2027 ICD-10-CM Diagnosis Code Z16.12Extended spectrum beta lactamase (ESBL) resistance
ICD-10-CM Codes›Z00–Z99›Z16›Z16
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Not a Principal Diagnosis
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 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 867 through 869. 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. 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 Escherichia coli
- Infection caused by extended-spectrum beta-lactamase-producing bacteria
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to Z16.12: its own notes plus those printed at Z16 and Chapter 21. A note printed at a category, block or chapter applies to every code under it.
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.
- Methicillin resistant Staphylococcus aureus infection in diseases classified elsewhere (B95.62)
Notes
General instructions on how these codes are used.
- The codes in this category are provided for use as additional codes to identify the resistance and non-responsiveness of a condition to antimicrobial drugs.
- Z codes represent reasons for encounters. A corresponding procedure code must accompany a Z code if a procedure is performed. Categories Z00-Z99 are provided for occasions when circumstances other than a disease, injury or external cause classifiable to categories A00-Y89 are recorded as 'diagnoses' or 'problems'. This can arise in two main ways:
- (a) When a person who may or may not be sick encounters the health services for some specific purpose, such as to receive limited care or service for a current condition, to donate an organ or tissue, to receive prophylactic vaccination (immunization), or to discuss a problem which is in itself not a disease or injury.
- (b) When some circumstance or problem is present which influences the person's health status but is not in itself a current illness or injury.
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Referenced in Other NotesGuidance
Instructional notes printed at other codes that name Z16.12, its category, or a range that includes it.
Excludes1 1
These codes carry an Excludes1 note naming Z16.12: they are not reported together with it, unless the two conditions are unrelated.
Use Additional Code 2
These codes say to use an additional code from the note, and Z16.12 is one of the codes named.
- Chapter 1 (A00-B99) Certain infectious and parasitic diseasescode to identify resistance to antimicrobial drugs (Z16.-) names Z16.-, which includes this code
- Block J09-J18 Influenza and pneumoniacode, if applicable, to identify resistance to antimicrobial drugs (Z16.-) names Z16.-, 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.
Convert Z16.12 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About Z16.12Overview
What is the ICD-10 code for extended spectrum beta lactamase (ESBL) resistance?
The ICD-10-CM code for extended spectrum beta lactamase (ESBL) resistance is Z16.12 (sometimes written as Z1612). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
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, 2026 through September 30, 2027.
What MS-DRG does Z16.12 group to?
On inpatient claims, extended spectrum beta lactamase (ESBL) resistance maps to MS-DRG 867, 869, 868, with relative weights from 0.6784 to 2.1855 depending on complications. Higher weights mean higher Medicare reimbursement.
Is Z16.12 a CC or MCC?
CMS lists Z16.12 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.
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.
