Rosen & Barkin's 5-Minute Emergency Medicine Consult (77 page)

714.0 Rheumatoid arthritis

BASICS

• Bacteria can be introduced into a joint by:
  
  • Hematogenous spread (most common)
    
  • Invasive procedures
    
  • Contiguous infection (e.g., osteomyelitis, cellulitis)
    
  • Direct inoculation such as plant thorns or nails
    
• Acute inflammatory process results in migration of WBCs into joint.
  
• Synovial hyperplasia, cartilage damage, and formation of a purulent effusion
  
• Irreversible loss of function in up to 50%
  
• Mortality rate reported as high as 11%
  

• Hip infections are most common:
  
  • Often in patients with otitis media, upper respiratory tract infections or history of femoral venipuncture
    
  • Complications of septic arthritis (SA) of hip in children: Avascular necrosis, epiphyseal separation, pathologic dislocation, and arthritis
    
• 50% occur in children <3 yr old.
  
• Infants present with irritability, fever, and loss of appetite.
  
• Older children present with fever, and a limp or refusal to bear weight or use joint.
  

• Risk factors:
  
  • Old age, infancy
    
  • Rheumatoid arthritis and degenerative joint disease
    
  • Intravenous drug user (IVDU), endocarditis
    
  • Females (gonococcal [GC] infection)
    
  • Immunosuppression (AIDS, diabetes, chemotherapy, steroid therapy)
    
  • Repeated joint injections, pre-existing joint diseases, trauma, or prosthesis
    
  • Skin infection, cutaneous ulcers
    
• No bacterial pathogen is identified in 10–20%.
  
• Most common organisms:
  
  • Staphylococcus aureus
    in adults, hip infections (80%), and patients with rheumatoid arthritis or diabetes
    
  • Multidrug-resistant S. aureus (MRSA) has been noted in some studies to be the most common organism in community-onset adult SA.
    
  • Neisseria gonorrhoeae
    most common in young, healthy, sexually active patients (incidence has decreased over the past decades due to a decrease in the incidence of mucosal GC infections)
    
• Other pathogens: Group A β-hemolytic and group B, C, and G streptococci:
  
  • Gram-negative rods (e.g.,
    Pseudomonas aeruginosa, Escherichia. coli
    ) in 10% of cases
    
  • Neisseria meningitides (12% of patients with meningococcal meningitis)
    
• Common in old age, infancy, immunosuppression, and IVDU (
  Pseudomonas
  )
  
• Anaerobes: Diabetes, prosthetic joints
  
• Mycobacterial and fungal causes: Atypical (e.g. in advanced HIV); more indolent course
  

DIAGNOSIS

• Presents abruptly as a single painful, swollen, warm, tender joint
  
• Common findings include:
  
  • Fever
    
  • A separate source of infection (e.g., skin)
    
  • Extremely painful joint motion in all planes
    
  • A joint effusion (less evident in sacroiliac, hip, and shoulder)
    
• Any joint can be involved:
  
  • Typically a single joint is involved.
    
  • Most commonly knee, then hip, shoulder, and ankle
    
• Commonly seen in IVDUs: Sacroiliac costochondral and sternoclavicular joints:
  
  • Vertebral involvement such as lumbar facets possible
    
• Human and animal bites, plant thorns, local steroid therapy, and trauma may lead to infection in atypical locations.
  
• Polyarticular involvement in 10–20%:
  
  • Mostly with rheumatoid arthritis; delay in diagnosis from low suspicion and more subtle presentations (fever in only 50%)
    
  • Patients with sepsis
    
• GC SA features:
  
  • Develops in 1–3% of untreated gonorrhea and in 42–85% of disseminated GC infection:
    
• Typically monoarticular but commonly polyarticular
  
• Migratory polyarthralgia, tenosynovitis (present in 20% of patients with arthritis), and dermatitis:
  
  • Involves small joints (e.g., fingers, wrist, elbow, ankle)
    
• Signs of urethral or vaginal GC infection may be present.
  
• Painless maculopapular lesions on trunk, arms, legs, and around affected joint
  

• Perform joint aspiration in any suspected case.
  
• Send fluid for protein and glucose, cell count, Gram stain, and culture.
  
• Typical SA findings:
  
  • A turbid, purulent, or serosanguineous fluid
    
  • A leukocytosis (50,000–150,000/mm
    ³
    ) with a polymorphonuclear predominance (>75%)
    
  • Often a decreased glucose and elevated protein level
    
• Appearance of crystals does not rule out SA.
  
