Determination of rapid identification and susceptibility of bacteria in blood culture
Project no. 100 · Status: Kapanmış · 2017
Summary
Aim of the study: Rapid identification of bacteria from the blood culture taken from patients with bloodstream infection and initiation of appropriate antimicrobial therapy in these patients is very important because it provides a decrease in morbidity and mortality in sepsis. The aim of this study is to identify the sepsis agents from blood culture bottles that give positive signal directly to MALDI-TOF MS and to apply an in-house method to perform antibiotic susceptibility test with an automated system on the same day. Material and methods: A total of 80 blood culture bottles were obtained from the patients followed up at Ege University Medical Faculty Hospital between June and September 2018. Gram-stained preparation was prepared from the samples and subculture was made on the solid media according to the routine procedure. Colonies formed after incubation were identified at the species level with MALDI-TOF MS system and antibiotic susceptibility tests of the bacteria were studied with the automated sensitivity system. On the other hand, the samples obtained from the positive blood culture bottles were gradually centrifuged and washed in order to obtain bacterial precipitation. The protein extraction process was applied to this precipitate and bacteria were identified by MALDI-TOF MS. From the same precipitates, the suspension of 0.5 McFarland density were prepared and performed in the automated antibiotic susceptibility system. Results: In the identification of bacteria, there was found 90% (72/80) similarity between the standard method used in routine and the “in-house” new method. In the standard approach, identification and susceptibility results took about 36-48 hours after given positive signal while it was taken about 10 hours using the “in-house” method. In addition, the antibiotic susceptibility results compared with the standard method were 97,9 % compatible. Conclusion: The new “in-house” method for laboratories with MALDI-TOF MS is very simple and easy. After positive signal, without using any expensive reagents or long run times, the identification and susceptibility tests results might be taken in 10 hours. The result of the rapid susceptibility results obtained by “in-house” method can be a life-saving value especially in intensive care patients.