Look for more steps with MRSA. Once the new ICD-9 codes go into effect Oct. 1, you'll need to identify whether your patient has a methicillin resistant Staphylococcus aureus infection (MRSA) or methicillin susceptible Staphylococcus au-reus infection (MSSA). For patients with MRSA infections, use the following steps, says Jun Mapili, PT, MAEd, rehabilitation therapies supervisor with Global Home Care in Troy, MI: Step 1: Identify the infection and select the appropriate code such as 998.59 (Other postoperative infection). Step 2: Code the causative organism --Staphylococcus aureus -- using one of the methicillin resistant codes such as 041.12 (Methicillin resistant Staphylococcus aureus). Step 3: Determine whether you will be providing antibiotics via a vascular catheter. If so, list V58.81 (Fitting and adjustment of vascular catheter). Step 4: List V58.62 (Long-term [current] use of antibiotics) if applicable. For patients with MSSA infections, he suggests: Step 1: Code the underlying infection, for example, 996.62 (Infection and inflammatory reaction due to other vascular device, implant, and graft). Step 2: Code the organism -- Staphylococcus aureus -- with the appropriate methicillin susceptible code such as 041.11 (Methicillin susceptible Staphy-lococcus aureus). Watch for: The fifth digit for MSSA codes is always "1", while MRSA codes end with "2" regardless of whether it's a combination code, Mapili says.