Will White Blood Cell (WBC) count be elevated in septic bursitis?

From the Guidelines

Yes, white blood cell (WBC) count is typically elevated in septic bursitis, as it is in other forms of septic arthritis, with counts often exceeding 12,000 cells/mm³, as indicated by the Kocher criteria 1.

Key Points to Consider

• Septic bursitis, similar to septic arthritis, is characterized by an inflammatory response to a bacterial infection, which typically leads to an elevation in WBC count.
• The Kocher criteria, which include a WBC count of at least 12,000 cells/mm³, are used to distinguish septic arthritis from transient synovitis and can be relevant in the context of septic bursitis as well 1.
• The elevation of WBC count is part of the body's immune response to the infection, and its degree can sometimes correlate with the severity of the infection.
• However, it's crucial to note that some patients, especially those who are immunocompromised, might not exhibit significant leukocytosis despite having a severe infection.

Diagnostic and Therapeutic Approach

• Diagnosis of septic bursitis involves clinical suspicion, laboratory tests including a complete blood count to assess WBC count, and bursal fluid aspiration for culture and analysis.
• Treatment typically involves prompt antibiotic therapy, with initial empiric coverage often targeting Staphylococcus aureus, and may include serial drainage of the infected bursa.
• The choice of antibiotic, such as cefazolin or vancomycin, depends on the suspected causative organism and local resistance patterns.

Importance of Prompt Diagnosis and Treatment

• Given the potential for significant morbidity associated with septic bursitis, prompt diagnosis and initiation of appropriate treatment are critical to prevent long-term sequelae and improve patient outcomes.
• Imaging and laboratory tests, including WBC count, play a crucial role in the diagnosis and management of septic bursitis, guiding both the initial treatment approach and the need for potential surgical intervention.

From the Research

White Blood Cell Count in Septic Bursitis

• The white blood cell (WBC) count is often elevated in cases of septic bursitis, as indicated by studies 2, 3.
• A case report of septic bursitis described a patient with an increased WBC count of 3040 cells/mm(3) in the synovial fluid analysis 2.
• Another study reviewed 49 episodes of septic bursitis and found that bursal fluid WBC counts varied widely, ranging from 350 to 392,500 WBC/mm(3) 3.
• However, the usefulness of WBC count as a diagnostic tool for septic bursitis is limited, and other biomarkers such as procalcitonin and neutrophil-lymphocyte count ratio may be more accurate 4, 5.

Diagnostic Evaluation of Septic Bursitis

• The diagnosis of septic bursitis is typically based on clinical presentation, and laboratory tests such as WBC count, inflammatory markers, and bursal aspiration can help confirm the diagnosis 6.
• Bursal aspiration and fluid analysis, including Gram stain, crystal analysis, glucose measurement, blood cell count, and culture, are essential for diagnosing septic bursitis 6.
• Imaging studies such as ultrasonography can help distinguish bursitis from cellulitis, while magnetic resonance imaging can help distinguish infectious from noninfectious causes 6.

Treatment of Septic Bursitis

• The treatment of septic bursitis typically involves antibiotics effective against Staphylococcus aureus, with surgery reserved for cases that do not respond to antibiotics or for recurrent cases 6.
• Outpatient antibiotics may be considered for patients who are not acutely ill, while those who are acutely ill should be hospitalized and treated with intravenous antibiotics 6.