2027 ICD-10-CM Diagnosis Code A49.9Bacterial infection, unspecified
ICD-10-CM Codes›A00–B99›A30-A49›A49
- Billable — Valid for Submission
- Not Chronic
A49.9 is a billable ICD-10-CM diagnosis code for bacterial infection, unspecified. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 867 through 869. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Bacterial infections.
Code Identity
Code Classification
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Abscess of aortic valve
- Abscess of mitral valve
- Abscess of pulmonary valve
- Acne with gram negative folliculitis
- Acute bacterial otitis externa
- Acute bacterial tubulointerstitial nephritis
- Acute infectious tubulointerstitial nephritis
- Acute infective otitis externa
- Acute pyelonephritis
- Acute pyelonephritis caused by bacterium
- Acute tubulointerstitial nephritis
- Angular cheilitis
- Angular cheilitis due to bacterial infection
- Autoinflammatory syndrome with pyogenic bacterial infection and amylopectinosis
- Autoinflammatory syndrome with pyogenic bacterial infection and amylopectinosis due to HOIP deficiency
- Bacterial abscess of aortic valve
- Bacterial abscess of mitral valve
- Bacterial abscess of pulmonary valve
- Bacterial cellulitis
- Bacterial corneal ulcer
- Bacterial encephalitis
- Bacterial endophthalmitis
- Bacterial esophagitis
- Bacterial folliculitis
- Bacterial genital infection
- Bacterial infection associated with peritoneal dialysis catheter
- Bacterial infection due to human immunodeficiency virus infection
- Bacterial infection of central nervous system
- Bacterial infection of skin
- Bacterial infectious disease
- Bacterial musculoskeletal infection
- Bacterial nephritis
- Bacterial oral infection
- Bacterial osteomyelitis
- Bacterial otitis externa
- Bacterial otitis media
- Bacterial respiratory infection
- Bacterial sinusitis
- Bacterial tenosynovitis
- Bacterial tonsillitis
- Bacterial upper respiratory infection
- Bacterial urogenital infection
- Beta lactam resistant bacterial infection
- Botryomycosis
- Cutaneous reaction caused by bacterial toxin
- Disease caused by Gram-negative bacteria
- Erythema nodosum due to bacterial infection
- Gram-negative bacterial cellulitis
- Gram-negative folliculitis
- Herpes zoster with secondary bacterial infection
- Infection associated with peritoneal dialysis catheter
- Infection caused by aminoglycoside resistant bacteria
- Infection caused by anaerobic bacteria
- Infection caused by antimicrobial resistant bacteria
- Infection caused by carbapenem resistant bacteria
- Infection caused by multi drug resistant bacteria
- Infection caused by quinolone and fluoroquinolone resistant bacteria
- Invasive bacterial infectious disease
- Moderate cavitated lesion limited to outer half of dentin
- Neonatal hyperbilirubinemia due to bacterial infection
- Neuropathy caused by bacterial toxin
- Non-pyogenic bacterial infection of skin
- Peripheral neuropathy caused by toxin
- Pleural effusion caused by bacteria
- Pyogenic bacterial infection due to MyD88 deficiency
- Recurrent bacterial infection
- Recurrent infection caused by Gram-negative bacteria
- Recurrent systemic infection caused by pyogenic bacteria
- Superficial bacterial infection of skin
- Toxic polyneuropathy
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to A49.9: its own notes plus those printed at A49 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.
- 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.
- bacteremia NOS (R78.81)
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.
- 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.
- code to identify resistance to antimicrobial drugs (Z16.-)
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Arthritis, arthritic (acute) (chronic) (nonpyogenic) (subacute) M19.90
bacterial disease See Also: subcategory M01; A49.9
Disease, diseased See Also: Syndrome;
bacterial A49.9
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Bacterial Infections
infections by bacteria, general or unspecified.
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 A49.9 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About A49.9Overview
What is the ICD-10 code for bacterial infection, unspecified?
The ICD-10-CM code for bacterial infection, unspecified is A49.9 (sometimes written as A499). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is A49.9 (Bacterial infection of unspecified site) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report bacterial infection, unspecified on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does A49.9 group to?
When bacterial infection, unspecified is the principal diagnosis on an inpatient stay, it groups to MS-DRG 867, 869, 868, with relative weights from 0.6784 to 2.1855 depending on complications. Higher weights mean higher Medicare reimbursement.
Can A49.9 be reported with R78.81?
Not as a rule. The Excludes1 note on A49.9 lists "bacteremia NOS (R78.81)". 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).
What is the ICD-9 equivalent of A49.9?
Under the General Equivalence Mappings, bacterial infection, unspecified converts to ICD-9-CM 041.9 (bacterial infection NOS). The mapping is approximate, so confirm the match fits the documentation.
