False-negative test results in the Slidex Staph Plus (bioMérieux) agglutination test are mainly caused by -type t001 and t001-related strains
Résumé
The relative sensitivity of commercial agglutination kits for fast identification of is usually given to be about 98%. This reported sensitivity has sometimes been questioned. In this study, three collections of molecularly defined, single-copy strains of were used to compare the sensitivities of agglutination-based identification and the MALDI-TOF mass spectrometry-based identification using the Biotyper 2.0 database to a molecularly defined reference method. Clinical isolates ( = 363) of methicillin-susceptible (MSSA) and 240 clinical isolates of methicillin-resistant (MRSA) were included. In order to rule out a predominance of local MRSA-strains, a collection of 104 pulsed-field-gel electrophoresis divergent MRSA strains were also tested. MALDI-TOF MS using Biotyper database (Bruker) identified all isolates, whereas the Slidex Staph Plus (bioMérieux) detected only 98.0% of the MSSA, 94.5% of the MRSA and only 70.1% of the MRSA of the molecularly divergent strain collection. Interestingly, strains with a false-negative test result in the agglutination methods were mostly -type t001 and t001 related. The MALDI-TOF MS based identification can thus be used as an alternative identification method for suspected false-negative results from the agglutination tests, especially if the local prevalence of t001 and t001 related strains is high.
Domaines
Sciences du Vivant [q-bio]Origine | Fichiers produits par l'(les) auteur(s) |
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