Help Please log in to determine if you are eligible to purchase PT Programs. METHICILLIN RESISTANT S AUREUS, 2 CHAL - MRS Analytes/procedures in bold type are regulated for proficiency testing by the Centers for Medicare & Medicaid Services (CMS). Procedure Challenges per Shipment Number of Shipments MRSA / MSSA detection 2 Two shipments per year Program Information Two swab specimens with diluents For laboratories performing culture‑based testing only or using culture and molecular testing Shipping Schedule Shipment A: February 1 Shipment C: October 4 Guest Log in/Register