A41.59
BillableOther Gram-negative sepsis
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is A41.59 an HCC code?
Yes. A41.59 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 A41.59
For A41.59to 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 A41.59 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
A41.59 is the ICD-10-CM diagnosis code for other gram-negative sepsis. This code describes a serious bloodstream infection caused by gram-negative bacteria (bacteria that don't retain certain dyes when tested) other than those specified by more specific codes. This is a life-threatening condition where bacteria have entered the bloodstream and are causing systemic inflammation throughout the body. A41.59 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, A41.59 maps to Septicemia, Sepsis, Systemic Inflammatory Response Syndrome/Shock (HCC 2) with a community, non-dual, aged base RAF weight of 0.500. Under the older V24 model, A41.59 mapped to the same category but with a base RAF weight of 0.352 — V28 recalibrated weights across the entire model. 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.
Use this code only when the gram-negative organism is not E. coli (A41.51), Pseudomonas (A41.52), or other specifically coded gram-negative bacteria; always verify the organism identified in culture results before coding. Because A41.59 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 A41.59 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Use this code only when the gram-negative organism is not E. coli (A41.51), Pseudomonas (A41.52), or other specifically coded gram-negative bacteria; always verify the organism identified in culture results before coding
- •Sepsis codes require documentation of the infection source and severity (uncomplicated vs. with septic shock); ensure the physician documentation clearly states 'sepsis' and link to the underlying infection site when applicable
Clinical Significance
Other gram-negative sepsis captures bloodstream infections caused by gram-negative organisms not classified elsewhere, including Klebsiella, Enterobacter, Proteus, Citrobacter, Stenotrophomonas, and other less common gram-negative bacteria. These organisms are increasingly associated with multidrug resistance, particularly carbapenem-resistant Enterobacteriaceae (CRE).
Documentation Requirements
- ✓Blood cultures identifying a specific gram-negative organism that does not have its own ICD-10 sepsis code
- ✓Sepsis criteria with organ dysfunction documentation
- ✓Source of infection identified and coded separately
- ✓Antibiotic susceptibility results, particularly for resistance patterns (ESBL, CRE)
- ✓Species-level identification documented from microbiology
Commonly Confused Codes
- •A41.51 (E. coli), A41.52 (Pseudomonas), A41.53 (Serratia), A41.54 (Acinetobacter) — Use organism-specific codes when available; A41.59 is for gram-negative organisms without their own code
- •A41.50 (Gram-negative sepsis, unspecified) — A41.59 identifies a specific organism (just not one with its own code); A41.50 is when no organism is specified
- •A41.89 (Other specified sepsis) — A41.59 is specifically for gram-negative organisms; A41.89 is for other organisms (fungi, etc.)