2026 ICD-10-CM Diagnosis Code Z16.12Extended spectrum beta lactamase (ESBL) resistance
Z16.12 is a billable ICD-10-CM diagnosis code for extended spectrum beta lactamase (ESBL) resistance. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 867 through 869. The code is not accepted as a principal diagnosis by the Medicare Code Editor. Coders also document this condition as bacterial infection caused by Proteus mirabilis. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Resistance to antimicrobial drugs.
Code Identity
Code Classification
Code EditsBilling
Medicare Code Editor checks that affect claim validity for Z16.12.
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Bacterial infection caused by Proteus mirabilis
- Infection caused by ESBL Klebsiella oxytoca
- Infection caused by ESBL Proteus mirabilis
- Infection caused by extended spectrum beta-lactamase producing bacteria
- Infection caused by extended spectrum beta-lactamase producing Escherichia coli
Tabular List NotesGuidance
Coding notes and annotation back-references applicable to this code.
Type 2 Excludes
- Methicillin resistant Staphylococcus aureus infection in diseases classified elsewhere B95.62
A type 2 excludes note represents "Not included here". An excludes2 note indicates that the condition excluded is not part of the condition represented by the code, but a patient may have both conditions at the same time. When an Excludes2 note appears under a code, it is acceptable to use both the code and the excluded code together, when appropriate.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
- to
- extended beta lactamase (ESBL) - Z16.12
External Cause of Injuries IndexGuidance
References for this code in the External Cause of Injuries Index.
- Resistance, resistant(to)
- organism (s)
- to
- drug
- extended beta lactamase (ESBL)
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Convert Z16.12 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About Z16.12Overview
Is Z16.12 (Resistance to beta lactam antibiotics) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report extended spectrum beta lactamase (ESBL) resistance on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What MS-DRG does Z16.12 group to?
On inpatient claims, extended spectrum beta lactamase (ESBL) resistance maps to MS-DRG 867, 868, 869, with relative weights from 0.7297 to 2.0932 depending on complications. Higher weights mean higher Medicare reimbursement.
Can Z16.12 be a principal diagnosis?
No. The Medicare Code Editor rejects this code as a principal diagnosis because extended spectrum beta lactamase (ESBL) resistance describes a circumstance that influences health status rather than a current illness. Report it as a secondary diagnosis.
What is the ICD-9 equivalent of Z16.12?
Under the General Equivalence Mappings, extended spectrum beta lactamase (ESBL) resistance converts to ICD-9-CM V09.1 (inf mcrg rstn b-lactam). The mapping is approximate, so confirm the match fits the documentation.
