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Serum (1 → 3) β-D-glucan assay for discrimination between Pneumocystis jirovecii pneumonia and colonization
Sadatomo Tasaka1, Seiki Kobayashi2, Kazuma Yagi1
1Division of Pulmonary Medicine, Keio University School of Medicine, Tokyo, Japan.
Abstract:
Polymerase chain reaction (PCR) technique is being increasingly used for the microbiological diagnosis of Pneumocystis pneumonia (PCP). As PCR is highly sensitive, it can be positive even in a patient with Pneumocystis colonization. In this study, we evaluated whether the β-d-glucan assay could be used to differentiate between PCP and Pneumocystis jirovecii colonization in immunocompromised patients with pulmonary infiltrates. We retrospectively evaluated data from 166 consecutive patients who underwent bronchoalveolar lavage for the diagnosis of PCP. Serum levels of β-d-glucan in the negative, colonization, probable PCP, and definite PCP groups were 20.2 ± 6.3, 48.8 ± 15.9, 89.9 ± 20.2, 224.9 ± 25.9 pg/mL, respectively. The β-D-glucan levels in the definite PCP group were significantly higher than those in the other 3 groups (p < 0.001). Serum β-d-glucan levels in patients with either definite or probable PCP (173.1 ± 18.8 pg/mL) were significantly greater than those in patients with colonization who had positive PCR results but improved without anti-PCP treatment (p < 0.002). The cut-off level for discrimination was estimated to be 33.5 pg/mL, with which the positive predictive value was 0.925. These results indicate that β-D-glucan is a useful marker to differentiate between PCP and Pneumocystis colonization. A positive β-D-glucan assay result might be a good indication to begin anti-PCP treatment.
Insights
The beta-D-glucan assay can distinguish between Pneumocystis pneumonia (PCP) and colonization in immunocompromised patients. Elevated beta-D-glucan levels indicate PCP, aiding in timely anti-PCP treatment decisions.
Area of Science:
- Medical Diagnostics
- Mycology
- Immunocompromised Patient Care
Background:
- Polymerase chain reaction (PCR) is a sensitive diagnostic tool for Pneumocystis pneumonia (PCP).
- PCR's high sensitivity can lead to false positives, detecting colonization rather than active infection.
- Differentiating PCP from Pneumocystis jirovecii colonization is crucial for appropriate patient management.
Purpose of the Study:
- To evaluate the utility of the beta-D-glucan assay in distinguishing PCP from Pneumocystis jirovecii colonization.
- To assess the correlation between serum beta-D-glucan levels and the presence of PCP or colonization.
- To determine a cut-off value for the beta-D-glucan assay to aid in clinical decision-making.
Main Methods:
- Retrospective analysis of 166 immunocompromised patients undergoing bronchoalveolar lavage for PCP diagnosis.
- Measurement of serum beta-D-glucan levels in patients categorized into negative, colonization, probable PCP, and definite PCP groups.
- Statistical comparison of beta-D-glucan levels across different patient groups.
Main Results:
- Serum beta-D-glucan levels were significantly higher in the definite PCP group compared to other groups (p < 0.001).
- Patients with definite or probable PCP showed significantly higher beta-D-glucan levels than those with colonization (p < 0.002).
- A beta-D-glucan cut-off level of 33.5 pg/mL demonstrated a positive predictive value of 0.925 for differentiating PCP.
Conclusions:
- The beta-D-glucan assay is a valuable biomarker for differentiating between PCP and Pneumocystis jirovecii colonization.
- Elevated serum beta-D-glucan levels can guide the initiation of anti-PCP treatment in immunocompromised patients.
- The beta-D-glucan assay offers a practical tool to improve the accuracy of PCP diagnosis.
