ICD10BillableValid for clinical use
ICD-10 Code A49.9: Bacterial infection, unspecified
Reviewed by HealthAssure Clinical TeamUpdated 26 May 2026
What is this code?
ICD-10 codes are diagnosis classification codes used in healthcare records, reporting, coding workflows, and billing support. This code sits within the broader ICD-10 area for Certain infectious and parasitic diseases (A00-B99).
đź“‹Clinical overview
This ICD-10 code is commonly used when documentation describes a bacterial infection without a clearly documented body site. The most accurate code depends on whether the chart identifies staphylococcal, streptococcal, Hemophilus influenzae, mycoplasma, other bacterial, or fully unspecified infection, and whether resistance detail such as MRSA versus MSSA is documented.
When is it used?
- May be used when a clinician documents bacterial infection, unspecified in a patient's medical record.
- May appear in hospital records, claims, referrals, and clinical documentation.
- This code can be used as a clinically usable diagnosis entry in standardized coding workflows.
What it does not mean
- A code alone does not explain severity, treatment plan, or outcome.
- A medical code should not be treated as a substitute for a doctor's diagnosis or advice.
đź©şClinical context
When commonly used
- Primary-care, urgent-care, emergency, inpatient, infectious-disease, and follow-up documentation where bacterial infection is part of the active assessment but the affected body site is not yet clearly documented on the page being reviewed.
- Coding and utilization-review workflows where organism detail or resistance detail changes final code specificity even before a more precise anatomic site is named elsewhere in the record.
Common management context
- Evaluation often includes symptom review, culture or molecular-test review, CBC or inflammatory-marker context, antibiotic-selection planning, and follow-up to clarify organism identity, resistance pattern, and the likely infectious source.
- Documentation usually becomes more specific when the chart identifies the organism more narrowly, distinguishes MRSA from MSSA, or names the affected body site rather than leaving it unspecified.
- Specialist context already linked on this page includes Infectious Disease Specialist, General Physician.
🔍Key distinctions
Important notes
- This ICD-10 family captures bacterial infections that remain unspecified by body site on the page, and it is distinct from more specific site-based infection coding because organism and resistance detail are doing most of the specificity work here.
- Named-organism detail matters across this branch, and MRSA-versus-MSSA detail is an additional specificity driver inside the staphylococcal subset.
- This title preserves fully unspecified bacterial-infection detail; if the chart identifies the organism or the affected body site more clearly, a more specific bacterial-infection code may be used.
- Documentation that describes bacterial infection is coded differently from viral, fungal, parasitic, or site-defined infectious conditions because organism and anatomic-site detail drive final code selection.
Important exclusions
- bacteremia NOS (R78.81)
Related codes to consider
A49.0Staphylococcal infection, unspecified site
Related bacterial-infection ICD-10 code; documentation often becomes more specific when the chart identifies the organism, distinguishes MRSA from MSSA, or names the affected body site.
A49.1Streptococcal infection, unspecified site
Related bacterial-infection ICD-10 code; documentation often becomes more specific when the chart identifies the organism, distinguishes MRSA from MSSA, or names the affected body site.
A49.2Hemophilus influenzae infection, unspecified site
Related bacterial-infection ICD-10 code; documentation often becomes more specific when the chart identifies the organism, distinguishes MRSA from MSSA, or names the affected body site.
A49.3Mycoplasma infection, unspecified site
Related bacterial-infection ICD-10 code; documentation often becomes more specific when the chart identifies the organism, distinguishes MRSA from MSSA, or names the affected body site.
Code hierarchy
chapter
1Certain infectious and parasitic diseases (A00-B99)
block
A30-A49Other bacterial diseases
category
A49Bacterial infection of unspecified site
currentA49
Official coding notes
Excludes1 (do not code together)
- bacteremia NOS (R78.81)
Where you may see this code
You may see this code in hospital records, discharge summaries, insurance claims, encounter documentation, referrals, or other healthcare billing and coding records.
Related specialists
Infectious Disease SpecialistGeneral Physician
Related codes
Sibling codes
Mapped diagnoses and classifications
SNOMED_CT 700220003high
Acute bacterial otitis externa
Source: SNOMED International ICD-10 map
SNOMED_CT 1258958003high
Acute bacterial simple cystitis
Source: SNOMED International ICD-10 map
SNOMED_CT 111212009high
Arthropathy associated with bacterial disease
Source: SNOMED International ICD-10 map
SNOMED_CT 5758002high
Bacteremia
Source: SNOMED International ICD-10 map
SNOMED_CT 1176998005high
Bacteremic skin rash
Source: SNOMED International ICD-10 map
SNOMED_CT 128944008high
Bacterial infection caused by Bacillus
Source: SNOMED International ICD-10 map
Coding guidelines
Compatibility
Legacy and official ICD code match exactly.
Legacy codes
A49.9
Common synonyms
Bacterial infection, unspecifiedBacterial infection
Frequently asked questions
About this content
This page is prepared by HealthAssure's clinical team using official coding standards from ICD-10. AI tools assist with drafting explanations, which are then reviewed and verified by healthcare professionals for accuracy. This content is for informational purposes and does not replace professional medical advice. Meet our team.