Sensitive detection of Pneumocystis jirovecii DNA in gastric wash using nested polymerase chain reaction

Area of Science:

• Medical Microbiology
• Pediatric Infectious Diseases
• Diagnostic Molecular Biology

Background:

• Pneumocystis jirovecii pneumonia (PCP) is a significant opportunistic infection in immunocompromised individuals.
• Accurate and sensitive diagnostic methods are crucial for timely treatment, especially in pediatric populations.
• Gastric lavage is a potential non-invasive sample source for diagnosing PCP.

Purpose of the Study:

• To evaluate the diagnostic performance of immunofluorescence antibody test (IFA), single-step PCR, and nested PCR for detecting Pneumocystis jirovecii in pediatric gastric washes.
• To compare the sensitivity and agreement of these methods.

Main Methods:

• Gastric wash samples were collected from 52 pediatric patients.
• Samples were tested using immunofluorescence antibody test (IFA).
• Nucleic acid was amplified using single-step and nested polymerase chain reaction (PCR) techniques.

Main Results:

• Pneumocystis jirovecii was detected in 10% of samples by IFA and 13% by single-step PCR.
• Nested PCR demonstrated a significantly higher detection rate of 62%.
• Moderate agreement (kappa = 0.5) was observed between IFA and single-step PCR, while agreement between IFA and nested PCR was poor (kappa = 0.1).

Conclusions:

• Nested PCR offers superior sensitivity for Pneumocystis jirovecii detection in pediatric gastric washes compared to IFA and single-step PCR.
• The low agreement between IFA and nested PCR suggests significant differences in diagnostic yield.
• Nested PCR may be a valuable tool for diagnosing PCP in pediatric patients using gastric samples.