Hospital Pseudomonas aeruginosa: surveillance of resistance to gentamicin and transfer of aminoglycoside R factor

Area of Science:

• Microbiology
• Molecular Biology
• Antimicrobial Resistance

Background:

• Hospital-acquired infections caused by Pseudomonas aeruginosa are a growing concern.
• Increasing antimicrobial resistance in Pseudomonas aeruginosa necessitates understanding resistance mechanisms.
• Gentamicin resistance in Pseudomonas aeruginosa has been observed to rise over time.

Purpose of the Study:

• To investigate the increasing resistance to gentamicin in hospital isolates of Pseudomonas aeruginosa.
• To determine if aminoglycoside resistance is transferable between Pseudomonas aeruginosa strains.
• To elucidate the mechanisms underlying transferable aminoglycoside resistance.

Main Methods:

• Tube dilution susceptibility tests were performed in Trypticase soy broth.
• Recombination experiments were conducted to assess drug resistance transfer.
• Sodium dodecyl sulfate was used to attempt curing of aminoglycoside resistance.

Main Results:

• Resistance to gentamicin among hospital isolates of Pseudomonas aeruginosa increased from 13.9% in 1969 to 38.9% in 1972.
• Transferable resistance to six aminoglycosides was demonstrated between wild Pseudomonas strains.
• The exconjugant exhibited resistance to all clinically employed antimicrobials, including amikacin.
• Sodium dodecyl sulfate treatment cured the aminoglycoside resistance in the exconjugant.
• The transferable resistance was not mediated by adenylylation or other antibiotic-inactivating processes.

Conclusions:

• A significant increase in gentamicin resistance in Pseudomonas aeruginosa was observed in hospital settings.
• Aminoglycoside resistance in Pseudomonas aeruginosa is transferable and may be mediated by novel mechanisms.
• Further research is needed to identify the specific genetic and biochemical basis of this transferable resistance.