2027 ICD-10-CM Diagnosis Code A42.7Actinomycotic sepsis
ICD-10-CM Codes›A00–B99›A30-A49›A42
- Billable — Valid for Submission
- MCC — Major Complication or Comorbidity
- Risk Adjusts — HCC 2
- Not Chronic
A42.7 is a billable ICD-10-CM diagnosis code for actinomycotic sepsis. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 791, 793, 870 through 872, 974 through 976. As a secondary diagnosis, it counts as a major complication or comorbidity (MCC) and places an inpatient stay in the highest severity level of its MS-DRG family. It does not count, however, when the principal diagnosis is one of 46 closely related codes. Coders also document this condition as sepsis caused by Actinomyces. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Bacterial infections and Septicemia.
For Medicare Advantage risk adjustment, A42.7 maps to CMS-HCC Category 2 (Septicemia, Sepsis, Systemic Inflammatory Response Syndrome/Shock) under the V28 model, adding a risk factor of about 0.500 for a community, non-dual, aged beneficiary in payment year 2027.
Code Identity
Code Classification
Medicare Risk Adjustment (HCC)Billing
A42.7 maps to a payment category in the CMS-HCC model used to risk-adjust Medicare Advantage payments. Weights are the published community factors for payment year 2027.
Source: CMS Payment Year 2027 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Sepsis caused by Actinomyces
- Sepsis caused by anaerobic bacteria
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to A42.7: its own notes plus those printed at A42 and Chapter 1. A note printed at a category, block or chapter applies to every code under it.
Includes
Further defines, or gives examples of, the content of the category.
- diseases generally recognized as communicable or transmissible
Excludes1
Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.
Excludes2
Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.
- carrier or suspected carrier of infectious disease (Z22.-)
- certain localized infections - see body system-related chapters
- infectious and parasitic diseases complicating pregnancy, childbirth and the puerperium (O98.-)
- infectious and parasitic diseases specific to the perinatal period (P35-P39)
- influenza and other acute respiratory infections (J00-J22)
Use Additional Code
Add a second code, after this one, to fully describe the condition.
- code to identify resistance to antimicrobial drugs (Z16.-)
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Referenced in Other NotesGuidance
Instructional notes printed at other codes that name A42.7, its category, or a range that includes it.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Actinomycosis
infections with bacteria of the genus actinomyces.
Patient EducationClinical
Bacterial Infections
Bacteria are tiny organisms (living things) that have only one cell. Under a microscope, they look like balls, rods, or spirals. They can be found almost everywhere on Earth. There are lots of bacteria in and on your body. In fact, your body has about 10 times more bacteria cells than human cells.
The full article covers:
- What are bacteria?
- How do bacterial infections spread?
- What are the treatments for bacterial infections?
- Can bacterial infections be prevented?
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert A42.7 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About A42.7Overview
What is the ICD-10 code for actinomycotic sepsis?
The ICD-10-CM code for actinomycotic sepsis is A42.7 (sometimes written as A427). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is A42.7 (Actinomycosis) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report actinomycotic sepsis on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does A42.7 group to?
When actinomycotic sepsis is the principal diagnosis on an inpatient stay, it groups to MS-DRG 793, 791, 974, 976, 872, 975, 871, 870, with relative weights from 0.7879 to 6.9432 depending on complications. Higher weights mean higher Medicare reimbursement.
Is A42.7 a CC or MCC?
CMS lists A42.7 as an MCC (major complication or comorbidity) for FY 2027. Reported as a secondary diagnosis, it places the inpatient stay in the highest-weighted DRG of its severity family. It does not count when the principal diagnosis is one of the 46 closely related codes in its exclusion list.
Can A42.7 be reported with B47.1?
Not as a rule. The Excludes1 note at A42, which applies to A42.7, lists "actinomycetoma (B47.1)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).
What HCC is A42.7?
A42.7 (actinomycotic sepsis) maps to CMS-HCC Category 2 (Septicemia, Sepsis, Systemic Inflammatory Response Syndrome/Shock), commonly written as HCC 2, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2027. It mapped to HCC 2 under the retired V24 model. It also maps in the PACE (CMS-HCC V22), ESRD (V21), and ESRD (V24) models. It does not map to any RxHCC in the Part D prescription drug model.
Does A42.7 risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, A42.7 adds a risk adjustment factor of about 0.500 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 0.447 to 0.780 depending on the payment segment). HCC 2 sits at the top of its hierarchy, so no other condition category supersedes it. See the full factor table on the HCC 2 category page.
