2027 ICD-10-CM Diagnosis Code A04.8Other specified bacterial intestinal infections

ICD-10-CM Codes›A00–B99›A00-A09›A04

ICD-10-CM A04.8
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

A04.8 is a billable ICD-10-CM diagnosis code for other specified bacterial intestinal infections. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 371 through 373. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 225 closely related codes. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Bacterial infections and Intestinal infection.

Code Identity

ICD-10-CM Code
A04.8
Billable Status
Yes — Valid for Submission
Code Describes
Other specified bacterial intestinal infections
Short Description
Other specified bacterial intestinal infections
Same as the full description in the CMS dataset.
Parent Code
A04
Other bacterial intestinal infections

Code Classification

ChapterA00–B99Certain infectious and parasitic diseases
SectionA00-A09Intestinal infectious diseases
CategoryA04Other bacterial intestinal infections
This CodeA04.8Other specified bacterial intestinal infections

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Bacterial infection caused by Morganella morganii
  • Bacterial infection caused by Proteus mirabilis
  • Chlamydial colitis
  • Chronic gastritis caused by Helicobacter heilmannii
  • Colitis caused by Brachyspira pilosicoli
  • Colitis caused by Chlamydia trachomatis
  • Colitis caused by Helicobacter
  • Colitis caused by Salmonella
  • Diarrhea caused by staphylococcus toxin
  • Enterobacterial enteritis of intestine
  • Enterobacterial enteritis of small intestine
  • Gastritis caused by Helicobacter
  • Gastroenteritis caused by Aeromonas
  • Gastroenteritis caused by Aeromonas hydrophila
  • Gastroenteritis caused by Aeromonas veronii
  • Gastrointestinal infection caused by Klebsiella aerogenes
  • Gastrointestinal infection caused by non-tuberculous Mycobacterium
  • Helicobacter heilmannii gastritis
  • Helicobacter pylori gastrointestinal tract infection
  • Infection caused by Enterobacter
  • Infection caused by Helicobacter pylori
  • Infection caused by Klebsiella aerogenes
  • Infection caused by Plesiomonas shigelloides
  • Infection of colon caused by Haemophilus ducreyi
  • Infection of colon caused by Spirochaetes
  • Infection of intestine caused by Vibrio
  • Intestinal Chlamydia trachomatis infection
  • Intestinal infection caused by Aeromonas hydrophila
  • Intestinal infection caused by Klebsiella aerogenes
  • Intestinal infection caused by Morganella morganii
  • Intestinal infection caused by Plesiomonas shigelloides
  • Intestinal infection caused by Proteus mirabilis
  • Intestinal infection caused by Pseudomonas
  • Intestinal infectious disease caused by anaerobic bacteria
  • Intestinal infectious disease caused by Gram-negative bacteria
  • Klebsiella oxytoca colitis
  • Methicillin resistant Staphylococcus aureus infection
  • Methicillin-resistant Staphylococcus aureus colitis
  • Methicillin-resistant Staphylococcus aureus enteritis of intestine
  • Methicillin-resistant Staphylococcus aureus enteritis of small intestine
  • Morganella infection
  • Morganella morganii gastrointestinal tract infection
  • Mycobacterial colitis
  • Mycobacterial enteritis of intestine
  • Mycobacterial enteritis of small intestine
  • Non-tuberculous mycobacterial colitis
  • Non-tuberculous mycobacterial enteritis of intestine
  • Non-tuberculous mycobacterial enteritis of small intestine
  • Proteus gastrointestinal tract infection
  • Proteus mirabilis gastrointestinal tract infection
  • Pseudomonas aeruginosa colitis
  • Pseudomonas gastrointestinal tract infection
  • Salmonella gastroenteritis
  • Staphylococcal enterocolitis
  • Staphylococcal gastroenteritis
  • Staphylococcal gastrointestinal tract infection

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to A04.8: its own notes plus those printed at A04 and Chapter 1. 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.

From Chapter 1 (A00-B99) Certain infectious and parasitic diseases applies to 1,068 codes
  • diseases generally recognized as communicable or transmissible

Excludes1

Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.

From A04 Other bacterial intestinal infections applies to 11 codes
  • bacterial foodborne intoxications, NEC (A05.-)
  • tuberculous enteritis (A18.32)

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.

From Chapter 1 (A00-B99) Certain infectious and parasitic diseases applies to 1,068 codes
  • carrier or suspected carrier of infectious disease (Z22.-)
  • certain localized infections - see body system-related chapters
  • infectious and parasitic diseases complicating pregnancy, childbirth and the puerperium (O98.-)
  • infectious and parasitic diseases specific to the perinatal period (P35-P39)
  • influenza and other acute respiratory infections (J00-J22)

Use Additional Code

Add a second code, after this one, to fully describe the condition.

From Chapter 1 (A00-B99) Certain infectious and parasitic diseases applies to 1,068 codes
  • code to identify resistance to antimicrobial drugs (Z16.-)

Source: CMS ICD-10-CM Tabular List. How to read instructional notes.

Referenced in Other NotesGuidance

Instructional notes printed at other codes that name A04.8, its category, or a range that includes it.

Excludes2 2

These codes carry an Excludes2 note naming A04.8: its condition is not part of those codes, and both may be reported when the patient has both.

  • Block P35-P39 Infections specific to the perinatal period
    intestinal infectious disease (A00-A09) names A00-A09, which includes this code
  • P37 Other congenital infectious and parasitic diseases
    infectious neonatal diarrhea (A00-A09) names A00-A09, which includes this code

Code First 1

These codes say to code first a condition named in the note, and A04.8 is one of the conditions named.

  • M49 Spondylopathies in diseases classified elsewhere
    enterobacterial infections (A01-A04) names A01-A04, which includes this code

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

Clinical ClassificationClinical

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

CCSR INF003
Bacterial infections
Default principal diagnosis: inpatient No · outpatient No
CCSR DIG001
Intestinal infection
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Bacterial Infections

Bacteria are tiny organisms (living things) that have only one cell. Under a microscope, they look like balls, rods, or spirals. They can be found almost everywhere on Earth. There are lots of bacteria in and on your body. In fact, your body has about 10 times more bacteria cells than human cells.

The full article covers:

  • What are bacteria?
  • How do bacterial infections spread?
  • What are the treatments for bacterial infections?
  • Can bacterial infections be prevented?

Read the full article at MedlinePlus

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

Convert A04.8 to ICD-9-CMHistory

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

ICD-9-CM
008.2 Aerobacter enteritis
Approximate The match is approximate rather than exact.
ICD-9-CM
008.41 Staphylococc enteritis
Approximate The match is approximate rather than exact.
ICD-9-CM
008.49 Bacterial enteritis NEC
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 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About A04.8Overview

What is the ICD-10 code for other specified bacterial intestinal infections?

The ICD-10-CM code for other specified bacterial intestinal infections is A04.8 (sometimes written as A048). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is A04.8 (Other bacterial intestinal infections) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report other specified bacterial intestinal infections on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What MS-DRG does A04.8 group to?

When other specified bacterial intestinal infections is the principal diagnosis on an inpatient stay, it groups to MS-DRG 372, 371, 373, with relative weights from 0.6945 to 1.7087 depending on complications. Higher weights mean higher Medicare reimbursement.

Is A04.8 a CC or MCC?

CMS lists A04.8 as a CC (complication or comorbidity) for FY 2027. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 225 closely related codes in its exclusion list.

Can A04.8 be reported with a code from A05?

Not as a rule. The Excludes1 note at A04, which applies to A04.8, lists "bacterial foodborne intoxications, NEC (A05.-)". 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).