Septic Bursitis: Causes, Symptoms, Diagnosis, and Treatment

What is septic bursitis?

Septic bursitis is a painful inflammation of a bursa, a small fluid-filled sac that acts as a cushion between bones, tendons, and muscles, caused by a bacterial infection. Unlike common bursitis, which is typically due to overuse or trauma, septic bursitis requires prompt medical attention to prevent serious complications.

Understanding Bursae: The Body's Friction Reducers

Bursae (plural of bursa) are thin, slippery, sac-like structures found throughout the body, strategically located at points where friction commonly occurs between tissues. Filled with a small amount of synovial fluid, their primary function is to reduce friction and cushion pressure points between bones, tendons, muscles, and skin, facilitating smooth movement during activity. While there are over 150 bursae in the human body, some are more susceptible to inflammation and infection due to their superficial location and exposure to external forces.

What is Septic Bursitis?

Septic bursitis refers specifically to the inflammation of a bursa that has become infected with bacteria. This distinguishes it from aseptic (or non-septic) bursitis, which is an inflammatory condition caused by trauma, overuse, or underlying conditions like gout or rheumatoid arthritis, without the presence of infection. The most common bacterial culprit in septic bursitis is Staphylococcus aureus (staph), although other bacteria can also be responsible.

Causes and Mechanisms of Infection

Bacteria typically enter a bursa through a break in the skin overlying the bursa. Common entry points include:

• Cuts, scrapes, or abrasions: Even minor skin injuries can provide a pathway for bacteria.
• Puncture wounds: Insect bites, splinters, or needle punctures can introduce bacteria directly into the bursa.
• Medical procedures: Injections (e.g., corticosteroid injections into or near a bursa), aspirations, or surgeries can sometimes lead to infection if sterile techniques are compromised.
• Spread from adjacent infection: Less commonly, bacteria from a nearby skin infection (e.g., cellulitis) or joint infection can spread to a bursa.

Once bacteria enter the bursa, they multiply within the synovial fluid, leading to an inflammatory response that is characteristic of infection.

Common Locations Affected

While any bursa can become infected, septic bursitis most frequently affects bursae that are superficial and thus more exposed to external trauma or pressure. These include:

• Olecranon bursitis (elbow): Located at the tip of the elbow, often affected by direct blows, falls, or repetitive pressure (e.g., leaning on elbows).
• Prepatellar bursitis (knee): Located over the kneecap, commonly known as "housemaid's knee" or "carpenter's knee" due to repetitive kneeling.
• Superficial infrapatellar bursitis (knee): Also over the knee, just below the kneecap.

Less commonly, deeper bursae such as the trochanteric bursa (hip) or subacromial bursa (shoulder) can also become infected, though this is often associated with deeper penetrating injuries or systemic infections.

Signs and Symptoms

The symptoms of septic bursitis are generally more severe and rapidly progressive than those of aseptic bursitis. Key indicators include:

• Acute Pain: Often localized, severe, and worsening with movement or pressure.
• Significant Swelling: The affected bursa becomes noticeably enlarged and distended.
• Erythema (Redness): The skin over the b bursa appears red and inflamed.
• Warmth: The area over the bursa feels hot to the touch.
• Fever and Chills: Systemic signs of infection are common, indicating the body's generalized response to the bacterial invasion.
• Limited Range of Motion: Pain and swelling can restrict movement of the adjacent joint.
• Malaise: A general feeling of discomfort, illness, or uneasiness.

Risk Factors

Several factors can increase an individual's susceptibility to septic bursitis:

• Skin integrity compromise: Any condition or activity that leads to breaks in the skin near a bursa.
• Compromised immune system: Individuals with diabetes, HIV/AIDS, kidney failure, chronic obstructive pulmonary disease (COPD), or those on immunosuppressive medications (e.g., corticosteroids) are at higher risk.
• Pre-existing bursitis: A bursa that is already inflamed or damaged from aseptic bursitis may be more vulnerable to infection.
• Repetitive pressure or trauma: Occupations or sports involving repetitive kneeling, leaning on elbows, or direct impact can predispose individuals to bursitis, which then increases the risk of infection if skin integrity is compromised.
• Gout or pseudogout: Crystals in the bursa can cause inflammation and potentially create an environment more susceptible to bacterial growth.

