Bacteriology of spirometer tubing and evaluation of methodology to prevent transmission of infection

Transmission of respiratory infection by a spirometer is a definite risk in countries like India where a majority of respiratory diseases are infective in nature. To assess this problem, scrapings and washing from a spirometer tube in regular use were taken for microbiological studies. Significant bacterial growth on culture included Aspergillus and acid fast bacilli. In order to check contamination, a segregation chamber was attached to the spirometer. Twenty-three patients used the spirometer with or without segregation chamber and a good correlation was shown between the two methods in forced expiratory volume in one second (r = 0.94), forced vital capacity (r = 0.92) and mid maximum expiratory flow rate (r = 0.90). It can be concluded that a spirometer may have significant growth of pathogenic bacteria and a segregation chamber may be used routinely with the spirometer in order to prevent its contamination.