Bacterial arthritis is a form of infectious arthritis in which the organisms invade the normally sterile joint space. Patients of any age may develop bacterial arthritis. The inflammatory immune system response to the infection and proteins produced by the invading bacteria irritate the cartilage within the affected joint, causing swelling and pain.
Types
Bacterial arthritis can occur in acute and chronic forms. Acute bacterial arthritis, with the sudden onset of symptoms, proves the more common form of the illness. With chronic bacterial arthritis, symptoms evolve gradually, which may lead to a delay in diagnosis, reports the medical reference text "Principles and Practice of Infectious Diseases."
Bacterial Causes
The bacterium Staphylococcus aureus proves the leading cause of acute bacterial arthritis, reports MayoClinic.com. Other bacteria that may cause acute arthritis include group A and B streptococci, pneumococci, Haemophilus influenzae and Neisseria gonorrhoeae. Slow-growing bacteria usually cause chronic bacterial arthritis, including various species of Mycobacterium and Brucella, notes "Principles and Practice of Infectious Diseases."
Symptoms of Acute Infection
Patients with acute bacterial arthritis, also known as septic arthritis, typically experience the rapid onset of severe joint pain, reports the medical information website eOrthopod. In most patients, the infection involves one joint. Among adults, septic arthritis most commonly affects the knee, followed by the hip. The knee also proves the most common site of joint infection among children, followed by the hip, ankle and elbow, according to "Principles and Practice of Infectious Diseases."
With acute bacterial arthritis, the skin overlying the affected joint reddens and feels warm. Patients experience increased pain with movement of the involved joint. Swelling typically occurs and may prove severe. Approximately 80 percent of patients experience a fever with acute bacterial arthritis, notes eOrthopod.
Symptoms of Chronic Infection
With the gradual onset of chronic bacterial arthritis, pain initially proves mild. A single affected joint typically swells slowly and without significant tenderness at the onset, reports "Principles and Practice of Infectious Diseases." Pain in the affected joint progresses over time, eventually prompting the patient to seek medical care. Infection-related inflammation may involve the tendons near the affected joint. Patients with chronic bacterial arthritis do not typically exhibit the sudden fever seen in most patients with acute bacterial arthritis.
Risk Factors
Certain medical conditions and patient characteristics increase the risk for development of bacterial arthritis. Risk factors associated with bacterial arthritis include pre-existing degenerative arthritis, diabetes mellitus, traumatic injury, orthopedic surgery or invasive joint treatments, a weakened immune system, and injection drug use, reports the medical reference text "Orthopaedic Pathology."
Treatment
Two to four weeks of antibiotic therapy is the standard treatment for most forms of acute bacterial arthritis, reports the Cleveland Clinic. Joint infections caused by slow-growing bacteria require a longer duration of therapy. Some patients may require surgical drainage and cleaning of the affected joint if antibiotic therapy fails to produce expected improvement.
References
- "Principles and Practice of Infectious Diseases, Sixth Edition"; Gerald L. Mandell, M.D., et al., Editors; 2004
- Mayo Clinic: Septic Arthritis
- EOrthopod: Septic Arthritis
- "Orthopaedic Pathology, Second Edition"; Vincent J. Vigorita, M.D.; 2008
- Cleveland Clinic: Septic Arthritis
