M Marí-Almirall1, C Cosgaya1, P G Higgins2, A Van Assche3, M Telli4, G Huys5, B Lievens3, H Seifert2, L Dijkshoorn6, I Roca7, Jordi Vila1. 1. Department of Clinical Microbiology and ISGlobal- Barcelona Ctr. Int. Health Res. CRESIB, Hospital Clínic - Universitat de Barcelona, Barcelona, Spain. 2. Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, Cologne, Germany; German Centre for Infection Research (DZIF), Partner site Bonn-Cologne, Germany. 3. Laboratory for Process Microbial Ecology and Bioinspirational Management (PME&BIM), Department of Microbial and Molecular Systems (M2S), KU Leuven, Sint-Katelijne-Waver, Belgium. 4. Department of Clinical Microbiology, School of Medicine, Adnan Menderes University, Aydin, Turkey. 5. BCCM/LMG Bacteria Collection & Laboratory of Microbiology, Faculty of Sciences, Ghent University, Ghent, Belgium. 6. Department of Infectious Diseases, Leiden University Medical Center, Leiden, The Netherlands. 7. Department of Clinical Microbiology and ISGlobal- Barcelona Ctr. Int. Health Res. CRESIB, Hospital Clínic - Universitat de Barcelona, Barcelona, Spain. Electronic address: Ignasi.roca@isglobal.org.
Abstract
OBJECTIVES: Rapid identification of Acinetobacter species is critical as members of the A. baumannii (Ab) group differ in antibiotic susceptibility and clinical outcomes. A. baumannii, A. pittii, and A. nosocomialis can be identified by MALDI-TOF/MS, while the novel species A. seifertii and A. dijkshoorniae cannot. Low identification rates for A. nosocomialis also have been reported. We evaluated the use of MALDI-TOF/MS to identify isolates of A. seifertii and A. dijkshoorniae and revisited the identification of A. nosocomialis to update the Bruker taxonomy database. METHODS: Species characterization was performed by rpoB-clustering and MLSA. MALDI-TOF/MS spectra were recovered from formic acid/acetonitrile bacterial extracts overlaid with α-cyano-4-hydroxy-cinnamic acid matrix on a MicroflexLT in linear positive mode and 2000-20 000 m/z range mass. Spectra were examined with the ClinProTools v2.2 software. Mean spectra (MSP) were created with the BioTyper software. RESULTS: Seventy-eight Acinetobacter isolates representative of the Ab group were used to calculate the average spectra/species and generate pattern recognition models. Species-specific peaks were identified for all species, and MSPs derived from three A. seifertii, two A. dijkshoorniae, and two A. nosocomialis strains were added to the Bruker taxonomy database, allowing successful identification of all isolates using spectra from either bacterial extracts or direct colonies, resulting in a positive predictive value (PPV) of 99.6% (777/780) and 96.8% (302/312), respectively. CONCLUSIONS: The use of post-processing data software identified statistically significant species-specific peaks to generate reference signatures for rapid accurate identification of species within the Ab group, providing relevant information for the clinical management of Acinetobacter infections.
OBJECTIVES: Rapid identification of Acinetobacter species is critical as members of the A. baumannii (Ab) group differ in antibiotic susceptibility and clinical outcomes. A. baumannii, A. pittii, and A. nosocomialis can be identified by MALDI-TOF/MS, while the novel species A. seifertii and A. dijkshoorniae cannot. Low identification rates for A. nosocomialis also have been reported. We evaluated the use of MALDI-TOF/MS to identify isolates of A. seifertii and A. dijkshoorniae and revisited the identification of A. nosocomialis to update the Bruker taxonomy database. METHODS: Species characterization was performed by rpoB-clustering and MLSA. MALDI-TOF/MS spectra were recovered from formic acid/acetonitrile bacterial extracts overlaid with α-cyano-4-hydroxy-cinnamic acid matrix on a MicroflexLT in linear positive mode and 2000-20 000 m/z range mass. Spectra were examined with the ClinProTools v2.2 software. Mean spectra (MSP) were created with the BioTyper software. RESULTS: Seventy-eight Acinetobacter isolates representative of the Ab group were used to calculate the average spectra/species and generate pattern recognition models. Species-specific peaks were identified for all species, and MSPs derived from three A. seifertii, two A. dijkshoorniae, and two A. nosocomialis strains were added to the Bruker taxonomy database, allowing successful identification of all isolates using spectra from either bacterial extracts or direct colonies, resulting in a positive predictive value (PPV) of 99.6% (777/780) and 96.8% (302/312), respectively. CONCLUSIONS: The use of post-processing data software identified statistically significant species-specific peaks to generate reference signatures for rapid accurate identification of species within the Ab group, providing relevant information for the clinical management of Acinetobacter infections.
Authors: Jonathan H K Chen; Vincent C C Cheng; Chun-Pong Wong; Sally C Y Wong; Wing-Cheong Yam; Kwok-Yung Yuen Journal: J Clin Microbiol Date: 2017-06-21 Impact factor: 5.948
Authors: Christian M Harding; Marina R Pulido; Gisela Di Venanzio; Rachel L Kinsella; Andrew I Webb; Nichollas E Scott; Jerónimo Pachón; Mario F Feldman Journal: J Biol Chem Date: 2017-04-03 Impact factor: 5.157
Authors: Farahiyah Mohd Rani; Nor Iza A Rahman; Salwani Ismail; Ahmed Ghazi Alattraqchi; David W Cleary; Stuart C Clarke; Chew Chieng Yeo Journal: Front Microbiol Date: 2017-12-12 Impact factor: 5.640