Β-lactamases
From IDWiki
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 A: inhibited by clavulanic acid or tazobactam
- 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.
