Antimicrobial Susceptibility Testing (AST) of Nocardia and Aerobic Actinomycetes

Consistent with O. Reg. 671/92 of the French Language Services Act, laboratory testing information on this page is only available in English because it is scientific or technical in nature and is for use only by qualified health care providers and not by members of the public.

This page provides testing information for antimicrobial susceptibility testing of Nocardia and Aerobic Actinomycetes at Public Health Ontario (PHO).

For information regarding other testing options, refer to the following PHO webpages:

Updates

This a new Test Information Sheet, separating susceptibility testing of Nocardia and Aerobic Actinomycetes from previous Fungus Culture-Susceptibility test information sheet
The following labstract(s) have been removed and information is included in this document:

LAB-SD-061 Susceptibility Testing of Yeast, Aspergillus and Nocardia

*Uncontrolled print copy. Valid only on day of print: 21 Nov 2024.

Testing Indications

Susceptibility testing for Nocardia species and other Aerobic Actinomycetes is performed upon request for patients with serious invasive infection.

Including, for example, the following organisms:

Nocardia spp.
Gordonia spp.
Tuskamurella spp.
Dietzia spp.
Streptomyces spp.
Other Aerobic Actinomycetes

Acceptance/Rejection Criteria

Isolates must be received as pure culture only. Samples received in a mixed or contaminated state will be cancelled upon receipt.

For Nocardia and Aerobic Actinomycetes susceptibility, testing can be performed on isolates repeatedly isolated from the same patient up to one time per week. Requests for repeat susceptibility testing within 7 days of each other will be cancelled and referred back to the most recent result.

Specimen Collection and Handling

Specimen Requirements

Test Requested

Required Requisition(s)

Specimen Type

Minimum Volume

Collection Kit

AST – Nocardia or Aerobic Actinomycetes

Reference Bacteriology Requisition

Pure culture of Nocardia or other Aerobic Actinomycetes isolate

N/A

Appropriate culture media for growth (slant or plate) or Swab from pure culture

(see note # 3 below)

Submission and Collection Notes

Complete all fields of the requisition form, fields a-c are mandatory:

Test(s) requests and indications for testing.
Patient setting/population/source.
Immune status – REQUIRED - important to note on the requisition if patient is in ICU, has had a transplant, has a haematological malignancy, or is otherwise immunocompromised.
Organism identification must be provided or requested by the submitting laboratory.
Any special drug requests – these must be discussed with the Microbiologist prior to submission.

Label the culture container(s) with the patient’s first and last name, date of collection of the specimen source, and one other unique identifier such as the patient’s date of birth or Health Card Number. For additional information see: Criteria for Acceptance of Patient Specimens. Failure to provide this information may result in rejection or testing delay.

Place isolate in a biohazard bag and seal. Store cultures at room temperature or 28°C until submitted. Specimens should be shipped to the lab ASAP.

Limitations

Culture must be submitted in pure state. Isolates received mixed (with other bacteria or fungi) or with contamination will result in cancellation.

Storage and Transport

Specimens should be stored at room temperature or 28°C following collection and shipped to PHO’s laboratory as soon as possible. All clinical specimens must be shipped in accordance to the Transportation of Dangerous Good Act.

Requisitions and Kit Ordering

Test Frequency and Turnaround Time (TAT)

The Nocardia and aerobic Actinomycetes susceptibility testing is set-up Mondays, Tuesdays and Fridays at PHO’s laboratory-Toronto.

Turnaround time for susceptibility testing from pure culture organisms, after receipt by PHO’s laboratory Toronto is within 7 business days

Test Methods

Antifungal susceptibility testing of Nocardia and Aerobic Actinomycetes is performed by micro broth dilution.

Interpretations are reported where available according to CLSI M24S Performance Standards for Susceptibility Testing of Mycobacteria, Nocardia spp., and Other Aerobic Actinomycetes. Results reported as ‘No Interpretation’ indicate that CLSI has not developed any clinical breakpoints to determine susceptibility or resistance.

Algorithm

Organism Group	Susceptibility testing	Drugs Tested	Notes
Nocardia and Aerobic Actinomycetes	Routinely performed on isolates from patients with serious invasive infection.	Amoxicillin-clavulanate, amikacin, gentamicin, tobramycin, ceftriaxone, ciprofloxacin, clarithromycin, imipenem, doxycycline, minocycline, TMP-SMX, linezolid

Interpretation

The following table provides possible test results with associated interpretations:

Organism	Result	Comments
Nocardia and Aerobic Actinomycetes	MIC values are routinely reported for: Amoxicillin-clavulanate, amikacin, gentamicin, tobramycin, ceftriaxone, ciprofloxacin, clarithromycin, imipenem, doxycycline, minocycline, TMP-SMX, linezolid	Interpretations are reported based on CLSI M24S.

Organism

Result

Comments

Nocardia and Aerobic Actinomycetes

MIC values are routinely reported for:

Amoxicillin-clavulanate, amikacin, gentamicin, tobramycin, ceftriaxone, ciprofloxacin, clarithromycin, imipenem, doxycycline, minocycline, TMP-SMX, linezolid

Interpretations are reported based on CLSI M24S.

MIC = minimal inhibitory concentration

Reporting

Results are reported to the physician, authorized health care provider (General O. Reg 45/22, s.18) or submitter as indicated on the requisition.

References

Clinical and Laboratory Standards Institute (CLSI). Principles and Procedures for Detection and Culture of Fungi in Clinical Specimens. 2^nd ed. CLSI guideline M54 (ISBN 978-1-68440-098-0 {Print}; ISBN 978-1-68440-099-7 {Electronic}). Clinical and Laboratory Standards Institute; 2021
Clinical and Laboratory Standards Institute (CLSI). Performance Standards for Susceptibility Testing of Mycobaceria, Nocardia spp. and other Aerobic Actinomycetes. 2^nd ed. CLSI supplement M24S (ISBN 978-1-68440-168-0 {Print}; ISBN 978-1-68440-169-7 {Electronic}). Clinical and Laboratory Standards Institute; 2023.
Hazen, K., Howell, S.A.. Mycology and antifungal susceptibility testing. In: Leber, A.M. Editor. Clinical Microbiology Procedures Handbook. 4^th ed. Washington, D.C.; ASM Press; 2016.