Test Catalog

Test Id : ZMMLS

Antimicrobial Susceptibility, Aerobic Bacteria, Varies

Useful For
Suggests clinical disorders or settings where the test may be helpful

Determining the in vitro susceptibility of aerobic bacteria involved in human infections

Reflex Tests
Lists tests that may or may not be performed, at an additional charge, depending on the result and interpretation of the initial tests.

Test Id Reporting Name Available Separately Always Performed
RMALD Ident by MALDI-TOF mass spec No, Bill Only No
BLA Beta Lactamase No, Bill Only No
SUS Susceptibility No, Bill Only No
HPCR1 H pylori + Clarithro Resistance PCR No, Bill Only No
MARP1 mecA PCR (Bill Only) No, Bill Only No

Additional Tests
Lists tests that are always performed, at an additional charge, with the initial tests.

Test Id Reporting Name Available Separately Always Performed
MIC Susceptibility, MIC No, Bill Only Yes

Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

When this test is ordered, the reflex tests may be performed at an additional charge.

 

All aerobically growing bacteria submitted will automatically have susceptibility testing performed and billed as appropriate. Antimicrobial agents appropriate to the organism and specimen source will be tested according to Mayo Clinic's practice and the laboratory's standard operating procedures.

 

If appropriate, testing for mecA will be performed by polymerase chain reaction (PCR) under MARP1 / mecA, Molecular Detection, PCR (Bill Only). Indications for mecA testing include inadequate growth by phenotypic antimicrobial susceptibility testing, lack of current organism breakpoints for oxacillin or cefoxitin, and assessment of discrepancies between cefoxitin and oxacillin phenotypic testing results.

 

In the event that an isolate of Helicobacter pylori does not grow from a client sample or does not grow for susceptibility testing, reflex testing for HPCR1 / Helicobacter pylori with Clarithromycin Resistance Prediction, Molecular Detection, PCR (Bill Only) may be added.

 

The following tables provide a listing of the antimicrobials routinely tested as well as antimicrobials that may be tested upon request. These tables are organized by isolate groups and are not all inclusive. Call 800-533-1710 and ask to speak to the Bacteriology Antimicrobial Susceptibility Testing Laboratory if the organism or antimicrobial of interest are not listed in these tables.

-Aerobic Gram-Negative Bacilli Antimicrobials

-Additional Gram-Negative Bacteria Antimicrobials

-Staphylococcus, Enterococcus, Bacillus, and Related Genera Antimicrobials

-Additional Gram-Positive Bacteria Antimicrobials

 

For test utilization options, see Helicobacter pylori Diagnostic Algorithm in Special Instructions.

Special Instructions
Library of PDFs including pertinent information and forms related to the test

Method Name
A short description of the method used to perform the test

Minimal Inhibitory Concentration (MIC) (Agar Dilution or Broth Microdilution or Gradient Diffusion) or Disk Diffusion(if appropriate)

NY State Available
Indicates the status of NY State approval and if the test is orderable for NY State clients.

Yes

Reporting Name
Lists a shorter or abbreviated version of the Published Name for a test

Susceptibility, Aerobic, MIC

Aliases
Lists additional common names for a test, as an aid in searching

Antibiotic Susceptibility

Bacterial Susceptibility Testing

Extended Spectrum Beta-Lactamase (ESBL)

MIC (Minimum Inhibitory Concentration)

Minimum Inhibitory Concentration (MIC)

