[Pathogenetic study on bronchopulmonary infections in 1,416 patients by transtracheal aspiration method]

We have performed transtracheal aspiration (TTA) in 1,416 patients, who were suspected to have bronchopulmonary infection, in order to collect non-contaminated specimens directly from the lower airway. The overall isolation rates in 1,416 TTA were 68.7% for any microorganisms. Aerobes had a high incidence but many kinds of microorganisms were associated with bronchopulmonary infections. Haemophilus influenzae was the major pathogen in patients with acute bronchitis. Streptococcus pneumoniae was the most important pathogen and mycoplasma was often isolated in patients with community-acquired pneumonia. Major pathogens of nosocomial pneumonia consisted of alpha-streptococcus spp., anaerobes and Pseudomonas aeruginosa. Anaerobes were isolated from transtracheal aspirates in 20 of 33 episodes of lung abscesses. H. influenzae and P. aeruginosa were the main persistent pathogens and H. influenzae, S. pneumoniae and anaerobes were important exacerbated pathogens in patients with chronic lower respiratory tract infection. S. pneumoniae was isolated more from TTA than expectorated sputa. Oropharyngeal flora bacteria were easily isolated in the culture of expectorated sputa. We assessed the final diagnosis or causative factor in 443 patients whom no microorganism was isolated from transtracheal aspirates. The final diagnosis was infectious diseases in 52 patients (11.7%) and non-infectious diseases in 80 patients (18.1%), respectively. The causative factor was unsuited TTA sample in 81 patients (18.3%), preceding antimicrobial chemotherapy in 95 patients (21.4%) and unknown in 135 patients (30.5%), respectively. The pathogenesis of bronchopulmonary infections is complex and various microorganisms are associated with pathogens of bronchopulmonary infections. Therefore, we should accurately diagnose the pathogens in patients with bronchopulmonary infections. TTA is one of the useful methods that we can accurately detect the respiratory pathogens.