Analysis of the microbial load in the instruments used in orthopedic surgeries / Análise da carga microbiana nos instrumentos utilizados em cirurgias ortopédicas




The failure in orthopedic surgical procedures due to infection can lead to devastating consequences such as the loss of implanted prostheses. Hospital infection is an outcome with a multifactorial cause, in which the safe sterilization of the surgical instruments has an extremely important role. To date, it is not known what microbiological challenges the Material and Sterilization Center (MSC) has been facing when reprocessing the variety of materials used during these surgical procedures. Are microorganisms with the capacity to sporulate present in significant quantity and frequency? It is known that these microorganisms constitute a measurable challenge in sterilization practice and that they are part of the biological indicators. This study aimed at measuring the microbial load recovered from surgical instruments after their use in orthopedic surgeries, quantifying and identifying the genus and species of the bacterial and fungal growth. The study was characterized as an exploratory research, field research and cross-sectional with quantitative approach. The samples were collected at the Institute of Orthopedics and Traumatology (IOT) of Hospital das Clínicas (HC) of the School of Medicine of the University of São Paulo (FMUSP), using an aseptic technique, the samples were then placed in a plastic bag that had been previously sterilized with 500 mL of injection solution. To obtain the microbial load, the instruments were sonicated in an ultrasonic (US) washer for three 5-second sessions each and consecutively agitated for 5 minutes to complement the extraction of the microbial load potentially present on the surface of the materials (external and internally). Subsequently, the washed samples were fragmented in three equal parts and these were submitted to filtration in a 0.45 µm Millipore® filter. Each membrane was cultured in medium adequate for the growth of aerobic and anaerobic organisms, as well as fungi and yeasts. The identification of the microorganisms was carried out with identification kits and tests used in clinical microbiology laboratory routine. The results demonstrated that the three different contamination potentials presented microbial growth. In clean surgeries, 47% of the instruments were contaminated and the most prevalent microorganism was coagulase-negative Staphylococcus (28%) followed by Bacillus subtilis (11%). In contaminated and infected surgeries, a growth of approximately 70% and 80%, respectively, was identified in the instruments, with the higher growth being that of coagulase-negative Staphylococcus (respectively, 32% and 29%) and Staphylococcus aureus (respectively, 28% and 43%). Considering that the Bacillus and the Clostridium genera are capable of sporulating, we concluded that the MSC faces a challenge in having to eliminate microorganisms capable of sporulating, although in a lower density than that of biological indicators (102 UFC) and, approximately, 78% of the recovered microorganisms were vegetative bacteria that presented their curve of death at around 80ºC


orthopedic surgery nursing staff in the material and sterilization center instrumental cirúrgico enfermagem em central de material e esterilização surgical instruments hospital infection microbial load cirurgia ortopédica infecção hospitalar carga microbiana

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