Occupational asthma in workers of a pharmaceutical company processing spiramycin

After investigation of one worker with occupational asthma, all 51 employees of a pharmaceutical company processing the macrolide antibiotic spiramycin were investigated to determine the frequency of the condition and the risk factors. The antibiotic was produced for short periods four to five times a year. The first part of the investigation, conducted before a production period, consisted of the following: questionnaire, skinprick tests, blood sample, spirometry, assessment of bronchial responsiveness to methacholine, and monitoring of peak expiratory flow rates (PEF). The second part of the survey was carried out in 48 of the 51 workers during the production period, and included the same assessments except for skin testing. No FEV1 values had changed by more than 9% or PEF by more than 19%. Inhalation challenge with spiramycin was performed in 12 of the 14 individuals who had a history of occupational asthma, a provocative concentration of methacholine (PC20) of 16 mg/ml or less, or a PC20 that fell by 2.5 fold or more during the production period (or a combination of these). Three subjects experienced immediate bronchoconstriction. All reported symptoms, and all had a fall in PC20 methacholine during the production period. It is concluded that the minimum frequency of occupational asthma in this company processing spiramycin is 4/51 (7.8%). The combination of a positive response to the questionnaire and a change in bronchial hyperresponsiveness during the production period appeared to be the best detector of individuals with occupational asthma, as confirmed by inhalation challenge with spiramycin.