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Antibacterial Susceptibility Test Interpretive Criteria

This web page provides information about the in vitro susceptibility of bacteria to certain drugs.

The safety and efficacy of these drugs in treating clinical infections due to such bacteria may or may not have been established in adequate and well-controlled clinical trials and the clinical significance of such susceptibility information in those instances is unknown.

The approved product labeling for specific drugs provides the uses for which the product is approved.

Labeling for these products can be found at Drugs@FDA or FDA Online Label Repository.

Recognized Standards

Performance Methods and Quality Control

FDA recognizes consensus standards for performance standards, methods standards, and quality control parameter standards including ranges for antimicrobial susceptibility testing.

Susceptibility Test Interpretive Criteria

The table below lists antibacterial drugs and indicates which, if any, susceptibility test interpretive criteria, also known as “breakpoints” (abbreviated as STIC), are recognized or identified by FDA for that drug.

With certain exceptions and additions, identified in the table, FDA recognizes the standard published in:

  • Clinical and Laboratory Standards Institute (CLSI). Performance Standards for Antimicrobial Susceptibility Testing. 34th ed. CLSI supplement M100. Clinical and Laboratory Standards Institute; 2024.

If the table indicates that STIC for a drug are included in CLSI M100 and there are no additions or exceptions, CLSI M100 contains all of the STIC recognized by FDA for that drug.

For specific drug/bacteria combinations, FDA recognizes in part the standards published in:

Clinical and Laboratory Standards Institute (CLSI). Methods for Antimicrobial Dilution and Disk Susceptibility Testing of Infrequently Isolated or Fastidious Bacteria. 3rd ed. CLSI document M45; 2015.

Clinical and Laboratory Standards Institute (CLSI). Performance Standards for Susceptibility Testing of Mycobacteria, Norcardia spp. and other Aerobic Actinomycetes. 1st ed. CLSI document M62; 2018.

Clinical and Laboratory Standards Institute (CLSI). Methods for Antimicrobial Susceptibility Testing for Human Mycoplasmas; Approved Guideline. CLSI document M43-A; 2011.

If one of these three standards is recognized in part, that information is provided in the hyperlinked information for the specific drug listed in the table below.

FDA recognition of STIC standard(s) for a drug does not include recognition of epidemiological cutoff values (ECVs) for that drug.

FDA recognition of STIC standard(s) for a drug and bacterial family or genus/species does include recognition of surrogate testing methods included in recognized standards for that drug and bacterial family or genus/species.

Susceptibility Test Interpretive Criteria Recognized or Otherwise Identified by FDA

The hyperlinks included for certain antibacterial drugs in the table below lead to information concerning:

  • Recognitions, Exceptions, or Additions to the recognized standard of CLSI M100
  • Additional STIC recognized in part from standards CLSI M45, M24-A2, and M43-A
  • Additional FDA-identified STIC for certain drug-bacteria combinations not included in a recognized standard

Downloadable File (XLS-23KB)


Route of

STIC for Drug
Included in the Recognized
CLSI Standard

Exceptions or
Additions to the Recognized
CLSI Standard

Amikacin Injection Yes Yes
Amoxicillin Oral Yes No
and clavulanate
Oral Yes Yes
Ampicillin Injection, Oral Yes No
Ampicillin and
Injection Yes Yes
Azithromycin Injection, Oral Yes Yes
Aztreonam Injection Yes Yes
Bacitracin* Injection No No
Bedaquiline* Oral No No
Bismuth subcitrate potassium, Metronidazole, and Tetracycline hydrochloride* Oral No No
Capreomycin* Injection No No
Cefaclor Oral Yes Yes
Cefadroxil Oral No Yes
Cefazolin Injection Yes Yes
Cefdinir Oral Yes Yes
Cefditoren pivoxil Oral Yes Yes
Cefepime Injection Yes Yes
Cefepime and Enmetazobactam Injection No No
Cefiderocol Injection Yes Yes
Cefixime Oral Yes No
Cefoperazone Injection Yes Yes
Cefotaxime Injection Yes Yes
Cefotetan Injection Yes Yes
Cefoxitin Injection Yes Yes
Oral Yes No
Cefprozil Oral Yes Yes
Ceftaroline fosamil Injection Yes No
Ceftazidime Injection Yes Yes
Ceftazidime and
Injection Yes No
Ceftibuten Oral Yes Yes
Ceftobiprole medocaril sodium Injection No No
Ceftolozane and
Injection Yes Yes
Ceftriaxone Injection Yes Yes
Cefuroxime axetil Oral Yes No
Cefuroxime Injection Yes Yes
Cephalexin Oral Yes No
Chloramphenicol Injection Yes Yes
Ciprofloxacin Oral, Injection Yes Yes
Clarithromycin Oral Yes Yes
Clindamycin Injection, Oral Yes No
Clofazimine* Oral No No
Colistimethate Injection Yes Yes
Dalbavancin Injection Yes No
Dapsone* Oral No No
Daptomycin Injection Yes Yes
Delafloxacin Injection, Oral No Yes
Demeclocycline Oral No Yes
Dicloxacillin Oral Yes No
Doripenem Injection Yes Yes
Doxycycline Oral, Injection Yes Yes
Eravacycline Injection No Yes
Ertapenem Injection Yes Yes
Erythromycin Oral, Injection Yes No
ethylsuccinate and
Oral No No
Ethambutol* Oral No No
Ethionamide* Oral No No
Fidaxomicin* Oral No No
Oral Yes No
Gemifloxacin Oral Yes No
Gentamicin Injection Yes Yes
Imipenem and
Injection Yes Yes
Injection Yes Yes
Isoniazid* Oral No No
Isoniazid, Pyrazinamide, and Rifampin* Oral No No
Kanamycin Injection Yes Yes
Lansoprazole, Amoxicillin, and Clarithromycin* Oral No No
Lefamulin Oral, Injection Yes Yes
Levofloxacin Oral, Injection Yes Yes
Lincomycin* Injection No No
Linezolid Injection, Oral Yes No
Loracarbef Oral Yes Yes
Meropenem Injection Yes Yes
Meropenem and
Injection Yes No
Oral No No
Metronidazole Injection, Oral Yes No
Minocycline Oral, Injection Yes Yes
Moxifloxacin Oral, Injection Yes Yes
Nafcillin* Injection No No
Neomycin sulfate* Oral No No
Nitrofurantoin Oral Yes No
Ofloxacin Oral Yes Yes
Omadacycline Injection, Oral No Yes
Omeprazole magnesium, Amoxicillin, and Rifabutin* Oral No No
Injection Yes No
Oxacillin Injection Yes No
Penicillin Injection Yes No
Penicillin V Oral Yes No
Piperacillin and
Injection Yes Yes
Pivmecillinam Oral Yes Yes
Plazomicin Injection Yes No
Polymyxin B
Injection Yes Yes
Pretomanid* Oral No No
Pyrazinamide* Oral No No
Quinupristin and
Injection Yes Yes
Rifabutin* Oral No No
Rifampin Oral, Injection Yes Yes
Rifapentine* Oral No No
Rifaximin* Oral No No
Spectinomycin Injection Yes No
Streptomycin Injection Yes No
Sulbactam and Durlobactam Injection Yes No
Tedizolid Oral, Injection Yes No
Telavancin Injection Yes No
Tetracycline Oral Yes Yes
Ticarcillin and
Injection Yes Yes
Tigecycline Injection No Yes
Tobramycin Injection Yes Yes
Oral Yes No
Trimethoprim and
Oral, Injection Yes Yes
Vancomycin Injection Yes Yes
Vancomycin* Oral No No

*No STIC are recognized by FDA for this drug at this time.

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