Search

Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) has emerged as a reliable tool for bacterial identification. This study compared the Bruker MALDI-TOF BioTyper MS (MBT) and 16S rRNA gene sequencing for the identification of Actinomyces and Actinotignum spp. The MBT identified 68/77 (88.3%) of Actinomyces isolates to the genus-level and 44/77 (57.1%) of Actinomyces isolates to the species-level using the manufacturer's identification criteria. The MBT did not yield reliable identification for only 1/77 (1.3%) and generated no identification for 8/77 (10.4%) of the isolates. No misidentifications were found. Discordance at the species level was observed for eight isolates. Overall, the MBT demonstrated good concordance with the 16S rRNA gene sequencing with the exception of the closely related species A. naeslundii, A. viscosus and A. oris. A variety of Actinomyces spp. were isolated from orocervicofacial/dental specimens, but only a limited number of species were isolated from urine or intra-abdominal specimens. This study confirms the utility of MBT in the identification of Actinomyces spp. and describes the diversity and anatomic niche of species in human clinical specimens from various body sites.Copyright © 2018 Elsevier Ltd

Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) has emerged as a reliable tool for bacterial identification. This study compared the Bruker MALDI-TOF BioTyper MS (MBT) and 16S rRNA gene sequencing for the identification of Actinomyces and Actinotignum spp. The MBT identified 68/77 (88.3%) of Actinomyces isolates to the genus-level and 44/77 (57.1%) of Actinomyces isolates to the species-level using the manufacturer's identification criteria. The MBT did not yield reliable identification for only 1/77 (1.3%) and generated no identification for 8/77 (10.4%) of the isolates. No misidentifications were found. Discordance at the species level was observed for eight isolates. Overall, the MBT demonstrated good concordance with the 16S rRNA gene sequencing with the exception of the closely related species A. naeslundii, A. viscosus and A. oris. A variety of Actinomyces spp. were isolated from orocervicofacial/dental specimens, but only a limited number of species were isolated from urine or intra-abdominal specimens. This study confirms the utility of MBT in the identification of Actinomyces spp. and describes the diversity and anatomic niche of species in human clinical specimens from various body sites.Copyright © 2018 Elsevier Ltd

Bacteroides pyogenes is part of the normal oral flora of domestic animals. There is one previous report of human infection, with B. pyogenes bacteremia following a cat bite (Madsen 2011). We report seven severe human infections where B. pyogenes was identified by Bruker matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDTI-TOF MS), but not by VITEK MS and was misidentified by VITEK ANC card.Copyright © 2016

Bacteroides pyogenes is part of the normal oral flora of domestic animals. There is one previous report of human infection, with B. pyogenes bacteremia following a cat bite (Madsen 2011). We report seven severe human infections where B. pyogenes was identified by Bruker matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDTI-TOF MS), but not by VITEK MS and was misidentified by VITEK ANC card.Copyright © 2016

Some Australian strain types of Clostridium difficile appear unique, highlighting the global diversity of this bacterium. We examined recent and historic local isolates, finding predominantly toxinotype 0 strains, but also toxinotypes V and VIII. All isolates tested were susceptible to vancomycin and metronidazole, while moxifloxacin resistance was only detected in recent strains.Copyright © 2015 Elsevier Ltd.

Some Australian strain types of Clostridium difficile appear unique, highlighting the global diversity of this bacterium. We examined recent and historic local isolates, finding predominantly toxinotype 0 strains, but also toxinotypes V and VIII. All isolates tested were susceptible to vancomycin and metronidazole, while moxifloxacin resistance was only detected in recent strains.

Some Australian strain types of Clostridium difficile appear unique, highlighting the global diversity of this bacterium. We examined recent and historic local isolates, finding predominantly toxinotype 0 strains, but also toxinotypes V and VIII. All isolates tested were susceptible to vancomycin and metronidazole, while moxifloxacin resistance was only detected in recent strains.Copyright © 2015 Elsevier Ltd.

Some Australian strain types of Clostridium difficile appear unique, highlighting the global diversity of this bacterium. We examined recent and historic local isolates, finding predominantly toxinotype 0 strains, but also toxinotypes V and VIII. All isolates tested were susceptible to vancomycin and metronidazole, while moxifloxacin resistance was only detected in recent strains.

We compared the identification of Clostridium species using mass spectrometry by two different Matrix-Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) platforms (Bruker MS and Vitek MS) against 16S rRNA sequencing as the reference standard. We then examined the impact of different sample preparations and (on one of those platforms) age of bacterial colonial growth on the performance of the MALDI-TOF MS systems.We identified 10 different species amongst the 52 isolates by 16S rRNA sequencing, with Clostridium perfringens the most prevalent (n=30). Spectrometric analysis using Vitek MS correctly speciated 47/52 (90.4%) isolates and was not affected by the sample preparation used. Performance of the Bruker MS was dependent on sample preparation with correct speciation obtained for 36 of 52 (69.2%) isolates tested using the Direct Transfer [DT] protocol, but all 52 (100%) isolates were correctly speciated using either an Extended Direct Transfer [EDT] or a Full Formic Extraction [EX] protocol. We then examined the effect of bacterial colonial growth age on the performance of Bruker MS and found substantial agreement in speciation using DT (Kappa=0.62, 95% CI: 0.46-0.75), almost perfect agreement for EDT (Kappa=0.94, 95% CI: 0.86-1.00) and exact agreement for EX (Kappa=1.00) between different days.Copyright © 2014 Elsevier Ltd.

We compared the identification of Clostridium species using mass spectrometry by two different Matrix-Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) platforms (Bruker MS and Vitek MS) against 16S rRNA sequencing as the reference standard. We then examined the impact of different sample preparations and (on one of those platforms) age of bacterial colonial growth on the performance of the MALDI-TOF MS systems.We identified 10 different species amongst the 52 isolates by 16S rRNA sequencing, with Clostridium perfringens the most prevalent (n=30). Spectrometric analysis using Vitek MS correctly speciated 47/52 (90.4%) isolates and was not affected by the sample preparation used. Performance of the Bruker MS was dependent on sample preparation with correct speciation obtained for 36 of 52 (69.2%) isolates tested using the Direct Transfer [DT] protocol, but all 52 (100%) isolates were correctly speciated using either an Extended Direct Transfer [EDT] or a Full Formic Extraction [EX] protocol. We then examined the effect of bacterial colonial growth age on the performance of Bruker MS and found substantial agreement in speciation using DT (Kappa=0.62, 95% CI: 0.46-0.75), almost perfect agreement for EDT (Kappa=0.94, 95% CI: 0.86-1.00) and exact agreement for EX (Kappa=1.00) between different days.Copyright © 2014 Elsevier Ltd.