Challenges in the identification of methicillin-resistant Staphylococcus argenteus by routine diagnostics

Current clinical diagnostic procedures have shortcomings in the differentiation of Staphylococcus argenteus from Staphylococcus aureus. This article presents three cases of Staphylococcus argenteus obtained from clinical samples. The initial results from biochemical and molecular methods led to an incorrect identification of the isolates as methicillin-resistant Staphylococcus aureus. Whole genome sequencing and real-time PCR targeting the nonribosomal peptide synthetase gene led to their correct identification as methicillin-resistant Staphylococcus argenteus. The study shows that real-time PCR can be used to differentiate the two species in routine diagnostics. For purposes of identification based on whole genome sequencing, the MinION portable sequencer is a simple and affordable approach which could be used by many laboratories.