Methacholine inhalation challenge in patients with post-Mycoplasma pneumoniae pneumonia

We studied methacholine bronchial inhalation challenge in 12 patients at 4th week and 12th week after recovered from Mycoplasma pneumoniae pneumonia, compared with 12 healthy subjects as controls. The aerosolized methacholine was produced by an atomized nebulizer of the Provocationtest I, Pari-Starnberg, Germany and the aerosol was kept into a reservoir bag. Then, it was inhaled slowly by a subject. Increasing concentration of methacholine solutions (0, 0.5, 1, 5, 10, and 25 mg/ml) were used. The results revealed that 67% of the patients had bronchial reactivity to methacholine at the first time of challenge with a mean concentration of methacholine producing a fall in FEV1 of 20% from baseline (PC20) of 12.3 +/- 6.44 mg/ml. Fifty percent of the patients were still positive to the test on the second time of challenge with a mean PC20 of 20.1 +/- 6.89 mg/ml. None of the healthy subjects had bronchial hyperreactivity (PC20 > 25 mg/ml). Two patients experienced wheezing and asthmatic attacks requiring bronchodilator therapy during acute phase pneumonia. They were also diagnosed as having bronchial asthma for the first time. Many patients had prolonged coughing during the recovery phase lasting more than 4 weeks. This prolonged coughing seemed to have a correlation with the development of bronchial hyperresponsiveness (BHR). We concluded that M. pneumoniae could induce BHR which may be transient or persistent. The effect of mycoplasma respiratory tract infection may result in airway inflammations and asthmatic attacks.