Analiza masnih spektrov MALDI-TOF bakterij iz pozitivnih hemokultur

Žnidar, Kitty (author), Mueller Premru, Manica (mentor)

Neposredna hitra identifikacija bakterij iz pozitivnih hemokultur je nepogrešljiva informacija tako za laboratorijsko osebje kot za lečečega zdravnika na kliniki. Polimikrobne hemokulture predstavljajo večje tveganje za smrt in daljše okrevanje bolnikov. Želeli smo ovrednotiti analizo masnih spektrov iz pozitivnih hemokultur s pomočjo standardne MALDI Biotyper Compass programske opreme in jih primerjati z modulom Sepsityper za zaznavanje mešanih kultur, pri čemer smo za referenco uporabili kulturo na gojišču. Hkrati smo želeli v laboratorijskem poskusu z zadostnim številom dveh bakterijskih vrst v različnih razmerjih ugotoviti optimalno končno razmerje za pravilno identifikacijo obeh z modulom Sepsityper. Ugotovili smo, da modul Sepsityper ni ustrezen za karakterizacijo polimikrobnih hemokultur. Ta nam je namreč podal le 4 pravilne identifikacije izmed 46/58 polimikrobnih hemokultur, za katere je uspel pridobiti določen spekter. V poskusu določitve meje zaznave je bila najbolj optimalna meja zaznave, ki je modulu Sepsityper omogočila ločiti dve bakterijski vrsti, 1:1, najnižja pa 8:1. Pri razmerju 20:1 modul Sepsityper ni več ločil bakterijskih vrst.

• Language: Slovenian
• Keywords: bakteriemija, pozitivne hemokulture, identifikacija bakterij, masna spektrometrija, modul Sepsityper
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: BF - Biotechnical Faculty
• Publisher: [K. Žnidar]
• Year: 2018
• PID: 20.500.12556/RUL-100085
• UDC: 616.94:579.6.083:543.51
• COBISS.SI-ID: 4884344
• Publication date in RUL: 04.03.2018

ŽNIDAR, Kitty, 2018, Analiza masnih spektrov MALDI-TOF bakterij iz pozitivnih hemokultur [online]. Master’s thesis. K. Žnidar. [Accessed 30 March 2025]. Retrieved from: https://repozitorij.uni-lj.si/IzpisGradiva.php?lang=eng&id=100085

Secondary language

• Language: English
• Title: MALDI-TOF mass spectra analysis of bacteria from positive blood cultures

Abstract

Direct fast identification of bacteria in positive blood culture presents key information for laboratory personel as well as for the coresponding clinician. Polymicrobial bacteremia correlate with a higher death risk and present a longer period of recovery than do monomicrobial bacteremias. Using the module Sepsityper we wanted to obtain information about the possible presence of more than one microorganism in blood culture. We thus wanted to evaluate the analysis of mass spectra of positive blood cultures with the standard MALDI Biotyper Compass and compare it to the analysis of mass spectra obtained via module Sepsityper for identification of mixed cultures. Our gold standard was the coresponding culture of hemoculture on agar plates. We also wished to determine the optimal ratio between two bacterial species for which the Sepsityper module would still give us a sufficient result. We concluded that the Sepsityper module isn't appropriate for the characterization of polymicrobial spectra. Through the Sepsityper settings we identified only 4 out of 46/58 polymicrobial blood cultures for which it determined some spectra, i.e. got a response. In our experiment, the optimal ratio for differentiating between two bacterial species was 1:1, with the lowest being 8:1 and at a ratio of 20:1 Sepsityper module could not differentiate the two any longer.

• Keywords: bacteremia, positive blood cultures, identification of bacteria, mass spectrometry, Sepsityper module