Corynebacterium spp. It is associated with inflammatory diseases of the respiratory tract (tracheitis, pharyngitis, rhinosinusitis, bronchitis, pneumonia, etc.). C. pseudodiphtheriticum can be the causative agent of bacterial coinfection in patients with a new coronavirus infection (COVID-19). The aim is to determine the pathogenic properties and resistance to antimicrobial drugs of Corynebacterium spp. strains to establish their etiological significance in the development of inflammatory diseases of the respiratory tract. Strains of Corynebacterium spp. isolated from patients with inflammatory diseases of the respiratory tract (43 pcs.) and practically healthy individuals (29 pcs.). Isolates were identified by mass spectrometric method (MALDI-TOF MS), their cytopathic effect in CHO-K1 cell culture, hemolytic, urease activity, antimicrobial drug resistance were determined. Strains of Corynebacterium spp. isolated from patients in the amount of 105 CFU/ml or more, practically healthy - 104 CFU/ml or less. Isolates of Corynebacterium spp. patients had a more pronounced cytopathic effect (83.7±11.1%) and were more often resistant to antimicrobial drugs than those isolated from practically healthy. To establish the etiological significance of Corynebacterium spp. isolates. in the development of inflammatory diseases of the respiratory tract, it is advisable to determine their amount in biological material (105 CFU/ml or more), the cytopathic effect on CHO-K1 cell culture, as well as the presence of multiple resistance to antimicrobial drugs. Differences in the characteristics of Corynebacterium spp. isolates. from patients with respiratory tract pathology and practically healthy individuals are associated with the strain, not the species, of corynebacteria.

Corynebacteria non-diphtheria and, in particular, C. pseudodiphtheriticum species that are closely related to C. propinquum and C. striatum form a group of new respiratory pathogens leading to the development of bronchitis, tracheitis, exacerbation of chronic obstructive pulmonary diseases, nosocomial pneumonia and other pathology. The goal is to analyze the frequency of the release of Сorynebacteria non-diphtheria from the upper respiratory tract of patients with various inflammatory diseases of the respiratory tract. Strains of Сorynebacteria non-diphtheria (C. pseudodiphtheriticum, C. propinquum, C. accolens, et al.), isolated from patients with inflammatory diseases of the respiratory tract (60 pcs.) and practically healthy individuals (31 pcs.) were studied. Identification of Сorynebacteria was performed using the method of mass spectrometry (MALDI-ToFMS). Сorynebacteria non-diphtheria in the amount of 105 and higher were more frequently detected with the development of chronic tonsillitis (60.0%) and nasopharyngitis (30%). The strains of C. pseudodiphtheriticum (40.0±6.4%) and the closely related species C. propinquum (21.7±5.3%) were mainly found; much less often - C. accolens (8.3±3.6%), C. afermentans (6.7±3.3%), et al. In 86.7% of cases, Corynebacteria non-diphtheria were isolated from children. In chronic tonsillitis, C. pseudodiphtheriticum and the closely related species of C. propinquum were isolated more often; in nasopharyngitis and bronchitis - С. pseudodiphtheriticum. Isolation of Corynebacteria non-diphtheria and, especially, C. pseudodiphtheriticum, C. propinquum, C. accolens species from patients with inflammatory diseases of the respiratory tract in the amount of 105 and above, if there are no other pathogenic microorganisms in the role of microbial associates, of clinical importance.