Usefulness of bronchoscopic microsampling to detect the pathogenic bacteria of respiratory infection

Bronchoscopic microsampling (BMS) is a method in which a device consisting of a wire with a polyester probe at the tip is used to collect bronchial epithelial lining fluid with bronchoscopy. In this study, we bacteriologically investigated sample collection using BMS to incorporate BMS into diagnosis of respiratory infection.

Strains of Streptococcus pneumoniae, Haemophilus influenzae, Pseudomonas aeruginosa, and Mycobacterium avium complex (MAC), were used for experiments. In the standard sampling procedure using BMS, the probe coming out of the sheath was immersed in approximately 6 x 10(6) cfu/mL bacterial suspension for 30 s and cut into a tube containing 1 mL of normal saline solution. The tube was stirred for 1 min using a vortex. The sampling rate was calculated by the following equation: (actual amount of bacteria collected by BMS [colony forming units per milliliter])/(bacterial amount in suspension for sampling [colony forming units per milliliter]) x 100 (percentage).

The sampling rate of S pneumoniae, H influenzae, and MAC showed no significant difference among three bacteria, but the sampling rate of P aeruginosa was higher. The shortened time of sampling, stirring, and the reduced bacterial amount in the suspension (1/100) did not significantly affect the rates of standard procedure. In contrast, in comparison with a protected specimen brush (PSB), the recoveries of S pneumoniae, H influenzae, and MAC using PSB were significantly lower than those by BMS, but the recovery of P aeruginosa was not significantly different.

This in vitro study might suggested the usefulness of BMS as a new diagnostic technique capable of quantitative and stable sampling.