2026 ICD-10-CM Diagnosis Code G00.9Bacterial meningitis, unspecified

ICD-10-CM Codes›G00–G99›G00-G09›G00

ICD-10-CM G00.9
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

G00.9 is a billable ICD-10-CM diagnosis code for bacterial meningitis, unspecified. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026). In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Bacterial infections and Meningitis.

Code Identity

ICD-10-CM Code
G00.9
Billable Status
Yes — Valid for Submission
Code Describes
Bacterial meningitis, unspecified
Short Description
Bacterial meningitis, unspecified
Same as the full description in the CMS dataset.
Parent Code
G00
Bacterial meningitis, not elsewhere classified

Code Classification

ChapterG00–G99Diseases of the nervous system
SectionG00-G09Inflammatory diseases of the central nervous system
CategoryG00Bacterial meningitis, not elsewhere classified
This CodeG00.9Bacterial meningitis, unspecified

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Acute meningitis
  • Acute purulent meningitis
  • Bacterial meningitis
  • Bacterial meningitis caused by Gram-negative bacteria
  • Epilepsy due to infectious disease of central nervous system
  • Epilepsy due to infectious meningitis
  • Hypertrophic pachymeningitis due to infection
  • Infective meningitis
  • Meningitis caused by gram-negative aerobic bacillus
  • Meningitis caused by gram-negative aerobic coccus
  • Meningitis following procedure
  • Pachymeningitis
  • Postoperative bacterial meningitis
  • Postoperative meningitis

Tabular List NotesGuidance

Coding notes and annotation back-references applicable to this code.

Inclusion Terms

  • Meningitis due to gram-negative bacteria, unspecified
  • Purulent meningitis NOS
  • Pyogenic meningitis NOS
  • Suppurative meningitis NOS

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Meningitis(basal) (basic) (brain) (cerebral) (cervical) (congestive) (diffuse) (hemorrhagic) (infantile) (membranous) (metastatic) (nonspecific) (pontine) (progressive) (simple) (spinal) (subacute) (sympathetic) (toxic)
      • bacterial
    • Meningitis(basal) (basic) (brain) (cerebral) (cervical) (congestive) (diffuse) (hemorrhagic) (infantile) (membranous) (metastatic) (nonspecific) (pontine) (progressive) (simple) (spinal) (subacute) (sympathetic) (toxic)
      • bacterial
        • gram-negative
    • Meningitis(basal) (basic) (brain) (cerebral) (cervical) (congestive) (diffuse) (hemorrhagic) (infantile) (membranous) (metastatic) (nonspecific) (pontine) (progressive) (simple) (spinal) (subacute) (sympathetic) (toxic)
      • fibrinopurulent
    • Meningitis(basal) (basic) (brain) (cerebral) (cervical) (congestive) (diffuse) (hemorrhagic) (infantile) (membranous) (metastatic) (nonspecific) (pontine) (progressive) (simple) (spinal) (subacute) (sympathetic) (toxic)
      • gram-negative cocci
    • Meningitis(basal) (basic) (brain) (cerebral) (cervical) (congestive) (diffuse) (hemorrhagic) (infantile) (membranous) (metastatic) (nonspecific) (pontine) (progressive) (simple) (spinal) (subacute) (sympathetic) (toxic)
      • gram-positive cocci
    • Meningitis(basal) (basic) (brain) (cerebral) (cervical) (congestive) (diffuse) (hemorrhagic) (infantile) (membranous) (metastatic) (nonspecific) (pontine) (progressive) (simple) (spinal) (subacute) (sympathetic) (toxic)
      • infectious
    • Meningitis(basal) (basic) (brain) (cerebral) (cervical) (congestive) (diffuse) (hemorrhagic) (infantile) (membranous) (metastatic) (nonspecific) (pontine) (progressive) (simple) (spinal) (subacute) (sympathetic) (toxic)
      • purulent
    • Meningitis(basal) (basic) (brain) (cerebral) (cervical) (congestive) (diffuse) (hemorrhagic) (infantile) (membranous) (metastatic) (nonspecific) (pontine) (progressive) (simple) (spinal) (subacute) (sympathetic) (toxic)
      • pyogenic
    • Meningitis(basal) (basic) (brain) (cerebral) (cervical) (congestive) (diffuse) (hemorrhagic) (infantile) (membranous) (metastatic) (nonspecific) (pontine) (progressive) (simple) (spinal) (subacute) (sympathetic) (toxic)
      • septic
    • Meningitis(basal) (basic) (brain) (cerebral) (cervical) (congestive) (diffuse) (hemorrhagic) (infantile) (membranous) (metastatic) (nonspecific) (pontine) (progressive) (simple) (spinal) (subacute) (sympathetic) (toxic)
      • suppurative

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR INF003
Bacterial infections
Default principal diagnosis: inpatient No · outpatient No
CCSR NVS001
Meningitis
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Bacterial Meningitis

    inflammation of the membranes surrounding the brain and spinal cord due to a bacterial infection.

Patient EducationClinical

Meningitis

Meningitis is inflammation of the thin tissue that surrounds the brain and spinal cord, called the meninges. There are several types of meningitis. The most common is viral meningitis. You get it when a virus enters the body through the nose or mouth and travels to the brain. Bacterial meningitis is rare but can be deadly.

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert G00.9 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
320.82 Mningts gram-neg bct NEC
Approximate The match is approximate rather than exact.
ICD-9-CM
320.9 Bacterial meningitis NOS
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About G00.9Overview

Is G00.9 (Bacterial meningitis, not elsewhere classified) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report bacterial meningitis, unspecified on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What is the ICD-9 equivalent of G00.9?

Under the General Equivalence Mappings, bacterial meningitis, unspecified converts to ICD-9-CM 320.82 (mningts gram-neg bct NEC) and 320.9 (bacterial meningitis NOS). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.