Diagnosis

Accurate and prompt diagnosis is crucial for effective treatment of septic bursitis. The diagnostic process typically involves:

• Physical Examination: A healthcare professional will examine the affected area, looking for the classic signs of infection (redness, warmth, swelling, tenderness) and assessing the range of motion.
• Bursal Fluid Aspiration: This is the most definitive diagnostic test. A sterile needle is used to withdraw fluid directly from the bursa. The fluid is then sent for laboratory analysis, which includes:
  • Cell count: To determine the number and type of white blood cells (elevated in infection).
  • Gram stain: To identify the type of bacteria present.
  • Culture and sensitivity: To grow the bacteria and determine which antibiotics will be most effective.
• Blood Tests: Blood tests such as a complete blood count (CBC) to check for elevated white blood cell count, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) can indicate systemic inflammation and infection.
• Imaging Studies: While not typically used to diagnose infection directly, ultrasound or MRI may be used to rule out other conditions (e.g., tendon tears, fractures) or to assess the extent of swelling and inflammation.

Treatment Strategies

Treatment for septic bursitis is aggressive and aims to eradicate the infection, alleviate symptoms, and prevent complications.

• Antibiotics: This is the cornerstone of treatment. Broad-spectrum antibiotics are usually started intravenously (IV) immediately after fluid aspiration, then adjusted based on culture and sensitivity results. Treatment typically continues with oral antibiotics for several weeks.
• Drainage/Aspiration: Repeated aspiration of the infected bursal fluid may be necessary to remove pus, reduce pressure, and facilitate healing.
• Surgical Intervention (Bursectomy): In severe, chronic, or recurrent cases where antibiotics and drainage are insufficient, surgical removal of the bursa (bursectomy) may be required. This is often performed after the acute infection has been controlled.
• Pain Management: Over-the-counter or prescription pain relievers (e.g., NSAIDs) can help manage pain and inflammation.
• Rest and Immobilization: Resting the affected area and sometimes using a splint or brace can help reduce irritation and promote healing.
• Ice: Applying ice packs can help reduce swelling and discomfort.

Prevention for Fitness Enthusiasts and Professionals

For those engaged in fitness activities or professions that involve repetitive movements or pressure, understanding prevention is key:

• Protect Vulnerable Areas: Use padding (e.g., knee pads for kneeling, elbow pads for certain sports) to reduce direct pressure and friction on superficial bursae.
• Maintain Skin Integrity: Promptly clean and cover any cuts, scrapes, or insect bites, especially over high-risk areas, to prevent bacterial entry.
• Practice Good Hygiene: Keep skin clean, particularly in areas prone to sweating or friction.
• Manage Underlying Health Conditions: Individuals with diabetes or other immune-compromising conditions should diligently manage their health to reduce infection risk.
• Optimize Technique: For athletes and those in physically demanding jobs, proper biomechanics and technique can reduce excessive stress and friction on joints and bursae.
• Address Aseptic Bursitis Promptly: If non-infectious bursitis develops, seek appropriate medical advice and treatment to prevent chronic inflammation, which could potentially make the bursa more susceptible to infection.

When to Seek Medical Attention

Septic bursitis is a medical emergency that requires immediate attention. If you experience any of the following symptoms, particularly in an area prone to bursitis, seek prompt medical evaluation:

• Sudden onset of severe pain, swelling, redness, and warmth over a joint or bony prominence.
• Fever, chills, or a general feeling of illness accompanying localized joint symptoms.
• Inability to move the affected joint or extreme pain with movement.
• Pus or drainage from a skin break near a bursa.

Early diagnosis and treatment are crucial to prevent the infection from spreading, leading to more serious complications such as cellulitis, osteomyelitis (bone infection), or even sepsis.