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The impact of resistance and virulence gene expressions of Staphylococcus epidermidis isolated from patients with poor outcome of orthopedic implant-associated infections


Staphylococcus coagulase negative (SCoN) are one of the most isolated bacteria in microbiology laboratories around the world. Such microorganisms are responsible to colonize skin, mucous and membranes. Among SCoN, the specie most clinically relevant is Staphylococcus epidermidis due to the adaptative ability to adhere and formation of biofilm in medical devices. Biofilms are defined as complex communities of adherent microorganisms encapsulated in a self-produced matrix of extracellular polymer substances (EPS). Such structures confer resistance to antibiotics and optimizing bacterial survival. In infections related to orthopedic devices (ODRIs), S. epidermidis are risible to cause about 20% to 30% of these infections and may increase 50% in late infections. The diagnosis is great challenge, since traditional microbiological methods used in peri-implant tissue cultures result in false negatives. For improve the diagnosis of osteoarticular infections after fractures it is necessary to disrupt the biofilm structure by removing sessile microorganisms using ultrasonic baths in retrieved implants (YANO, et al., 2014; ZITRON, et al., 2016). The main risk factors associated to ODRIs are different traumas (exposed or closed fractures), rates of contamination, comorbidities and infections associated with other pathogenic microorganisms such as S. aureus and Pseudomonas aeruginosa. However, in literature are few data of identification of genetic factors related with S. epidermidis and their role in the ODRIs, specially que manly factors that contribute to failure of surgical treatment. In this context the objective of this study is to evaluate the associations between relapse of osteoarticular infections associated with orthopedic implants caused by S. epidermidis and the genomic and phenotypic variations. The identified will be performed by Whole Genome Sequencing (WGS) of samples isolated from sonication fluid of implants. Minimal inhibitory concentrations (MIC) will be tested by agar and microdilution techniques and the minimum bactericidal concentration (MBEC) in bacterial biofilm will be evaluated through the "MBEC Assay". As a result, are expected to characterize and establish the correlation between virulence and resistance genes in clinical outcome in patients with orthopedic device-related infections (ODRIs). (AU)

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