ICD-10-CM Code A31.9

Mycobacterial infection, unspecified

Version 2020 Billable Code

Valid for Submission

A31.9 is a billable code used to specify a medical diagnosis of mycobacterial infection, unspecified. The code is valid for the year 2020 for the submission of HIPAA-covered transactions. The ICD-10-CM code A31.9 might also be used to specify conditions or terms like acid-fast bacteria present, atypical mycobacterial infection, atypical mycobacterial infection of hand, disseminated atypical infection caused by mycobacterium co-occurrent with human immunodeficiency virus infection, disseminated atypical mycobacterial infection, disseminated mycobacteriosis, etc

Short Description:Mycobacterial infection, unspecified
Long Description:Mycobacterial infection, unspecified

Tabular List of Diseases and Injuries

The Tabular List of Diseases and Injuries is a list of ICD-10 codes, organized "head to toe" into chapters and sections with guidance for inclusions, exclusions, descriptions and more. The following references are applicable to the code A31.9:

Inclusion Terms

Inclusion Terms
These terms are the conditions for which that code is to be used. The terms may be synonyms of the code title, or, in the case of "other specified" codes, the terms are a list of the various conditions assigned to that code. The inclusion terms are not necessarily exhaustive. Additional terms found only in the Alphabetic Index may also be assigned to a code.
  • Atypical mycobacterial infection NOS
  • Mycobacteriosis NOS

Index to Diseases and Injuries

The Index to Diseases and Injuries is an alphabetical listing of medical terms, with each term mapped to one or more ICD-10 code(s). The following references for the code A31.9 are found in the index:


The following clinical terms are approximate synonyms or lay terms that might be used to identify the correct diagnosis code:

  • Acid-fast bacteria present
  • Atypical mycobacterial infection
  • Atypical mycobacterial infection of hand
  • Disseminated atypical infection caused by Mycobacterium co-occurrent with human immunodeficiency virus infection
  • Disseminated atypical mycobacterial infection
  • Disseminated mycobacteriosis
  • Infection due to mycobacteria resistant to multiple antimycobacterial agents
  • Infection due to Mycobacteroides abscessus
  • Mycobacterial infection
  • Mycobacterial infection of the central nervous system
  • Mycobacteriosis
  • Mycobacteriosis associated with AIDS
  • Skin and soft tissue atypical mycobacterial infection

Diagnostic Related Groups

The ICD-10 code A31.9 is grouped in the following groups for version MS-DRG V37.0 What are Diagnostic Related Groups?
The Diagnostic Related Groups (DRGs) are a patient classification scheme which provides a means of relating the type of patients a hospital treats. The DRGs divides all possible principal diagnoses into mutually exclusive principal diagnosis areas referred to as Major Diagnostic Categories (MDC).
applicable from 10/01/2020 through 09/30/2020.


Convert A31.9 to ICD-9

  • 031.9 - Mycobacterial dis NOS

Code Classification

  • Certain infectious and parasitic diseases (A00–B99)
    • Other bacterial diseases (A30-A49)
      • Infection due to other mycobacteria (A31)

Code History

  • FY 2016 - New Code, effective from 10/1/2015 through 9/30/2016
    (First year ICD-10-CM implemented into the HIPAA code set)
  • FY 2017 - No Change, effective from 10/1/2016 through 9/30/2017
  • FY 2018 - No Change, effective from 10/1/2017 through 9/30/2018
  • FY 2019 - No Change, effective from 10/1/2018 through 9/30/2019
  • FY 2020 - No Change, effective from 10/1/2019 through 9/30/2020

Information for Patients

Mycobacterial Infections

Mycobacteria are a type of germ. There are many different kinds. The most common one causes tuberculosis. Another one causes leprosy. Still others cause infections that are called atypical mycobacterial infections. They aren't "typical" because they don't cause tuberculosis. But they can still harm people, especially people with other problems that affect their immunity, such as AIDS.

Sometimes you can have these infections with no symptoms at all. At other times, they can cause lung symptoms similar to tuberculosis:

  • Cough
  • Weight loss
  • Coughing up blood or mucus
  • Weakness or fatigue
  • Fever and chills
  • Night sweats
  • Lack of appetite and weight loss

Medicines can treat these infections, but often more than one is needed to cure the infection.

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