Mobile genetic elements responsible for discordant Staphylococcus aureus phenotypes and genotypes in the same blood culture bottle

Document Type

Article

Publication Date

12-2020

Publication Source

Diagnostic Microbiology and Infectious Disease

Abstract

Approximately 15-20% of the S. aureus genome contains mobile genetic elements that can cause discrepancies between phenotypic and genotypic identification methods. Three blood culture bottles (each from a different patient) that showed discordant results, were shown to contain 2 S. aureus isolates after additional subcultures. One bottle had MRSA and MSSA that by DNA sequence analysis differed only by 31 kb; however, the deletions encompassed parts of SCCmec including mecA and SCCM1. The second bottle contained MRSA and MSSA that differed by 124 kb; the MSSA was missing the entire SCCmec and spa regions. The last bottle contained 2 MRSA, one with ACME II disrupting SCCmec and a 24 bp spa deletion. The deletions in SCCmec and the other elements gave rise to the discrepancies between molecular and the original culture results. Such discrepancies should prompt a search for additional strains in the blood culture bottle.

ISBN/ISSN

Print ISSN: 0732-8893; Online ISSN: 1879-0070

Publisher

Elsevier

Volume

98

Issue

4

Keywords

Blood culture, Evolution, MRSA, Mobile genetic elements, Staphylococcus aureus, Whole genome sequencing

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