Identificación directa de microorganismos a partir de muestras de orina y hemocultivos utilizando MALDI-TOF

Objective: To evaluate the utility of the direct identification of microorganisms in urine and blood cultures samples, using MALDI-TOF by evaluating concordance for identification, time to obtain an identification result and associated costs. Materials and Methods: A descriptive study from February to October 2017 in 180 urine samples and 129 positive blood cultures samples of patients from the El Rosario Clinic in Medellin-Colombia. The clinical samples were processed directly for microorganisms identification by using MALDI-TOF (Vitek® MS‚ bioMérieux). This result was compared with the result obtained with Maldi tof-MS done for the cultured microorganism. An analysis of cost and time to achieve an identification result was made to determinate the utility of this technology in the laboratory procedures. Results: 79,6 % of positive urines and the 76 % of blood cultures were identified directly from the sample by MALDI-TOF. MALDI-TOF applied directly had a mean time for obtaining an identification of 6 hours compared to 29 hours to obtain an identification from cultures. The cost of direct identification was $8.200 (2,58 USD) in urine samples and $9.720 (3,06 USD) in blood cultures (without including the equipment cost). This cost is variable depending of the number of identifications that the laboratory performs. Conclusions: These results support the usefulness of MALDI-TOF for getting rapid identification results using the direct methodology in clinical samples. However, the capability to identify gram positive bacteria needs to be improved. The incorporation of this methodology in microbiology laboratories may improve the opportunity in the etiological diagnosis and should have a positive impact on patient care.