All microorganisms commonly isolated in our laboratory are now routinely identified by MALDI-TOF MS with Andromas database. We wanted to take stock of our experience specifically relating two months of activity.
The identified microorganisms include bacteria isolated on solid media, bacteria extracted directly from the blood culture bottles, mycobacteria, yeast and Aspergillus .
The MALDI-TOF MS was used on 2768 isolated bacteria on solid medium, either all bacteria isolated during this period except Escherichia coli grown on chromogenic medium identified on color and indole. From the first acquisition, 90.9% of analyzes allowed to give an extraction without identification. When the first acquisition was not contributory, the strain was ironed spectrometer either the same day or the next day from the antibiogram.We obtained an overall rate of 98.9% successful identification. The failures reported on 24 strains were due to an unknown spectrum or insufficient identification score. Final identification was given by biochemical techniques (n = 9) or molecular (n = 15).
The MALDI-TOF MS has been applied since the positivity from the broth of 162 blood culture bottles without coal.The identification rate was 89.5% at the species level and 92.6% at the genus level.
All mycobacteria isolated during this period (n = 21) were passed by MALDI-TOF MS and identified correctly.
For 92.9% of yeast and 78.7% of Aspergillus , identification was given on the first pass. A second passage has an identification rate of 99.4% for yeast (160/161) and 98.5% (64/65) for Aspergillus .
In conclusion, this technique, performed under routine conditions by many manipulators within our laboratory, gave a very high identification rate, since the positivity of the culture. This confirms the interest there is to rapidly scale its presence in all laboratories of Microbiology.
Full conference title:
- RICAI 30th (2010)