Manu Chaudhary and Anurag Payasi
Aims: To evaluate the effect of EDTA on conjugation and plasmid transfer also to study the effect of different antibiotics on the conjugation.
Methods and Results: The minimum inhibitory concentration (MIC) of each antibacterial agent was determined using a broth dilution method. In-vitro conjugation study was performed in the presence of different concentration of EDTA. Following selection of appropriate concentration of EDTA which inhibits conjugation process and susceptibility profiles, the same concentration was corelated with Sulbactomax and a comparative study against ceftriaxone and ceftriaxone+sulbactam without EDTA was performed. Further to confirm the inhibition of conjugal transfer of plasmid, plasmid DNA was isolated from donor, recipient and transconjugates and processed for electrophoresis. Results of in vitro study shows that EDTA when used alone strongly inhibits conjugation process at 10 mM. Sulbactomax at half of MIC strongly inhibited the conjugation process as compared to ceftriaxone and ceftriaxone+sulbactam without EDTA. Further, it is clearly evident from agarose gel electrophoresis that conjugation process is inhibited by EDTA alone at 10 mM and higher as well as Sulbactomax.
Conclusions: The results obtained in the present study, suggests that EDTA alone at 10 mM and at a very low concentration Sulbactomax inhibits the conjugation process and plasmid transfer. Thus, the inhibition of conjugation process is potentially a novel antimicrobial approach in the prevention of transfer of antibiotic resistance.
Significance and Impact of Study: The increasing prevalence of microbial pathogens which are resistant to antibiotics has been encouraging investigation of new strategies for controlling bacterial infections. Conjugative plasmids are potential targets because of the high frequency of antibiotic resistance arising from conjugation and conjugative transfer of plasmid DNA by which antibiotic resistance genes spread between bacterial strains. Since conjugation can happen between closely related (e.g., within Enterobacteriaceae) or distantly related organisms (e.g., grampositive to gram-negative) such as E coli. In the present study, EDTA when used alone at 10 mM and at very low concentration in Sulbactomax prevents bacterial conjugation and plasmid transfer effectively and hence prevents development of bacterial resistance ocuuring due to transfer of plasmid DNA.