• Use special stain or culture media when indicated (e.g., GC, anaerobes, fungus, mycobacterium)
  
• Intra-articular lidocaine reduces the sensitivity of subsequent cultures; immediate emptying of aspirated sample into a blood culture flask increases the yield.
  
• In non-GC SA, Gram stain and culture are positive in 50% and 90% of cases, respectively:
  
  • Drops to nearly 10% and 50% in GC SA, respectively
    
• Real-time PCR can detect bacterial pathogen DNA in many culture-negative aspirates.
  
• Fluoroscopic, sonographic, or CT guidance can be used in technically difficult aspirations.
  
• CT scan and MRI may aid in the diagnosis for joints such as the sacroiliac joint.
  
• Arthrocentesis is contraindicated whenever there is an underlying joint prosthesis or an overlying skin infection:
  
  • If cellulitis present, use an alternate approach through normal skin.
    

• Nonspecific serum leukocytosis (more common in children), left shift, and C-reactive protein (CRP) and ESR elevation are usually present.
  
• Procalcitonin can be a helpful aid to rule in rather than rule out SA
  
• UA and culture can reveal a urologic source for the pathogen.
  
• Blood cultures may be useful: Positive in 50–70% of non-GC SA.
  
• Culture any potential focus of infection (pharynx, urine, cervix, or anus), particularly when suspecting GC.
  

• Plain radiographs to identify:
  
  • Effusion
    
  • Baseline status of the joint
    
  • Contiguous osteomyelitis
    
  • Concurrent rheumatologic diseases
    
  • Fractures or foreign body
    
  • Joint loosening (a late nonspecific sign)
    
• US, CT, and MRI are more sensitive:
  
  • US may be used to guide aspiration of some joints (e.g., hip) and to detect joint effusions.
    
• Scintigraphic techniques are sensitive and specific in diagnosis of SA. However, they are often not available through ED.
  
• Other tests:
  
  • Bacterial DNA amplification techniques in rapid detection and identification of organisms
    

• Viral arthritis
  
• Rheumatoid arthritis
  
• Gout or pseudogout
  
• HIV-associated arthritis
  
• Reactive arthritis
  
• Lyme disease
  
• Osteomyelitis
  
• Endocarditis
  
• Septic bursitis
  
• Trauma
  
• In children:
  
  • Juvenile idiopathic arthritis
    
  • Slipped capital femoral epiphysis
    
  • Legg–Calvé–Perthes disease
    
  • Metaphyseal osteomyelitis
    
  • Transient synovitis
    

• Because of vaccine,
  Haemophilus influenzae
  is no longer the most common agent.
  
• S. aureus
  is most common.
  
• Group B streptococcus, enterobacteria, and gram-negative rods in the newborn
  

TREATMENT

No specific considerations

• Patient may be septic and require resuscitation.
  
• If patient is toxic, do not delay antibiotics for aspiration results.
  

• Promptly aspirate joint fluid.
  
• Obtain cultures.
  
• Start empiric antibiotics based on Gram stain (if available) and age group or risk factors—consider staphylococcal, streptococcal, and gram-negative coverage; and MRSA in the appropriate setting. Recommended duration of treatment is 2–4 wk. Intra-articular antibiotics are contraindicated.
  
• No risk factors for atypical organisms:
  
  • Use Flucloxacillin or equivalent 2 g QDS IV. Local policy may be to add gentamicin IV.
    
  • If penicillin allergic, clindamycin 450–600 mg QDS IV or 2nd or 3rd generation cephalosporin IV.
    
• High risk of gram-negative sepsis (elderly, frail, recurrent UTI, and recent abdominal surgery):
  
  • 2nd or 3rd generation cephalosporin for example, cefuroxime 1.5 g TDS IV. Local policy may be to add flucloxacillin IV to 3rd generation cephalosporin.
    
  • Gram stain may influence antibiotic choice.
    
• MRSA risk (known MRSA, recent inpatient, nursing home resident, leg ulcers or catheters, or other risk factors determined locally):
  
  • Vancomycin IV + 2nd or 3rd generation cephalosporin IV
    
• Suspected gonococcus or meningococcus:
  
  • Ceftriaxone IV or similar
    
  • Dependent on local policy or resistance
    
• IVDUs: Discuss with microbiologist
  
• ICU patients, known colonization of other organs (e.g., cystic fibrosis): Discuss with microbiologist
  
• Early orthopedic consultation to evaluate eligibility for surgical drainage
  
• Pain control: Narcotics and moderately flexed splinting
  
• Immunologic therapies are experimental.
  
• Prosthesis: Some may try to preserve the limb unless it is loose on plain films.
  
• Patients should be at rest with joint maintained in optimal position to prevent damage.