Avaliação in vitro da capacidade da formação de biofilme, investigação dos mecanismos de resistência e virulência utilizando ensaios in vivo com larvas de Galleria mellonella com amostras de Staphylococcus capitis e Staphylococcus hominis

Abstract

Coagulase-negative Staphylococcus (CoNS), members of the resident microbiota of human skin, have the potential to cause opportunistic complications, especially when the skin barrier is disrupted. Among the SCoN, Staphylococcus capitis, and Staphylococcus hominis stand out as one of the most frequent species in complications related to health care (HAI), and their lethality is directly associated with the expression of virulence factors and resistance to antimicrobial agents by these microorganisms. The study aimed to investigate the phenotypic aspects of manipulation of interaction with abiotic and biotic surfaces and with G. mellonella and to genotypically analyze virulence factors and resistance to antimicrobial agents except S. capitis and S. hominis compensated from blood cultures. There were 18 samples of SCoN from blood cultures of patients hospitalized at HUPE/UERJ, 12 samples of the S. capitis species, and 6 samples of the S. hominis species. 6 multidrug-resistant and 1 non-multidrug-resistant profiles were determined, and all samples were considered sensitive to vancomycin, teicoplanin, and linezolid, while 66.67% of the samples were gentamicin-resistant and 77.78% moxifloxacin-resistant. The mecA gene was detected in 91.67% and 83.33% of the S. capitis and S. hominis samples respectively. The production of slime was observed in 41.67% of S. capitis and 33.33% of S. hominis, and all samples were able to adhere to the abiotic surface of the glass. All S. capitis samples were able to produce biofilm on the hydrophobic polystyrene surface at different intensities, however, 66.67% of S. hominis samples do not have this ability. Regarding hydrophobicity, 66.67% of S. capitis and 83.33% of S. hominis samples were considered hydrophilic, while 33.33% of S. capitis and 16.67% of S. hominis were hydrophobic. All 6 representative samples used in the study were able to produce biofilm on the steel surface and the surface of the bovine pericardium, in both standard times, in addition to the surface of the polyurethane and silicone catheters, forming a smooth mat, also confirmed in the analysis by ME V. The presence of the icaA gene, 75% of the atl gene, 25% of the bap gene and 16.67% of the fbp gene was detected for 91.67% of the S. capitis samples. For S. hominis, the presence of the icaA gene was detected in 66.67% of the sample, 16.67% of the atl gene, and 16.67% of the fbp gene. No samples were positive for aap, epbS, and fnbA genes. It was possible to observe in the 6 representative samples of the study, the association with Detroit 562 cells and the variable lethality capacity used in the in vivo model of Galleria mellonella, with median survival on the third day in 83.33% of the samples and with curves without difference statistics, except H15 (S. hominis). The increase in the number of multifactorial and multifactorial organisms, which favor the pathogenicity of both S. capitis and S. hominis, must continue to be investigated since the dissemination of multidrug resistance in the hospital environment has become a growing challenge for public health.