Pneumococcus Susceptibility

Streptococcus pneumoniae Susceptibility

Susceptibility Testing

Amikacin

Amoxicillin

Amoxicillin-clavulanate

Ampicillin

Ampicillin-sulbactam

Azithromycin

Aztreonam

Cefaclor

Cefazolin

Cefdinir

Cefepime

Cefixime

Cefotaxime

Cefpodoxime

Ceftaroline

Ceftazidime

Ceftazidime-avibactam

Ceftolozane-tazobactam

Ceftriaxone

Chloramphenicol

Ciprofloxacin

Clarithromycin

Clindamycin

Colistin

Daptomycin

Doxycycline

Ertapenem

Erythromycin

Fosfomycin

Gentamicin

Imipenem

Levofloxacin

Linezolid

Meropenem

Metronidazole

Minocycline

Mupirocin

Nitrofurantoin

Ofloxacin

Oxacillin

Penicillin

Piperacillin

Piperacillin-tazobactam

Polymyxin

Quinupristin-dalfopristin

Rifampin

Sulfamethoxazole

Tedizolid

Tetracycline

Tigecycline

Tobramycin

Trimethoprim

Trimethoprim-sulfamethoxazole

Vancomycin

Achromobacter

Acinetobacter

Aeromonas

Aggregatibacter

Arcanobacterium

Arthrobacter

Bacillus

Brevibacillus

Brevibacterium

Brevundimonas

Burkholderia

Campylobacter

Cardiobacterium

Citrobacter

Cohnella

Coli

Corynebacterium

CRE

Cronobacter

Dermatobacter

Eikenella

Enterobacter

Enterococcus

Erysipelothrix

ESBL

Escherichia

Gemella

Gonorrhoeae

Gram negative

Gram positive

Haemophilus

Helicobacter

Klebsiella

Kingella

Lactobacillus

Lactococcus

Leifsonia

Leuconostoc

Listeria

Lysinibacillus

Meningitidis

MDR

MDRO

Microbacterium

MRSA

Moraxella

Neisseria

Ochrobactrum

Paenibacillus

Pandoraea

Pasteurella

Pediococcus

Pneumo

Pneumococcus

Proteus

Pseudomonas

Raoultella

Rothia

Salmonella

Serratia

Shewanella

Shigella

Sphingomonas

Sporolactobacillus

Staph

Staphylococcus

Stenotrophomonas

Strep

Streptococcus

Trueperella

Turicella

VISA

Vibrio

Viridans

VRE

Yersinia

Oerskovia

Avibactam-ceftazidime

Avycaz

Meropenem-vaborbactam

Sivextro

Vabormere

Zerbaxa

Lelliottia

Delafloxacin

Omadacycline

H pylori

H. pylori

mecA

Nuzyra

Abiotrophia

Cefiderocol

Colistin Agar Testing

Enterobacteriales

Granulicatella

Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

When this test is ordered, the reflex tests may be performed at an additional charge.

 

All aerobically growing bacteria submitted will automatically have susceptibility testing performed and billed as appropriate. Antimicrobial agents appropriate to the organism and specimen source will be tested according to Mayo Clinic's practice and the laboratory's standard operating procedures.

 

If appropriate, testing for mecA will be performed by polymerase chain reaction (PCR) under MARP1 / mecA, Molecular Detection, PCR (Bill Only). Indications for mecA testing include inadequate growth by phenotypic antimicrobial susceptibility testing, lack of current organism breakpoints for oxacillin or cefoxitin, and assessment of discrepancies between cefoxitin and oxacillin phenotypic testing results.

 

In the event that an isolate of Helicobacter pylori does not grow from a client sample or does not grow for susceptibility testing, reflex testing for HPCR1 / Helicobacter pylori with Clarithromycin Resistance Prediction, Molecular Detection, PCR (Bill Only) may be added.

 

The following tables provide a listing of the antimicrobials routinely tested as well as antimicrobials that may be tested upon request. These tables are organized by isolate groups and are not all inclusive. Call 800-533-1710 and ask to speak to the Bacteriology Antimicrobial Susceptibility Testing Laboratory if the organism or antimicrobial of interest are not listed in these tables.

-Aerobic Gram-Negative Bacilli Antimicrobials

-Additional Gram-Negative Bacteria Antimicrobials

-Staphylococcus, Enterococcus, Bacillus, and Related Genera Antimicrobials

-Additional Gram-Positive Bacteria Antimicrobials

 

For test utilization options, see Helicobacter pylori Diagnostic Algorithm in Special Instructions.

