ZMMLS - Specimen: Antimicrobial Susceptibility, Aerobic Bacteria, MIC

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Test ID: ZMMLS    
Antimicrobial Susceptibility, Aerobic Bacteria, MIC

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 reflex tests may be performed and charged separately. All aerobically growing bacteria submitted will automatically have susceptibility testing performed and billed as appropriate. Antimicrobial agent appropriate to the organism and specimen source will be chosen from the panels listed below.

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


Gram-negative bacillus: amikacin, ampicillin, ampicillin/sulbactam, aztreonam, cefazolin, cefdinir, cefepime, ceftazidime, ceftriaxone, ciprofloxacin, ertapenem, fosfomycin, gentamicin, levofloxacin, meropenem, nitrofurantoin, piperacillin/tazobactam, tobramycin, and trimethoprim/sulfamethoxazole (TMP/SMX). The 2011 Clinical and Laboratory Standards Institute (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. Klebsiella pneumoniae carbapenemase (KPC)/New Dehli-metallo-beta-lactamase (NDM) molecular testing, modified Hodge testing, and/or Carbapenemase-Carba NP Test are available for individual order.


Staphylococcus species: ceftaroline (methicillin-resistant Staphylococcus aureus: MRSA only), clindamycin, levofloxacin, linezolid, minocycline, mupirocin, nitrofurantoin, oxacillin, 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

See Helicobacter pylori Diagnostic Algorithm in Special Instructions.

For antimicrobial agents not part of above panels: testing is available upon special request at an additional charge per antimicrobial (eg, ceftolozane/tazobactam, colistin, daptomycin, tigecycline).

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. Do not submit mixed cultures.

2. Place specimen in a large infectious container (Supply T146) and label as an etiologic agent/infectious substance.

Additional Information:

1. Organism identification and specimen source are required for processing.

2. See Infectious Specimen Shipping Guidelines in Special Instructions

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

Specimen Minimum Volume Defines the amount of specimen required to perform an assay once, including instrument and container dead space. Submitting the minimum specimen volume makes it impossible to repeat the test or perform confirmatory or perform reflex testing. In some situations, a minimum specimen volume may result in a QNS (quantity not sufficient) result, requiring a second specimen to be collected.


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








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 TypeTemperatureTime
VariesAmbient (preferred)