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MIcrobial diseases laboratory branch​

Expanded Carbapenemase Te​​sting S​​​​​​​​​ervices
Frequently Asked Questio​​ns (​F​AQs) F​eb​​ruary 5, 2025 Update

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  1. Wha​t types of samples should we send?​

  1. ​​Carbapenem-resistant​ Enter​obacterales (CRE):

    Submit carbapenem-resistant Escherichia coli, Klebsiella oxytoca, Klebsiella pneumoniae, and Enterobacter spp. that are resistant to imipenem, meropenem or ertapenem by standard antimicrobial susceptibility testing (AST) methods (i.e., minimum inhibitory concentrations (MIC) of ≥ 4 µg/mL for imipenem or meropenem, or ≥2 µg/mL for ertapenem).​​​
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  2. 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 nonsusceptible (i.e., intermediate or resistant MIC ≥ 16µg/ml) to cefepime,  ceftazidime, ​or ceftolozane-tazobactam.​​​


  3. Carbapenem-resistant Acinetobacter baumannii (CRAB):

    ​Carbapenem-resistant Acinetobacter baumannii (CRAB) isolates are defined by resistance to imipenem or meropenem by standard susceptibility testing methods (i.e., MIC of ≥8 μg/mL). 

  4. ​Other C​RE not listed in (1.a):

    ​​​Testing is available for other CRE, including Providencia, Proteus, Morganella, Citrobacter, and Serratia spp. 
      • ​Providencia, Proteus, and Morganella spp. are intrinsically resistant to imipenem; please only submit isolates that are resistant to meropenem or ertapenem by standard AST methods (i.e., MIC of ≥4 µg/mL for meropenem, or MIC of ≥2 µg/mL for ertapenem). 
      • Serratia spp. Isolates resistant to carbapenems and susceptible to 3rd generation cephalosporins indicate a SME gene; do NOT submit these isolates. Please only submit Serratia spp. that are resistant to meropenem or ertapenem by standard AST methods (i.e., MIC of ≥4 µg/mL for meropenem, or MIC of ≥2 µg/mL for ertapenem).

    ​​If your institution uses nonstanadard AST or does not test all of the requested drugs, we will review the provided AST results and perform testing on a case-by-case basis.​ 
    ​​​

  1. ​​​Pan-nonsusceptible CRE, and pan-resistant CRPA/CRAB isolates: A pan-nonsusceptible (pan-NS) isolate is defined as an isolate nonsusceptible to all drugs tested to date. A pan-resistant (pan-R) isolate is defined as an isolate resistant to all drugs tested to date. Routinely submit all pan-nonsusceptible CRE (including those listed in 1.d), and all pan-R CRPA and CRAB to MDL for surveillance purposes. These isolates will either be tested at MDL or an AR Lab Network regional laboratory. Slants and shipping materials can be provided to submitting clinical laboratories at no charge. Detailed information for submittal criteria, forms, and shipping instructions can be found at: ARLN Lab Network Test Menu. Please contact the HAI Program at HAI Program​ and MDL Bacterial Diseases Section (BDS) at ​MDLBDS@cdph.ca.gov​​ for any assistance. 

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  2. ​Isolates from patients being investigated as part of a cluster or outbreak, or containing novel resistance mechanisms, may be referred for Whole Genome Sequencing (WGS) by the CDPH HAI Program. ​In general, approval is required by the HAI Program and the MDL Molecular Characterization Unit (MCU) prior to submission. Contact the HAI Program at HAI Program and MDL MCU at MDL.Submissions@CDPH.ca.gov​ prior to submitting isolates for submittal instructions.

  3. ​​​CRE Isolates must be identified to at least the genus level by the submitter. CRPA and CRAB must be identified to the species level by the submitter. 

  4. Mixed cultures received by MDL will not be tested.​​​

  1. ​How should samples be sent in for the laboratory testing?​
  1. Submit isolates to MDL BDS using the MDL Lab Web Portal (LWP). It is also known as Electronic Test Orders and Reporting (ETOR). For submitters that do not have access to the LWP, please contact MDL at MDL.Submissions@CDPH.ca.gov​​.
    • In the Submitter Information section, the Facility Name and contact information should be autofilled with information provided during registration for portal access. Please select the Original Healthcare Facility from the drop down or choose “Other” and type in the full name of the original health care facility where it says Specify Other.​
    • ​​In Patient Information, be sure to search for the patient name before creating a new record. To create a new record, press the + symbol and enter the following required information: 
      • ​​​Last Name and First Name
      • ​Date of Birth
      • State
      • Gender Identity​
    • Under Specimen Information, please check the box for CRO Test(s) Requested that corresponds with the sample being submitted and enter the following required information: ​​
      • ​Submitter Specimen # (should be a unique identifier for that specimen, i.e. Patient MRN does not work)
      • Date Collected
      • Submitter’s Identification of Organism
      • Material Submitted
      • Source

    • ​​​If isolate is pan-non-susceptible (pan-NS) or being submitted for other further testing available through the AR Lab Network, please indicate this in the Clinical Findings and Symptoms section.

    • Once the requisiton form has been completed (click “Submit” at the bottom of the page), please print requisitions for all samples being submitted and include in the shipment to MDL. 

