Infection with Mycoplasma pneumoniae is not related to asthma control, asthma severity, and location of airway obstruction

BACKGROUND Mycoplasma pneumoniae is an organism that reportedly has a strong relationship to asthma. However, asthma severity and location of airway obstruction have not been compared between asthmatic patients with and without evidence for remote mycoplasma infection. OBJECTIVES The aim of this research was to study the relationship between previous M. pneumoniae infections in asthmatic patients and presence of any predilection for the involvement of central or peripheral airways, the severity of the disease, and asthma control. METHODS Sixty-two patients with asthma were assessed by a validated asthma control test (ACT). All patients underwent spirometry and lung volume studies by body plethysmography. The forced expiratory volume in 1 second (FEV(1)), forced vital capacity (FVC), total lung capacity (TLC), residual volume (RV), and functional residual capacity (FRC) were measured. An oropharyngeal swab was obtained for polymerase chain reaction analysis to detect the mycoplasma antigen. Moreover, blood samples were obtained to measure the titration of antimycoplasma immunoglobulin M (IgM) and IgG antibodies. The asthmatic patients with a positive IgG for mycoplasma and negative PCR and negative IgM antibody were considered to have remote history of mycoplasma infection. The relationship between the asthma control using ACT score and pulmonary function variables were compared in patients with and without evidence for remote mycoplasma infection. RESULTS The incidence of postnasal drip was higher among the patients with asthma who had no evidence for remote mycoplasma infection (61.3% vs 32%, P = 0.035). The median ACT score was 16.5 (11-22) and 20 (13.75-24) in patients with and without remote M. pneumoniae infection, respectively (P > 0.05). In addition, the medians of the predicted values of the pulmonary function test parameters (FEV(1), FEV(1)/FVC, FRC, FRC/TLC, RV/TLC, maximal mean expiratory flow 25%-75%, forced expiratory flow [FEF] 50%, and FEF 75%) and actual values of 5 Hz and 20 Hz resistance were not different between asthmatic patients with and without evidence of mycoplasma infection (P > 0.05). CONCLUSIONS The present study revealed that the asthma control status and parameters of lung function tests did not differ between asthmatic patients with and without evidence of chronic M. pneumoniae infection. The latter indicates the similar location of airway obstruction and comparable severity of asthma between the two groups.