Comparison of microarray and lysis filtration combined maldi tof ms procedures for the rapid diagnosis of gram positive bacteries and their resistance genes in adult intensive care unit patients

Bacteremia is the presence of viable bacteria in the circulating blood. Sepsis can be described as an infection causing damage to tissues and organs. If it is not diagnosed rapidly and not treated, it causes shock, multiple organ failure, and eventually death. Bacteriemia and sepsis can rapidly reach the dimensions that can threaten life and have high mortality. Therefore, it is necessary to determine the etiological agent rapidly and start treatment. The aim of the study is to compare three methods for the identification of the bacteria in blood culture: Post-culture MALDI TOF MS, MALDI TOF MS (LFM) after lysis filtration and microarray method. Determination of the resistance profiles by microarray method was the additional objective of the study.Between August 2016 and October 2016, 40 blood culture bottles in which gram positive bacteria were detected from patients in adult intensive care units of Ege University Hospital were included in the study. After obtaining positive signals from the blood culture bottles, three methods were used for identification: MALDI TOF MS from subculture, MALDI TOF MS after lysis filtration directly from the liquid sample and Verigene System BC-GP microarray (Nanosphere Inc. Northbrook, ABD) test method. The consistency of LFM identification and microarray method compared to post-culture identification MALDI TOF MS was 75% (30/40) and 90% (36/40) respectively. The similarity of LFM and microarray method was 83.3% (30/36). In 67.5% (27/40) of the bottles three methods gave consistent results.Based on the data obtained from the study, it was concluded that both lysis filtration and microarray test methods were useful for rapid diagnosis in patients with sepsis. Both lysis filtration and microarray test methods have advantages an disadvantages. As a result of our study, it is concluded that MALDI TOF MS identification method after lysis filtration can be used in laboratories with mass spectrophotometer due to its cost efficiency, speed and database width, By combining MALDI TOF MS after lysis filtration and automatic susceptibility testing method which is made from suspension after filtration, it is possible to give results in about 9-10 hours instead of 48-72 hours.