Test ID: ZMMLS
Antimicrobial Susceptibility, Aerobic Bacteria, MIC
NY State Approved 
Indicates the status of NY State approval and if the test is orderable for NY State clients.
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 test(s) that may or may not be performed, at an additional charge, depending on the result and interpretation of the initial test(s)
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| BLA | Beta Lactamase | No, (Bill Only) | No |
| KPC1 | KPC PCR | No, (Bill Only) | No |
| HODGB | Carbapenamase-Modified Hodge Test | No, (Bill Only) | No |
| SUS | Susceptibility | No, (Bill Only) | No |
Testing Algorithm Delineates situation(s) when tests are added to the initial order. This includes reflex and additional tests.
When this test is ordered, the additional tests may be performed and charged.
Antimicrobial agent appropriate to the organism and specimen source will be chosen from the panels listed below.
Gram-negative bacillus: amikacin, ampicillin, ampicillin/sulbactam, cefazolin, cefdinir, cefepime, ceftazidime, ceftriaxone, ciprofloxacin, ertapenem, fosfomycin, gentamicin, levofloxacin, meropenem, nitrofurantoin, piperacillin/tazobactam, ticarcillin/clavulanic acid, tobramycin, and trimethoprim/sulfamethoxazole (TMP/SMX). The 2011 CLSI breakpoints for cephalosporins and carbapenems have been implemented. Confirmation testing for extended spectrum beta-lactamases is performed on Escherichia coli, Klebsiella species, and Proteus mirabilis isolates by request. KPC molecular testing and/or modified Hodge testing are available for individual order.
Staphylococcus species: clindamycin, levofloxacin, linezolid, minocycline, mupirocin, nitrofurantoin, oxacillin, penicillin, rifampin, TMP/SMX, and vancomycin. D-test is performed on all isolates for detection of clindamycin resistance.
Enterococcus species: gentamicin synergy, levofloxacin, linezolid, nitrofurantoin, penicillin, and vancomycin.
Streptococcus species: cefepime, ceftriaxone, erythromycin, levofloxacin, meropenem, penicillin, tetracycline, TMP/SMX, and vancomycin.
Haemophilus species: ampicillin if beta-lactamase negative.
Neisseria gonorrhoeae: cefixime, ceftriaxone ciprofloxacin, tetracycline
Helicobacter pylori: amoxicillin, ciprofloxacin, clarithromycin, metronidazole, tetracycline
For antimicrobial agents not part of above panels: testing is available upon special request at an additional charge per antimicrobial (eg, ceftaroline, colistin, daptomycin, tigecycline).
See the following in Special Instructions:
-Antimicrobial Susceptibility Tests
-Infectious Material
Special Instructions and Forms Describes specimen collection and preparation information, test algorithms, and other information pertinent to test. Also includes pertinent information and consent forms to be used when requesting a particular test
Method Name A short description of the method used to perform the test
Minimum Inhibitory Concentration (MIC) by Agar Dilution
Reporting Name A shorter/abbreviated version of the Published Name for a test; an abbreviated test name
Aliases Lists additional common names for a test, as an aid in searching
Bacterial Susceptibility Testing
Extended Spectrum Beta-Lactamase (ESBL)
MIC (Minimum Inhibitory Concentration)
Minimum Inhibitory Concentration (MIC)
Pneumococcus Susceptibility
Streptococcus pneumoniae Susceptibility
Susceptibility Testing
Linezolid (Zyvox)
Specimen Type Describes the specimen type needed for testing
Specimen Required Defines the optimal specimen. This field describes the type of specimen required to perform the test and the preferred volume to complete testing. The volume allows automated processing, fastest throughput and, when indicated, repeat or reflex testing.
Testing is not performed on select agents such as Brucella species, Francisella species, or Bacillus anthracis.
Container/Tube: Agar slant or other appropriate media
Specimen Volume: Organism in pure culture
Collection Instructions:
1. Organism must be in pure culture, actively growing.
2. Place specimen in a large infectious container (Supply T146) and label as an etiologic agent.
Additional Information: Specimen source and organism identification are required.
Forms: If not ordering electronically, submit a Microbiology Request Form (Supply T244) with the specimen.
Reject Due To Identifies specimen types and conditions that may cause the specimen to be rejected
| Hemolysis | NA |
| Lipemia | NA |
| Icterus | NA |
| Other | Agar plate |
Specimen Stability Information Provides a description of the temperatures required to transport a specimen to the laboratory. Alternate acceptable temperature(s) are also included.
| Specimen Type | Temperature | Time |
|---|---|---|
| Varies | Ambient (preferred) | |
| Refrigerated | ||
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Antimicrobial susceptibility testing (AST) determines the minimum inhibitory concentration (MIC) (of a series of increasing concentrations) of antimicrobial incorporated in agar plates, which inhibits the growth of bacteria inoculated on the surface of the agar.
Prior studies have determined for each antimicrobial a "breakpoint" or MIC value, above which the bacterium being tested would be considered resistant to that agent. The most important factor contributing to the determination of the "breakpoint" is probably the expected serum concentration of antimicrobial achieved after giving the usual dosage. The "category" result ("susceptible" or "resistant") provided along with the MIC is determined by comparing the MIC result with the "breakpoint."
AST should be performed on pure culture isolates of pathogenic (or potentially pathogenic in special situations) bacteria grown from specimens that have been appropriately collected so as not to confuse clinically significant isolates with normal flora.
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.
Results are reported as MIC in mcg/mL and as susceptible, intermediate, or resistant according to the CLSI guidelines.
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.
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 Provides recommendations for further in-depth reading of a clinical nature
Cockerill FR: Conventional and genetic laboratory tests used to guide antimicrobial therapy. Mayo Clin Proc 1998;73:1007-1021
Method Description Describes how the test is performed and provides a method-specific reference
An agar dilution method is used for routine testing. 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 16 to 18 hours at 35 degrees C. Complete inhibition of all but 1 colony or a very fine residual haze represents the end-point.(Antimicrobial susceptibility testing. In Color Atlas and Textbook of Diagnostic Microbiology. Fifth edition. Edited by EW Koneman, SD Allen, WM Janda, et al. Philadelphia, Lippincott-Raven Publishers, 1997, pp 785-856)
Day(s) and Time(s) Test Performed Outlines the days and times the test is performed. This field reflects the day and time the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time required before the test is performed. Some tests are listed as continuously performed, which means assays are performed several times during the day.
Monday through Sunday; continuously
Analytic Time Defines the amount of time it takes the laboratory to setup and perform the test. This is defined in number of days. The shortest interval of time expressed is "same day/1 day," which means the results may be available the same day that the sample is received in the testing laboratory. One day means results are available 1 day after the sample is received in the laboratory.
Maximum Laboratory Time Defines the maximum time from specimen receipt at Mayo Medical Laboratories until the release of the test result
Specimen Retention Time Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
Performing Laboratory Location The location of the laboratory that performs the test
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's instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR), Investigation Use Only (IUO) product, or a Research Use Only (RUO) product.
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 Medical Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.
Antimicrobial Susceptibility, Aerobic Bacteria, MIC
87186-Per organism for routine battery
87187-Per drug and per organism for drugs not in routine battery
87184-Disk diffusion method (if appropriate)
Beta Lactamase
87185 (if appropriate)
KPC PCR
87150 (if appropriate)
Carbapenemase Detection, Modified Hodge Test
87185 (if appropriate)
LOINC® Code Information Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the result codes returned for this test or profile.
| Result ID | Reporting Name | LOINC Code |
|---|---|---|
| ZMMLS | Susceptibility, Aerobic, MIC | In Process |
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