Specimen Type
Describes the specimen type validated for testing

Varies

Ordering Guidance

Mayo Clinic Laboratories will not perform susceptibility testing on select agents (eg, Bacillus anthracis, Brucella species, Burkholderia mallei, Burkholderia pseudomallei, Francisella tularensis, and Yersinia pestis). Consult with your state health department or the CDC regarding antimicrobial susceptibility testing of such isolates.

Shipping Instructions

1. See Infectious Specimen Shipping Guidelines in Special Instructions.

2. Place specimen in a large infectious container and label as an etiologic agent/infectious substance.

Necessary Information

Organism identification and specimen source are required.

Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing

Supplies: Infectious Container, Large (T146)

Container/Tube: Agar slant or other appropriate media

Specimen Volume: Organism in pure culture

Collection Instructions:

1. Perform isolation of infecting bacteria.

2. Organism must be in pure culture, actively growing. Do not submit mixed cultures.

Special Instructions
Library of PDFs including pertinent information and forms related to the test

Forms

If not ordering electronically, complete, print, and send a Microbiology Test Request (T244) with the specimen.

Reject Due To
Identifies specimen types and conditions that may cause the specimen to be rejected

Agar plate Reject

Specimen Stability Information
Provides a description of the temperatures required to transport a specimen to the performing laboratory, alternate acceptable temperatures are also included

Specimen Type Temperature Time Special Container
Varies Ambient (preferred)
Frozen
Refrigerated

Useful For
Suggests clinical disorders or settings where the test may be helpful

Determining the in vitro susceptibility of aerobic bacteria involved in human infections

Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

When this test is ordered, the reflex tests may be performed at an additional charge.

 

All aerobically growing bacteria submitted will automatically have susceptibility testing performed and billed as appropriate. Antimicrobial agents appropriate to the organism and specimen source will be tested according to Mayo Clinic's practice and the laboratory's standard operating procedures.

 

If appropriate, testing for mecA will be performed by polymerase chain reaction (PCR) under MARP1 / mecA, Molecular Detection, PCR (Bill Only). Indications for mecA testing include inadequate growth by phenotypic antimicrobial susceptibility testing, lack of current organism breakpoints for oxacillin or cefoxitin, and assessment of discrepancies between cefoxitin and oxacillin phenotypic testing results.

 

In the event that an isolate of Helicobacter pylori does not grow from a client sample or does not grow for susceptibility testing, reflex testing for HPCR1 / Helicobacter pylori with Clarithromycin Resistance Prediction, Molecular Detection, PCR (Bill Only) may be added.

 

The following tables provide a listing of the antimicrobials routinely tested as well as antimicrobials that may be tested upon request. These tables are organized by isolate groups and are not all inclusive. Call 800-533-1710 and ask to speak to the Bacteriology Antimicrobial Susceptibility Testing Laboratory if the organism or antimicrobial of interest are not listed in these tables.

-Aerobic Gram-Negative Bacilli Antimicrobials

-Additional Gram-Negative Bacteria Antimicrobials

-Staphylococcus, Enterococcus, Bacillus, and Related Genera Antimicrobials

-Additional Gram-Positive Bacteria Antimicrobials

 

For test utilization options, see Helicobacter pylori Diagnostic Algorithm in Special Instructions.

Clinical Information
Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Antimicrobial susceptibility testing (AST) determines the minimal inhibitory concentration (MIC) of antimicrobial agents. The MIC is a measurement of the activity of an antimicrobial agent against an organism. It is defined as the lowest concentration of an antimicrobial agent that inhibits growth of the microorganism. Clinical breakpoints are derived from a number of data including:

-The pharmacokinetics/pharmacodynamics of an antimicrobial agent

-The MIC distribution of a large number of isolates

-Clinical outcome data for a patient population treated with the antimicrobial of interest

 

AST should be performed on pure culture isolates of pathogenic bacteria (or those potentially pathogenic in special situations) grown from specimens that have been appropriately collected so as not to confuse clinically significant isolates with normal or contaminating microbiota. Susceptibility testing is indicated for any organism that contributes to an infectious process warranting antimicrobial chemotherapy if its susceptibility cannot be reliably predicted from the organism's identity.

 

The MIC obtained during AST is helpful in indicating the concentration of antimicrobial agent required at the site of infection necessary to inhibit the infecting organism. For each organism-antimicrobial agent combination, the Clinical and Laboratory Standards Institute and/or the European Committee on Antimicrobial Susceptibility Testing provides interpretive criteria for determining whether the MIC should be interpreted as susceptible, susceptible dose dependent, intermediate, nonsusceptible, resistant, or epidemiological cutoff value if applicable.

Reference Values
Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

Susceptibility results are reported as minimal inhibitory concentration (MIC) in mcg/mL Breakpoints (also known as "clinical breakpoints") are used to categorize an organism as susceptible, susceptible-dose dependent, intermediate, resistant, or nonsusceptible according to breakpoint setting organizations, either the Clinical and Laboratory Standards Institute (CLSI) or the European Committee on Antimicrobial Susceptibility Testing (EUCAST), as applicable.

In some instances, an interpretive category cannot be provided based on available data and the following comment will be included: "There are no established interpretive guidelines for agents reported without interpretations."

 

Clinical and Laboratory Standards Institute (CLSI) Interpretive Category Definitions:

Susceptible:

A category defined by a breakpoint that implies that isolates with an MIC at or below or a zone diameter at or above the susceptible breakpoint are inhibited by the usually achievable concentrations of antimicrobial agent when the dosage recommended to treat the site of infection is used, resulting in likely clinical efficacy.

 

Susceptible-Dose Dependent:

A category defined by a breakpoint that implies that susceptibility of an isolate depends on the dosing regimen that is used in the patient. To achieve levels that are likely to be clinically effective against isolates for which the susceptibility testing results (either MICs or zone diameters) are in the susceptible-dose dependent (SDD) category, it is necessary to use a dosing regimen (ie, higher doses, more frequent doses, or both) that results in higher drug exposure than that achieved with the dose that was used to establish the susceptible breakpoint. Consideration should be given to the maximum literature-supported dosage regimens, because higher exposure gives the highest probability of adequate coverage of a SDD isolate. The drug label should be consulted for recommended doses and adjustment for organ function.

 

Intermediate:

A category defined by a breakpoint that includes isolates with MICs or zone diameters within the intermediate range that approach usually attainable blood and tissue levels and/or for which response rates may be lower than for susceptible isolates.

Note: The intermediate category implies clinical efficacy in body sites where the drugs are physiologically concentrated or when a higher than normal dosage of a drug can be used. This category also includes a buffer zone, which should prevent small, uncontrolled, technical factors from causing major discrepancies in interpretations, especially for drugs with narrow pharmacotoxicity margins.

 

Resistant:

A category defined by a breakpoint that implies that isolates with an MIC at or above or a zone diameter at or below the resistant breakpoint are not inhibited by the usually achievable concentrations of the agent with normal dosage schedules and/or that demonstrate MICs or zone diameters that fall in the range in which specific microbial resistance mechanisms are likely, and clinical efficacy of the agent against the isolate has not been reliably shown in treatment studies.

 

Nonsusceptible:

A category used for isolates for which only a susceptible breakpoint is designated because of the absence or rare occurrence of resistant strains. Isolates for which the antimicrobial agent MICs are above or the zone diameters are below the value indicated for the susceptible breakpoint should be reported as nonsusceptible.

Note: An isolate that is interpreted as nonsusceptible does not necessarily mean that the isolate has a resistance mechanism. It is possible that isolates with MICs above the susceptible breakpoint that lack resistance mechanisms may be encountered within the wild-type distribution after the time the susceptible-only breakpoint was set.

 

Epidemiological Cutoff Value:

The MIC that separates microbial populations into those with and without phenotypically detectable resistance (non-wild-type or wild-type, respectively). The epidemiological cutoff value (ECV) defines the highest MIC for the wild type population of isolates. ECVs are based on in vitro data only, using MIC distributions. ECVs are not clinical breakpoints, and the clinical relevance of ECVs for a particular patient has not yet been identified or approved by CLSI or any regulatory agency.

 

When an ECV is reported, an interpretive category is not assigned, and the following comment will be included: "This MIC is consistent with the Epidemiological Cutoff Value (ECV) observed in isolates (WITH / WITHOUT) acquired resistance; however, correlation with treatment outcome is unknown."

-Wild-type (WT) – an interpretive category defined by an ECV that describes the microbial population with no phenotypically detectable mechanisms of resistance or reduced susceptibility for an antimicrobial agent being evaluated.

-Non-wild-type (NWT) – an interpretive category defined by an ECV that describes the microbial population with phenotypically detectable mechanisms of resistance or reduced susceptibility for the antimicrobial agent being evaluated.

Note: MIC values for which ECV’s are defined are not to be interpreted or reported as susceptible, intermediate or resistant but rather as WT or NWT. The ECV’s should not be used as clinical breakpoints.

(Clinical and Laboratory Standards Institute [CLSI]. Performance Standards for Antimicrobial Susceptibility Testing. 31st ed. CLSI supplement M100. CLSI; 2021:4-6, 268-269

)

 

European Committee on Antimicrobial Susceptibility Testing (EUCAST) Interpretive Category Definitions:

S - Susceptible, standard dosing regimen: A microorganism is categorized as "Susceptible, standard dosing regimen", when there is a high likelihood of therapeutic success using a standard dosing regimen of the agent

 

I - Susceptible, increased exposure*: A microorganism is categorized as "Susceptible, Increased exposure*" when there is a high likelihood of therapeutic success because exposure to the agent is increased by adjusting the dosing regimen or by its concentration at the site of infection.

 

R - Resistant: A microorganism is categorized as "Resistant" when there is a high likelihood of therapeutic failure even when there is increased exposure*.

 

*Exposure is a function of how the mode of administration, dose, dosing interval, infusion time, as well as distribution and excretion of the antimicrobial agent will influence the infecting organism at the site of infection.

 

(The European Committee on Antimicrobial Susceptibility Testing. Breakpoint tables for interpretation of MICs and zone diameters. v11.0, 2021. Available at www.eucast.org.)

Interpretation
Provides information to assist in interpretation of the test results

A "susceptible" category result and a low minimum inhibitory concentration value indicate in vitro susceptibility of the organism to the antimicrobial tested.

 

Refer to Reference Values for interpretation of various antimicrobial susceptibility interpretive categories (ie, susceptible, susceptible-dose dependent, intermediate, nonsusceptible, resistant, or epidemiological cutoff value).

Cautions
Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

In vitro susceptibility does not guarantee clinical response. Therefore, the decision to treat with a particular agent should not be based solely on the antimicrobial susceptibility testing result.

Clinical Reference
Recommendations for in-depth reading of a clinical nature

1. Jorgensen JH, Ferraro MJ: Antimicrobial susceptibility testing: a review of general principles and contemporary practices. Clin Infect Dis. 2009 Dec 1;49(11):1749-1755

2. Jenkins SG, Schuetz AN: Current concepts in laboratory testing to guide antimicrobial therapy. Mayo Clin Proc. 2012 Mar;87(3):290-308

3. Procop GW, Church DL, Hall GS, et al: Antimicrobial susceptibility testing. In: Koneman's Color Atlas and Textbook of Diagnostic Microbiology. 7th ed. Wolters Kluwer Health; 2017:1074-1171

Special Instructions
Library of PDFs including pertinent information and forms related to the test

Method Description
Describes how the test is performed and provides a method-specific reference

An agar dilution method is used for routine testing. The agar dilution method employs the use of antimicrobial agents incorporated in agar plates. The antimicrobial is added to agar in various concentrations depending upon levels attainable in serum, urine, or both. A standardized suspension of the organism is applied to the agar plates, which are incubated for a minimum of 16 to 18 hours at 35 degrees C. Complete inhibition of all but one colony or a very fine residual haze represents the end point.(Clinical and Laboratory Standards Institute [CLSI]: Methods for Dilution Antimicrobial Susceptibility Tests for Bacteria That Grow Aerobically. 11th ed. CLSI standard M07.CLSI; 2018.)

 

Daptomycin and tigecycline are tested by agar gradient diffusion.(Clinical and Laboratory Standards Institute [CLSI]: Methods for Dilution Antimicrobial Susceptibility Tests for Bacteria That Grow Aerobically. 11th ed. CLSI standard M07. CLSI; 2018; package insert: Etest Biomerieux;15203E-EN-2016/07. Available at: www.biomerieux.com/techlib)

 

Colistin is tested by the CLSI-approved Colistin agar test for Enterobacterales and Pseudomonas aeruginosa. (Clinical and Laboratory Standards Institute [CLSI]. Performance Standards for Antimicrobial Susceptibility Testing. 31st ed. CLSI supplement M100. CLSI; 2021: 142-147.).

 

Cefiderocol is tested by disk diffusion.(Clinical and Laboratory Standards Institute [CLSI]. Performance Standards for Antimicrobial Disk Susceptibility Tests. 13th ed. CLSI standard M02. CLSI; 2018.)

PDF Report
Indicates whether the report includes an additional document with charts, images or other enriched information

No

Day(s) Performed
Outlines the days the test is performed. This field reflects the day that the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time before the test is performed. Some tests are listed as continuously performed, which means that assays are performed multiple times during the day.

Monday through Sunday

Report Available
The interval of time (receipt of sample at Mayo Clinic Laboratories to results available) taking into account standard setup days and weekends. The first day is the time that it typically takes for a result to be available. The last day is the time it might take, accounting for any necessary repeated testing.

4 to 7 days

Specimen Retention Time
Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded

Bacterial isolates: 30 days.

Performing Laboratory Location
Indicates the location of the laboratory that performs the test

Rochester

Fees
Several factors determine the fee charged to perform a test. Contact your U.S. or International Regional Manager for information about establishing a fee schedule or to learn more about resources to optimize test selection.

  • Authorized users can sign in to Test Prices for detailed fee information.
  • Clients without access to Test Prices can contact Customer Service 24 hours a day, seven days a week.
  • Prospective clients should contact their Regional Manager. For assistance, contact Customer Service.

Test Classification
Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR) product.

This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.

CPT Code Information
Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Clinic Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.

CPT codes are provided by the performing laboratory.

87077-Ident by MALDI-TOF mass spec (if appropriate)

87185-Beta lactamase (if appropriate)

87186-Antimicrobial Susceptibility, Aerobic Bacteria, MIC-per organism for routine battery (if appropriate)

87181-Susceptibility per drug and per organism for drugs not in routine battery (if appropriate)

87150-H pylori + Clarithro Resistance PCR (if appropriate)

87150-mecA PCR (if appropriate)

LOINC® Information

Test Id Test Order Name Order LOINC Value
ZMMLS Susceptibility, Aerobic, MIC 50545-3
Result Id Test Result Name Result LOINC Value
Result LOINC Value Tooltip
ZMMLS Susceptibility, Aerobic, MIC 21070-8

Test Setup Resources

Setup Files
Test setup information contains test file definition details to support order and result interfacing between Mayo Clinic Laboratories and your Laboratory Information System.

Excel | Pdf

Sample Reports
Normal and Abnormal sample reports are provided as references for report appearance.

Normal Reports | Abnormal Reports

SI Sample Reports
International System (SI) of Unit reports are provided for a limited number of tests. These reports are intended for international account use and are only available through MayoLINK accounts that have been defined to receive them.

SI Normal Reports | SI Abnormal Reports