2026 ICD-10-CM Diagnosis Code Z16.10Resistance to unspecified beta lactam antibiotics

ICD-10-CM Codes›Z00–Z99›Z16›Z16

ICD-10-CM Z16.10
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

Z16.10 is a billable ICD-10-CM diagnosis code for resistance to unspecified beta lactam antibiotics. 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 beta lactam resistant bacterial infection. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Resistance to antimicrobial drugs.

Code Identity

ICD-10-CM Code
Z16.10
Billable Status
Yes — Valid for Submission
Code Describes
Resistance to unspecified beta lactam antibiotics
Short Description
Resistance to unspecified beta lactam antibiotics
Same as the full description in the CMS dataset.
Parent Code
Z16.1
Resistance to beta lactam antibiotics

Code Classification

ChapterZ00–Z99Factors influencing health status and contact with health services
SectionZ16Resistance to antimicrobial drugs
CategoryZ16Resistance to antimicrobial drugs
This CodeZ16.10Resistance to unspecified beta lactam antibiotics

Code EditsBilling

Medicare Code Editor checks that affect claim validity for Z16.10.

Unacceptable principal diagnosis
There are selected codes that describe a circumstance which influences an individual's health status but not a current illness or injury, or codes that are not specific manifestations but may be due to an underlying cause. These codes are considered unacceptable as a principal diagnosis.

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Beta lactam resistant bacterial infection

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Resistance, resistant(to)
      • organism (s)
        • to
          • drug
            • beta lactam antibiotics

Clinical ClassificationClinical

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

CCSR FAC015
Resistance to antimicrobial drugs
Default principal diagnosis: inpatient No · outpatient Yes

Convert Z16.10 to ICD-9-CMHistory

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

ICD-9-CM
V09.1 Inf mcrg rstn b-lactam
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 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About Z16.10Overview

Is Z16.10 (Resistance to beta lactam antibiotics) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report resistance to unspecified beta lactam antibiotics on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does Z16.10 group to?

On inpatient claims, resistance to unspecified beta lactam antibiotics 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 Z16.10 be a principal diagnosis?

No. The Medicare Code Editor rejects this code as a principal diagnosis because resistance to unspecified beta lactam antibiotics 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 Z16.10?

Under the General Equivalence Mappings, resistance to unspecified beta lactam antibiotics converts to ICD-9-CM V09.1 (inf mcrg rstn b-lactam). The mapping is approximate, so confirm the match fits the documentation.