Multiresistance plasmid from commensal Neisseria strains

Area of Science:

• Microbiology
• Molecular Biology
• Genetics

Background:

• Commensal Neisseria spp. and Branhamella catarrhalis can exhibit antibiotic resistance.
• Understanding the genetic basis of this resistance is crucial for public health.

Purpose of the Study:

• To investigate the genetic mechanisms of antibiotic resistance in commensal Neisseria spp. and B. catarrhalis.
• To identify the role of plasmids in mediating resistance.

Main Methods:

• Isolation of antibiotic-resistant strains from throat cultures.
• Characterization of plasmids using restriction enzyme analysis (HinfI).
• Transfer of resistance genes via conjugation and transformation into Escherichia coli.

Main Results:

• Several Neisseria strains and B. catarrhalis showed resistance to beta-lactams, streptomycin, and sulfonamides.
• A common 6.0-megadalton plasmid with identical HinfI patterns was found in resistant strains.
• This plasmid mediated the transfer of resistance to beta-lactams, streptomycin, and sulfonamides (but not trimethoprim) to E. coli.
• The plasmid complemented a mutation affecting dihydropteroate synthetase, indicating sulfonamide resistance.

Conclusions:

• A shared 6.0-megadalton R plasmid is responsible for resistance to beta-lactams, streptomycin, and sulfonamides in these commensal bacteria.
• This plasmid carries genes for beta-lactamase, streptomycin phosphotransferase, and a sulfonamide-resistant dihydropteroate synthetase.
• The findings highlight the potential for plasmid-mediated antibiotic resistance transfer among commensal bacteria.