Propriedades adesivas e resistência a agentes antimicrobianos de isolados clínicos de Corynebacterium hesseae

Abstract

To date, the genus Corynebacterium comprises 168 species of irregular Gram-positive bacilli. In addition to environmental species, this genus harbors classical pathogens, such as Corynebacterium diphtheriae, the main etiological agent of diphtheria. It also harbors commensal species that occasionally cause infections, especially in individuals with long periods of hospitalization or immunocompromised. Recently, Corynebacterium hesseae was described as part of the urinary microbiome of healthy women. However, a recent study reported the isolation of this species in urine samples from patients with kidney disease and sebaceous cysts. Considering the need to confirm the pathogenic potential of the species, the present study aimed to investigate its adhesive properties on abiotic surfaces and its resistance to antimicrobial agents. The isolates of C. hesseae were first subjected to adhesion and biofilm formation tests on different abiotic surfaces (silicone, latex and polyurethane catheters, and on glass). The degree of surface hydrophobicity was then determined by the n-hexadecane assay, and the isolates were tested on Congo Red Agar for detection of extracellular polysaccharides. Antimicrobial susceptibility profiles were determined according to the most recent guidelines of the Brazilian Committee on Antimicrobial Susceptibility Testing (BrCAST). Additionally, the genomes of the strains were analyzed using the VFanalyser and ResFinder tools to predict genes involved in l adherence and antimicrobia resistance, respectively. Finally, mutations previously associated with antimicrobial resistance were investigated using ClustalW. All isolates were able to form biofilm on silicone, latex and polyurethane surfaces, but did not interact well with the glass surface. Hydrophobicity analysis revealed that all isolates are highly hydrophobic, which may favor adhesion and biofilm formation. The search for extracellular polysaccharide was negative, as was the search for genes involved in bacterial adherence. All isolates were sensitive to vancomycin, tetracycline, rifampin, linezolid and moxifloxacin. Some were resistant to ciprofloxacin (n=2) and penicillin (n=1), while most were resistant to clindamycin (n=4). No genes related to resistance to β-lactams were found. The ermX gene, related to resistance to macrolides, lincosamides and streptogramin B, was detected in 3 of the clindamycin-resistant strains. Mutations in the gyrase A gene were found in 1 of the ciprofloxacin-resistant isolates. The results obtained showed that one of the mechanisms that may be associated with the virulence potential of C. hesseae is the ability to form biofilms on abiotic surfaces, especially those of a hydrophobic nature. The isolation of antimicrobial-resistant isolates of this species in clinical samples reinforces the importance of determining the susceptibility profiles of clinical isolates of corynebacteria, particularly when originating from immunocompromised patients, in whom infection needs to be considered.