Carbapenemases: Difference between revisions
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*Directed by susceptibility testing |
*Directed by susceptibility testing |
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*For ESBLs and AmpCs: |
*For ESBLs and AmpCs, consider: |
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**[[Ceftazidime-avibactam]] (not active against metallo-β-lactamases) |
**[[Ceftazidime-avibactam]] (not active against metallo-β-lactamases) |
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**[[Meropenem-vaborbactam]] (limited activity against metallo-β-lactamases and oxacillinases) |
**[[Meropenem-vaborbactam]] (limited activity against metallo-β-lactamases and oxacillinases) |
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*For metallo-β-lactamases: |
*For metallo-β-lactamases, consider: |
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**[[Colistin]] |
**[[Colistin]], though increasing resistance |
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**[[Tigecycline]] |
**[[Tigecycline]] |
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**[[Fosfomycin]] |
**[[Fosfomycin]] |
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**[[Aztreonam-avibactam]] |
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**[[Cefiderocol]] |
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**[[Eravacycline]] |
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**[[Plazomicin]] |
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*For carbapenem-resistant [[Pseudomonas aeruginosa]], consider: |
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**[[Cefiderocol]] |
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**[[Imipenem-relebactam]] |
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[[Category:Gram-negative bacilli]] |
[[Category:Gram-negative bacilli]] |
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Revision as of 21:19, 14 September 2020
Background
- Enzymes that hydrolyze carbapenems
- Includes members of most Ambler classes
- Class A: KPC
- Class B: NDM, IMI, VIM
- Class C: AmpCs
- Class D: OXA-48
Identification
- Screening is done by identifying isolates with decreased susceptibility to one or more carbapenems
- Testing "not susceptible" to ertapenem is the most sensitive indicator
- Typically also resistant to third-generation cephalosporins, as well, with the exception of SME in Serratia marcescens and IMI
- A modified Hodge test can confirm the presence of a carbapenemase, but is no longer routinely recommended
- Modified carbapenem inactivation method (mCIM)
- Place meropenem disc in a suspension of the test isolate, and incubate at 35ºC for 4 hours
- Remove disc, squeezing out excess fluid, and place on a lawn of susceptible Escherichia coli
- Positive for carbapenemase if zone diameter is clear ≤15 mm (or pinpoint colonies up to 18 mm)
- Negative if zone diameter is clear ≥19 mm
- Indeterminate if clear diameter 16 to 18 mm, or pinpoint colonies ≥19 mm
- EDTA-modified carbapenem inactivation method (eCIM)
- Only done if mCIM is positive, to test for metallo-β-lactamases
- As above for mCIM, but adds EDTA to the tube
- Positive for metallo-β-lactamase if zone diameter increases ≥5 mm from mCIM
- Ignore pinpoint colonies within any zones of inhibition in the eCIM
Inhibitors
- Avibactam: active against ESBLs, AmpCs, KPC, and OXA-48, but not MBLs and other OXAs
- Only inhibitor with some activity against class D (OXAs)
- Relebactam: active against ESBLs, AmpCs, and KPC, but not OXA-48, VIM, GES, or MBLs
- Tazobactam: active against Pseudomonas, but limited activity against carbapenemases otherwise
- Vaborbactam: active against KPC, but limited activity against MBLs and OXA-48, Pseudomonas, or Acinetobacter
Management
- Directed by susceptibility testing
- For ESBLs and AmpCs, consider:
- Ceftazidime-avibactam (not active against metallo-β-lactamases)
- Meropenem-vaborbactam (limited activity against metallo-β-lactamases and oxacillinases)
- For metallo-β-lactamases, consider:
- Colistin, though increasing resistance
- Tigecycline
- Fosfomycin
- Aztreonam-avibactam
- Cefiderocol
- Eravacycline
- Plazomicin
- For carbapenem-resistant Pseudomonas aeruginosa, consider:
