The oral cavity as a site for developing a heterogeneous bacterial population in patients with cystic fibrosis

Cystic fibrosis is an important medical and social problem. Despite significant advances in modern science and practice, bacterial complications are still among the main causes of patient mortality. One of the crucial bacterial pathogens in cystic fibrosis is Pseudomonas aeruginosa, which can lead to rapidly decreased pulmonary function. At the same time, the lungs are not the only site for microbial colonization. The oral cavity can also serve as a reservoir for initial entry and adaptation of microbial strains, which, however, were only sparsely investigated. A clinical case of isolated heterogeneous microbial population of P. aeruginosa from various loci of the oral cavity and sputum of a patient with cystic fibrosis is described. A proteomic mass-spectrum analysis obtained from eleven isolates as well as their mutual comparison with the control strain of P. aeruginosa ATCC 27853 visualized with CCI matrix was performed. As a result, a high level of heterogeneity of the studied population was revealed, while high CCI Score values were obtained only for individual pairs of isolates. It was shown that the bacterial strains isolated from the patient sputum turned out to be more homogeneous in protein profiles than cultures detected from various oral sites. At the same time, in case of isolated several morphotypes of P. aeruginosa from single oral site, no closely related strains were found. Thus, it is shown that the oral cavity is more important viewed from microbial dissociation in cystic fibrosis, which may be due to more diverse microecological conditions. Representatives of the microbiological community can recolonize the tracheobronchial tree through microaspiration, thereby contributing to the maintenance of infectious inflammation in the lower respiratory tract and partially accounting for ineffectiveness of nebulized antibacterial therapy. At the same time, clones adapted to the lung tissue upon coughing up sputum are able to colonize oral sites. The data obtained actualize the question of the need for a comprehensive microbiological approach while examining patients to increase effectiveness of eradication measures in cystic fibrosis.