Emergency Central is a collection of disease, drug, and test information including 5-Minute Emergency Medicine Consult, Davis’s Drug, McGraw-Hill Medical’s Diagnosaurus®, Pocket Guide to Diagnostic Tests, and MEDLINE Journals created for emergency medicine professionals. Explore these free sample topics:
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- 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