TÉCNICA ESTÉRIL MODIFICADA VERSUS LIMPA PARA REDUZIR A CONTAMINAÇÃO DAS AMOSTRAS DE HEMOCULTURA: ENSAIO CLÍNICO RANDOMIZADO DUPLO-CEGO

Abstract

Blood cultures are one of the most important laboratory tests performed for the diagnosis of patients with clinical pictures of bacteremia. Contamination of the samples leads to inappropriate use of antibiotics and additional laboratory tests, in addition to increasing the length of hospital stay, morbidity and mortality rates, the suffering of patients and their families and the demand for human and material resources. There is no consensus in the literature about the most appropriate technique for obtaining blood culture samples. Some organizations empirically recommend using the sterile glove technique, but this has never been tested in isolation by a scientific study. Thus, the objective of this study was to test whether the blood culture collection using a modified sterile technique reduces the contamination rate of blood culture samples. The study was previously approved by the Ethics and Research Committee of the Federal University of Mato Grosso do Sul, under opinion No. 3,622,902. A randomized double-blind clinical trial was conducted to test the alternative hypothesis that the use of the modified sterile technique would reduce the contamination rate of blood culture samples when compared to the clean technique. The study was carried out in the Intensive Care Unit of a private hospital. Patients aged 18 years or older with a medical request for blood culture collection were included. Patients who presented any contraindications for the collection of biological material and those whose collectors were unable to access the vascular system were excluded from the study. Patients were allocated to the sterile and clean groups by simple randomization and independently. All microbiological processing and issuing of results was carried out by independent microbiologists and blinded to the study protocols. To support data collection, a structured collection instrument was used. Two paired samples were collected from different blood sample sites (arterial or venous) for culture, microbial isolation and antimicrobial sensitivity test. All data were tabulated in a Microsoft Excel® spreadsheet. Of the 200 blood culture samples collected, seven were positive (3.5%) and two were contaminated (1%), one for each research group, therefore, without statistical difference (p = 1.00). However, there was a statistically significant difference between the baseline and intervention moments (p = 0.05), whose relative risk of contamination with a non-standard clean technique was 6.39 times higher when compared to the intervention, that is, harvesting with modified sterile technique and standardized clean technique. It was concluded that both techniques for collecting blood culture samples are able to keep the contamination rates below the internationally accepted 3% Benchmark and that there was no difference in contamination rates between the techniques, which proves that more important than that the sterile technique itself is the aseptic care provided in obtaining the samples, the standardization of the collection protocol and the qualification and calibration of the collectors. Previously registered in the Brazilian Registry of Clinical Trials (ReBEC) with accepted BR-44cs34.