Name
ARTHRITIS, INFECTIOUS, GRANULOMATOUS
DESCRIPTION
DETAIL
DIFFERENTIAL DIAGNOSIS β’ Gout β’ Pseudogout (calcium pyrophosphate deposition disease) β’ Spondyloarthropathy (Reiter syndrome, psoriatic arthritis, ankylosing spondylitis, the arthritis of inflammatory bowel disease) β’ Juvenile rheumatoid arthritis β’ Type IIa hyperlipoproteinemia β’ Foreign body synovitis β’ Rheumatoid arthritis β’ Rheumatic fever β’ AIDS β’ Cellulitis β’ Palindromic rheumatism β’ Neuropathic arthropathy β’ Lyme arthritis β’ Sarcoidosis β’ Pyogenic arthritis -------------------------------------------------------------------------- CAUSES β’ Hematogenous invasion by microorganisms (80-90%) β’ Contiguous spread (10-15%) β’ Direct penetration of micro-organisms secondary to traumaβ’ Synovial fluid usually cloudy with > 20,000 WBC/HPF, but may have fewer white blood cells present or over 100,000. (Caveat - cell count must be performed within 1 hour of obtaining specimen to be valid). β’ Synovial fl uid white count can be recognized as elevated (in presence of trauma) if RBC:WBC ratio significantly less than 700 β’ Polymorphonuclear leukocytes usually predominate in synovial fl uid. (Granulomatous and viral arthritis may have a mononuclear cell predominance, but polymorphonuclear leukocytes usually predominate). β’ Synovial fl uid glucose often more than 40 mg/dL (2.22 mmol/L) less than in a simultaneously obtained serum glucose value (in fasting patient). However, arthrocentesis should not be delayed simply to obtain fasting synovial fluid glucose level. β’ Synovial fl uid eosinophilia may occasionally be seen in the healing phase of an infection, but parasitic (e.g., guinea-worm) infection must also be considered β’ Westergren erythrocyte sedimentation - often elevated, but normal in 20% β’ Rheumatoid factor positive in 50% - if endocarditis present β’ Elevated peripheral white blood cell count β’ Cryoglobulins β’ Immune complexes β’ Febrile agglutinins (to include Brucella and rickettsial related titers) β’ Antistreptolysin O (ASO) titer is usually normal β’ Depressed synovial fluid and occasionally serum levels of complement β’ Presence of crystals in synovial fl uid (e.g., urate or calcium pyrophosphate) does not exclude infectious arthritis β’ Polymerase chain reaction for specific microorganisms - Synovial biopsy may reveal granulomas and possibly the causative organism . Arthrocentesis - bacterial - for silver and acid fast stain and culture . Arthrocentesis - mycobacterial - acid fast (positive in 20%); culture (positive in 80%) . Drug sensitivity testing recommended . Blood, urine cultures . Sputum cultures . Gastric lavage for acid fast - increases yield 7% . Fungal blood cultures . All cultures should be held for 2 weeks; acid-fast cultures for 6 weeks . Polymerase chain reaction (PCR) DNA analysis for tuberculosis IMAGING . X-ray . Soft tissue swelling . Osteoporosis . Effacement of the obturator fat pad (with hip involvement) or psoas shadow . X-ray changes are usually a late phenomenon . Rarefaction of subchondral bone . Joint space loss . Erosions . Joint destruction with ankylosis . Subchondral erosion with preservation of joint space is highly suggestive of granulomatous infection . Other imaging techniques: . Technetium joint scans - reveal distribution of infl ammation, not just infection . Gallium or Ceretec WBC scan-Indium scans - reveal inflammation as well as infection . Computerized tomography - to identify sequestration . Magnetic resonance imaging - perhaps early cartilage damage, osteomyelitis DIAGNOSTIC PROCEDURES β’ Arthrocentesis with gram, silver and acid fast stain, and culture. Must be done in all patients when possibility of infectious arthritis considered. β’ Arthrocentesis approach must avoid contaminated tissue (e.g., overlying cellulitis) β’ Biopsy and culture synovial membrane
TYPENOTES
GENERAL MEASURES β’ Repeat arthrocentesis to drain the joint, as fl uid reaccumulates β’ Avoid adding anti-infl ammatory therapy so as not to compromise assessment of therapeutic response (to antibiotic) β’ Infection associated with prosthetic joints may be difficult to eradicate without removal β’ For Brucella or fungal infections, treatment is continued for 1-2 weeks after total resolution of all signs of inflammation, and 6-8 weeks if the joint was previously diseased (e.g., involved by arthritis) β’ Anti-granulomatous therapy requires a long program β’ Intra-articular antibiotics are not indicated β’ Infectious disease consultation may be helpful SURGICAL MEASURES β’ Arthrotomy indicated only if fl uid accumulated is loculated and/or not amenable to needle drainage DRUG(S) OF CHOICE β’ Medications based on sensitivity of organisms β’ Mycobacterial: (use a combination of these three) isoniazid at 5 mg/kg, up to 300 mg po qd, rifampin at 10 mg/kg, up to 600 mg PO qd, and pyrazinamide at 15-30 mg/kg up to 2 gm/d. The latter is replaced after 2 months with ethambutol 15 mg/kg. Continue therapy for 9-24 months. Request infectious disease consultation. β’ Brucella: tetracycline plus streptomycin or trimethoprim-sulfamethoxazole or rifampin (for dosage, see manufacturerβs literature) β’ Fungal infection: amphotericin B, ketoconazole, flucytosine (5-fl uorocytosine), dependent upon organism
RELATED DISEASE
Not Available Disease
DISEASE
INVESTIGATION
SERUM URIC ACID, RA FACTOR, ASLO TITER, C-REACTIVE PROTEIN, URINE ROUTINE, COMPLETE BLOOD COUNT, MRI, CT SCAN, X-RAY, BIOPSY