Comparison among four proposed direct blood culture microbial identification methods using MALDI-TOF MS.
Matrix-assisted laser desorption-ionization time-of-flight (MALDI-TOF) mass spectrometry facilitates rapid and accurate identification of pathogens, which is critical for sepsis patients. In this study, we assessed the accuracy in identification of both Gram-negative and Gram-positive bacteria, except for Streptococcus viridans, using four rapid blood culture methods with Vitek MALDI-TOF-MS. We compared our proposed lysis centrifugation followed by washing and 30% acetic acid treatment method (method 2) with two other lysis centrifugation methods (washing and 30% formic acid treatment (method 1); 100% ethanol treatment (method 3)), and picking colonies from 90 to 180min subculture plates (method 4). Methods 1 and 2 identified all organisms down to species level with 100% accuracy, except for Streptococcus viridans, Streptococcus pyogenes, Enterobacter cloacae and Proteus vulgaris. The latter two were identified to genus level with 100% accuracy. Each method exhibited excellent accuracy and precision in terms of identification to genus level with certain limitations.
Microbiology Laboratory, Johns Hopkins Aramco Healthcare, Dhahran, Saudi Arabia. Electronic address: ali.bazzi@jhah.com.
Ali M
AM
Bazzi
Molecular Diagnostic Laboratory, Johns Hopkins Aramco Healthcare, Dhahran, Saudi Arabia.
Ali A
AA
Rabaan
Microbiology Laboratory, Johns Hopkins Aramco Healthcare, Dhahran, Saudi Arabia.
Zeyad
Z
El Edaily
Microbiology Laboratory, Johns Hopkins Aramco Healthcare, Dhahran, Saudi Arabia.
Susan
S
John
Microbiology Laboratory, Johns Hopkins Aramco Healthcare, Dhahran, Saudi Arabia.
Mahmoud M
MM
Fawarah
Specialty Internal Medicine, Johns Hopkins Aramco Healthcare, Dhahran, Saudi Arabia; Indiana University School of Medicine, Indiana, USA.
Jaffar A
JA
Al-Tawfiq
D001431:Bacteriological Techniques; D006090:Gram-Negative Bacteria / Q000302:isolation & purification*; D006094:Gram-Positive Bacteria / Q000302:isolation & purification*; D012680:Sensitivity and Specificity; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
Blood culture; Gram-negative; Gram-positive; MALDI-TOF; Sepsis