Studies of polymicrobial infection on pneumonia by transtracheal aspiration in the elderly

Abstract

We studied the polymicrobial infection by transtracheal aspiration (TTA) on pneumonia in the elderly. Incidence of mixed isolation of organisms from TTA was 35% or 39 out of 111 episodes. The principal organisms in polymicrobial infection detected from TTA were S. aureus (N.23), P. aeruginosa (N. 15), K. pneumoniae (N. 12) and S. pneumoniae (N. 11). The principal combination of mixed infection were S. aureus + P. aeruginosa (N.7), S. aureus + K. pneumoniae (N.5), S. aureus + S. marcescens (N.5), S. aureus + S. pneumoniae (N.5), S. aureus + Anaerobes (N.4) and K. pneumoniae + P. aeruginosa (N.4). Hospital acquired pneumonia was of a higher rate of mixed infection than the nursing home acquired pneumonia. In the mixed infection on pneumonia in the elderly, normal upper airway flora was highly detected with pathogens from transtracheal aspirates. From these results, we realize that aspiration and superinfection were important factors in mixed infection in the elderly.