MALDI-TOF as a Tool for Rapid Species Identification from Blood Culture Vials
Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
Early adequate antimicrobial therapy improves outcome in septicemia. Rapid species identification (ID) from blood cultures is thus important. Matrix-assisted laser desorption-ionisation time of flight (MALDI-TOF) can provide species ID within an hour from blood culture (BC) vials. The present study aimed at comparing the performance and hands on time of two methods for preparing samples from BC vials prior to species ID using MALDI-TOF analysis: sample preparation with SepsityperTM kit and samples smeared from inoculated agar plates after 1-5 hours incubation.
Aerobic and anaerobic BC vials, BacT/Alert and BacTEC, were inoculated in triplicates with five reference strains. Viable count was applied as a control of growth in the BC vials. Thereafter two methods were tested for species ID: sample preparation with the SepsityperTM kit (Bruker Daltonics) followed by Ethanol/Formic Acid Extraction and MALDI-TOF analysis as well as a plating method were 100μl of BC-suspension were inoculated on chocolate agar and incubated in CO2in 1, 2, 3, 4 and 5 h followed by MALDI-TOF analysis without extraction.
Using the SepsityperTM all species were identified with ID score >2.0 from BacTEC, while none from the BacT/Alert vials. The time to result using the plating method was quite similar for BacT/Alert and BacTEC: Escherichia coli could be detected after 2h, Enterococcus faecalis and Pseudomonas aeruginosa after 3h. Staphylococcus aureus and Streptococcus agalactiae could not be identified. Sample preparation with the SepsityperTM kit followed by MALDI-TOF analysis allows a rapid ID from BacTEC vials with a hands on time of one hour for 12 samples. However, ID from the plating method is less laborious and seems as a promising alternative.
Place, publisher, year, edition, pages
2011. , 21 p.
Biomedical Laboratory Science/Technology
IdentifiersURN: urn:nbn:se:lnu:diva-16509OAI: oai:DiVA.org:lnu-16509DiVA: diva2:471997
Subject / course
Biomedical Laboratory Science Programme, 180 credits
Sundqvist, Martin, MD, PhDBergström, Maria, PhD
Marklund, Britt-Inger, Universitetslektor