Methodology for Whole-Genome Sequencing of Methicillin-Resistant Staphylococcus aureus Isolates in a Routine Hospital Microbiology Laboratory.


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Type
Article
Change log
Authors
Raven, Kathy E 
Blane, Beth 
Leek, Danielle 
Churcher, Carol 
Kokko-Gonzales, Paula 
Abstract

There is growing evidence for the value of bacterial whole-genome sequencing in hospital outbreak investigations. Our aim was to develop methods that support efficient and accurate low-throughput clinical sequencing of methicillin-resistant Staphylococcus aureus (MRSA) isolates. Using a test panel of 25 MRSA isolates previously associated with outbreak investigations, we devised modifications to library preparation that reduced the processing time by 1 hour. We determined the maximum number of isolates that could be sequenced per run using an Illumina MiniSeq platform and a 13-hour (overnight) run time, which equated to 21 MRSA isolates and 3 controls (no template, positive, and negative). Repeatability and reproducibility assays based on this sequencing methodology demonstrated 100% accuracy in assigning species and sequence type (ST) and in detecting mecA Established genetic relatedness between isolates was recapitulated. Quality control (QC) metrics were evaluated over nine sequencing runs. Of the test panel MRSA genomes, 168/173 (97%) passed QC metrics based on the correct species assigned, detection of mecA and ST, and depth/coverage metrics. An evaluation of contamination in these 9 runs showed that positive and negative controls and test MRSA sequence files contained <0.14% and <0.48% of fragments that matched another species, respectively. Deliberate contamination experiments confirmed that this was insufficient to impact data interpretation. These methods support reliable and reproducible clinical MRSA sequencing with a turnaround time (from DNA extraction to availability of data files) of 24 hours.

Description
Keywords
MRSA, clinical application, whole-genome sequencing, Diagnostic Tests, Routine, Genome, Bacterial, Humans, Laboratories, Hospital, Methicillin-Resistant Staphylococcus aureus, Microbiological Techniques, Multilocus Sequence Typing, Staphylococcal Infections, Whole Genome Sequencing
Journal Title
J Clin Microbiol
Conference Name
Journal ISSN
0095-1137
1098-660X
Volume Title
57
Publisher
American Society for Microbiology
Sponsorship
Wellcome Trust (098600/Z/12/Z)