An RND-type multidrug efflux pump SdeXY from Serratia marcescens

Area of Science:

• Microbiology
• Molecular Biology
• Bacterial Pathogenesis

Background:

• Serratia marcescens is a significant cause of hospital-acquired infections.
• Multidrug resistance is a growing concern in bacterial pathogens.
• Efflux pumps are key mechanisms contributing to multidrug resistance in bacteria.

Purpose of the Study:

• To characterize the multidrug efflux pumps in multidrug-resistant Serratia marcescens.
• To identify the specific genes responsible for the observed multidrug resistance phenotype.

Main Methods:

• Genes conferring multidrug resistance in S. marcescens were cloned into a drug-hypersusceptible E. coli strain.
• Nucleotide sequencing was performed on the cloned genes.
• Protein similarity searches were conducted using GenBank.
• Functional analysis involved introducing the cloned genes into E. coli strains with and without the tolC gene.

Main Results:

• The sdeXY genes were cloned and sequenced.
• Clones carrying sdeXY exhibited reduced susceptibility to multiple antimicrobial agents and dyes.
• SdeY was identified as a Resistance Nodulation-Division (RND) family efflux protein, and SdeX as a membrane fusion protein.
• Multidrug resistance was dependent on the presence of both sdeXY and the tolC gene in E. coli, with energy-dependent ethidium efflux observed.

Conclusions:

• SdeXY represents the first characterized RND-type multidrug efflux pump in multidrug-resistant S. marcescens.
• The SdeXY-TolC system is crucial for the multidrug resistance phenotype in S. marcescens.
• Understanding this efflux system provides insights into combating nosocomial infections caused by S. marcescens.