What is ICD-10 code A42.7?

A42.7 is the ICD-10-CM diagnosis code for Actinomycotic sepsis. It belongs to the ICD-10-CM chapter for certain infectious and parasitic diseases (a00-b99). A42.7 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. A42.7 is part of the FY2026 ICD-10-CM code set published by the CMS National Center for Health Statistics and used on Medicare, Medicaid, and commercial claims in the United States.

Yes. A42.7 is a billable ICD-10-CM code that can be reported on professional and institutional claims as a primary or secondary diagnosis when the provider documentation supports the specific condition described. Billable codes in ICD-10-CM are coded to the highest level of specificity available for the documented diagnosis. A42.7 is current for fiscal year 2026 and remains in the active CMS ICD-10-CM code set published by the National Center for Health Statistics.

Which HCC does A42.7 map to under V28?

A42.7 maps to CMS-HCC V28 HCC 2 (Septicemia, Sepsis, Systemic Inflammatory Response Syndrome/Shock). The category numbers, labels, and conditions come from the CMS-HCC V28 model file for payment year 2026.

2026 ICD-10-CM A42.7: Actinomycotic sepsis

A42.7 maps to CMS-HCC V28 2. A source-labeled RAF reference is available. Confirm the documented diagnosis and applicable coding requirements. MEAT criteria · RAF Calculator · HCC coding software

ICD-10-CM Code View

HCC Buddy Code Card

Digital ICD-10 code-book layout with official code detail, always-visible risk models, Code Trumping, and Buddy coding guidance.

Code lookupA42.7

Effective periodFY2026 Apr Update (Apr 1-Sep 30)

FY 2026 Apr update / Certain infectious and parasitic diseases (A00-B99) / Other bacterial diseases (A30-A49)

A42.7

Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidance

Actinomycotic sepsis

A serious bloodstream infection caused by Actinomyces bacteria, a type of organism that normally lives in the mouth and can cause severe infection if it spreads throughout the body. This is a life-threatening condition requiring immediate medical treatment with antibiotics.

Buddy Insight

Actinomycotic sepsis is a rare but severe bloodstream infection caused by Actinomyces species, indicating advanced disseminated disease.

Overview Risk Models Code Book Documentation Audit Notes Edition comparison

CMS-HCC V28

Mapped

HCC 2

Septicemia, Sepsis, Systemic ...

Code-level coefficient reference

CMS-HCC V24

Historical

Not used for standard CY2026 Medicare Advantage payment. Select a historical period to review V24.

Not used for CY2026 payment

ACA/HHS

Mapped

HCC 002

HHS-HCC 002 adult, RAF varies...

Code-level coefficient reference

ESRD/PACE

Mapped

HCC 2

Septicemia/Sepsis/Systemic In...

Code-level coefficient reference

RXHCC

N/A

—

Not risk-adjusted for this model/period.

Not mapped

Code Book Path

Official

A42Actinomycosis A42.7Actinomycotic sepsis

Inclusion Terms

Official

No inclusion terms are included in this display for A42.7. Check the code and parent instructions in the Code Book.

Excludes 2

Official

carrier or suspected carrier of infectious disease (Z22.-)Inherited from A00-B99
infectious and parasitic diseases complicating pregnancy, childbirth and the puerperium (O98.-)Inherited from A00-B99
infectious and parasitic diseases specific to the perinatal period (P35-P39)Inherited from A00-B99
influenza and other acute respiratory infections (J00-J22)Inherited from A00-B99

Related Codes

Official

A42.0Pulmonary actinomycosis A42.1Abdominal actinomycosis A42.2Cervicofacial actinomycosis A42.8Other forms of actinomycosis A42.9Actinomycosis, unspecified

Includes

Official

diseases generally recognized as communicable or transmissibleInherited from A00-B99

Excludes 1

Official

certain localized infections - see body system-related chaptersInherited from A00-B99, A42
actinomycetoma (B47.1)Inherited from A00-B99, A42

Code First

Official

No Code First sequencing instructions are included in this display for A42.7. Check the code and parent instructions in the Code Book.

Use Additional

Official

code to identify resistance to antimicrobial drugs (Z16.-)Inherited from A00-B99

Code Also

Official

No Code Also instructions are included in this display for A42.7. Check the code and parent instructions in the Code Book.

Buddy Documentation Tip

HCC Buddy guidance

Blood cultures positive for Actinomyces species (note: requires prolonged incubation of anaerobic bottles)

Clinical documentation of sepsis with systemic inflammatory response

Source of dissemination identified (cervicofacial, thoracic, abdominopelvic, or IUD-associated pelvic actinomycosis)

Organ dysfunction and severity assessment

MEAT Support

HCC Buddy guidance

Blood cultures positive for Actinomyces species (note: requires prolonged incubation of anaerobic bottles)

Clinical documentation of sepsis with systemic inflammatory response

Source of dissemination identified (cervicofacial, thoracic, abdominopelvic, or IUD-associated pelvic actinomycosis)

Organ dysfunction and severity assessment

Audit Caution

HCC Buddy guidance

Actinomyces blood cultures require extended incubation (14+ days) and anaerobic conditions — negative routine cultures do not exclude the diagnosis

