Identification of Bacteria in Blood Culture Broths Using Matrix-Assisted Laser Desorption-Ionization Sepsityper™ and Time of Flight Mass Spectrometry

Abstract

Matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS) is a novel method for the direct identification of bacteria from blood culture broths. We evaluate for the first time, the performance of the MALDI Sepsityper™ Kit and MS for the identification of bacteria compared to standard phenotypic methods using the manufacturer's specified bacterial identification criteria (spectral scores ≥1.700–1.999 and ≥2.000 indicated identification to genus and species level, respectively). Five hundred and seven positive blood culture broths were prospectively examined, of which 379 (74.8%; 358 monomicrobial, 21 polymicrobial) were identified by MALDI-TOF MS; 195 (100%) and 132 (67.7%) of 195 gram-positive; and 163 (100%) and 149 (91.4%) of 163 gram-negative organisms from monomicrobial blood cultures were correctly identified to genus and species level, respectively. Spectral scores <1.700 (no identification) were obtained in 128/507 (25.2%) positive blood culture broths, including 31.6% and 32.3% of gram-positive and polymicrobial blood cultures, respectively. Significantly more gram-negative organisms were identified compared to gram-positive organisms at species level (p<0.0001). Five blood cultures were misidentified, but at species level only; including four monomicrobial blood cultures with Streptococcus oralis/mitis that were misidentified as Streptococcus pneumoniae. Positive predictive values for the direct identification of both gram-positive and gram-negative bacteria from monomicrobial blood culture broths to genus level were 100%. A diagnostic algorithm for positive blood culture broths that incorporates gram staining and MALDI-TOF MS should identify the majority of pathogens, particularly to genus level.

Identification of Staphylococci Directly from Positive Blood Culture Bottles by MALDI-TOF MS System

“…Sonuçlarımız, önceki bazı çalışmalar 18,21,23,24 ile uyumlu olarak bulunmuş; ancak diğer bazı çalışmalardan 6,16,19,20,22 elde edilen tanım-lama oranlarından daha yüksek olduğu gözlenmiştir. Sonuçlar arasındaki farkların,…”

“…Bu yöntemlerde, hastanın kan örneği önce kan kültür şişelerine alına-rak inkübe edilmekte, bakteriyel üreme tespit edildikten sonra 18 ile 48 saat süren tür düzeyinde tanımlama ve antibiyotik duyarlılık testi işlemleri yapılmaktadır. Zor üreyen mikroorganizmalar için bu süre uzayabilmektedir 6 . KAE'ye neden olan mikroorganizmaların tanımlanma zamanını kısaltmak için gerçek zamanlı Taqman PCR, multipleks PCR, floresan in situ hibridizasyon (FISH) ve peptid nükleik asit FISH yöntemleri geliştirilmiş ve halen kullanılmaktadır.…”

Rapid Identification of <i>Mycoplasma pulmonis</i> Isolated from Laboratory Mice and Rats Using Matrix-Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry

“…The culture method is one of the most common and specific methods to detect bacteria; however, a laborious step is needed to identify the colonies [4], such as morphological studies, reversion studies, or the sterol requirement and metabolism inhibition test. Recently, sequence analysis of the 16S rRNA gene has also been used as a simple method for identification of the bacteria [16].More recently, matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) has been applied to analyze the protein composition and used for direct identification of pathogens in the culture agar and/ or broth [8,14,15]. However, there has been limited work thus far on the use of MALDI-TOF MS for the identification of pathogens in laboratory animals.…”

“…More recently, matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) has been applied to analyze the protein composition and used for direct identification of pathogens in the culture agar and/ or broth [8,14,15]. However, there has been limited work thus far on the use of MALDI-TOF MS for the identification of pathogens in laboratory animals.…”

“…MALDI-TOF MS, which is sensitive and efficacious, has been applied to analyze the protein composition of bacteria [8,14,15]. The method provides an easy-to-handle system to identify different bacterial pathogens and is useful in the determination of bacterial species.…”