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Aminoglycoside resistance in Pseudomonas aeruginosa due to outer membrane stabilization
1Department of Cellular Information Sciences, Tokai University, School of Medicine, Isehara, Japan.
Abstract:
Pseudomonas aeruginosa PAO1 released a significant amount of a cytoplasmic enzyme, glucose-6-phosphate dehydrogenase, in the presence of aminoglycoside and lysozyme. The extent of the enzyme release was inversely related to the MICs of the aminoglycoside. However, the aminoglycoside-resistant strain F3721, treated in the same way; released a less enzyme. The F3721 LPS was extracted in the phenol phase instead of the water phase in which PAO1 LPS was easily extracted. Electrophoretic analysis of the F3721 LPS showed the ladder bands at the high Mr position, suggesting that the LPS of the aminoglycoside-resistant cells has a structural modification(s) which somehow protects the outer membrane from aminoglycoside-mediated damage.
Insights
Aminoglycoside antibiotics damage Pseudomonas aeruginosa outer membranes, causing enzyme release. Resistance in strain F3721 involves modified lipopolysaccharide (LPS) that protects against this damage.
Area of Science:
- Microbiology
- Bacterial Pathogenesis
- Drug Resistance
Background:
- Aminoglycosides are crucial antibiotics for treating Pseudomonas aeruginosa infections.
- Outer membrane damage is a key mechanism of aminoglycoside action against Gram-negative bacteria.
- Understanding resistance mechanisms is vital for developing effective antimicrobial strategies.
Purpose of the Study:
- To investigate the mechanism of aminoglycoside resistance in Pseudomonas aeruginosa.
- To determine the role of lipopolysaccharide (LPS) structure in aminoglycoside resistance.
Main Methods:
- Comparing enzyme release (glucose-6-phosphate dehydrogenase) from susceptible (PAO1) and resistant (F3721) P. aeruginosa strains upon antibiotic treatment.
- Extracting LPS from both strains using phenol-water method.
- Analyzing LPS structure via electrophoresis.
Main Results:
- Susceptible P. aeruginosa PAO1 released significant cytoplasmic enzyme when treated with aminoglycoside and lysozyme.
- Aminoglycoside-resistant strain F3721 showed reduced enzyme release.
- F3721 LPS was extracted differently and showed structural modifications (high molecular weight ladder bands) compared to PAO1 LPS.
Conclusions:
- Aminoglycoside resistance in P. aeruginosa F3721 is associated with structural modifications in LPS.
- Altered LPS structure likely protects the bacterial outer membrane from aminoglycoside-induced damage, contributing to resistance.