Avaliação dos aspectos clínicos, perfil molecular e virulência de amostras de Corynebacterium pseudodiphtheriticum isoladas de nasofaringe de crianças admitidas em um Hospital Universitário do Estado do Rio de Janeiro

• Autor(a) principal: Colodette, Sabrina Santos
• Data de Publicação: 2019
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UERJ
• Texto Completo: http://www.bdtd.uerj.br/handle/1/14341
• topic: Corynebacterium pseudodiphtheriticum; MALDI-TOF MS; Erythromycin; Tn5432; Biofilm; Corynebacterium pseudodiphtheriticum; MALDI-TOF MS; Eritromicina; Tn5432; Biofilme; Corynebacterium; Eritromicina; Nasofaringe; Fator de virulência; Biofilmes; CNPQ::CIENCIAS BIOLOGICAS::MICROBIOLOGIA::MICROBIOLOGIA APLICADA::MICROBIOLOGIA MEDICA

Corynebacterium pseudodiphtheriticum is a Gram-positive rod species belonging to the human nasopharyngeal microbiota that has been associated as an infectious agent of the respiratory tract with high mortality in immunocompromised and immunocompetent patients. As the descriptions related to the pathogenic potential of <i>C. pseudodiphtheriticum</i> are scarce, mainly in the pediatric population, this study consisted of the clinical evaluation and phenotypic and genotypic characterization of 22 samples isolated from the nasopharynx of children admitted to a university hospital from the county of the State of Rio de Janeiro. Patients up to 5 years of age, of both sexes and immunized with tetravalent or pentavalent vaccines participated in the study. Specimens were characterized by genus and species by MALDI-TOF MS and conventional methods. The results of MALDI-TOF MS revealed values of different scores depending on the type of protocol employed. Protein extracts obtained by precipitation with ethanol (protocol assigned by Bruker) and treatment with acids showed effective results. The analysis of the spectra showed a higher correlation between the isolates of <i>C. pseudodiphtheriticum</i> and, in turn, a perfect discrimination with other <i>Corynebacterium</i> spp. Specific sets of biomarkers for genus and species were proposed. No isolate had physiological atypia. Antimicrobial susceptibility assays showed that 100 % of the isolates were sensitive to 11 antimicrobials. However, 12 isolates (54.5 %) showed resistance to erythromycin and clindamycin. Determination of MIC revealed resistance to high levels of erythromycin for MLSBc isolates. The presence of <i>erm</i>(X) was detected in 15 isolates (68.2 %), however, three of them presented incongruence in the genotype/phenotype relation. It has been found that the <i>erm</i>(X) gene is well conserved in the genus and the like. The investigation of Tn5432 elements revealed the presence of 11 polymorphic types. Similar elements to the transposon (profile A) were observed in only two isolates. The E profile was the only one that comprised three isolates, two of them from patients hospitalized in the same ward. <i>C. pseudodiphtheriticum</i> formed biofilm on the polystyrene surface, with varying intensities, after 48 h of incubation and showed significant decrease in biofilm formation after treatment with erythromycin subCIM. The data indicated that: methodological resources, such as, MALDI-TOF MS, are fundamental for the identification of isolates of this species; the Tn5432 polymorphism can be exploited in the tracking of transmission routes, monitoring the dispersion of these elements and investigating the evolution of MLSB isolates as circulating resistance reservoirs; and isolates of this species formed biofilms on the abiotic surface. The results reinforced the need for continuous surveillance in the hospital environment and showed the lack of national and international data about the epidemiology and general characteristics of this microorganism.