ICD-10 Code A31 – Infection due to other mycobacteria (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code A31 – Infection due to other mycobacteria
What it is
A31 identifies infections caused by mycobacteria other than the organisms that cause tuberculosis or leprosy. Use it when documentation names an “other mycobacterial” infection and no more specific code is available.
Clinical signs
Clinical features vary; refer to documentation. These infections may involve the lungs, lymph nodes, skin, or soft tissues, and the record should support the site and organism when known.
When to use this code
Use A31 when the provider documents infection due to nontuberculous or other mycobacteria without a more specific ICD-10-CM option. It is appropriate for confirmed infections, not mere exposure or colonization. If the note identifies a specific subtype or site, code that documentation instead.
Do not use for
Do not use A31 for tuberculosis, leprosy, or nonspecific bacterial infections. If the chart only says “mycobacterial disease” or the organism is unclear, check documentation before assigning the code.
Coding tip
Code the most specific mycobacterial diagnosis and site documented; if details are missing, query the provider.