Clinical Utility of a Droplet Digital PCR-Based Assay for Quantitative Detection of Pneumocystis jirovecii in Suspected Fungal Pneumonia
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Published on: March 22, 2012
Ziyang Jiang1, Yi Zhou1, Hengjian Huang2
1Department of Laboratory Medicine/Clinical Laboratory Medicine Research Center/Sichuan Clinical Research Center for Laboratory Medicine, West China Hospital of Sichuan University, Chengdu, Sichuan, 610041, People's Republic of China.
Purpose:
Pneumocystis jirovecii typically causes life-threatening Pneumocystis pneumonia (PCP), calling for accurate detection of P. jirovecii in clinical samples to facilitate PCP management.
Patients And Methods:
An observational cohort of 193 patients with suspected fungal pneumonia was enrolled. The cell-free DNA (cfDNA) in bronchoalveolar lavage fluid (BALF) and serum samples was prepared and quantitated via a ddPCR assay targeting the mitochondrial large subunit rRNA gene of P. jirovecii. The correlations between ddPCR results and medical data were analyzed.
Results:
The cases with complete data were classified into a PCP group (N=30) and a non-PCP group (N=139). This ddPCR assay demonstrated a sensitivity of 91.3% and a specificity of 96.8% for BALF, in contrast to a sensitivity of 57.1% and a specificity of 100% for serum. The area under the curve of 0.896 for diagnosis was obtained via ddPCR assay, compared with 0.627 via G-test (P<0.0001). The cfDNA copies were positively correlated with antifungal agents usage, certain clinical characteristics, lactate dehydrogenase levels, and G-test results (all P<0.05). Moreover, higher cfDNA copies were associated with increased in-hospital mortality (aHR>1, P<0.05).
Conclusion:
The ddPCR assay exhibited robust diagnostic performance for PCP in BALF samples and cfDNA copies may serve as an indicator for improving the management of patients.
Insights
A novel digital droplet PCR (ddPCR) assay accurately detects Pneumocystis pneumonia (PCP) in bronchoalveolar lavage fluid (BALF). Cell-free DNA (cfDNA) levels correlate with disease severity and mortality, aiding PCP patient management.
Area of Science:
- Clinical Microbiology
- Molecular Diagnostics
- Infectious Diseases
Background:
- Pneumocystis jirovecii causes life-threatening Pneumocystis pneumonia (PCP).
- Accurate detection of P. jirovecii in clinical samples is crucial for effective PCP management.
- Current diagnostic methods may have limitations in sensitivity and specificity.
Purpose of the Study:
- To evaluate the diagnostic performance of a digital droplet PCR (ddPCR) assay for detecting P. jirovecii in clinical samples.
- To assess the correlation between P. jirovecii cell-free DNA (cfDNA) levels and clinical characteristics, treatment, and outcomes in patients with suspected fungal pneumonia.
Main Methods:
- An observational cohort of 193 patients with suspected fungal pneumonia was enrolled.
- Cell-free DNA (cfDNA) was extracted from bronchoalveolar lavage fluid (BALF) and serum samples.
- A ddPCR assay targeting the P. jirovecii mitochondrial large subunit rRNA gene was employed for quantification.
Main Results:
- The ddPCR assay showed high sensitivity (91.3%) and specificity (96.8%) for PCP diagnosis in BALF samples.
- Serum ddPCR demonstrated lower sensitivity (57.1%) but high specificity (100%).
- Higher cfDNA copies were associated with increased antifungal agent usage, specific clinical features, elevated lactate dehydrogenase levels, and higher in-hospital mortality.
Conclusions:
- The ddPCR assay exhibits robust diagnostic performance for PCP in BALF samples.
- P. jirovecii cfDNA levels may serve as a valuable biomarker for improving the management of PCP patients.
- Further validation in larger cohorts is warranted to fully establish the clinical utility of this ddPCR assay.
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