title: Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry for the identification of Burkholderia pseudomallei from Asia and Australia and differentiation between Burkholderia species.
abstract: Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is increasingly used for rapid bacterial identification. Studies of Burkholderia pseudomallei identification have involved small isolate numbers drawn from a restricted geographic region. There is a need to expand the reference database and evaluate B. pseudomallei from a wider geographic distribution that more fully captures the extensive genetic diversity of this species. Here, we describe the evaluation of over 650 isolates. Main spectral profiles (MSP) for 26 isolates of B. pseudomallei (N = 5) and other Burkholderia species (N = 21) were added to the Biotyper database. MALDI-TOF MS was then performed on 581 B. pseudomallei, 19 B. mallei, 6 B. thailandensis and 23 isolates representing a range of other bacterial species. B. pseudomallei originated from northeast and east Thailand (N = 524), Laos (N = 12), Cambodia (N = 14), Hong Kong (N = 4) and Australia (N = 27). All 581 B. pseudomallei were correctly identified, with 100% sensitivity and specificity. Accurate identification required a minimum inoculum of 5 x 107 CFU/ml, and identification could be performed on spiked blood cultures after 24 hours of incubation. Comparison between a dendrogram constructed from MALDI-TOF MS main spectrum profiles and a phylogenetic tree based on recA gene sequencing demonstrated that MALDI-TOF MS distinguished between B. pseudomallei and B. mallei, while the recA tree did not. MALDI-TOF MS is an accurate method for the identification of B. pseudomallei, and discriminates between this and other related Burkholderia species.
authors.affiliation: Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.
authors.forename: Vichaya
authors.initials: V
authors.lastname: Suttisunhakul
authors.affiliation: Department of Clinical Pathology, Faculty of Medicine, Navamindradhiraj University, Bangkok, Thailand.
authors.forename: Apinya
authors.initials: A
authors.lastname: Pumpuang
authors.affiliation: Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.
authors.forename: Peeraya
authors.initials: P
authors.lastname: Ekchariyawat
authors.affiliation: Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.
authors.forename: Vanaporn
authors.initials: V
authors.lastname: Wuthiekanun
authors.affiliation: Bacterial Special Pathogens Branch, Division of High-Consequence Pathogens and Pathology, National Center for Zoonotic and Emerging Infectious Diseases, Centers for Disease Control and Prevention (CDC), Atlanta, Georgia, United States of America.
authors.forename: Mindy G
authors.initials: MG
authors.lastname: Elrod
authors.affiliation: Cambodia-Oxford Medical Research Unit, Angkor Hospital for Children, Siem Reap, Cambodia; Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom.
authors.forename: Paul
authors.initials: P
authors.lastname: Turner
authors.affiliation: Department of Infectious Diseases, Royal Darwin Hospital, Darwin, Northern Territory, Australia; Global and Tropical Health Division, Menzies School of Health Research, Darwin, Northern Territory, Australia.
authors.forename: Bart J
authors.initials: BJ
authors.lastname: Currie
authors.affiliation: Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit, Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao People's Democratic Republic; Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, United Kingdom.
authors.forename: Rattanaphone
authors.initials: R
authors.lastname: Phetsouvanh
authors.affiliation: Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit, Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao People's Democratic Republic; Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, United Kingdom.|London School of Hygiene and Tropical Medicine, London, United Kingdom.
authors.forename: David A B
authors.initials: DA
authors.lastname: Dance
authors.affiliation: Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.|Department of Tropical Hygiene, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.
authors.forename: Direk
authors.initials: D
authors.lastname: Limmathurotsakul
authors.affiliation: London School of Hygiene and Tropical Medicine, London, United Kingdom.
authors.forename: Sharon J
authors.initials: SJ
authors.lastname: Peacock
authors.affiliation: Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.|Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.
authors.forename: Narisara
authors.identifier: http://orcid.org/0000-0003-3906-7379
authors.initials: N
authors.lastname: Chantratita
mesh_terms: D001208:Asia; D001315:Australia; D016957:Burkholderia pseudomallei / Q000145:classification* / Q000235:genetics; D003470:Culture Media; D005798:Genes, Bacterial; D007841:Latex Fixation Tests; D058885:Multilocus Sequence Typing; D010802:Phylogeny; D013045:Species Specificity; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*
chemical_list: D003470:Culture Media