Detection of Pseudomonas aeruginosa type III antibodies in children with tracheostomies.

Pseudomonas aeruginosa is often cultured from the airways of children with tracheostomies. P. aeruginosa produces exotoxin A (ETA) and type III cytotoxins. This study tested the hypothesis that children with tracheostomies are colonized by P. aeruginosa that express these virulence factors and will have antibodies directed against these virulence factors, indicating infection rather than only colonization. A convenience sample of 30 patients, ranging in age from 2 months-22 years, was recruited. Serum was tested for the presence of antibodies to ETA and components of the type III system by Western blot analysis. Twenty-one of 39 patients (70%) had antibodies to components of the type III system. Fifteen of 30 (50%) were seropositive for ETA. Sera from patients who were antibody-positive for ETA were also seropositive for either ExoS or ExoU. Nine of 30 patients (30%) did not possess antibodies to ETA or components of the type III system. In conclusion, these data identified a seropositive reaction to P. aeruginosa cytotoxins in some patients with tracheostomies, suggestive of infection by cytotoxic strains of P. aeruginosa. Future studies will determine the utility of measuring seroconversion to these cytotoxins as an early indication of infection in children with tracheostomies.