin lesions: scattered small painless erythematous macules or petechiae-->pustular -->necrotic lesions
-Transient painful extensor tenosynovitis (writs, hands, ankles)
-Asymmtric polyarthralgia of extremity joints
DiagnosisCx everything - jt, mucosal surfaces, lesions
Treatment
CTX 1gIV qd OR
Cefotax 1g q8
Empirically treat Chlamydia
Nongonococcal Arthritis
Background
Fulminant presentation (abrupt, swelling, toxicity and fever) unless elderly
-Hematogenous
-Contiguous
-Direct traumatic implantation
-Postop
Causes
Bacterial
Mycobacterial
Spirochete (lyme, syphilis)
Fungal
VIral (HIV, Hep B, Rubella, etc)
Postinfectious
Diagnosis
Synovial fluid aspiration
Cx - if only one test, use BCx bottles (may enhance yield)
Grm stain - 80% positive in gram-positive infxn; less sens in gram-negative
Cell count with dif - >50,000-150,000; PMN > 90%
Treatment
PCN-ase resistant synthetic PCN:
Nafcillin 1-2g
Cefazolin 1-2g
AND
3rd gen ceph
OR
Vanc^
^new evidence suggests significantly increased rate of MRSA septic arthritis
^^cell counts are as low as 20,000 in MRSA Cx + synovial fluid
Treatment
- drainage of the joint
- IV Antibiotics
- generally Oxacillin or Nafcillin with a cephalosporin (ceftriaxone, feotaxme, ceftizoxime) will cover
- add vancomycin if you suspect MRSA
- in IVDA patients use IV aminoglycoside + antipseudomonal cephalosporin
- patients with prosthetic joints are at higher risk of MRSA, MRSE, Enterobacteriaceae, and Pseudomonas
- consider gonococcal infection in young sexually active patients (treat with ceftriaxone)
- Open drainage and lavage in the OR
Disposition
- All patients should be admitted with Ortho consult and continued on IV antibiotics
See Also
Source
http://emprocedures.com/arthrocentesis/analysis.htmEmedicine