Isolation of a rare pathogen <i>Chryseobacterium indologenes</i> in patients with pneumonia

Abstract

Introduction. Chryseobacterium indologenes bacteria are rarely detected, poorly studied opportunistic bacteria of the nonfermenting gram-negative bacilli group that are characterized by high intrinsic and acquired multidrug resistance and involvement in healthcare associated infections.Aim. To analyze detection rate of C. indologenes strains from various biomaterials obtained from patients with pneumonia, as well as levels of pathogen drug resistance to antimicrobial drugs.Materials and methods. The research included 1740 clinical samples obtained from patients with pneumonia hospitalized in in-patient facilities of the Khabarovsk city during the COVID-19 pandemic. Clinical samples included 1305 respiratory samples (744 sputum samples and 561 nasopharyngeal swabs), 435 samples of autopsy material (lung tissue) obtained from patients with a fatal outcome of the disease. The study was performed via classical bacteriological method. Pathogens were identified with Vitek 2 bacteriological analyzer and Vitek MS mass spectrometer. Sensitivity to antimicrobial drugs was determined by disk-diffusion method and in a bacteriological analyzer.Results. A comparative analysis of detection of the entire nonfermenting gram-negative bacteria (NFGNB) group and C. indologenes from various clinical samples was carried out. Detection rate of NFGNB equaled 17.3%. NFGNB were isolated from autopsy material most often ‒ in 31.7% of cases, less often ‒ from sputum and nasopharyngeal smears (13.8% and 10.7%, respectively). C. indologenes was detected in 0.5% of the cases (8 isolates out of 1740 samples). Isolation of this pathogen was most frequent in nasopharyngeal smears – in 1.1% (6 cases out of 561 samples), least frequent ‒ from sputum, which totaled 0.3% (2 isolates from 744 samples). The detection rate of the pathogen in respiratory samples equaled 0.6% (8 isolates out of 1305 samples). This pathogen was not found in the autopsy material. Carbapenem-resistant variants of C. indologenes were isolated in 75% (6 cases out of 8) of the cases.Conclusion. Further intensifying of diagnostic methods will result in more frequent detection of these unusual pathogens, clinical significance of which needs more justification.