Differentiating necrotizing soft tissue infections from cellulitis by soft tissue infectious fluid analysis: a pilot...

Area of Science:

• Infectious Diseases
• Biochemistry
• Medical Diagnostics

Background:

• Soft tissue infections (STIs) require accurate differentiation between cellulitis and necrotizing soft tissue infection (NSTI).
• NSTI is a severe condition necessitating prompt surgical intervention, while cellulitis is typically managed medically.
• Distinguishing between these two conditions based on clinical presentation alone can be challenging.

Purpose of the Study:

• To evaluate the biochemical characteristics of infectious fluid in STIs.
• To investigate the utility of biochemical tests and Gram stain smears of infectious fluid in differentiating NSTI from cellulitis.
• To identify specific fluid biomarkers with high diagnostic accuracy for NSTI.

Main Methods:

• A retrospective cohort study involving 25 patients with suspected NSTI and infectious fluid accumulation.
• Patients were divided into NSTI (n=13) and cellulitis (n=12) groups based on final diagnosis.
• Ultrasound-guided aspiration of infectious fluid was performed, followed by biochemical analysis and Gram stain smear.

Main Results:

• Lactate (AUC=0.937) and LDH (AUC=0.929) in infectious fluid demonstrated outstanding discrimination between NSTI and cellulitis.
• Optimal cut-off values were identified: lactate at 69.6 mg/dL (sensitivity 100%, specificity 76.9%) and LDH at 566 U/L (sensitivity 83.3%, specificity 92.3%).
• Albumin, total protein (TP), and pH in the fluid also showed excellent diagnostic accuracy for NSTI.

Conclusions:

• Analysis of infectious fluid along the deep fascia provides high diagnostic accuracy for differentiating NSTI from cellulitis.
• Biochemical markers in the fluid, such as lactate and LDH, are valuable tools for distinguishing these conditions.
• These findings can aid in timely diagnosis and appropriate management of severe soft tissue infections.