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A simple method for the identification of aminoglycoside-modifying enzymes
The Journal of Antimicrobial Chemotherapy
|October 1, 1984
Summary
Identifying aminoglycoside-modifying enzymes in resistant bacteria is crucial. A stepwise determination scheme using antibiotic sensitivity discs accurately identifies these enzymes in 84% of clinical isolates.
Area of Science:
- Microbiology
- Antimicrobial Resistance
- Enzyme Kinetics
Background:
- Aminoglycoside-modifying enzymes (AMEs) are a primary mechanism of bacterial resistance to aminoglycoside antibiotics.
- Understanding the prevalence and types of AMEs in clinical isolates is vital for effective treatment strategies.
- Previous methods for AME identification in resistant bacteria have shown limitations.
Purpose of the Study:
- To evaluate the effectiveness of a stepwise determination scheme for identifying AMEs in clinical bacterial isolates.
- To compare the stepwise method with traditional biochemical analysis for AME detection.
- To assess the correlation between AME presence and bacterial susceptibility to aminoglycosides.
Main Methods:
- Collected 133 aminoglycoside-resistant bacterial strains representing common AMEs.
- Identified enzymes using substrate profiles for eight aminoglycosides in vitro.
- Developed and applied a stepwise determination scheme based on inhibition zone diameters from six aminoglycoside antibiotic discs.
- Compared results from the stepwise scheme with biochemical enzyme analysis.
Main Results:
- Thirteen different enzymes or combinations were identified, with seven cases of non-enzyme-mediated resistance.
- Enzyme activities did not consistently correlate with bacterial susceptibility data.
- The stepwise determination scheme successfully identified AMEs in 84% of the 133 resistant strains.
- The stepwise scheme and biochemical method yielded identical results for 97% of 100 tested clinical isolates.
Conclusions:
- The stepwise determination scheme is a more effective and accurate method for identifying aminoglycoside-modifying enzymes in clinical isolates compared to cluster analysis of sensitivity data.
- This method offers a practical approach for rapid AME identification in diagnostic laboratories.
- Accurate AME identification can guide antibiotic therapy and help combat antimicrobial resistance.