Β-lactamases: Difference between revisions

Revision as of 00:27, 2 February 2020

Definition

Bacteria containing a plasmid that codes for an extended-spectrum beta-lactamase (ESBL)
Most common with Escherichia coli and Klebsiella

Classification

Classes A, B, and C: serine β-lactamases
- Class A: inhibited by clavulanic acid or tazobactam
  - Constitutively expressed plasmid
  - Most common ESBL in Gram-negative bacteria
  - Resistance to 2nd and 3rd generation cephalosporins
  - Examples include penicillinase, TEM-1 (common in GNBs), CTX-M, K. pneumoniae carbapenemase (KPC) family
  - Common in E. coli, Klebsiella, and Proteus spp.
- Class C: not inhibited by clavulanic acid or EDTA, resistant to cefoxitin, inhibited by clox in vitro
  - AmpC = chromosomal
  - Often an inducible AmpC gene present in the genome
  - Common in Citrobacter, Serratia, and Enterobacter
- Class D: not inhibited by EDTA, variably inhibited by clavulanic acid; hard to identify
  - Common in Acinetobacter
Class B: metallo-β-lactamase, inhibited by EDTA, not inhibited by clavulanic acid
- Examples include New Delhi metallo-beta-lactamase (NDM-1)

Management

Antibiotic therapy tailored to the resistance pattern
Carbapenems, aminoglycosides, fluoroquinolones, and Septra typically work well

References

^ R. Cantón, M.I. Morosini, O. Martin, S. de la Maza, E. Gomez G. de la Pedrosa. IRT and CMT β-lactamases and inhibitor resistance. Clinical Microbiology and Infection. 2008;14:53-62. doi:10.1111/j.1469-0691.2007.01849.x.

@@ Line 6: / Line 6: @@
 == Classification ==
+* Classes A, B, and C: serine β-lactamases
-* '''Class A'''
+** '''Class A''': inhibited by clavulanic acid or tazobactam
-** Constitutively expressed plasmid
+*** Constitutively expressed plasmid
-** Most common ESBL in Gram-negative bacteria
+*** Most common ESBL in Gram-negative bacteria
-** Resistance to 2nd and 3rd generation cephalosporins
+*** Resistance to 2nd and 3rd generation cephalosporins
-** Examples include penicillinase, TEM-1 (common in GNBs), CTX-M, ''K. pneumoniae'' carbapenemase (KPC) family
+*** Examples include penicillinase, TEM-1 (common in GNBs), CTX-M, ''K. pneumoniae'' carbapenemase (KPC) family
-** Common in ''[[E. coli]]'', ''[[Klebsiella]]'', and ''[[Proteus]]'' spp.
+*** Common in ''[[E. coli]]'', ''[[Klebsiella]]'', and ''[[Proteus]]'' spp.
-* '''Class B''': metallobetalactamases
+** '''Class C''': not inhibited by clavulanic acid or EDTA, resistant to cefoxitin, inhibited by clox in vitro
+*** AmpC = chromosomal
+*** Often an inducible AmpC gene present in the genome
+*** Common in ''[[Citrobacter]]'', ''[[Serratia]]'', and ''[[Enterobacter]]''
+** '''Class D''': not inhibited by EDTA, variably inhibited by clavulanic acid; hard to identify
+*** Common in ''[[Acinetobacter]]''
+* '''Class B''': metallo-β-lactamase, inhibited by EDTA, not inhibited by clavulanic acid
 ** Examples include New Delhi metallo-beta-lactamase (NDM-1)
-* '''Class C''': ampC
-** Inducible AmpC gene present in the genome
-** Common in ''[[Citrobacter]]'', ''[[Serratia]]'', and ''[[Enterobacter]]''
-* '''Class D''': OXA
-** Common in ''[[Acinetobacter]]''
 == Management ==