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[Metallo-beta-lactamase producing bacteria]
1Laboratory of Drug Resistance in Bacteria, Gunma University School of Medicine.
Abstract:
Metallo-beta-lactamases are the carbapenemases belonging to the class B beta-lactamases on a molecular level. Two types of the metallo-beta-lactamase, IMP-1 and VIM-1, which have been detected mainly from Pseudomonas aeruginosa, respectively, in Japan and in Europe are especially important, because of the broad substrate specificity. These enzymes confer resistance to not only the carbapenems but also almost all beta-lactam antibiotics expect for monobactams. Clinical strains producing IMP-1 type enzymes are easily detectable by the PCR method or by the double-disk method using the enzyme inhibitor of mercapto-compound and the substrate antibiotic such as imipenem or ceftazidime. The gene blaIMP is frequently identified as a cassette inserted in the integron structure on the transmissible plasmids, disseminating among various gram-negative bacteria.
Insights
Metallo-beta-lactamases (MBs) are enzymes conferring resistance to carbapenems and other beta-lactam antibiotics. IMP-1 and VIM-1 are key MBs found in Pseudomonas aeruginosa, with rapid detection methods available.
Area of Science:
- Microbiology
- Molecular Biology
- Biochemistry
Background:
- Metallo-beta-lactamases (MBs) are a significant class of carbapenemases.
- IMP-1 and VIM-1 are clinically important MBs found in Pseudomonas aeruginosa.
- These enzymes confer resistance to a wide range of beta-lactam antibiotics, excluding monobactams.
Purpose of the Study:
- To highlight the importance of IMP-1 and VIM-1 metallo-beta-lactamases.
- To discuss their broad substrate specificity and resistance patterns.
- To present methods for detecting clinical strains producing IMP-1.
Main Methods:
- Polymerase Chain Reaction (PCR) for gene detection.
- Double-disk synergy assay using enzyme inhibitors and substrate antibiotics.
- Analysis of integron structures and plasmid dissemination.
Main Results:
- IMP-1 and VIM-1 enzymes are prevalent in Pseudomonas aeruginosa.
- These enzymes provide resistance to carbapenems and most beta-lactams.
- The blaIMP gene is often found on transmissible plasmids within integrons.
Conclusions:
- Metallo-beta-lactamases, particularly IMP-1 and VIM-1, pose a significant threat due to broad-spectrum resistance.
- Efficient detection methods like PCR and double-disk assays are crucial for clinical management.
- The genetic structure, including integrons and plasmids, facilitates the dissemination of these resistance genes among gram-negative bacteria.