Metagenomic next-generation sequencing in diagnosing Pneumocystis jirovecii pneumonia: A case report

Area of Science:

• Medical Diagnostics
• Infectious Diseases
• Rheumatology

Background:

• Diagnosing Pneumocystis jirovecii pneumonia (PJP) conventionally is difficult, often resulting in delayed treatment and increased mortality, particularly in rheumatoid arthritis (RA) patients.
• RA patients with acute respiratory failure present diagnostic challenges, with imaging findings often indistinguishable from other forms of pneumonia.

Observation:

• A 69-year-old female RA patient presented with acute respiratory failure; CT scans showed bilateral lung opacities.
• Metagenomic next-generation sequencing (mNGS) detected Pneumocystis jirovecii in serum and bronchoalveolar lavage fluid (RPM 17 and 437, respectively).
• Conventional diagnostic tests failed to identify any pathogens, highlighting the limitations of standard methods.

Findings:

• mNGS demonstrated high sensitivity in identifying P. jirovecii, confirmed by quantitative PCR.
• A significant decrease in P. jirovecii DNA reads per million (RPM) was observed after treatment with trimethoprim/sulfamethoxazole.
• Despite early detection via mNGS, the patient's outcome was poor, underscoring the critical need for timely and effective treatment.

Implications:

• Metagenomic next-generation sequencing (mNGS) shows significant promise for the early and sensitive diagnosis of PJP, especially in immunocompromised patients.
• The case emphasizes the potential of mNGS to guide treatment decisions and improve patient prognosis in complex cases.
• Further standardization and normalization of mNGS are crucial for its widespread clinical adoption and reliable interpretation.