Would pulmonary function tests (PFTs) be normal in Mycoplasma pneumonia?

From the Guidelines

In Mycoplasma pneumonia, pulmonary function tests (PFTs) are typically abnormal during active infection. Patients with Mycoplasma pneumonia often demonstrate restrictive lung patterns on PFTs, characterized by decreased forced vital capacity (FVC) and total lung capacity (TLC), while maintaining a normal or increased FEV1/FVC ratio. Additionally, diffusion capacity (DLCO) may be reduced due to inflammation in the alveolar-capillary membrane. These abnormalities occur because Mycoplasma pneumoniae causes inflammation in the bronchioles and surrounding interstitial tissue, leading to impaired gas exchange and reduced lung volumes. The severity of PFT abnormalities generally correlates with the extent of infection. As the infection resolves with appropriate treatment, PFT values gradually return to normal in most patients. However, in some cases, especially with delayed treatment or severe infection, subtle abnormalities in lung function may persist for weeks to months after clinical recovery. Some key points to consider when interpreting PFTs in Mycoplasma pneumonia include:

• The quality of the test, as noted in the European Respiratory Journal 1, is crucial for accurate interpretation.
• The interpretation of spirometry, bronchodilator response, carbon monoxide diffusing capacity (DL,CO), and lung volumes, as outlined in the European Respiratory Journal 1, can help identify patterns of lung dysfunction.
• Serological tests, as mentioned in the European Respiratory Journal 1, are not recommended for routine management of individual patients with Mycoplasma pneumonia, but rather for epidemiological studies.
• The use of macrolide antibiotics, such as azithromycin, or respiratory fluoroquinolones, can help resolve the infection and improve PFT values. It is essential to consider the clinical context and the patient's overall condition when interpreting PFT results in Mycoplasma pneumonia.

From the Research

Pulmonary Function Test (PFT) in Mycoplasma Pneumonia

• A PFT may not always be normal in patients with Mycoplasma pneumonia, as the infection can cause respiratory symptoms and affect lung function 2.
• In some cases, Mycoplasma pneumonia can lead to severe respiratory illness, including bronchiolitis, which can result in abnormal PFT results 2.
• Studies have shown that patients with Mycoplasma pneumonia can have impaired pulmonary function, including decreased forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) 3.
• Treatment with azithromycin and inhaled terbutaline has been shown to improve pulmonary function in children with Mycoplasma pneumonia, suggesting that PFT results can be abnormal in these patients 3.

Factors Affecting PFT Results

• The severity of the infection and the presence of underlying respiratory conditions can affect PFT results in patients with Mycoplasma pneumonia 4, 3.
• Age and lactate dehydrogenase levels have been identified as risk factors for refractory Mycoplasma pneumonia, which can also impact PFT results 5.
• The use of corticosteroids and other treatments can also influence PFT results in patients with Mycoplasma pneumonia 2, 3.

Diagnosis and Treatment

• Diagnosis of Mycoplasma pneumonia is typically based on serological tests, such as the rapid IgM test, rather than PFT results 6.
• Treatment with antibiotics, such as azithromycin, and corticosteroids can help improve symptoms and PFT results in patients with Mycoplasma pneumonia 2, 5, 3.