title: MALDI-TOF Mass Spectrometry for Multilocus Sequence Typing of Escherichia coli Reveals Diversity among Isolates Carrying blaCMY₋₂-Like Genes.
abstract: Effective surveillance and management of pathogenic Escherichia coli relies on robust and reproducible typing methods such as multilocus sequence typing (MLST). Typing of E. coli by MLST enables tracking of pathogenic clones that are known to carry virulence factors or spread resistance, such as the globally-prevalent ST131 lineage. Standard MLST for E. coli requires sequencing of seven alleles, or a whole genome, and can take several days. Here, we have developed and validated a nucleic-acid-based MALDI-TOF mass spectrometry (MS) method for MLST as a rapid alternative to sequencing that requires minimal operator expertise. Identification of alleles was 99.6% concordant with sequencing. We employed MLST by MALDI-TOF MS to investigate diversity among 62 E. coli isolates from Sydney, Australia, carrying a blaCMY-2-like gene on an IncI1 plasmid to determine whether any dominant clonal lineages are associated with the spread of this globally-disseminated resistance gene. Thirty-four known sequence types were identified, including lineages associated with human disease, animal and environmental sources. This suggests that the dissemination of blaCMY-2-like-genes is more complex than the simple spread of successful pathogenic clones. E. coli MLST by MALDI-TOF MS, employed here for the first time, can be utilised as an automated tool for large-scale population analyses or for targeted screening for known high-risk clones in a diagnostic setting.
authors.affiliation: Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research, The University of Sydney and Westmead Hospital, Westmead, New South Wales, Australia.
authors.forename: Kaitlin A
authors.initials: KA
authors.lastname: Tagg
authors.affiliation: Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research, The University of Sydney and Westmead Hospital, Westmead, New South Wales, Australia.
authors.forename: Andrew N
authors.initials: AN
authors.lastname: Ginn
authors.affiliation: Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research, The University of Sydney and Westmead Hospital, Westmead, New South Wales, Australia.
authors.forename: Sally R
authors.initials: SR
authors.lastname: Partridge
authors.affiliation: Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research, The University of Sydney and Westmead Hospital, Westmead, New South Wales, Australia.
authors.forename: Jonathan R
authors.initials: JR
authors.lastname: Iredell
mesh_terms: D000483:Alleles; D001315:Australia; D015373:Bacterial Typing Techniques / Q000379:methods; D015139:Blotting, Southern; D017931:DNA Primers; D004269:DNA, Bacterial / Q000032:analysis; D004926:Escherichia coli / Q000235:genetics*; D029968:Escherichia coli Proteins / Q000235:genetics*; D015723:Gene Library; D005798:Genes, Bacterial; D014644:Genetic Variation; D058885:Multilocus Sequence Typing / Q000379:methods*; D010957:Plasmids / Q000378:metabolism; D017422:Sequence Analysis, DNA / Q000379:methods*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D037521:Virulence Factors / Q000235:genetics; D001618:beta-Lactamases / Q000235:genetics*
chemical_list: D017931:DNA Primers; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D037521:Virulence Factors; D001618:beta-Lactamases; C000605810:beta-lactamase CMY-2, E coli