Validity of direct identification and antibiotic susceptibility of microrganisms from bottles of blood culture

The blood culture is a very important laboratory test: if bacteremia or sepsis are suspected, the diagnosis of the pathogen and antibiotic therapy may be achieved making use of it. Identification and antibiotic susceptibility test carried out directly from the bottle may give important information in a shorter time. The introduction of the automatic instrumentation has improved the discovering of pathogens in the blood, however the elapsing time between the positive detection and the microbiological report is still along.The aim of our work was to verify the validity of the direct use of blood culture broth in which growth of microorganisms has been detected, which could reduce the response time of the bacteremia diagnosis. During the period February - July 2009, a total of 150 blood cultures were analysed:we compared the results obtained both by direct method and by reference method. 20 Gram positive microrganisms and 13 Gram negative microrganisms were respectively isolated and identified. The identification of Gram-negative and Gram-positive microrganisms showed an agreement of 100% between the direct and the reference method. For antibiotic susceptibility tests, among the Gram positive has reported 1.3% very major error, 2.9% major error and 1.4% minor error, while the Gram negative, respectivety 0.3%, 1.4%, 0%. The use of direct identification and susceptibility testing from positive blood cultures, can improve the response time and better efficiency in diagnostic procedures.