Pneumonia due to methicillin suscep staph

This code identifies pneumonia caused by Staphylococcus aureus that is sensitive to methicillin. It indicates a bacterial lung infection where the causative organism has not developed resistance to methicillin-class antibiotics.

Apply this code when documentation confirms pneumonia and laboratory culture results specifically identify Methicillin-susceptible Staphylococcus aureus (MSSA) as the etiologic agent. This is typically supported by microbiology reports showing susceptibility to oxacillin or cefoxitin.

• Ensure documentation explicitly states "methicillin-susceptible" or "MSSA" for Staphylococcus aureus pneumonia.
• Do not use this code if the Staphylococcus aureus is documented as methicillin-resistant (MRSA); a different code applies for MRSA pneumonia.
• Always sequence this code as the primary diagnosis when the pneumonia is the reason for the encounter, unless another condition is clearly identified as the principal diagnosis.