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Aminoglycoside-modifying enzymes associated with hospital isolates of Gram-negative rods
Abstract:
Multi-resistant Enterobacteriaceae and Pseudomonas isolated from clinical specimens at RNS were characterized for resistance phenotype and transferred resistant phenotype. These isolates were obtained over a two year period from different specimens and from patients with varying clinical syndromes. Twenty-six of these isolates were further characterized with respect to their aminoglycoside modifying enzymes. Only three enzymes were detected: AAC(3)-I, APH(3')-I and AAD(2")-II. The substrate range of these enzymes was investigated and not always found to coincide with the transferred phenotype. AAD(2")-II was found only in association with APH(3')-I and not alone. The substrate range of AAC(3)-I from Pseudomonas was different from AAC(3)-I from Enterobacteriaceae but not sufficiently dissimilar to classify them as separate isoenzymes. The relatively few aminoglycoside-inactivating enzymes suggest that within this hospital there may be a limited gene pool for these enzymes.
Insights
Multi-resistant bacteria like Enterobacteriaceae and Pseudomonas show limited aminoglycoside-modifying enzymes. This suggests a restricted gene pool for these resistance mechanisms within the RNS hospital environment.
Area of Science:
- Microbiology
- Molecular Biology
- Clinical Science
Background:
- Multi-resistant bacteria pose a significant threat in healthcare settings.
- Enterobacteriaceae and Pseudomonas are common causes of hospital-acquired infections.
- Understanding resistance mechanisms is crucial for effective treatment strategies.
Purpose of the Study:
- To characterize the resistance phenotype of multi-resistant Enterobacteriaceae and Pseudomonas.
- To identify and analyze aminoglycoside modifying enzymes in these clinical isolates.
- To investigate the substrate range and genetic basis of aminoglycoside resistance.
Main Methods:
- Isolation and characterization of multi-resistant bacteria from clinical specimens.
- Phenotypic analysis of antibiotic resistance.
- Biochemical characterization of aminoglycoside modifying enzymes (AAC(3)-I, APH(3 étaire)-I, AAD(2")-II).
- Investigation of enzyme substrate ranges and co-occurrence.
Main Results:
- Three aminoglycoside modifying enzymes were detected: AAC(3)-I, APH(3 étaire)-I, and AAD(2")-II.
- The substrate range of detected enzymes did not always align with the observed transferred resistance phenotype.
- AAD(2")-II was exclusively found in conjunction with APH(3 étaire)-I.
- AAC(3)-I from Pseudomonas exhibited a different substrate range compared to Enterobacteriaceae, but not enough to be classified as separate isoenzymes.
Conclusions:
- The limited number of aminoglycoside-inactivating enzymes suggests a potentially restricted gene pool for these enzymes within the RNS hospital.
- Further research is needed to confirm the extent of this limited gene pool and its implications for resistance.
- Understanding these specific resistance mechanisms can inform infection control and treatment protocols.