Adherence of mucoid and nonmucoid Pseudomonas aeruginosa to acid-injured tracheal epithelium

Abstract

A model of the adherence of Pseudomonas aeruginosa to injured lower respiratory tract cells is described. Mouse tracheas were injured by exposure to 0.1 N HCl for 15 min, cut into pieces of 2 to 4 rings, and placed in petri dishes for adherence studies. Adherence was quantitated by direct count of the number of bacteria attached to a fixed surface area as viewed by scanning electron microscopy. Optimal conditions for study were 1 h of incubation with an inoculum of 107 to 108 CFU/ml. Both mucoid and nonmucoid P. aeruginosa adhered to the injured cells in this system, and no major differences in adherence between these strains was apparent. Adherence to injured tracheal cells was a phenomenon limited to P. aeruginosa and did not occur with Escherichia coli and Klebsiella pneumoniae. Besides adherence to injured cells, this model allowed the demonstration of adherence of mucoid P. aeruginosa and K. pneumoniae to mucin strands of uninjured control tracheas. This model is an alternative to the buccal cell model and has the advantages of allowing the study of the adherence of both mucoid and nonmucoid strains of P. aeruginosa.