Actinobaculum schaalii: identification with MALDI-TOF

Abstract

Actinobaculum schaalii is an emerging uropathogen. So far, its identification has been performed with 16S rRNA gene sequencing or PCR. The diagnosis has often been delayed due to fastidious growth and identification problems. Eleven clinical isolates of A. schaalii from bloodstream infections that were initially identified with 16S rRNA sequencing analysis were recovered and later identified with matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF). We present a review of bacteriological data of these patients, an algorithm for fast laboratory work-up and advocate the use of sensitized culture of urine to allow better recovery of A. schaalii in susceptible patients.

Actinobaculum schaalii bacteremia: A report of two cases

“…As there is no commercially available biochemical identification system that reliably identifies this bacteria, diagnosis is made with molecular methods, usually by 16S rRNA gene sequencing, or by MALDI-TOF MS [1,10,11]. In one study, the investigators were able to reliably identify A. schaalii in 11 of 11 clinical isolates using MALDI-TOF MS with Bruker Biotyper scores above 2.0, which is considered a score compatible with accurate species level identification [10].…”

“…In one study, the investigators were able to reliably identify A. schaalii in 11 of 11 clinical isolates using MALDI-TOF MS with Bruker Biotyper scores above 2.0, which is considered a score compatible with accurate species level identification [10]. Farfour evaluated the use of MALDI in identifying GPB, with 16S rRNA gene sequencing as the reference identification technique, and the investigators were able to correctly identify A. schaalii in 100% of their isolates [11].…”

A validation of the Danish microbiology database (MiBa) and incidence rate of Actinotignum schaalii (Actinobaculum schaalii) bacteraemia in Denmark

“…The unexpected increase in the incidence rate of A. schaalii in abscesses, pus and tissue also suggests that A. schaalii has been overlooked as a cause of abscesses. MALDI-TOF MS is a powerful tool for identifying rare bacterial species [9,12]. The implementation of MALDI-TOF MS in routine diagnostics in most microbiological departments in Denmark has made it much easier to identify A. schaalii.…”

“…schaalii is a Gram-positive capnophilic rod, resembling the commensal coryneform bacteria on the skin and mucosa. It is difficult to identify with conventional biochemical tests, and identification often requires molecular techniques (PCR) or matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry (MS) [3,4,8,9]. A. schaalii is therefore often overlooked, and is mostly found as monocultures after 2-3 days of incubation in CO 2 [3,4,10].…”

Comparison of Vitek MS and MALDI Biotyper for Identification of Actinomycetaceae of Clinical Importance

“…The purpose of this study was to compare the performances of two commercially available MALDI-TOF MS systems, the Vitek MS in vitro diagnostic (IVD) (bioMérieux, Marcy l'Etoile, France) and MALDI Biotyper IVD (Bruker Daltonics, Wissembourg, France) systems, for the identification of relevant isolates of Actinomycetaceae. It is known that due to the thick cell wall of Gram-positive bacteria, a preliminary extraction step may be warranted before the acquisition of mass spectra, as was already shown for the Biotyper system (6)(7)(8)(9). However, to the best of our knowledge, the impact of such pretreatment has not systematically been evaluated for the Vitek MS system.…”