ATS Guidelines on Invasive Pulmonary Aspergillosis and Antifungal Strategies in Critically Ill Adults

Introduction: This summary provides an overview of a recent American Thoracic Society clinical practice guideline addressing two core questions in adult pulmonary and critical care practice. First, it examines whether combination therapy with a mold-active triazole (most data concern voriconazole, though newer agents such as isavuconazole or posaconazole may also be considered) plus an echinocandin (specifically caspofungin, micafungin, or anidulafungin) offers added benefit over mold-active triazole monotherapy for patients with proven or probable invasive pulmonary aspergillosis (IPA). Second, it evaluates whether routine use of prophylactic or empiric antifungal agents against Candida species is advisable in critically ill, nonneutropenic, nontransplant patients at risk of invasive candidiasis (IC). By synthesizing available evidence using the GRADE approach, this guideline aims to support clinicians in optimizing therapeutic strategies and improving patient outcomes in these complex infections.

Key Recommendations:

Initial Combination Therapy vs. Monotherapy for IPA

• For patients with proven or probable IPA, the guideline makes a conditional recommendation, meaning the best choice isn’t entirely clear. Both initial combination therapy (mold-active triazole + echinocandin) and monotherapy (mold-active triazole alone) are considered reasonable options.
• Evidence stems primarily from studies in hematologic malignancy (HM) or hematopoietic stem cell transplant (HSCT) recipients, with mixed findings in observational cohorts and a key randomized trial favoring combination therapy, particularly in a subgroup diagnosed by positive galactomannan assays.
• When critical illness or triazole resistance is a concern, combination therapy may be considered, but there is insufficient evidence to categorically endorse one approach over the other.

Prophylactic or Empiric Antifungal Therapy for Candida in Critically Ill Patients

• In nonneutropenic, nontransplant adult ICU patients at risk for IC, the guideline makes a conditional recommendation against routinely using prophylactic or empiric antifungal therapy. This means the benefits of withholding these treatments likely outweigh the risks, but there’s still some uncertainty.
• Low-quality evidence from multiple randomized controlled trials showed no significant mortality benefit in administering antifungals prophylactically or empirically compared with placebo.
• Although IC carries substantial morbidity and mortality, its overall incidence in this population remains low, and ongoing surveillance or targeted diagnostics may be preferable to universal antifungal administration.

Conclusion: The panel emphasizes that these recommendations should be applied with clinical judgment, especially in patients with severe disease, likely high fungal burden, or concerns for antifungal resistance. Combination therapy for IPA may be particularly relevant when critical illness or limited triazole efficacy is suspected. Meanwhile, prophylactic or empiric anti-Candida therapy in the broader ICU setting does not appear to substantially reduce mortality. Continued advances in rapid diagnostics, close monitoring of local resistance patterns, and new antifungal agents may further refine best practices. Future research should focus on validating these findings in diverse patient populations, exploring novel combination regimens, and establishing more precise risk assessments for IC in the ICU.

Reference: Epelbaum O, Marinelli T, Haydour Q, Pennington KM, Evans SE, Carmona EM, Husain S, Knox KS, Jarrett BJ, Azoulay E, Hope WW, and others. “Treatment of Invasive Pulmonary Aspergillosis and Preventive and Empirical Therapy for Invasive Candidiasis in Adult Pulmonary and Critical Care Patients: An Official American Thoracic Society Clinical Practice Guideline.” American Journal of Respiratory and Critical Care Medicine (2025). https://doi.org/10.1164/rccm.202410-2045ST