Pseudomonas aeruginosa in the oral cavity and sputum of patients with cystic fibrosis.

Patients with cystic fibrosis (CF) are often hosts to colonies of both mucoid and nonmucoid strains of Pseudomonas aeruginosa. The major pathogens for chronic and recurrent pulmonary infection in these patients are the mucoid variants of P. aeruginosa. Of the 31 CF patients studied, 14 patients yielded both mucoid and nonmucoid strains of P. aeruginosa from the various oral ecologic sites and saliva. Of the sites tested, the dorsum of the tongue gave the highest yield of P. aeruginosa (27 strains), followed by the buccal mucosa (17 strains), saliva (15 strains), and dental plaques (6 strains). Eleven patients had P. aeruginosa in the oral cavity and sputum simultaneously. Antibiotic susceptibility tests on these multiple isolates suggest that CF patients may be cocolonized or coinfected by two or more strains of P. aeruginosa. Therefore, it may be important to identify multiple isolates of P. aeruginosa, not only from sputum cultures but also from oral cultures, for antibiotic-susceptibility testing. Oral colonization by the mucoid variants of P. aeruginosa may lead to further colonization in the lower respiratory tract and subsequent pulmonary infection in CF patients.