IUD-associated pelvic actinomycosis can rarely lead to sepsis — document the IUD as the source when applicable

Do not confuse actinomycotic sepsis with other anaerobic sepsis — A42.7 is the specific code for Actinomyces

Always add R65.20/R65.21 for severe sepsis or septic shock

Common Mistakes

HCC Buddy guidance

A41.4 (Sepsis due to anaerobes) — A41.4 is for other anaerobic sepsis; A42.7 is specifically for Actinomyces-caused sepsis

A41.9 (Sepsis, unspecified) — Use A42.7 when Actinomyces is identified as the causative organism

A42.0 (Pulmonary actinomycosis) — A42.0 is localized lung disease; A42.7 is systemic bloodstream infection — code both if applicable

Current with CMS: FY2026 ICD-10-CM Apr 1 update (effective Apr 1 – Sep 30, 2026) · CMS-HCC V28, 100% phased in for payment year 2026. FY2027 code set already staged for October 1, 2026. How HCC Buddy stays current →

Is A42.7 an HCC code?

Yes. A42.7 (Actinomycotic sepsis) maps to HCC 2, Septicemia, Sepsis, Systemic Inflammatory Response Syndrome/Shock under the CMS-HCC V28 risk adjustment model, with a source-labeled community non-dual aged reference coefficient of 0.500. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes. It is billable for payment year 2026.

Coder answer: A42.7 is billable and maps to V28 HCC 2, Septicemia, Sepsis, Systemic Inflammatory Response Syndrome/Shock. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.

Code: A42.7
Description: Actinomycotic sepsis
HCC (V28): HCC 2 — Septicemia, Sepsis, Systemic Inflammatory Response Syndrome/Shock
RAF reference coefficient: 0.500
Billable: Yes
Payment year: 2026

HCC Category Mapping

V28HCC 2, Septicemia, Sepsis, Systemic Inflammatory Response Syndrome/Shock

0.500

ESRDHCC 2, Septicemia/Sepsis/Systemic Inflammatory Response Syndrome/Shock

Not separately weighted

These are source-labeled model coefficients, not member totals. A category may still be removed by hierarchy or model cleanup rules. Weights are not directly comparable across models: CMS-HCC V28 and V24 use Community, Non-Dual, Aged; ESRD uses the dialysis continuing-enrollee model; RxHCC is the Part D continuing-enrollee, non-low-income, aged weight (a larger scale than CMS-HCC). ACA/HHS has no single weight — it varies by metal level. Actual per-patient RAF contribution depends on member context, hierarchy and cleanup rules, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains available for historical review.

Work A42.7 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →

MEAT review for A42.7

For A42.7, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule.

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

Coder workflow notes

Get the V28 mapping + MEAT cheat sheet

One printable reference: check representative V28 mappings and the documentation reminders your note needs. Free, no card.

Free PDF. No card. Unsubscribe anytime.

What This Code Means

A42.7 is the ICD-10-CM diagnosis code for actinomycotic sepsis. A serious bloodstream infection caused by Actinomyces bacteria, a type of organism that normally lives in the mouth and can cause severe infection if it spreads throughout the body. This is a life-threatening condition requiring immediate medical treatment with antibiotics. A42.7 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, A42.7 maps to Septicemia, Sepsis, Systemic Inflammatory Response Syndrome/Shock (HCC 2) with a source-labeled community, non-dual, aged reference coefficient of 0.500. No V24 mapping is shown for A42.7; use the applicable model and payment year when reviewing the V28 mapping. For CY2026 non-PACE Medicare Advantage, CMS uses 100% of the 2024 CMS-HCC model (V28). PACE uses a separate model blend. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes.

Verify that sepsis is documented in the medical record along with the actinomycotic infection; sepsis requires specific documentation to support this code. For A42.7, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule. 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, source-labeled coefficient references, and MEAT documentation criteria for A42.7 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•Verify that sepsis is documented in the medical record along with the actinomycotic infection; sepsis requires specific documentation to support this code
•Check for any associated conditions or complications (such as abscesses, endocarditis, or organ involvement) that may require additional codes

Clinical Significance

Actinomycotic sepsis is a rare but severe bloodstream infection caused by Actinomyces species, indicating advanced disseminated disease. Actinomyces species are fastidious anaerobes that may be missed on routine blood cultures if anaerobic cultures are not held for sufficient time (typically requires 14+ days of incubation).

Documentation Requirements

✓Blood cultures positive for Actinomyces species (note: requires prolonged incubation of anaerobic bottles)
✓Clinical documentation of sepsis with systemic inflammatory response
✓Source of dissemination identified (cervicofacial, thoracic, abdominopelvic, or IUD-associated pelvic actinomycosis)
✓Organ dysfunction and severity assessment
✓Prolonged antibiotic treatment plan (IV penicillin transitioning to oral, 6-12 months total)

Commonly Confused Codes

•A41.4 (Sepsis due to anaerobes): A41.4 is for other anaerobic sepsis; A42.7 is specifically for Actinomyces-caused sepsis
•A41.9 (Sepsis, unspecified): Use A42.7 when Actinomyces is identified as the causative organism
•A42.0 (Pulmonary actinomycosis): A42.0 is localized lung disease; A42.7 is systemic bloodstream infection: code both if applicable