Conjugative R plasmids in group C and G streptococci

Area of Science:

• Microbiology
• Genetics
• Molecular Biology

Background:

• Streptococcal bacteria are significant human pathogens.
• Antibiotic resistance in bacteria poses a global health threat.
• R plasmids are key vectors for the spread of antibiotic resistance.

Purpose of the Study:

• To characterize R plasmids from Group C and G streptococcal isolates.
• To identify antibiotic resistance genes harbored by these plasmids.
• To investigate the genetic relatedness of the identified plasmids.

Main Methods:

• Plasmid DNA isolation and molecular weight determination.
• Conjugation experiments to assess plasmid transferability.
• Antibiotic resistance profiling of host strains.
• Restriction enzyme digestion (HindIII) to analyze plasmid DNA patterns.

Main Results:

• Two conjugative R plasmids, pIP646 (17 x 10^6 Da) and pIP920 (20 x 10^6 Da), were identified in Group C and G streptococci.
• pIP646 conferred resistance to macrolides and related antibiotics.
• pIP920 conferred resistance to macrolides, related antibiotics, and chloramphenicol.
• Both plasmids exhibited very similar HindIII restriction enzyme patterns, suggesting a close genetic relationship.

Conclusions:

• Conjugative R plasmids carrying clinically relevant antibiotic resistance genes are present in Group C and G streptococci.
• The genetic similarity of these plasmids may facilitate the dissemination of antibiotic resistance within streptococcal populations.
• These findings highlight the importance of monitoring antibiotic resistance in streptococcal pathogens.