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Antimicrobial Susceptibility Testing for Pure Cultures of Select Organisms (click to review criteria)* *isolates that do NOT meet laboratory criteria will be rejected

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*Accredited by the Standards Council of Canada to Laboratory no. 594 (ISO/IEC 17025)

Requisition Forms

Reference Details


Antimicrobial Susceptibility Testing (AST) is done by the broth microdilution method as described by the Clinical and Laboratory Standards Institute (CLSI) guidelines.

Test Category:
Specialized Testing
Bacterial pathogens
Illnesses and Diseases:
  • Various

Pure cultures of isolates recovered from normally sterile sites and serious wound infections.

Collection Method:

Slants (preferred) or plates of any suitable media and swabs in transport media are all acceptable. Frozen specimens are also acceptable however, may extend turnaround times.

Specimen Processing, Storage and Shipping:

Store slants and swabs at room temperature until shipped for testing. Ship actively growing cultures at room temperature. Frozen specimens should be kept frozen and shipped on dry ice.

Transportation of Dangerous Goods:

Shipping of specimens shall be done by a TDG certified individual in accordance with TDG regulations. For additional information regarding classification of specimens for the purposes of shipping, consult either Part 2 Appendix 3 of the TDG Regulations or section 3.6.2 of the IATA Dangerous Goods Regulations as applicable.

Patient Criteria:

The patient criteria MUST be met for AST to be performed on the following organisms:

Abiotrophia spp., Aerococcus spp., Aeromonas spp..I, Bacillus spp. & Related Genera (excluding B. anthracis), Bacteroides spp., Burkholderia cepacia complex., Corynebacterium spp.*., Coryneforms§*, Granulicatella spp., Gemella spp., HACEK Group (excluding Haemophilus spp.), Lactobacillus spp., Leuconostoc spp., Lactococcus spp., Micrococcus spp., Moraxella catarrhalis, Non-Enterobacteriaceae Gram negative non-fermenters¥, Parabacteroides spp., Pasteurella spp., Pediococcus spp., and Rothia mucilaginosa.

  1. Isolates must relate to a patient that is demonstrating evidence of treatment failure and/or treatment contraindication to standard treatment antimicrobials AND;
  2. Isolates must be recovered from normally sterile sites, in pure culture, within the last 30 calendar days AND/OR;
  3. Confirmatory testing or other specialized testing is required – rationale must be provided, or communication with the laboratory prior to sending must occur

§  Includes the Genera Arcanobacterium, Arthrobacter, Brevibacterium, Cellulomonas, Cellulosimicrobium, Dermabacter, Leifsonia, Microbacterium, Oerskovia, Rothia, Trueperella, and Turicella.

I Includes members of Aeromonas caviae complex, Aeromonas hydrophilia complex, and Aeromonas veronii complex.

¥ Excludes the following organisms: Enterobacteriaceae, Pseudomonas spp., Achromobacter spp., Stenotrophomonas spp., Acinetobacter spp., Neisseria spp., and Bordetella pertussis – related organisms.

Accompanying Documentation:

The most recent version of the Special Bacteriology requisition must be completed, detailing relevant patient criteria for testing. If possible, attach lab results that have already been done at local or provincial laboratories. Samples accompanied by past versions of the requisition may be subject to rejection. Samples submitted without prior contact with the laboratory and/or are missing patient criteria, will be rejected.

  • Testing does NOT include Risk Group 3 organisms, Capnocytophaga spp., capnophiles or Streptobacillus moniliformis.
  • Other non-mycobacterial, non-enteric, Gram positive/negative bacteria which are not described by a CLSI guideline may be tested upon request, and at the discretion of the Special Bacteriology Laboratory.
  • Please note that duplicate bacterial isolates that have been isolated from the same patient, source, and identified as the same organism by the sender, will be rejected unless additional information is provided to warrant testing
  • Acceptance and/or rejection of the additional sample(s) is at the discretion of the Special Bacteriology lab.

Please contact the Special Bacteriology laboratory for further information.

Methods and Interpretation of Results:
  • Broth microdilution using commercially-available Sensititre® panels. 
  • Interpretations are based on the most recent CLSI guidelines. 
  • Interpretations for rare or undescribed taxons may not be possible.
Turnaround Time:

16 calendar days.  In cases where staff or resources are limited final report may be delayed and status of request will be forwarded in a preliminary report.   Frozen, Poor- , or slow-growing isolates may require longer turnaround times.

Phone #: (204) 789-2137
Fax: (204) 784-7509
  1. Clinical and Laboratory Standards Institute. 2024. Performance Standards for Antimicrobial Susceptibility Testing; M100-Ed34. Clinical and Laboratory Standards Institute, Wayne, Pennsylvania.
  2. Clinical and Laboratory Standards Institute. 2016. Methods for Antimicrobial Dilution and Disk Susceptibility Testing of Infrequently Isolated or Fastidious Bacteria; M45-Ed3. Volume 35, Number 17. Clinical and Laboratory Standards Institute, Wayne, Pennsylvania.
  3. Clinical and Laboratory Standards Institute. 2018. Methods for Antimicrobial Susceptibility Testing of Anaerobic Bacteria; Approved Standard-Ninth Edition.  Volume 38. Number 19.  M11-Ed9. Clinical and Laboratory Standards Institute, Wayne, Pennsylvania.
  4. Clinical and Laboratory Standards Institute. 2024.  Methods for Dilution Antimicrobial Susceptibility Tests for Bacteria That Grow Aerobically; M07-Ed12.  Clinical and Laboratory Standards Institute, Wayne, Pennsylvania.  
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