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Assess the role of respiratory Gram stain in conjunction with molecular pneumonia panels in ICU patients.

January 14, 2026Open Forum Infectious Diseases0 citationsOpen Access

P-612. Is Respiratory Gram Stain Useful in the Era of Rapid, Highly Sensitive Molecular Pneumonia Panels?

CACalvin M. AlbrechtUniversity of Nebraska Medical Center JRJonathan H RyderUniversity of Nebraska Medical Center ELElizabeth LydenUniversity of Nebraska Medical Center

Key Points

Assess the role of respiratory Gram stain in conjunction with molecular pneumonia panels in ICU patients.
Evaluated respiratory tract specimens from ICU patients who underwent PNP testing.
Calculated positive and negative percent agreement compared to culture as gold standards.
Performed concordance analysis among PNP, Gram stain, and culture.
Low to moderate positive percent agreement for Gram stain compared to gold standards.
High negative predictive value for Gram stain, particularly for Gram positive organisms.
Gram stain shows limited utility in determining antibiotic therapy with PNP.

Abstract

Abstract Background Historically, respiratory tract Gram stain (GS) has provided rapid results. A randomized trial showed GS can guide empiric antibiotics and facilitate de-escalation. The emergence of the BioFire pneumonia panel (PNP), a multiplex PCR test, calls the utility of GS into question. Our goal is to assess the role of GS in the era of highly sensitive molecular testing. Methods Respiratory tract specimens from ICU patients who underwent PNP testing at our academic hospital from 02/2021-01/2022 were evaluated for concordance among PNP, GS, and culture (Cx). Positive and negative percent agreement (PPA and NPA) were calculated and compared to the “gold standards” of PNP NPA (70-80%) and NPV (80-90%) were high. Conclusion Respiratory tract GS results have poor concordance with PNP and Cx, as shown by low kappa statistics. BAL GS has higher NPV and NPA than sputum, and GS has high NPA and NPV (especially for MRSA and Pseudomonas). GS has limited PPA and PPV with PNP or Cx. Consistent with prior studies, our conclusion is that GS alone is useful in ruling out resistant pathogens such as MRSA and Pseudomonas and when combined with PNP increases confidence in therapy de-escalation. Next steps include evaluating the performance of combined GS and PNP in ruling out the need for MRSA and Pseudomonas therapy. Disclosures Trevor C. Van Schooneveld, MD, FSHEA, FIDSA, BioMerieux: Advisor/Consultant|BioMerieux: Grant/Research Support

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