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Test ID GENS Bacterial Culture, Aerobic with Antimicrobial Susceptibilities, Varies

Shipping Instructions

Specimen must arrive within 24 hours of collection. Ship ambient or refrigerated. Frozen specimens will be rejected.

Necessary Information

Specimen source is required; include the specific anatomic source. Indicate whether it is a "surface" or "deep/surgical" specimen. Do not label only as "wound."

Specimen Required


Specimen Type: Closed abscess; deep tissue or fluid

Container/Tube: Sterile container

Specimen Volume: Entire collection

Collection Instructions: Aspirate the abscess contents/fluid with a syringe or excise a portion of tissue.



Specimen Type: Open abscess, superficial lesion/wound, swab, tissue, or fluid


-Culturette (BBL Culture Swab) (T092)

-BD E-Swab (T853)

Container/Tube: Sterile container, culture transport swab (Dacron or rayon swab with aluminum or plastic shaft with either Stuart or Amies liquid medium) or ESwab

Collection Instructions: For most open lesions and abscesses, remove superficial flora by decontaminating skin before collecting a specimen from advancing margin or base.

Additional Information:

1. If submitting a specimen from a source contaminated with usual flora, send at refrigerated temperature.

2. Refrigerated specimens are not suitable for isolation of Neisseria species.

Useful For

Detecting bacteria responsible for infections of sterile body fluids, tissues, or wounds


Determining the in vitro antimicrobial susceptibility of potentially pathogenic aerobic bacteria, if appropriate


This test is not intended for medicolegal use.

Reflex Tests

Test ID Reporting Name Available Separately Always Performed
COMM Identification Commercial Kit No, (Bill Only) No
RMALD Ident by MALDI-TOF mass spec No, (Bill Only) No
GID Bacteria Identification No, (Bill Only) No
REFID Additional Identification Procedure No, (Bill Only) No
STAP Identification Staphylococcus No, (Bill Only) No
STRP Identification Streptococcus No, (Bill Only) No
SALS Serologic Agglut Method 1 Ident No, (Bill Only) No
EC Serologic Agglut Method 2 Ident No, (Bill Only) No
SHIG Serologic Agglut Method 3 Ident No, (Bill Only) No
SIDC Ident Serologic Agglut Method 4 No, (Bill Only) No
ISAE Aerobe Ident by Sequencing No, (Bill Only) No
PCRID Identification by PCR No, (Bill Only) No
TISSR Tissue Processing No, (Bill Only) No
BLA Beta Lactamase No, (Bill Only) No
MIC Susceptibility, MIC 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

Testing Algorithm

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


The following tables provide a listing of the antimicrobials routinely tested in the laboratory 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

Method Name

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

Reporting Name

Bacterial Culture, Aerobic + Susc

Specimen Type


Specimen Minimum Volume

0.5 mL or 0.5 × 0.2 × 0.2-cm sized piece of tissue

Specimen Stability Information

Specimen Type Temperature Time Special Container
Varies Ambient (preferred) 24 hours
  Refrigerated  24 hours

Reference Values

No growth or usual flora


Identification of probable pathogens


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:


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.



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.



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.



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 and 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. Version 11.0, 2021. Available at

Day(s) Performed

Monday through Sunday

Report Available

5 to 14 days

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Test Classification

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

87070-Bacterial Culture, Aerobic

87077-Identification commercial kit (if appropriate)

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

87077-Bacteria Identification (if appropriate)

87077-Additional Identification procedure (if appropriate)

87077-Identification Staphylococcus (if appropriate)

87077-Identification Streptococcus (if appropriate)

87147 x 1-3-Serologic agglut method 1 ident (if appropriate)

87147-Serologic agglut method 2 ident (if appropriate)

87147 x 4-Serologic agglut method 3 ident (if appropriate)

87147 x 2-6-Serologic Agglut Method 4 Ident (if appropriate)

87153-Aerobe ident by sequencing (if appropriate)

87150-Identification by PCR (if appropriate)

87176-Tissue Processing (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-mec A PCR (if appropriate)

LOINC Code Information

Test ID Test Order Name Order LOINC Value
GENS Bacterial Culture, Aerobic + Susc 634-6


Result ID Test Result Name Result LOINC Value
GENS Bacterial Culture, Aerobic + Susc 634-6