Clindamycin resistance transfer in Bacteroides fragilis

Area of Science:

• Microbiology
• Antimicrobial Resistance
• Bacteriology

Background:

• Clindamycin is a critical antibiotic for treating anaerobic bacterial infections.
• Increasing clindamycin resistance in Bacteroides fragilis poses a significant clinical challenge.
• Understanding resistance mechanisms and transferability is crucial for effective treatment strategies.

Purpose of the Study:

• To investigate cross-resistance patterns to beta-lactam agents in clindamycin-resistant B. fragilis.
• To determine the transferability of clindamycin resistance among B. fragilis isolates.
• To elucidate the role of plasmids versus non-plasmid mechanisms in resistance transfer.

Main Methods:

• Collection and characterization of 30 clindamycin-resistant B. fragilis strains.
• Assessment of antimicrobial susceptibility, including to imipenem.
• Filter-mating experiments to evaluate resistance transferability and co-transfer of tetracycline and beta-lactam resistance.
• Plasmid detection using alkaline lysis method in transconjugants.

Main Results:

• Imipenem demonstrated the highest activity against the studied B. fragilis isolates.
• Clindamycin resistance was transferable via filter-mating in 12 of 30 strains.
• Non-plasmid-mediated transfer was suggested as the predominant mechanism, with only 3 of 12 transconjugants harboring detectable plasmids.
• Tetracycline resistance was co-transferred in 6 instances; beta-lactam resistance co-transfer was not observed.

Conclusions:

• Non-plasmid-mediated transfer may be a key driver in the dissemination of clindamycin resistance in B. fragilis.
• The findings highlight the complex nature of antimicrobial resistance spread in this important pathogen.
• Further research is needed to fully understand the genetic basis of non-plasmid-mediated resistance transfer.