Direct identification from positive blood broth culture by matrix-assisted laser desorption-ionization time-of-flight mass spectrometry (MALDI-TOF MS)

Abstract

Bloodstream infections (BSIs) are among the most concerning bacterial infections. They are one of the leading causes of morbidity and mortality, and occur in 30-70% of critical care patients. The prompt identification of the causative microorganism can help choosing the appropriate antimicrobial therapy that will lead to better clinical outcomes. Blood culture is one of the most relevant tests for microbiological diagnosis of bacterial infections. The introduction of the MALDI-TOF microbiological diagnosis significantly decreased the time of identifying microorganisms. However, it depends on the growth on solid culture medium. In this study, 538 bottles of positive blood cultures were evaluated to test the accuracy of an in house modified protocol. The study sample consisted of 198 Gram-negative and 350 Gram-positive bacteria. In all, 460 (83.94%) species were identified based on the direct plate findings. The protocol allowed the identification of 185/198 (93.43%) of the Gram-negative bacteria, including aerobes, anaerobes, and non-fermenters, and 275/350 (78.85%) of the Gram-positive bacteria. The proposed method has the potential to provide accurate results in comparison to the traditional method with the potential to reduce the turnaround time for the results and optimize antimicrobial therapy in BSI.

Bloodstream infections caused by multidrug-resistant gram-negative bacteria: epidemiological, clinical and microbiological features

“…The blood cultures were performed on BacT/ALERT® 3D (bioMeriéux-France) and microbial identification was performed by MALDI-TOF MS (bioMeriéux-France) as described by Barberino et al [27]. All GNB identified were stored in Trypticase Soy Broth (TSB) enriched with 10% glycerol at − 70 °C until it was reactivated for molecular tests.…”

Rapid identification of bacteria directly from positive blood cultures by a modified method using a serum separator tube and matrix-assisted laser desorption ionization – time of flight MS

“…This method based on the use of SST has already been described by other authors [17][18][19][20][21][22][23][24][25][26] using a simplified procedure dependent on Gram staining. Considering a score >1.7 as a reliable identification, we obtained an overall reliable identification rate of 68.8 %.…”

“…Some studies have recently investigated the rapid identification of microorganisms by MALDI-TOF using the serum separator tube (SST), with different performances and methodologies [17][18][19][20][21][22][23][24][25][26]. The present study evaluated bacterial identification from positive BCs by MALDI-TOF using an SST-based method and compared it with MALDI-TOF after subculture for 18-24 h.…”

Detecção de microrganismos em dispositivos ortopédicos sonicados clínicos usando cultura convencional e qPCR

“…17 Além disso, a ionização e dessorção a laser assistida por matriz com espectrometria de massa por tempo de voo (matrix-assisted laser desorption/ionization time-offlight mass spectrometry, MALDI-TOF MS, em inglês) tem sido usada em vários ambientes para a detecção direta de amostras biológicas; ela identifica precocemente e de forma confiável os microrganismos, e é uma alternativa à cultura. [18][19][20] O objetivo deste estudo foi avaliar a sensibilidade e a especificidade da reação em cadeia de polimerase em tempo real quantitativa (quantitative real-time polymerase chain reaction, qPCR, em inglês) em rastrear o gene rDNA 16S, em amostras de fluidos sonicados obtidas de implantes ortopédicos.…”