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Conjugative transfer of multiple antibiotic resistance markers in Streptococcus pneumoniae
Abstract:
Two antibiotic-resistant isolates of Streptococcus pneumoniae were investigated for conjugative transfer of their drug resistance markers into streptococcal (groups B and D) and pneumococcal (encapsulated and non-encapsulataed) recipients. Of these, 7 wild-type donor pneumococci transferred all their resistance markers (except Pc [penicillin], Su [sulfonamide], and Tp [trimethoprim]) into group D Streptococcus and non-encapsulated S. pneumoniae recipients at a low frequency (10(-5) to 10(-6)). The resistance markers transferred were Tc (tetracycline); Tc and Cm (chloramphenicol); Tc and MLS (macrolides, lincosamides, and streptogramin B); Tc, MLS, Km (kanamycin), and Cm. The transconjugants obtained retransferred their resistance markers into appropriate streptococcal or pneumococcal recipients or both. The resistance markers of streptococcal transconjugants could not be cured by chemical agents. All attempts to detect extra-chromosomal deoxyribonucleic acid from pneumococcal or streptococcal transconjugants were unsuccessful. The molecular weight of a streptococcal conjugative R plasmid (pIP501) was investigated after transfer into the non-encapsulated S. pneumoniae recipient and was found to be similar to that of the wild-type group B Streptococcus host (20 x 10(6)).
Insights
Antibiotic resistance genes can transfer between bacteria. This study shows Streptococcus pneumoniae can transfer resistance markers to other streptococci and pneumococci, highlighting potential spread of drug resistance.
Area of Science:
- Microbiology
- Genetics
- Molecular Biology
Background:
- Antibiotic resistance in bacteria is a growing public health concern.
- Understanding the mechanisms of resistance gene transfer is crucial for combating resistance.
- Streptococcus pneumoniae is a significant human pathogen.
Purpose of the Study:
- To investigate the conjugative transfer of antibiotic resistance markers from Streptococcus pneumoniae to other streptococcal and pneumococcal recipients.
- To characterize the transferred resistance markers and their stability in recipient strains.
Main Methods:
- Conjugative transfer experiments were performed using antibiotic-resistant Streptococcus pneumoniae donor strains.
- Recipient strains included group B and D Streptococcus, and encapsulated and non-encapsulated Streptococcus pneumoniae.
- Transconjugants were analyzed for retransfer of resistance markers and screened for extrachromosomal DNA.
Main Results:
- Seven wild-type donor pneumococci successfully transferred multiple resistance markers (tetracycline, chloramphenicol, macrolides, kanamycin) to group D Streptococcus and non-encapsulated S. pneumoniae recipients at low frequencies.
- Transferred resistance markers were stable and could be retransferred to new recipients.
- Extrachromosomal DNA was not detected in transconjugants, and the R plasmid pIP501 maintained a similar molecular weight after transfer.
Conclusions:
- Conjugative transfer of antibiotic resistance markers from Streptococcus pneumoniae to other streptococci and pneumococci is feasible.
- The findings suggest a potential mechanism for the dissemination of antibiotic resistance within and between bacterial species.
- Further research is needed to fully elucidate the mobile genetic elements involved in this transfer.