Rapid identification of microorganisms directly from positive blood cultures by MALDI-TOF MS

2019 ◽  
Vol 37 (5) ◽  
pp. 287-289
Author(s):  
Marina Oviaño
Author(s):  
Hazan Zengin Canalp ◽  
Banu Bayraktar

Using MALDI-TOF MS directly from blood culture bottles reduces the time required for pathogen identification, and the turnaround times for final identification have been compared with overnight incubation from solid media in previous studies. However, identification from a short incubation of agar plates has been increasingly accepted and successfully implemented in routine laboratories, but there is no data comparing direct MALDI-TOF MS with the short-term, incubated agar plates.


2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Cesira Giordano ◽  
Elena Piccoli ◽  
Veronica Brucculeri ◽  
Simona Barnini

Rapid identification of bloodstream pathogens by MALDI-TOF MS and the recently introduced rapid antimicrobial susceptibility testing (rAST) directly from positive blood cultures allow clinicians to promptly achieve a targeted therapy, especially for multidrug resistant microorganisms. In the present study, we propose a comparison between phenotypical rASTs performed in light-scattering technology (Alfred 60AST, Alifax®) and fluorescencein situhybridization (Pheno™, Accelerate) directly from positive blood cultures, providing results in 4–7 hours. Blood samples from 67 patients admitted to the Azienda Ospedaliero-Universitaria Pisana were analyzed. After the direct MALDI-TOF MS identification, the rAST was performed at the same time both on Alfred 60AST and Pheno. Alfred 60AST provided qualitative results, interpreted in terms of clinical categories (SIR). Pheno provided identification and MIC values for each antibiotic tested. Results were compared to the broth microdilution assay (SensiTitre™, Thermo Fisher Scientific), according to EUCAST rules. Using Alfred 60AST, an agreement was reached, 91.1% for Gram-negative and 95.7% for Gram-positive bacteria, while using Pheno, the agreement was 90.6% for Gram-negative and 100% for Gram-positive bacteria. Both methods provided reliable results; Alfred 60AST combined with MALDI-TOF MS proved itself faster and cheaper. Pheno provided identification and MIC determination in a single test and, although more expensive, may be useful whenever MIC value is necessary and where MALDI-TOF MS is not present.


2013 ◽  
Vol 303 (4) ◽  
pp. 205-209 ◽  
Author(s):  
Christian Leli ◽  
Elio Cenci ◽  
Angela Cardaccia ◽  
Amedeo Moretti ◽  
Francesco D’Alò ◽  
...  

Author(s):  
Xue Wan ◽  
Shuang Wang ◽  
Min Wang ◽  
Jinhua Liu ◽  
Yu Zhang

Gram-positive anaerobic cocci (GPAC) are a commensal part of human flora but are also opportunistic pathogens. This is possibly the first study to report a case of Peptoniphilus harei bacteremia in an abdominal aortic aneurysm (AAA) patient. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) failed to identify the isolate and molecular analysis confirmed it as P. harei. A comprehensive literature review revealed that P. harei is an emergent pathogen. This study serves as a reminder for practicing clinicians to include anaerobic blood cultures as part of their blood culture procedures; this is particularly important situations with a high level of suspicion of infection factors in some noninfectious diseases, as mentioned in this publication. Clinical microbiologists should be aware that the pathogenic potential of GPAC can be greatly underestimated leading to incorrect diagnosis on using only one method for pathogen identification. Upgradation and correction of the MALDI-TOF MS databases is recommended to provide reliable and rapid identification of GPAC at species level in medical diagnostic microbiology laboratories.


2019 ◽  
Vol 19 (1) ◽  
Author(s):  
Walter Florio ◽  
Susanna Cappellini ◽  
Cesira Giordano ◽  
Alessandra Vecchione ◽  
Emilia Ghelardi ◽  
...  

Abstract Background The application of matrix-assisted laser desorption/ionization time of flight (MALDI-TOF) mass spectrometry (MS) to microbial identification has allowed the development of rapid methods for identification of microorganisms directly in positive, blood cultures (BCs). These methods can yield accurate results for monomicrobial BCs, but often fail to identify multiple microorganisms in polymicrobial BCs. The present study was aimed at establishing a rapid and simple method for identification of bacteria and yeast in polymicrobial BCs from patients with bloodstream infection. Results The rapid method herein proposed is based on short-term culture in liquid media allowing selective growth of microorganisms recovered from polymicrobial BCs, followed by rapid identification by MALDI-TOF MS. To evaluate the accuracy of this method, 56 polymicrobial BCs were comparatively analyzed with the rapid and routine methods. The results showed concordant identification for both microbial species in 43/50 (86%) BCs containing two different microorganisms, and for two microbial species in six BCs containing more than two different species. Overall, 102/119 (85.7%) microorganisms were concordantly identified by the rapid and routine methods using a cut-off value of 1.700 for valid identification. The mean time to identification after BC positivity was about 4.2 h for streptococci/enterococci, 8.7 h for staphylococci, 11.1 h for Gram-negative bacteria, and 14.4 h for yeast, allowing a significant time saving compared to the routine method. Conclusions The proposed method allowed rapid and reliable microbial identification in polymicrobial BCs, and could provide clinicians with timely, useful information to streamline empirical antimicrobial therapy in critically ill patients.


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