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Efflux pump Lde is associated with fluoroquinolone resistance in Listeria monocytogenes
Sylvain Godreuil1, Marc Galimand, Guy Gerbaud
1Unité des Agents Antibactériens. Laboratoire des Listeria, Institut Pasteur, 75724 Paris Cedex 15, France.
Abstract:
Five Listeria monocytogenes isolates (CLIP 21369, CLIP 73298, CLIP 74811, CLIP 75679, and CLIP 79372) were found to be resistant to fluoroquinolones during the screening for antibiotic resistance of 488 L. monocytogenes isolates from human cases of listeriosis in France. On the basis of a fourfold or greater decrease in the ciprofloxacin MIC in the presence of reserpine, fluoroquinolone resistance was attributed to active efflux of the drugs. The lde gene (Listeria drug efflux; formerly lmo2741) encodes a 12-transmembrane-segment putative efflux pump belonging to the major facilitator superfamily of secondary transporters that displayed 44% identity with PmrA from Streptococcus pneumoniae. Insertional inactivation of the lde gene in CLIP 21369 indicated that the corresponding protein was responsible for fluoroquinolone resistance and was involved in the level of susceptibility to dyes such as ethidium bromide and acridine orange.
Insights
Five Listeria monocytogenes strains resistant to fluoroquinolones were identified. This resistance is linked to the lde gene, which encodes an efflux pump responsible for expelling antibiotics and dyes.
Area of Science:
- Microbiology
- Molecular Biology
- Drug Resistance
Background:
- Listeria monocytogenes is a significant foodborne pathogen causing listeriosis.
- Antibiotic resistance in L. monocytogenes is a growing public health concern.
- Fluoroquinolones are critical antibiotics used to treat bacterial infections.
Purpose of the Study:
- To investigate the mechanisms of fluoroquinolone resistance in Listeria monocytogenes isolates.
- To identify the genetic basis of fluoroquinolone resistance in clinical isolates.
- To characterize the role of efflux pumps in antibiotic resistance.
Main Methods:
- Screening of 488 L. monocytogenes isolates for antibiotic resistance.
- Determination of ciprofloxacin Minimum Inhibitory Concentration (MIC) in the presence of reserpine.
- Identification and characterization of the lde gene and its encoded efflux pump.
- Insertional inactivation of the lde gene to assess its function.
Main Results:
- Five L. monocytogenes isolates exhibited resistance to fluoroquinolones.
- Fluoroquinolone resistance was attributed to active drug efflux.
- The lde gene encodes a major facilitator superfamily efflux pump.
- Disruption of the lde gene abolished fluoroquinolone resistance and altered susceptibility to dyes.
Conclusions:
- The lde gene is responsible for fluoroquinolone resistance in the studied L. monocytogenes isolates.
- Efflux pumps play a crucial role in mediating antibiotic resistance in L. monocytogenes.
- Understanding these resistance mechanisms is vital for effective listeriosis treatment.