Eligible Submitters
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Test is available to all pre-approved submitters within the state of California. Submissions from clinical laboratories should route through the corresponding county public health laboratories (PHL), unless otherwise arranged.
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Test Methodology
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Carbapenemase Gene Detection: PCR based assay (Xpert Carba-R). This is a FDA-approved test.
Expanded AST (ExAST): Test provided through Antibiotic Resistance Laboratory Network (ARLN). Please see MDL Expanded Carbapenemase Testing Frequently Asked Questions (FAQ) for submission instruction.
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Reflex Testing
Criteria |
Isolates detected positive for a carbapenemase gene may be reflexed to Whole Genome Sequencing or other testing for public health investigation or surveillance purposes.
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Pre-Approval Required |
Carbapenem resistant
Escherichia coli,
Klebsiella oxytoca,
Klebsiella pneumoniae,
Klebsiella aerogenes,
Enterobacter species,
Pseudomonas aeruginosa, and
Acinetobacter baumannii that meet the criteria listed in the Expanded Carbapenemase Testing Services Frequently Asked Questions (FAQs) and ‘Acceptable Sample/Specimen Type for Testing’ can be routinely submitted (pre-approval not required).
Please routinely submit pan-non susceptible
Pseudomonas aeruginosa,
Acinetobacter baumannii, and
Enterobacterales isolates for surveillance testing (pre-approval not required). Testing is available for carbapenem resistant
Enterobacterales other than those listed above; please refer to the criteria listed in the FAQs.
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Supplemental Information and Required Form(s) |
Use MDL Lab Web Portal for ordering the test, select Test Requisition for "Antimicrobial Susceptibility Testing– AST".
For submitters who do not have access to the MDL LWP; please contact
MDL.Submissions@CDPH.ca.gov for additional information.
MDL Expanded Carbapenemase Testing Frequently Asked Questions (FAQs) - April 2026
Please attach a copy of AST results, and other available molecular or phenotypic test results, to the requisitions when submitting isolates for carbapenemase testing.
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Required Specimen Type(s)
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Pure culture isolates.
Isolate must be identified to at least the genus level for
Enterobacterales and the species level for Pseudomonas aeruginosa and
Acinetobacter baumannii by the submitter.
Isolates
must meet one of the following criteria:
Carbapenem resistant Enterobacterales (CRE)
Enterobacterales must be resistant to at least one relevant carbapenem, i.e., imipenem, ertapenem, or meropenem (i.e., minimum inhibitory concentrations (MIC) of ≥4 µg/mL for imipenem or meropenem, or ≥2 µg/mL for ertapenem).
Carbapenem-resistant
Pseudomonas aeruginosa (CRPA)
Submit carbapenem-resistant
P. aeruginosa isolates that are resistant to imipenem or meropenem by standard AST methods (i.e., MIC of ≥ 8 µg/mL)
and non-susceptible (i.e., intermediate or resistant MIC ≥ 16µg/ml) to cefepime, ceftazidime, or ceftolozane-tazobactam.
Carbapenem resistant Acinetobacter baumannii
(CRAB)
Submit carbapenem-resistant
A. baumannii isolates that are resistant to imipenem or meropenem by standard AST methods (i.e., MIC of ≥8 μg/mL).
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 FAQs and contact MDL at MDL.Submissions@CDPH.ca.gov to request a review of the available AST results prior to submission as needed. On occasion, 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.
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Minimum Volume Required |
Not applicable
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Specimen Stability
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It is recommended to store pure culture isolates at room temperature (15 to 25 °C) for up to 7 days; or refrigerated (2 to 8 °C) up to 14 days. Limit subpassages as this may lead to plasmid loss.
If isolates are being stored more than 14 days prior to shipping, it is recommended to freeze it in Trypticase Soy Broth (TSB) with 15% glycerol (–20 °C or lower) for long-term storage.
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Rejection Criteria
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Storage/Transport Conditions
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Ship cultures on nonselective nutrient or similar agar in tubes with leak proof screw cap closures.
Ship isolates grown on agar slants at ambient temperature (up to 35°C), or ship cultures frozen in trypticase soy broth (TSB) with 15% glycerol on dry ice. Isolates that are improperly frozen or shipped at high temperatures (>35°C) may lose viability.
Ship isolates as soon as possible to ensure viability and to avoid loss of antimicrobial resistance mechanisms.
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Transport Medium,
if applicable
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Ship cultures on nonselective nutrient or similar agar in tubes with leak-proof screw cap closures.
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Specimen Labeling |
Testing subject to CLIA regulations. Minimum label requirement on the specimen includes patient name and one other identifier (e.g. preferably submitter sample ID, or patient medical record number, or patient date of birth) on the specimen container and the test requisition.
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Shipping Instructions and Specimen Handling Requirements
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The shipper is responsible for making sure that all samples and specimens are packaged and shipped according to current federal and state packaging and shipping regulations for Category A infectious substance and/or Category B diagnostic samples.
Ship to: California Department of Public Health
Microbial Diseases Laboratory
ATTN: Bacterial Diseases Section
850 Marina Bay Parkway, Specimen Receiving Room B106
Richmond, CA 94804
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Specimen Collection Instructions, if applicable
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Not applicable
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Turnaround Time |
Carbapenemase Genotypic Detection: 7–10 business days
Expanded AST (ExAST): Defined by ARLN testing laboratory
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Interferences & Limitations | 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.
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Reference Range | Not Detected
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Additional Information |
MDL Expanded Carbapenemase Testing Frequently Asked Questions (FAQs) - April 2026
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MDL Point of Contact |
MDL - Bacterial Diseases Section: 510-412-3700
Monday – Friday 8 AM to 5 PM PT
Email: MDL.Submissions@CDPH.ca.gov
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