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HelpOrder Code LAB7576 Antimicrobial Susceptibility, Aerobic Bacteria, Varies
Infectious
Additional Codes
Mayo Test Code: ZMMLS
Reporting Name
Susceptibility, Aerobic, MICUseful For
Determining the in vitro susceptibility of aerobic bacteria involved in human infections
Testing Algorithm
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 MECAB / Methicillin Resistance Gene, mecA Test (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.
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Specimen Type
VariesOrdering 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 Centers for Disease Control and Prevention regarding antimicrobial susceptibility testing of such isolates. For more information see www.selectagents.gov/sat/list.htm.
Shipping Instructions
1. See Infectious Specimen Shipping Guidelines
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
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.
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Varies | Ambient (preferred) | ||
| Frozen | |||
| Refrigerated | |||
Special Instructions
Reference Values
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; therefore, the following comment will be included on the report: There are no established interpretive guidelines for agents reported without interpretations.
For information regarding CLSI and EUCAST susceptibility interpretations, see Susceptibility Interpretative Category Definitions.
Day(s) Performed
Monday through Friday
CPT Code Information
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)
Reflex 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 |
| MECAB | mecA PCR Test, Bill Only | No, (Bill Only) | No |
Method Description
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° 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, 07/2016)
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)
Reject Due To
| Agar plate | Reject |
Method Name
Minimal Inhibitory Concentration (MIC) (Agar Dilution or Broth Microdilution or Gradient Diffusion) or Disk Diffusion(if appropriate)
Forms
If not ordering electronically, complete, print, and send a Microbiology Test Request (T244) with the specimen.
Additional Tests
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| MIC | Susceptibility, MIC | No, (Bill Only) | Yes |