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Study of resistance to bacterial infection of polypropylene screens covered with MnO2 implanted in the subcutaneous tissue of rats

Grant number: 17/01507-2
Support type:Scholarships in Brazil - Scientific Initiation
Effective date (Start): August 01, 2017
Effective date (End): July 31, 2018
Field of knowledge:Health Sciences - Medicine - Surgery
Principal Investigator:Cássio Luís Zanettini Riccetto
Grantee:Amanda Bishop Perseguim
Home Institution: Faculdade de Ciências Médicas (FCM). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil

Abstract

Advances in biomaterial engineering have minimized the risk of failure of medical devices. However, infection is the most common and feared complication of those implants, which in most cases results in removal of the device and morbidity from local or systemic infection, depending on the clinical conditions of the patient and the pathogenicity of the bacteria involved. In addition, these complications have a strong impact on the health system, causing increased health care costs. These reasons were sufficient to create the need for the development of novel antibacterial coatings to prevent bacterial adhesion to the surface of medical devices. Techniques using synthetic screens represent, at present, the basis of the treatment of abdominal hernias, urinary incontinence and, in specific situations, are also used for vaginal prolapses. The monofilament polypropylene is the most widely used synthetic material. Despite high success rates, complications related to infection and integration, exposure or erosion of the screens, represent challenges to its routine use. It is postulated that the coating of medical implants with manganese dioxide may alter the adhesion of proteins in the implant and thus prevent the adhesion and, consequently, the proliferation of bacteria that form the biofilm. Objective. To determine the characteristics of bacterial infection and biofilm around MnO2-coated monofilament polypropylene screens implanted in the subcutaneous tissue of the dorsum of inoculated rats with different concentrations of homogeneous Escherichia coli strain. Methods. The study will be performed using 27 Wistar rates male adults with a mean weight of 250 grams and 12 weeks of age. In each mouse, two fragments of polypropylene monofilament and two of silicone, both 10 mm x 10 mm, each of them previously coated with MnO2, will be implanted on the back of the abdomen. The animals will be divided into three equal groups, which will receive bacterial inoculums of Escherichia coli in both implants immediately after the implant and will be euthanized, respectively after 2 and 7 and 30 days of the implant. The specimens will be dissected with incision of the skin at the implant site, in order to completely expose the implanted screens, which will be sectioned in half, one of the halves being seeded in culture medium to determine the presence, concentration and bacterial identification and the other Half will be submitted to biofilm study. The analysis will be performed by means of quantification of the bacterial colonization in specific culture medium and evaluation of the area covered by the biofilm by means of scanning electron microscopy. The information will be submitted to descriptive statistical analysis and comparisons in order to identify possible differences attributable to the overlap. (AU)