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J Clin Microbiol. 2018 Aug 27;56(9). pii: e01815-17. doi: 10.1128/JCM.01815-17. Print 2018 Sep.

Accuracy of Different Bioinformatics Methods in Detecting Antibiotic Resistance and Virulence Factors from Staphylococcus aureus Whole-Genome Sequences.

Author information

1
Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom.
2
Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom dona.foster@ndm.ox.ac.uk.
3
NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford, United Kingdom.
4
Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom.
5
Staphylococcus Reference Service, National Infection Service, Public Health England, London, United Kingdom.
6
National Infection Service, Public Health England, London, United Kingdom.
7
The National Institute for Health Research (NIHR) Health Protection Research Unit in Healthcare Associated Infections and Antimicrobial Resistance, University of Oxford, Oxford, United Kingdom.
#
Contributed equally

Abstract

In principle, whole-genome sequencing (WGS) can predict phenotypic resistance directly from a genotype, replacing laboratory-based tests. However, the contribution of different bioinformatics methods to genotype-phenotype discrepancies has not been systematically explored to date. We compared three WGS-based bioinformatics methods (Genefinder [read based], Mykrobe [de Bruijn graph based], and Typewriter [BLAST based]) for predicting the presence/absence of 83 different resistance determinants and virulence genes and overall antimicrobial susceptibility in 1,379 Staphylococcus aureus isolates previously characterized by standard laboratory methods (disc diffusion, broth and/or agar dilution, and PCR). In total, 99.5% (113,830/114,457) of individual resistance-determinant/virulence gene predictions were identical between all three methods, with only 627 (0.5%) discordant predictions, demonstrating high overall agreement (Fleiss' kappa = 0.98, P < 0.0001). Discrepancies when identified were in only one of the three methods for all genes except the cassette recombinase, ccrC(b). The genotypic antimicrobial susceptibility prediction matched the laboratory phenotype in 98.3% (14,224/14,464) of cases (2,720 [18.8%] resistant, 11,504 [79.5%] susceptible). There was greater disagreement between the laboratory phenotypes and the combined genotypic predictions (97 [0.7%] phenotypically susceptible, but all bioinformatic methods reported resistance; 89 [0.6%] phenotypically resistant, but all bioinformatics methods reported susceptible) than within the three bioinformatics methods (54 [0.4%] cases, 16 phenotypically resistant, 38 phenotypically susceptible). However, in 36/54 (67%) cases, the consensus genotype matched the laboratory phenotype. In this study, the choice between these three specific bioinformatic methods to identify resistance determinants or other genes in S. aureus did not prove critical, with all demonstrating high concordance with each other and phenotypic/molecular methods. However, each has some limitations; therefore, consensus methods provide some assurance.

KEYWORDS:

Staphylococcus aureus; antibiotic resistance; bioinformatics; whole-genome sequencing

PMID:
29925638
PMCID:
PMC6113501
DOI:
10.1128/JCM.01815-17
[Indexed for MEDLINE]
Free PMC Article

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