A41.01
BillableSepsis due to Methicillin susceptible Staphylococcus aureus
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is A41.01 an HCC code?
Yes. A41.01 maps to Septicemia, Sepsis, Systemic Inflammatory Response Syndrome/Shock under the CMS-HCC V28 risk adjustment model (and Septicemia, Sepsis, Systemic Inflammatory Response Syndrome/Shock under V24).
HCC Category Mapping
RAF weights shown are the community, non-dual, aged base weights from the CMS risk adjustment model file. Actual per-patient RAF contribution depends on member segment, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains in use during the transition and for historical data.
MEAT Criteria for A41.01
For A41.01 to count as a valid HCC diagnosis in a given encounter, the provider's documentation must show MEAT: Monitor, Evaluate, Assess, or Treat. A diagnosis from a prior year does not carry forward automatically — it has to be re-documented and supported each calendar year.
- MMonitor: signs, symptoms, disease progression, or lab trending documented in the note
- EEvaluate: test results, medication response, or physical findings reviewed by the provider
- AAssess: explicit mention in the assessment or plan with acknowledgment of status
- TTreat: medication, referral, procedure, therapy, or counseling tied to the diagnosis
Only one of M/E/A/T is required to support the code, but the documentation must be specific enough to show that the provider actually addressed A41.01 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
A41.01 is the ICD-10-CM diagnosis code for sepsis due to methicillin susceptible staphylococcus aureus. This is a serious bloodstream infection caused by a common bacteria called Staphylococcus aureus that responds to the antibiotic methicillin. The infection has spread throughout the body and triggered a severe inflammatory response that can affect multiple organs. A41.01 sits in the ICD-10-CM chapter for certain infectious and parasitic diseases (a00-b99), within the section covering other bacterial diseases (a30-a49).
Under the CMS-HCC V28 risk adjustment model, A41.01 maps to Septicemia, Sepsis, Systemic Inflammatory Response Syndrome/Shock (HCC 2) with a community, non-dual, aged base RAF weight of 0.455. The V24 model used during the PY2024–PY2025 transition mapped A41.01 the same way and at the same RAF weight. V28 is the CMS-HCC risk adjustment model that reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition.
Ensure documentation specifies that the S. aureus is methicillin-susceptible (not resistant) to assign this code correctly, as methicillin-resistant strains use different codes (A41.02). Because A41.01 maps to a payment HCC, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's Medicare Advantage risk adjustment score. When documentation is ambiguous, coders should issue a provider query rather than assume the highest-specificity variant.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for A41.01 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Ensure documentation specifies that the S. aureus is methicillin-susceptible (not resistant) to assign this code correctly, as methicillin-resistant strains use different codes (A41.02)
- •This code requires a secondary code to identify the source/site of infection (e.g., skin, urinary tract, wound) when documented, and may require additional codes for organ dysfunction if septic shock is present
Clinical Significance
Sepsis due to methicillin-susceptible Staphylococcus aureus (MSSA) is a common and serious bloodstream infection with significant morbidity and mortality. MSSA sepsis carries a risk of metastatic complications including endocarditis, osteomyelitis, and deep-seated abscesses. The methicillin susceptibility designation is clinically important as it determines antibiotic therapy (nafcillin/oxacillin preferred over vancomycin).
Documentation Requirements
- ✓Blood cultures positive for Staphylococcus aureus with susceptibility testing showing methicillin susceptibility
- ✓Documentation explicitly stating MSSA (not just S. aureus without susceptibility information)
- ✓Sepsis criteria met with identified source when possible
- ✓Echocardiogram results to evaluate for endocarditis (recommended for all S. aureus bacteremia)
- ✓Follow-up blood cultures to document clearance (standard of care for S. aureus bacteremia)