DOI: 10.4103/prcm.prcm_24_25 ISSN: 2543-0343

Comparing Nasopharyngeal Swab and Sputum in Detecting Mycoplasma pneumoniae Pneumonia in Children: A Single-Centre Study in Hong Kong

Chung Yan Michelle Lam, Shu Yan David Lam
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Abstract

Background:

Mycoplasma pneumoniae is an important causative pathogen in childhood pneumonia. Sputum monoplex polymerase chain reaction (PCR) is commonly used for detecting the infection. Recently, the nasopharyngeal swab (NPS) multiplex PCR test has become available. It detects 22 common respiratory tract viruses and bacteria, including M. pneumoniae , with a shorter turnover time. This study aimed to compare the NPS multiplex PCR test and the sputum monoplex PCR test in detecting M. pneumoniae infection in children with pneumonia.

Methods:

This retrospective study reviewed test results of paediatric patients diagnosed with pneumonia in Tuen Mun Hospital from January 1, 2023, to December 31, 2024, with both the NPS multiplex PCR test and the in-house sputum monoplex PCR test performed. Detection rates were compared. Sensitivity, specificity, likelihood ratios, positive predictive value (PPV), and negative predictive value (NPV) of the NPS test were compared against the sputum test.

Results:

A total of 1148 pneumonia cases with both NPS and sputum tests performed were included in this study. The detection rate of M. pneumoniae in sputum was significantly higher (51.3%) than that of NPS (21.0%; P < 0.001). The two tests show fair agreement ( κ value = 0.38). Although comparing with the sputum test, NPS has a sensitivity of 39.9% and specificity of 98.9% for diagnosing M. pneumoniae infection.

Discussion and Conclusions:

Although representativeness is limited by the in-house sputum test used, and results may be affected by NPS collection variability by different nurses, the significantly lower detection rate and sensitivity in the NPS multiplex PCR test reflects it cannot replace the sputum test locally as the major test for detecting M. pneumoniae infection.

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