Dynamic observation of upper airways colonization in a cystic fibrosis patient infected with <i>Roseomonas aerofrigidens</i> under targeted therapy

Cystic fibrosis (CF) is a disease characterized by a varying microbiological diversity, including bacteria such as Pseudomonas aeruginosa, Burkholderia cepacia complex, Achromobacter xylosoxidans/ruhlandii. Additionally, there are microorganisms with unknown clinical significance, including Roseomonas aerofrigidens. The main goal of the study is to evaluate the prevalence of such microorganisms among CF patients undergoing regular examinations at the microbiological laboratory of the Samara State Medical University, Ministry of Health of the Russian Federation. An analysis of 12 094 clinical material cultures was carried out, with identification done by using MALDI-ToF mass spectrometry. A composite correlation index was calculated. The Jaccard similarity coefficient was used to assess the nature of symbiotic or antagonistic interactions. A total of 20 strains of Roseomonas spp. bacteria was isolated. Four strains were obtained from the mucous membrane of the posterior pharyngeal wall, while the remaining strains — from nasal lavage fluid. The patient with F508del/F508del genetics had been receiving dual targeted therapy since October 2022. Before treatment, no clinically significant Gram-negative species or Roseomonas aerofrigidens strains were noted in the patient’s anamnesis. However, during observation, Roseomonas aerofrigidens cultures were obtained from nasal lavage fluid at the third, fifth, sixth, eighth, ninth, eleventh, and eighteenth months of observation, with no concurrent bacterial strain growth in sputum samples. The study of the protein profiles demonstrated a high degree of kinship among the isolates, with a correlation index exceeding 0.8, confirming the hypothesis on long-term colonization of the paranasal sinuses by same Roseomonas aerofrigidens strain. While assessing the consistency criterion, it was found that among 30 microbial species isolated from nasal lavage fluid over 18-month observation, two microorganisms were classified as representatives of the constant microbiota, four (including Roseomonas aerofrigidens) as additional microbiota. The remaining species belong to random microbiota. Based on the Jaccard coefficient, it was found that four pairs of microorganisms are characterized by a synergistic nature of the relationship. These observations demonstrate a case of multi-month colonization with a unique strain of Roseomonas aerofrigidens in a patient with cystic fibrosis receiving targeted therapy.