Antimicrobial Susceptibility Testing for Pure Cultures of Select Organisms

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

Abiotrophia spp.
Aerococcus spp.
Bacillus spp. & Related Genera (excluding B. anthracis)
Bacteroides spp.
Corynebacterium spp.*
Coryneforms§*
Granulicatella spp.
Gemella spp.
HACEK Group¥ .
Lactobacillus spp.
Leuconostoc spp.
Lactococcus spp.
Micrococcus spp.
Moraxella catarrhalis
Pasteurella spp.
Pediococcus spp.
Rothia mucilaginosa

§ Includes the Genera Arcanobacterium, Arthrobacter, Brevibacterium, Cellulomonas, Cellulosimicrobium, Dermabacter, Leifsonia, Microbacterium, Oerskovia, Rothia, Trueperella, and Turicella.
¥ Aggregatibacter spp., Cardiobacterium spp, Eikenella corrodens, Kingella spp. Excludes Haemophilus spp.

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

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.

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.

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.

Clinical illness with symptoms suggestive of bacterial infection.

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.

• 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.

Testing is performed, in whole or in part, using an IVD testing kit which has not been fully validated/verified for the following organisms: Bacillus spp. and related genera (excluding B. anthracis), Pasteurella spp., Moraxella catarrhalis, Bacteroides spp., Aeromonas spp. and Micrococcus spp.

Testing is performed, in whole or in part, using a “Research Use Only” testing kit which has not been fully validated/verified for the organism Parabacteroides spp.

Testing is performed using a test which has not been fully validated/verified for this particular sample type for the following organisms: Granulicatella spp., Leuconostoc spp., Abiotrophia spp., HACEK group, Lactobacillus spp., Pediococcus spp., Aerococcus spp., Gemella spp., Lactococcus spp., and Rothia mucilaginosa. 

• Broth microdilution using commercially-available lyophilized Sensititre® panels.
  
• Interpretations are based on the most recent CLSI guidelines. 
• Interpretations for rare or undescribed taxons may not be possible.

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.

1. Clinical and Laboratory Standards Institute. 2026. Performance Standards for Antimicrobial Susceptibility Testing; M100-Ed36. 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.