Transferable plasmid-mediated antibiotic resistance in Bacteroides

Area of Science:

• Microbiology
• Molecular Biology
• Genetics

Background:

• Antibiotic resistance in anaerobic bacteria, particularly Bacteroides species, is a growing clinical concern.
• The role of plasmids in the dissemination of antibiotic resistance among Bacteroides and related gut bacteria is not fully understood.

Purpose of the Study:

• To investigate the transferability of plasmid-mediated antibiotic resistance genes between Bacteroides species and Escherichia coli.
• To characterize the frequency and stability of antibiotic resistance gene transfer mediated by plasmids.

Main Methods:

• Conjugative transfer experiments using membrane-filter and centrifugation techniques.
• Agarose-gel electrophoresis to identify plasmid DNA.
• Curing experiments using subinhibitory concentrations of aminoacridines and ethidium bromide.

Main Results:

• High-frequency transfer of chloramphenicol, erythromycin, and clindamycin resistance, but low-frequency transfer of tetracycline resistance.
• Successful plasmid-mediated transfer to B. fragilis, B. distasonis, and E. coli recipients.
• Segregation of resistance markers observed under specific selection pressures.
• Plasmid DNA confirmed in donor and transcipient strains, absent in recipients and cured strains.

Conclusions:

• Plasmid-mediated antibiotic resistance is readily transferable among Bacteroides and to E. coli.
• The transfer of these resistance genes can compromise antibiotic treatment efficacy.
• Bacteroides species act as a potential reservoir for antibiotic resistance genes within the intestinal flora.