Clinical Investigation of Cough Associated with or without Cough-Variant Asthma or Bronchial Asthma In the Outpatient Cases Including Pertussis, Chlamydophilia Pneumoniae Bronchitis, and Mycoplasma Pneumoniae Bronchitis

Background: To prospectively investigate the incidence and clinical findings of cough among adult patients with or without cough-variant asthma (CVA) or bronchial asthma (BA), we studied antibodies against Bordetella pertussis (BP), Chlamydophilia pneumoniae (CP), or Mycoplasma pneumoniae (MP) in the sera of patients with cough.

Methods: Fifty adult patients were enrolled from April 2009 through January 2010 at Nara Hospital, Kinki University School of Medicine. The diagnoses of CVA and BA were made with criteria from the 2006 guidelines of the Global Initiative for Asthma. The diagnoses of BP, CP, and MP infections were based on serological criteria using single or paired sera. However, paired sera could be used in only 38%, 30%, and 28% of patients, respectively.

Results: Pertussis, CP bronchitis, and MP bronchitis were diagnosed on the basis of serological criteria in 30%, 18%, and 4% of all patients, respectively. Among the patients with CVA and BA, the percentages who had the complications of pertussis, CP, or MP were 39.1%, 17,4%, or 14.3%, and 20.0%, 10.0%, or 0%, respectively. The percentage of the predicted forced expiratory flow at 25% vital capacity in patients with pertussis was significantly higher than that in patients with CVA or BA. Both CVA and BA prolonged the duration of cough, although the difference was not statistically significant.

Conclusions: Of patients with CVA or BA who visited our hospital with cough, 10% to 39.1% also had pertussis or CP bronchitis. Although CP and MP are ideally diagnosed on the basis of antibody increases in paired sera, such examinations are difficult to perform in outpatient clinics in Japan. We expect that cut-off titers of antibodies against the bacteria causing these 3 diseases in single samples of serum will be determined rapidly.