A high prevalence of selx was reported for S. aureus clinical isolates from blood, diabetic foot ulcers, and cystic fibrosis, as well as for those from colonization [8,9,10,11], showing comparable or higher detection rates than those of sea, sec, and egc. Furthermore, selx was revealed to be highly conserved, despite the presence of various subtypes. Here, MSRB1 is linked to cystic fibrosis.