ICD10BillableValid for clinical use
ICD-10 Code A31.9: Mycobacterial infection, unspecified
Reviewed by HealthAssure Clinical TeamUpdated 26 May 2026
What is this code?
ICD-10 codes are diagnosis classification codes used in healthcare records, reporting, coding workflows, and billing support. This code sits within the broader ICD-10 area for Certain infectious and parasitic diseases (A00-B99).
When is it used?
- May be used when a clinician documents mycobacterial infection, unspecified in a patient's medical record.
- May appear in hospital records, claims, referrals, and clinical documentation.
- This code can be used as a clinically usable diagnosis entry in standardized coding workflows.
What it does not mean
- A code alone does not explain severity, treatment plan, or outcome.
- A medical code should not be treated as a substitute for a doctor's diagnosis or advice.
Code hierarchy
chapter
1Certain infectious and parasitic diseases (A00-B99)
block
A30-A49Other bacterial diseases
category
A31Infection due to other mycobacteria
currentA31
Official coding notes
Inclusion terms
- Atypical mycobacterial infection NOS
- Mycobacteriosis NOS
Where you may see this code
You may see this code in hospital records, discharge summaries, insurance claims, encounter documentation, referrals, or other healthcare billing and coding records.
Related specialists
Infectious Disease SpecialistGeneral Physician
Related codes
Sibling codes
Mapped diagnoses and classifications
SNOMED_CT 111812000high
Atypical mycobacterial infection
Source: SNOMED International ICD-10 map
SNOMED_CT 430945004high
Infection caused by Mycobacterium resistant to multiple antimycobacterial agents
Source: SNOMED International ICD-10 map
SNOMED_CT 111811007high
Mycobacterial infection (excluding tuberculosis AND leprosy)
Source: SNOMED International ICD-10 map
SNOMED_CT 88415009high
Mycobacteriosis
Source: SNOMED International ICD-10 map
SNOMED_CT 1010255009high
Recurrent infection caused by Mycobacterium
Source: SNOMED International ICD-10 map
Coding guidelines
Compatibility
Legacy and official ICD code match exactly.
Legacy codes
A31.9
Common synonyms
Mycobacterial infection, unspecifiedMycobacterial infection
Frequently asked questions
About this content
This page is prepared by HealthAssure's clinical team using official coding standards from ICD-10. AI tools assist with drafting explanations, which are then reviewed and verified by healthcare professionals for accuracy. This content is for informational purposes and does not replace professional medical advice. Meet our team.