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microbial diseases laboratory BRANCH

Test Name - Carbapenemase Gene Detection

Pre-Approval Required

​​Carbapenem resistant Escherichia coli, Klebsiella oxytoca, Klebsiella pneumonia, Klebsiella aerogenes, Enterobacter species and Pseudomonas aeruginosa that meet the criteria listed in the FAQ and ‘Acceptable Specimen type for testing section’ can be routinely submitted. Please routinely submit Pan Non-susceptible Pseudomonas aeruginosa, Acinetobacter spp., and Enterobacterales isolates, including other than those listed above for surveillance testing. Testing is available for carbapenem resistant Enterobacterales other than those listed above and Acinetobacter spp. , but pre-approval is required prior to submission. Contact the HAI program at or MDL at for pre-approval.

Supplemental Information or Form

Form Lab AST (PDF)

MDL Expanded Carbapenemase Testing Frequently Asked Questions (FAQ​​)​

Performed on Specimens From

Human source

Acceptable Sample/Specimen Type for Testing

Pure culture isolate.

​​Isolate must be identified to at least the genus level by the submitter.

Mixed cultures received in MDL will not be tested.

​Isolates must meet one of the following criteria

Please Note: If the species is intrinsically resistant to a carbapenem antibiotic (for example Proteus and Morganella morganii and imipenem) they must also be resistant to another relevant carbapenem. Please refer to the FAQ and contact MDL to request a review of the available AST results prior to submission as needed.

​​​Carbapenem resistant Enterobacterales (CRE)

Enterobacterales must be resistant to at least one relevant carbapenem, i.e., imipenem, ertapenem, doripenem, or meropenem.

Carbapenem-resistant Pseudomonas aeruginosa(CRPA)

Submit carbapenem-resistant P. aeruginosa isolates that are resistant to imipenem, meropenem, or doripenem by standard AST methods (i.e., MIC of ≥ 8 µg/mL) and Nonsusceptible (i.e., intermediate or resistant MIC ≥ 16µg/ml) to cefepime or ceftazidime.

​​Carbapenem resistant Acinetobacter spp. (CRAB)

Pan-NS Acinetobacter can be routinely submitted to CDPH without preapproval. Testing of other carbapenem resistant CRAB is available at MDL and the ALRN regional laboratory but requires pre-approval before submission. 

Very rarely isolates can carry a carbapenemase gene and not express it. These isolates may test positive for a carbapenemase gene via a genotypic assay but not demonstrate carbapenem resistance in a phenotypic assay such as AST. Isolates with a positive genotypic result that do not demonstrate carbapenem resistance can be tested at MDL or sent out to other ARLN labs for further testing. Please contact MDL prior to submission of these or other unusual isolates. 

​Minimum Volume Required


Storage & Preservation of Sample/Specimen Prior to Shipping

Store at ambient temperature


Ship cultures on nonselective nutrient or similar agar in tubes with leak-proof screw cap closures.

Sample/Specimen Labeling

Testing subject to CLIA regulations require two patient identifiers on the specimen container and the test requisition

Shipping Instructions which Include Specimen Handling Requirements

Ship at ambient temperature.

Test Methodology

Carbapenemase Genotypic Detection: PCR based assay

Expanded AST (ExAST): Test provided through Antibiotic Resistance Laboratory Network (ARLN). Please see MDL Expanded Carbapenemase Testing Frequently Asked Questions (FAQ) for submission instruction.

Turnaround Time

Carbapenemase Genotypic Detection: 7 business days

Expanded AST (ExAST): Defined by ARLN testing laboratory

Interferences & Limitations


Additional Information


MDL Points of Contact

MDL – Bacterial Diseases Section (510) 412-3903

Monday-Friday 8 AM to 5 PM PT


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