Extended-spectrum β-lactamases: Difference between revisions
From IDWiki
(Aidan moved page Extended-spectrum beta-lactamases to β-lactamases) Tag: New redirect |
(Removed redirect to β-lactamases) Tags: Removed redirect Visual edit |
||
| Line 1: | Line 1: | ||
== Background == |
|||
#REDIRECT [[Β-lactamases]] |
|||
* Extended-spectrum β-lactamases (ESBLs) are generally defined as [[β-lactamases]] that hydrolyze [[penicillins]], first-, second-, and third-generation [[cephalosporins]], and [[aztreonam]], but not [[cephamycins]] or [[carbapenems]] |
|||
* This definition excludes AmpC (which hydrolyze [[cephamycins]]) and carbapenemases (which hydrolyze [[carbapenems]]) |
|||
* Includes primarily Ambler Class A β-lactamases |
|||
=== Identification === |
|||
* ESBLs are screened for by identifying organisms with increased MICs to one or more third-generation [[Cephalosporins|cephalosporin]] or [[Monobactams|monobactam]] |
|||
** CLSI uses [[cefpodoxime]], [[ceftazidime]], [[aztreonam]], [[cefotaxime]], or [[ceftriaxone]] |
|||
{| class="wikitable" |
|||
|+Screening for ESBL production |
|||
!Bacterium |
|||
!Antibiotic |
|||
!Disc Diffusion |
|||
!Broth Microdilution |
|||
|- |
|||
| rowspan="5" |[[Klebsiella pneumoniae]], [[Klebsiella oxytoca]], and [[Escherichia coli]] |
|||
|[[cefpodoxime]] |
|||
|≤17 mm |
|||
|≥8 μg/mL |
|||
|- |
|||
|[[ceftazidime]] |
|||
|≤22 mm |
|||
|≥2 μg/mL |
|||
|- |
|||
|[[aztreonam]] |
|||
|≤27 mm |
|||
|≥2 μg/mL |
|||
|- |
|||
|[[cefotaxime]] |
|||
|≤27 mm |
|||
|≥2 μg/mL |
|||
|- |
|||
|[[ceftriaxone]] |
|||
|≤25 mm |
|||
|≥2 μg/mL |
|||
|- |
|||
| rowspan="3" |[[Proteus mirabilis]] |
|||
|[[cefpodoxime]] |
|||
|≤22 mm |
|||
|≥2 μg/mL |
|||
|- |
|||
|[[ceftazidime]] |
|||
|≤22 mm |
|||
|≥2 μg/mL |
|||
|- |
|||
|[[cefotaxime]] |
|||
|≤27 mm |
|||
|≥2 μg/mL |
|||
|} |
|||
* For organisms that screen positive, they are then tested for third-generation [[Cephalosporins|cephalosporin]] resistance that is attenuated by [[clavulanic acid]] |
|||
** CLSI uses either [[ceftazidime]] or [[cefotaxime]], with and without [[clavulanic acid]] |
|||
** An increase in the zone of ≥5 mm is diagnostic of ESBL production |
|||
Revision as of 13:06, 12 September 2020
Background
- Extended-spectrum β-lactamases (ESBLs) are generally defined as β-lactamases that hydrolyze penicillins, first-, second-, and third-generation cephalosporins, and aztreonam, but not cephamycins or carbapenems
- This definition excludes AmpC (which hydrolyze cephamycins) and carbapenemases (which hydrolyze carbapenems)
- Includes primarily Ambler Class A β-lactamases
Identification
- ESBLs are screened for by identifying organisms with increased MICs to one or more third-generation cephalosporin or monobactam
- CLSI uses cefpodoxime, ceftazidime, aztreonam, cefotaxime, or ceftriaxone
| Bacterium | Antibiotic | Disc Diffusion | Broth Microdilution |
|---|---|---|---|
| Klebsiella pneumoniae, Klebsiella oxytoca, and Escherichia coli | cefpodoxime | ≤17 mm | ≥8 μg/mL |
| ceftazidime | ≤22 mm | ≥2 μg/mL | |
| aztreonam | ≤27 mm | ≥2 μg/mL | |
| cefotaxime | ≤27 mm | ≥2 μg/mL | |
| ceftriaxone | ≤25 mm | ≥2 μg/mL | |
| Proteus mirabilis | cefpodoxime | ≤22 mm | ≥2 μg/mL |
| ceftazidime | ≤22 mm | ≥2 μg/mL | |
| cefotaxime | ≤27 mm | ≥2 μg/mL |
- For organisms that screen positive, they are then tested for third-generation cephalosporin resistance that is attenuated by clavulanic acid
- CLSI uses either ceftazidime or cefotaxime, with and without clavulanic acid
- An increase in the zone of ≥5 mm is diagnostic of ESBL production
