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)

Drug	Route of Administration	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
Amoxicillin and clavulanate	Oral	Yes	Yes
Ampicillin	Injection, Oral	Yes	No
Ampicillin and sulbactam	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
Cefpodoxime proxetil	Oral	Yes	No
Cefprozil	Oral	Yes	Yes
Ceftaroline fosamil	Injection	Yes	No
Ceftazidime	Injection	Yes	Yes
Ceftazidime and avibactam	Injection	Yes	No
Ceftibuten	Oral	Yes	Yes
Ceftobiprole medocaril sodium	Injection	No	No
Ceftolozane and tazobactam	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	No
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
Erythromycin ethylsuccinate and sulfasoxazole acetyl*	Oral	No	No
Ethambutol*	Oral	No	No
Ethionamide*	Oral	No	No
Fidaxomicin*	Oral	No	No
Fosfomycin tromethamine	Oral	Yes	No
Gemifloxacin	Oral	Yes	No
Gentamicin	Injection	Yes	Yes
Imipenem and cilastatin	Injection	Yes	Yes
Imipenem- cilastatin- relebactam	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 vaborbactam	Injection	Yes	No
Methenamine Hippurate*	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
Oritavancin diphosphate	Injection	Yes	No
Oxacillin	Injection	Yes	No
Penicillin	Injection	Yes	No
Penicillin V	Oral	Yes	No
Piperacillin and tazobactam	Injection	Yes	Yes
Pivmecillinam	Oral	Yes	Yes
Plazomicin	Injection	Yes	No
Polymyxin B Sulfate	Injection	Yes	Yes
Pretomanid*	Oral	No	No
Pyrazinamide*	Oral	No	No
Quinupristin and dalfopristin	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
Sulopenem etzadroxil and probenecid	Oral	No	Yes
Tedizolid	Oral, Injection	Yes	No
Telavancin	Injection	Yes	No
Tetracycline	Oral	Yes	Yes
Ticarcillin and clavulanate	Injection	Yes	Yes
Tigecycline	Injection	No	Yes
Tobramycin	Injection	Yes	Yes
Trimethoprim hydrochloride	Oral	Yes	No
Trimethoprim and sulfamethoxazole	Oral, Injection	Yes	Yes
Vancomycin	Injection	Yes	Yes
Vancomycin*	Oral	No	No