    • ​Please provide printouts of any organism identification (ID), AST results, phenotypic carbapenemase testing results, or other available molecular testing results for each specimen with the requisition when submitting to MDL.

    • Shipping instructions and submittal forms for testing only available through the AR Lab Network will be provided by the HAI Program when testing is approved. Shipping to MDL instead of the AR Lab Network regional lab may result in delays in testing.

    • Transport medium: Nonselective nutrient agar slant or equivalent.

    • Ship at ambient temperature (up to 35°C).  If sending frozen, isolates should be stored/transported in a cryopreservative. Additional test information and shipping instructions can be found on our website in our MDL Services and Test Catalog. 

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  1. ​Please contact the HAI Program at HAI Program, and MCU/MDL at MDL.Submissions@CDPH.ca.gov​ to get approval to submit isolates for WGS. Once the submission has been approved, the submittal form and shipping instructions will be provided.

  1. What is the shipping address?

​California Deparment of Public Health
Microbial Diseases Laboratory
850 Marina Bay Parkway
MS B106​
Richmond, CA 94804

  1. Who can submit isolates for testing?​​

​Isolates will be accepted from California Local Public Health Laboratories ​ only. Isolates will not be accepted directly from hospitals or other healthcare facilities unless approved by the MDL, and the Local Public Health Laboratories or CDPH HAI Program.​​ 
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  1. ​If I already have molecular testing results for carbapenemase gene detection, can I still submit my sample?
​

​​​Yes.​ CRE, CRPA, or CRAB isolates that have tested negative for known carbapenemase genes by a validated molecular test method can be submitted to MDL for  MBL STAR​​®-Carba testing (molecular testing of these isolates will not be repeated at MDL). CRE, CRPA, or CRAB isolates that have tested negative for known carbapenemase genes but positive by a phenotypic test may indicate a novel or unusual carbapenemase; ​​in these cases, isolate may be reflexed to WGS or the AR Lab Network for additional testing.   ​​


  1. Can isolates be submitted for real-time PCR testing for carbapenemase gene detection​​​
​

​Yes. CRE, CRPA, or CRAB isolates determined to be carbapenemase-producers by a phenotypic test but with no PCR previously performed may be submitted to MDL for carbapenemase gene testing by real-time PCR.​

  1. Do I need to submit isolates for the SensititreTM AST?​​​
​

​No.​ ​CRE, CRPA, and CRAB isolates are currently selected for comfirmatory Sensititre AST based on the priorities detailed below. The Sensititre AST is for surveillance purposes only. 

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  1. ​​​​​Pan-Resistant and pan-Non-​Susceptible CRE, CRPA and CRAB isoaltes. 

  2. Non-KPC CRE isolates that are positive for blaNDM, blaOXA-48-like, blaVIM, and blaIMP by real-time PCR​​​​.
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  3. ​​​CRPA isolates that are positive for carbapenemase production or/and carbapenemase gene ( blaKPC, blaNDM, blaIMP, blaVIM and blaOXA-48-like)​​.

  4. Other isolates that are associated with outbreaks and/or requested by CDPH HAI Program.

  1. Can Enterobacterales be submitted for Expanded AST (ExAST) for hard-to-treat infections?​​​​

Yes. With approval from the HAI Program and MDL, ExAST on CRE isolates that are highly resistant (​non-susceptible to all beta-lactams​) or possess metallo-beta-lactamase genes (NDM, VIM, IMP) for clinical-decision making purposes is available directly through the ARLN Regional Lab. Det​ailed information for submittal criteria, forms, and shipping instructions can be found here:   ARLN Lab Test Menu.​

Contact the HAI Program at HAI Program  and MDL BDS at MDLBDS@cdph.ca.gov​ prior to submitting isolates. Submitting isolates to MDL may result in delays in testing.


  1. Can duplicate isolates be submitted for testing?
​

​No.​ Duplicates are defined as isolates from the same patient within the past 12 months that have the same organism ID. If a carbapenemase mechanism was identified in the original isolate, do not submit the new isolate. If a carbapenemase mechanism was not identified in the original isolate, but the AST profile is not significantly different, do not submit the new isolate. However, if there is a special need to test the duplicate isolate, please contact HAI Program for approval prior to submission.


  1. Can isolates be submitted for WGS only?
​

​Yes.​ Prior approval is required by the HAI Program and MDL prior to submission. Please contact the HAI Program at HAI Program , and MCU/MDL at MDL.Submissions@CDPH.ca.gov​ to get approval to submit isolates for WGS. Once the submission has been approved, the submittal form and shipping instructions will be provided.

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  1. What is the turn-around-time (TAT) for testing?​​

  • ​ Turn-around-times may be extended during holiday weeks.

  • MBT STAR®​-Carba testing results will be available within 7-10 business days after isolate receipt for phenotypic testing.

  • Real-time PCR testing results will be available within 7-10 business days after isolate receipt for genotypic testing.

  • Sensititre​ AST results will be available within 14 business days after isolate receipt for this testing. (Surveillance only)

  • WGS results will be available within 14-21 business days after receipt by MCU/MDL. (Epidemiologic purposes only)

  • Refer to the WA ARLN test catalog for turn-around-times for isolates forwarded to the AR Lab Network regio​nal lab for further testing. ​​

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