ICD-10-CM 2027
ICD-10 code for MSSA colonization
Carrier or suspected carrier of Methicillin susceptible Staphylococcus aureus
From the official ICD-10-CM alphabetic index entry “Colonization › MSSA (Methicillin susceptible Staphylococcus aureus)”. Page updated September 29, 2026.
About coding MSSA colonization
The ICD-10-CM code for MSSA colonization is Z22.321 (Carrier or suspected carrier of Methicillin susceptible Staphylococcus aureus).
Within Z22.32 (carrier of bacterial disease due to staphylococci), Z22.321 is specifically for carrier or suspected carrier of Methicillin susceptible Staphylococcus aureus. Related codes cover resistant Staphylococcus aureus (Z22.322).
It is not a CC or MCC, so as a secondary diagnosis it doesn't change the MS-DRG severity level.
In MS-DRG v44.0, it is part of the grouping logic for DRG 951 (Other Factors Influencing Health Status, relative weight 0.5577), in MDC 23 (Factors Influencing Health Status and Other Contacts with Health Services), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.
Common questions about MSSA colonization ICD-10 codes
What is the ICD-10 code for MSSA colonization?
- Z22.321 — Carrier or suspected carrier of Methicillin susceptible Staphylococcus aureus.
Is Z22.321 billable?
- Yes. Z22.321 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can Z22.321 be used as a principal diagnosis?
- No. It is not acceptable as the principal diagnosis for an inpatient stay; it may be reported as a secondary diagnosis.
Is Z22.321 a CC or MCC?
- No. Z22.321 is neither a CC nor an MCC under MS-DRG v44.0.