Heterogeneidade de perfis de resistência, expressão de multirresistência e de produção de biofilme em superfícies abióticas e biomateriais utilizados em procedimentos cirúrgicos (aço e pericárdio bovino) na presença de agentes antimicrobianos de amostras de Staphylococcus capitis e Staphylococcus hominis detectadas em fômites diversos em ambiente hospitalar

Abstract

Coagulase-negative Staphylococci (CoNS) which belong to the normal microbiota of the skin and mucous membranes of human and others animals, are opportunistic pathogens, particularly in patients who are immunocomprimised. Staphylococcus capitis has been considered a comensal, but about its pathogenicity, there´s not a great amount of knowledge about the subject. Staphylococcus hominis is the third species of CoNS identified in bloodstream infections, associated predominantly with infection in the setting of indwelling devices. This study aimed to investigate the presence of S. hominis and S. capitis on fomites within nosocomial environment, antimicrobial susceptibility profiles, biofilm formation and the effects of minimal inhibitory concentrations (MICs) of antimicrobial agents on slime production and adherence properties on abiotics surfaces and biomaterial, besides the lethality assays using nematodes Caenorhabditis elegans. The results demonstrated in the operation room, were isolated 61 strains from fomites’s surfaces. 14.7% of the strains were characterized as Gram-negative and 85.2% as Gram-positive, where 78.6% belongs to CoNS. Among CoNS strains, ten strains were identified as S. hominis and nine strains as S. capitis. Were determinated eleven multiresistance profiles and five non-multiresistance profiles. All strains were oxacillin-resistant and one strain of each species were vancomycin-intermediate. The presence of mecA gene was detected in 40% and 33.3% of S. capitis and S. hominis respectively. Were slime-positive 66% of S. capitis and 50% of S. hominis. All strains were able to adhere to the abiotic surface of the glass and showed the ability to produce biofilm in poliestirene’s surface on different levels in the absence of antimicrobials. In the presence of antimicrobials, some strains lost the ability to slime production and/or adherence an abiotic surfaces. All strains displayed the ability of biofilm formation in the surgical steel’s surface, on different levels, with a significant increase in the presence of oxacillin. The results of the SEM analyzes demonstrated, an intensification in self-aggregation and biofilm formation in the presence of both oxacillin and vancomycin. In the patches of bovine pericardium’s surfaces, the strain S. hominis MDS SHo-07 showed more biofilm production capacity than the strain S. capitis MDR SC-03. The presence of icaA, atl and fbp genes were detected in 77.7% of the S. capitis isolated and the aap gene was detected in 66%. The presence of fbp gene was detected in 80% of the S. hominis isolated, the icaA and aap genes were detected in 70% and the atl gene was detected in 60%. Three strains had similar biotypes, revealing their pathogenicity, being submitted to the nematode infection model. Other studies may elucidate the different mechaniscms of adhesion in the pathogenesis of infections cause by S. capitis and S. hominis, including cases associated with medical devices.