Optimized identification of microorganisms directly from positive blood cultures by MALDI-TOF to improve antimicrobial treatment

INTRODUCTION: Bacteriemia is a major cause of morbidity and mortality among hospitalized patients worldwide. Early identification of microorganisms from blood culture can lead to improvement of treatment and outcomes. METHODS: The study was divided into two phases. The first phase when a comparison of the methods was made to check the concordance between them, using as a reference the standard method implemented in the laboratory. In a second phase, both methods are combined. We used the rapid identification method and when it could not identify we used the standard method. The microorganisms that were not identified by either of the two methods were identified from colony at 24 hours RESULTS: A total of 589 microbial positive blood cultures have been included in the present study. With the rapid method we obtained 96% and 88% identification results for Gram-negative bacilli (GNB) and Gram-positive cocci (GPC) respectively. In this study we observed that the combination of the rapid and standard method achieved identifications of 98% and 97% for GNB and GPC respectively. CONCLUSIONS: The data analysed shows that both methods combined perform better than individually. We achieved an optimization of the identification of microorganisms directly from positive blood cultures by MALDI-TOF. This combination identified 98% of the microorganisms in between ten minutes to one hour and a half since the blood culture flagged positive.