What is the treatment for septic bursitis of the elbow?

Differential Diagnosis for Septic Bursitis of the Elbow

The differential diagnosis for septic olecranon bursitis primarily includes non-septic (aseptic) olecranon bursitis, cellulitis, abscess, septic arthritis of the elbow joint, osteomyelitis, gout, and pseudogout.

Primary Differential Considerations

Non-Septic (Aseptic) Olecranon Bursitis

• Traumatic or inflammatory bursitis is the most common alternative diagnosis, often resulting from repetitive trauma or pressure on the elbow 1
• Physical activities associated with increased mechanical stress distinguish this from infectious causes 1
• Bursal fluid analysis typically shows lower white blood cell counts (<3000 cells/mm³) without bacteria 2

Cellulitis

• Superficial skin infection can mimic septic bursitis with erythema, warmth, and swelling 1
• Distinguished by lack of discrete fluctuant collection and absence of bursal fluid on aspiration 2
• May coexist with septic bursitis, complicating diagnosis 1

Septic Arthritis of the Elbow Joint

• Intra-articular infection presents with severe pain, restricted range of motion, and joint effusion 3
• Requires joint aspiration rather than bursal aspiration for diagnosis 3
• More severe systemic symptoms and functional impairment than isolated bursitis 1

Abscess Formation

• Subcutaneous or deep soft tissue abscess may present similarly with fluctuance and erythema 1
• Imaging (ultrasound or MRI) helps distinguish location and extent 3

Microbiological Differential

Typical Bacterial Pathogens

• Staphylococcus aureus causes >80% of septic bursitis cases 1
• Other gram-positive organisms (Streptococcus species, Staphylococcus epidermidis) account for most remaining cases 1, 4

Atypical Pathogens

• Mycobacterium gordonae and other atypical mycobacteria cause rare cases with insidious onset and delayed diagnosis 5
• Gram-negative organisms, fungi, and other infectious agents represent uncommon causes requiring specialized testing 1
• PCR and extended culture periods may be necessary for identification 5

Crystal Arthropathy Differential

Gout and Pseudogout

• Crystal-induced bursitis can present with acute inflammation mimicking infection 1
• Bursal fluid analysis with polarized microscopy distinguishes crystals from infection 2
• May coexist with septic bursitis in immunocompromised patients 1

Osteomyelitis

• Underlying bone infection of the olecranon may extend to involve the bursa 3
• MRI with gadolinium is the imaging modality of choice for detection 3
• Requires longer antibiotic duration (minimum 8 weeks) compared to isolated bursitis 3

Key Diagnostic Pitfalls

Bursal aspiration with synovial fluid analysis is essential to differentiate septic from non-septic causes 2. Fluid should be sent for:

• Cell count and differential (>3000 cells/mm³ suggests infection) 2
• Gram stain and bacterial culture 1
• Crystal analysis to exclude gout/pseudogout 1
• Consider PCR if atypical mycobacteria suspected 5

Systemic conditions increase severity and complicate diagnosis, including immunocompromised states, diabetes, chronic kidney disease, and chronic corticosteroid use 1. These patients warrant lower threshold for hospitalization and parenteral antibiotics 1.