Genomic insights into methicillin-resistant Staphylococcus aureus spa type t899 isolates belonging to different sequence types.

This study provides a genomic insight into the diversity of t899 isolates using cgMLST, SNP-based phylogeny and the description of selected antimicrobial resistance and virulence markers. The SNP-based phylogenic tree showed that isolates sharing the same spa type (t899) but different STs highly diverged in their core and accessory genomes, revealing discriminant antimicrobial-resistant (AMR) and virulence markers. Our results highlighted that, in a surveillance context where only spa typing is used, an additional multiplex PCR for the detection of the tet(M), sak and seg genes would valuably allow to distinguish ST9 from ST398 isolates on a routine basis.Importance This study showed the genetic diversity and population structure of S. aureus presenting the same spa type t899 but belonging to different STs. Our findings revealed that these isolates vary deeply in their core and accessory genomes, contrary to what is regularly inferred from studies using spa typing only. Given that identical spa types can be associated with different STs, and knowing that spa typing only is not appropriate for S. aureus isolates that underwent major recombination events which include the passage of the spa gene (such as in t899-positive MRSA), the combination of both MLST and spa typing methods is recommended. However, spa typing only is still largely used in surveillance studies and basic characterization. Our data suggest that additional markers, such as tet(M), sak and seg genes, could be i...
Source: Applied and Environmental Microbiology - Category: Microbiology Authors: Tags: Appl Environ Microbiol Source Type: research