Vigilância epidemiológica e caracterização fenotípica e molecular de fatores de virulência empregando métodos in vivo e in vitro de amostras de Corynebacterium striatum isoladas de pacientes internados em Hospital Universitário localizado na região metropolitana do Rio de Janeiro (2009 a 2018)

Abstract

We recently observed an increase in the report of nosocomial Corynebacterium striatum infections, especially in patients undergoing invasive procedures. However, studies on factors that may contribute to C. striatum virulence remain scarce. In this sense, we aim the epidemiological surveillance, phenotypic and molecular characterization of clinical, microbiological and virulence factors of C. striatum samples isolated from patients admitted to a University Hospital of the metropolitan region of Rio de Janeiro. Microorganisms were qualitatively and quantitatively submitted to the following evaluations: (i) interactions with abiotic surfaces (polyurethane, polystyrene, surgical steel, glass, PVC and silicone) and biotics in vitro (human sera/matrix proteins - fibrinogen, fibronectin and collagen - monocytic U-937 mice cells) and in vivo (mouse subcutaneous and guinea pig liver regions); (ii) susceptibility to various antimicrobial agents and biocides subjected to different treatment conditions; (iii) nature of biofilm composition produced in vitro and in vivo (iv) C. striatum interaction with Caenorhabditis elegans nematodes (v) investigation of the presence of ermX (macrolides) tetA (tetracycline), cmxB resistance genes (chloramphenicol) aphA1 (amino glycosides) and related to the expression of spaA, spaD and spaF fimbriae in the genome of C. striatum strains by PCR assays; (vi) partial genome sequencing of MDS C. striatum 1961 BR-RJ/09 urine strain. Data currently demonstrated different properties of C. striatum virulence potential observed in vitro and in vivo experiments. The multifactorial nature of virulence of C. striatum MDR and MDS samples has been evidenced by several aspects. C. striatum MDR samples were detected with different clonal profiles capable of producing biofilms at different levels and substrates as well as causing serious, sometimes fatal diseases, including hematogenous infections and nosocomial outbreaks. In most cases, clinical findings were related to catheterization procedures and mainly to patients admitted to intensive care centers undergoing endotracheal intubation; (ii) gene expression and tolerance and/or resistance behaviour to different antimicrobial agents including antibiotics and biocides used in the nosocomial environment. The majority of C. striatum strains were MDR. Both planktonic and sessile forms, including the MDS 1961/ urine strains also expressed varied tolerance levels to hospital disinfectants and antiseptics tested including high-level glutaraldehyde and peracetic acid. The ermX, cmxB aphA1 resistance genes were detected only in MDR strains, unlike the spaD fimbriae expression-related gene that was detected in both MDS and, all biofilm positive MDR strains. (iii) C. striatum of different pulse types were able to cause 60% to 100% death of C. elegans. Bagging capacity was detected in 100% of the strains, while star formation was observed only with the same samples that caused the death of 100% of the nematodes. The Dar phenotype was observed post-infection with all MDR strains; (iv) the murine model experiments demonstrated that C. striatum was able to produce biofilm on the surface of polyurethane catheter inserted into the dorsal subcutaneous tissue 48h post inoculation. In addition, hematological changes, including thrombocytopenia and presence of platelet aggregates were detected, as well as anisocytosis and mild polychromasia, increased number of segmented neutrophils, and discrete presence of activated monocytes on hematoscopy, suggesting inflammation and/or infectious reaction. The ability of biofilm formation on varied surfaces that may be present on the structure of several medical devices used in the hospital environment, their resistance profiles and/or tolerance to multiple drugs, difficulty in identification and lack of studies on aspects related to their virulence factors may be favoring the establishment and dissemination of C. striatum in a hospital setting, making C. striatum a dangerous pathogen. Therefore, additional studies clarifying phenotypic and molecular characteristics remain necessary for the knowledge and consequently the adoption of efficient measures for the correct isolation, diagnosis and eradication of C. striatum.