Treatment of Polymicrobial Infections with Gram-Positive Bacilli and Yeast

Initial Empiric Therapy

The Infectious Diseases Society of America recommends initiating empiric broad-spectrum antibacterial therapy targeting gram-positive organisms plus antifungal therapy for Candida species in patients with abundant PMNs, gram-positive bacilli, and moderate yeast cells, indicating active polymicrobial infection requiring dual antimicrobial coverage 1, 2
For gram-positive bacilli coverage, vancomycin 15-20 mg/kg IV every 8-12 hours is recommended if MRSA or resistant gram-positive organisms are suspected, particularly in healthcare-associated settings 1, 2
Alternative agents for gram-positive bacilli coverage include linezolid 600 mg IV/PO every 12 hours, daptomycin, or ceftaroline if vancomycin is not suitable 1

The Infectious Diseases Society of America recommends first-line antifungal therapy with echinocandins (caspofungin 70 mg loading dose, then 50 mg daily; micafungin 100 mg daily; or anidulafungin 200 mg loading, then 100 mg daily) for moderate yeast cells with abundant PMNs, indicating active Candida infection requiring treatment 1
Fluconazole 800 mg loading dose, then 400 mg daily is an alternative for Candida parapsilosis 1

In neutropenic patients (ANC <500 cells/mm³), yeasts and molds are primary causes of persistent fever, making empiric antifungal therapy mandatory 1, 2
The duration of antifungal therapy should be continued for 2 weeks after clearance of infection or resolution of clinical signs 1
Antibiotics should be adjusted based on identified organisms and their susceptibilities within 48-72 hours 1, 2

For documented Staphylococcus aureus infections, switch to oxacillin, nafcillin, or cefazolin for MSSA, and continue vancomycin or linezolid for MRSA 3
For Candida species, echinocandins remain first-line except for C. parapsilosis (use fluconazole or lipid amphotericin B), and C. krusei and C. glabrata are fluconazole-resistant 1