Efeito bactericida de diferentes soluções para Staphylococcus aureus e Staphylococcus epidermidis em estado séssil e planctônico– um estudo in vitro

Abstract

Surgical site infections are common, even in patients using prophylactic antibiotic therapy. Surgical site infections are a major contributor to morbidity and mortality in postoperative care. Biofilms are a complex group of microbial cells that adhere to the exopolysaccharide matrix present on the surface of medical devices. Infections associated with biofilm in medical devices pose a serious public health problem and affect the function of the device. Infection in the silicone breast implant occurs in 7 to 24% of breast reconstructions. These infections cause morbidity and possible decrease in quality of life for patients, in addition to high costs with their treatment. Local anesthetics are commonly used as an agent for postoperative analgesia and have a low cost, but their action as a microbicidal agent is still controversial. Objective: To evaluate the bactericidal effect of different solutions for Staphylococcus aureus and Staphylococcus epidermidis associated with surgical wound infection and silicone prostheses in vitro. Material and methods: For this study, the following microrganisms were evaluated: S. aureus and S. epidermidis. Analysis was carried out with suspensions in sterile saline solution with the microrganisms. The study was carried out in two stages: first the agar diffusion test and then the analysis of silicone prostheses. In the first stage, for the agar diffusion test (evaluation of bacteria in planktonic state), the suspensions with the microrganisms were inoculated with the aid of a sterile swab on the surface of the blood agar. Then, equidistant holes were made measuring 3mm in diameter and 3 mm deep in the blood agar. One orifice was filled with 1 drop of saline only, another with 1 drop of antiseptic solution, another with 1 drop of pure Lidocaine, another with 1 drop of Lidocaine solution and another with 1 drop of the antibiotic solution. In the second stage, 36 silicone prostheses (assessment of bacteria in sessile state) were used, which were divided into 3 groups: prostheses contaminated by the bacteria and which did not receive treatment; prostheses contaminated by bacteria and which received treatment before contamination; and prostheses contaminated by bacteria and which received treatment after contamination. Treatments were performed with chlorhexidine, lidocaine solution, pure lidocaine and antibiotics solution (cefazolin and gentamicin). The incubation was 1 week. The prostheses were sown by rolling in a blood agar culture medium, which was incubated for 48 hours and the area with colony formation was evaluated using an image analysis program. Results: The plates tested with lidocaine solution and pure lidocaine did not present an inhibition halo. The antibiotic solution showed the greatest inhibition halos in all the tested bacteria. In the prewash, there was no growth of S. epidermidis with antibiotic solution. In the post-contamination wash, none of the bacteria grew with the antibiotic solution. In post-contamination washing, there was a decrease in the density of colonization with chlorhexidine and absence of growth of S. aureus with pure lidocaine and lidocaine solution. Conclusion: The antibiotic solution proved to be a good alternative for the control, mainly S. epidermidis, in the pre and post-contamination washing in silicone prostheses. Lidocaine (pure or in solution) although it did not inhibit bacterial growth on plates with culture medium, was able to decrease colonization by S. aureus in post-contamination washing, showing that it can be used as an adjuvant treatment in these cases.