TOPLINE:

Polymerase chain reaction (PCR) on oropharyngeal wash (OW) could serve as a reliable non-invasive diagnostic tool for Pneumocystis pneumonia (PCP) in patients without HIV. The OW PCR had a better positive predictive value (PPV) for PCP than the bronchoalveolar lavage (BAL) PCR. Its combination with serum beta-1,3-D-glucan (BDG) further enhanced diagnostic accuracy.

METHODOLOGY:

• Researchers conducted a prospective study across three university hospitals in France from January 2016 to November 2022 to assess the performance of a PCR assay on OW for the diagnosis of PCP.
• A total of 369 immunocompromised patients without HIV in their mid-sixties undergoing BAL were enrolled and classified as those with definite PCP (n = 76), Pneumocystis colonisation (n = 55), no PCP (n = 214), or possible PCP (n = 24) on the basis of microbiological results, clinical findings, and treatment response.
• OW specimens were collected from patients via a self-administered mouth rinse with 10 mL of sterile saline for about 30 seconds for the PCR assay; the BAL procedure was performed immediately after OW. Blood samples were also collected for the measurement of BDG.
• The diagnostic performance of PCR on OW specimens for PCP was assessed in terms of sensitivity and PPV.

TAKEAWAY:

• PCR on OW was positive in 81.6%, 30.9%, 0%, and 45.8% of patients with definite PCP, Pneumocystis colonisation, no PCP, and possible PCP, respectively, with mean fungal loads significantly higher in those with definite PCP vs Pneumocystis colonisation (4251 vs 3 copies/mL; P < .0001).
• The PPV of OW PCR was higher than that of BAL PCR (78.5% vs 58%), with a sensitivity of 81.6%. A threshold of ≥ 7 copies/mL was identified for OW PCR to achieve a PPV of 90%; however, BAL PCR required ≥ 1200 copies/mL for comparable performance.
• Definite PCP was significantly associated with PCR on OW ≥ 7 copies/mL (adjusted odds ratio [aOR], 27.9; P < .0001), along with risk factors such as hypoxaemia (aOR, 17.84; P = .0040) and fever (aOR, 3.81; P = .0244).
• The combination of positive BDG with the PCR assay on OW yielded the highest PPV of 91.7%, outperforming serum BDG alone.

IN PRACTICE:

"OW is a useful non-invasive tool for diagnosing PCP, which could be used as a non-invasive adjunctive or triage diagnostic test that may help support the diagnosis of PCP but cannot safely exclude it," the authors wrote.

SOURCE:

The study was led by Florence Robert-Gangneux, Univ Rennes, Inserm, EHESP, Irset, Rennes, France. It was published online on June 11, 2026, in Clinical Infectious Diseases.

LIMITATIONS:

The study evaluated OW PCR only in patients able to tolerate BAL, so findings may not apply to patients with frailty who were unable to undergo bronchoscopy. The PPV and the identified threshold of ≥ 7 copies/mL were dependent on the prevalence. Finally, the classification of cases was performed retrospectively on the basis of medical records.

DISCLOSURES:

The study was supported by the Direction Générale de l'Offre de Soins. The authors declared having no competing interests.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.