Plasmid-mediated streptomycin resistance of listeria monocytogenes

Area of Science:

• Microbiology
• Molecular Biology
• Food Safety

Background:

• Listeria monocytogenes is a significant foodborne pathogen.
• Antibiotic resistance in foodborne bacteria is a growing public health concern.
• Understanding the genetic basis of antibiotic resistance is crucial for control strategies.

Purpose of the Study:

• To investigate the mechanism of streptomycin resistance in a Listeria monocytogenes strain (LM35) isolated from imported frozen beef.
• To determine if streptomycin resistance can be transferred to other Listeria monocytogenes strains.
• To identify the genetic element responsible for streptomycin resistance.

Main Methods:

• Conjugation experiments were performed using streptomycin-resistant Listeria monocytogenes LM35 as the donor strain.
• Streptomycin-sensitive and plasmidless Listeria monocytogenes LM65 and LM100 strains served as recipient strains.
• Plasmid profiles of donor and transconjugant strains were analyzed.

Main Results:

• Streptomycin resistance was successfully transferred from LM35 to LM65 and LM100 strains at specific frequencies.
• Concomitant transfer of a 54 kilobase plasmid from the donor strain was observed during conjugation.
• The frequencies of transfer were 3.3 × 10(-8) for LM65 and 1.2 × 10(-9) for LM100 per input donor cell.

Conclusions:

• The 54 kilobase plasmid mediates streptomycin resistance in Listeria monocytogenes LM35.
• Plasmid-mediated antibiotic resistance can be transferred between Listeria monocytogenes strains.
• This finding highlights the potential for the spread of antibiotic resistance within foodborne pathogens.