Method Comparison Protocol: MALDI Biotyper-Clinical Applications (MBT-CA) Phase 2

Bacteria or yeast isolates (1) fresh from primary culture plates, (2) collected directly from clinical samples, stored in the refrigerator or frozen or (3) well characterized organisms from a variety of contemporary culture collections will be included in the study. All organisms to be included in the study will be cultured on an agar medium prior to measurement.

Testing will be performed for various Gram negative and Gram positive bacteria and yeasts as outlined below. Several thousands of samples will be measured via MBT-CA systems based on MALDI-TOF MS technology (matrix assisted laser desorption ionisation time-of-flight mass spectrometry) at the test sites as fresh or frozen isolates of bacteria and yeasts. Lower prevalence organisms may be supplemented from banked culture collections.

The MBT-CA system uses an organism identification based on unique protein patterns of the microorganisms obtained from mass spectrometry. The test organism's spectrum (a pattern of mass peaks) is compared with a reference spectra library (database). Using biostatistical analysis, a probability ranking of the organism identification is generated. The probability ranking is represented as a log(score) between 0.00 and 3.00. Organism identification is reported with high confidence if the log(score) is ≥ 2.00. An organism identification is reported with low confidence if the log(score) is between 1.70 and <2.00.

In the last step the samples are sent to a special site for sequencing. Finally, the respective sequencing results are compared with the MBT-CA results.

Target microorganisms of study: