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Emerging carbapenemases in Gram-negative aerobes
1Service de Bactériologie-Virologie, Hôpital de Bicêtre, Assistance Publique-Hôpitaux de Paris and Faculté de Médecine Paris-Sud, Université Paris XI, Paris, France. nordmann.patrice@bct.ap-hop-paris.fr
Summary
Carbapenemases, enzymes conferring resistance to critical antibiotics like imipenem and meropenem, are classified into Ambler classes A, B, and D. Understanding their spread is crucial for combating antimicrobial resistance.
Area of Science:
- Microbiology
- Molecular Biology
- Infectious Diseases
Background:
- Carbapenemases are beta-lactamases that hydrolyze carbapenem antibiotics, including imipenem and meropenem.
- Acquired carbapenem resistance involves Ambler molecular classes A, B, and D enzymes.
Purpose of the Study:
- To review the characteristics and classification of carbapenemases.
- To discuss the clinical significance and detection challenges of carbapenemase-producing bacteria.
Main Methods:
- Literature review of carbapenemase classification and epidemiology.
- Analysis of carbapenemase mechanisms, including Ambler classes A, B, and D.
Main Results:
- Class A carbapenemases (e.g., KPC, GES) are rare and often inhibited by clavulanic acid.
- Class B carbapenemases (metalloenzymes like IMP, VIM) are clinically significant, hydrolyzing most beta-lactams except aztreonam.
- Class D carbapenemases (e.g., in Acinetobacter baumannii) confer reduced susceptibility to carbapenems.
Conclusions:
- Carbapenemase diversity (Classes A, B, D) presents varied resistance mechanisms.
- Metalloenzymes (Class B) are a major global concern.
- Underdetection of carbapenemases, especially in Enterobacteriaceae, may underestimate resistance spread.