2027 ICD-10-CM Diagnosis Code G00.9Bacterial meningitis, unspecified
ICD-10-CM Codes›G00–G99›G00-G09›G00
- Billable — Valid for Submission
- MCC — Major Complication or Comorbidity
- Not Chronic
G00.9 is a billable ICD-10-CM diagnosis code for bacterial meningitis, unspecified. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 23 through 24, 94 through 96, 791, 793. As a secondary diagnosis, it counts as a major complication or comorbidity (MCC) and places an inpatient stay in the highest severity level of its MS-DRG family. It does not count, however, when the principal diagnosis is one of 106 closely related codes. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Bacterial infections and Meningitis.
Code Identity
Code Classification
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
- Recurrent meningitis
- Recurrent meningitis caused by bacterium
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to G00.9: its own notes plus those printed at G00 and Chapter 6. A note printed at a category, block or chapter applies to every code under it.
Includes
Further defines, or gives examples of, the content of the category.
- bacterial arachnoiditis
- bacterial leptomeningitis
- bacterial meningitis
- bacterial pachymeningitis
Applicable To
Conditions this code is used for: synonyms of the title or, for "other specified" codes, the conditions assigned to it. The list is not exhaustive.
- Meningitis due to gram-negative bacteria, unspecified
- Purulent meningitis NOS
- Pyogenic meningitis NOS
- Suppurative meningitis NOS
Excludes1
Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.
Excludes2
Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.
- certain conditions originating in the perinatal period (P04-P96)
- certain infectious and parasitic diseases (A00-B99)
- complications of pregnancy, childbirth and the puerperium (O00-O9A)
- congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)
- endocrine, nutritional and metabolic diseases (E00-E88)
- injury, poisoning and certain other consequences of external causes (S00-T88)
- neoplasms (C00-D49)
- symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Referenced in Other NotesGuidance
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Meningitis (basal) (basic) (brain) (cerebral) (cervical) (congestive) (diffuse) (hemorrhagic) (infantile) (membranous) (metastatic) (nonspecific) (pontine) (progressive) (simple) (spinal) (subacute) (sympathetic) (toxic) G03.9
bacterial G00.9
gram-negative G00.9
fibrinopurulent G00.9
gram-negative cocci G00.9
gram-positive cocci G00.9
infectious G00.9
purulent G00.9
pyogenic G00.9
septic G00.9
suppurative G00.9
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Meningitis, Bacterial
bacterial infections of the leptomeninges and subarachnoid space, frequently involving the cerebral cortex, cranial nerves, cerebral blood vessels, spinal cord, and nerve roots.
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
Code HistoryHistory
Questions About G00.9Overview
What is the ICD-10 code for bacterial meningitis, unspecified?
The ICD-10-CM code for bacterial meningitis, unspecified is G00.9 (sometimes written as G009). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
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, 2026 through September 30, 2027.
What MS-DRG does G00.9 group to?
When bacterial meningitis, unspecified is the principal diagnosis on an inpatient stay, it groups to MS-DRG 793, 791, 24, 23, 96, 95, 94, with relative weights from 2.3173 to 5.7422 depending on complications. Higher weights mean higher Medicare reimbursement.
Is G00.9 a CC or MCC?
CMS lists G00.9 as an MCC (major complication or comorbidity) for FY 2027. Reported as a secondary diagnosis, it places the inpatient stay in the highest-weighted DRG of its severity family. It does not count when the principal diagnosis is one of the 106 closely related codes in its exclusion list.
Can G00.9 be reported with G04.2?
Not as a rule. The Excludes1 note at G00, which applies to G00.9, lists "bacterial meningoencephalitis (G04.2)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).
