Management of Positive Beta-D-Glucan in Patients on Cefepime

Diagnostic Considerations

A positive beta-D-glucan test in a patient receiving cefepime should not automatically trigger antifungal therapy, as beta-lactam antibiotics can cause false-positive results, and the test has limited positive predictive value (PPV) requiring clinical correlation and additional diagnostic workup 1, 2
The specificity of beta-D-glucan ranges from 65-95% in various studies, with PPV as low as 11.8-18% in some populations, meaning many positive results do not represent true invasive fungal infection 5, 1
Additional causes of false positivity include: bacteremia, hemodialysis, administration of albumin or immunoglobulin products, hemolysis, exposure to surgical gauze, and gastrointestinal mucositis 3, 1, 2, 4

High-risk features that increase likelihood of true invasive fungal infection include: neutropenia (absolute neutrophil count <500 cells/μL) 3, 5, 4, hematologic malignancy or hematopoietic stem cell transplantation 3, 2, 4, prolonged ICU stay with multiple risk factors (>7 days with central venous catheter, broad-spectrum antibiotics, parenteral nutrition, dialysis, surgery, pancreatitis, or immunosuppressive therapy) 5, recent abdominal surgery with complications or tertiary peritonitis 5, and persistent fever despite 4+ days of appropriate antibacterial therapy 3, 5, 4

Echinocandins are the first-line empirical therapy for suspected invasive candidiasis in critically ill patients with positive beta-D-glucan plus clinical risk factors 5, 2
Specific indications for treatment initiation include: consecutive positive beta-D-glucan results (2+ tests) PLUS high-risk clinical features PLUS signs of sepsis unresponsive to antibiotics 5, positive blood cultures for Candida species (even a single positive culture constitutes candidemia requiring treatment) 1, 2, radiographic findings suggestive of invasive fungal infection (halo sign, nodular lesions) PLUS positive beta-D-glucan 3, 4, and proven or probable invasive fungal infection by EORTC/MSG criteria 5, 2

For non-neutropenic critically ill patients: Echinocandin (preferred) with caspofungin 70 mg loading dose, then 50 mg daily; OR micafungin 100 mg daily; OR anidulafungin 200 mg loading dose, then 100 mg daily 5, 2
For neutropenic patients: Echinocandin OR liposomal amphotericin B (3-5 mg/kg daily) 3, 4

Treatment duration for documented candidemia: Minimum 14 days after first negative blood culture AND resolution of clinical symptoms 7, 8
Mandatory ophthalmologic examination to rule out endophthalmitis in all candidemia cases 7

Cefepime itself is not specifically listed as causing false-positive beta-D-glucan, but all beta-lactams carry theoretical risk 3, 4
If patient has bacteremia while on cefepime, this is an independent cause of false-positive beta-D-glucan 3, 1, 2, 4