CRAB Isolate Submission and Laboratory Testing

On this page:
Criteria for submission of isolates
Appropriate specimen types
Specimen submission forms
Shipping to MDH-PHL
Laboratory testing
Questions

Criteria for submission of isolates

• Acinetobacter baumannii and Acinetobacter baumannii complex isolates meeting the following CLSI breakpoints (current CLSI M100 Performance Standard) should be reported and an isolate submitted to the MDH-PHL. Isolates meeting either the MIC or disk diffusion criteria should be reported.

• Isolates found to carry a carbapenemase enzyme (such as KPC) as demonstrated by testing methods such as polymerase chain reaction (PCR), or other molecular method.

Appropriate specimen types

• A pure, low passage CRAB isolate is preferred as some carbapenem resistance mechanisms are plasmid-based and can be lost with multiple subcultures.
• Submit isolate on a non-inhibitory, non-selective agar plate or slant (e.g., Sheep blood agar, etc.).

Specimen submission forms

MDH-PHL requests the following documentation to be included with each isolate submission:

• General Infectious Disease Laboratory Submission Form (PDF) (required):
  
  • Be sure to include the following information:
    • project number (2178)
    • patient information
    • facility information
    • specimen source
    • collection date
    • isolate genus/species

• Antimicrobial Susceptibility Testing (AST) Report Printout (required):
  • Submit the raw data MIC profile obtained from your AST Instrument (i.e. Vitek2, Microscan, Phoenix)
    • Note: for manual Microscan users, a handwritten AST report is acceptable
  • If disk diffusion or gradient diffusion testing is performed, document results on the CRE/CRA/CRPA Supplemental Submission Form and submit with isolate

• CRE/CRA/CRPA Isolate - Supplemental Submission Form (PDF)
  (optional - print and fill out manually):
  • This form was created to allow MLS laboratories to record results for any CRAB testing performed prior to isolate submission.
  • Results could include: Carbapenem E-test Results, Carbapenem Disk Diffusion, Select Antimicrobial Agent, and/or carbapenemase testing (e.g., Verigene, PCR).

Shipping to MDH-PHL

• Ship specimens to MDH-PHL by an overnight delivery service or local courier.
  Note: It is the responsibility of the submitting laboratory to determine the appropriate packaging and shipping for patient specimens and culture isolates. See U.S. Department of Transportation Regulations: Hazardous materials shipping for more information.

• Isolates can be shipped at either room temperature or with refrigeration.

• Ship to:
  Minnesota Department of Health
  Public Health Laboratory
  Attn: Biological Accessioning
  601 Robert St. N
  St. Paul, Minnesota 55155-2531

Laboratory testing

• MDH-PHL performs testing on submitted CRAB isolates:
  • Isolate identification is confirmed through a combination of MALDI-TOF Mass Spectrometry and biochemical methods.
• If the CRAB isolate meets the surveillance case definition, the isolate will be further characterized by polymerase chain reaction (PCR) testing for the presence of the five most common carbapenemase genes (bla_KPC, bla_NDM, bla_OXA-48, bla_IMP, bla_VIM), and three CRAB-specific OXA genes (bla_OXA-23, bla_OXA-24, and bla_OXA-58).

Questions?

MDH-PHL Microbiology Laboratory is available during regular business hours for consultation on CRAB testing and result interpretation at 651-201-5073.