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Characterization of a Conjugative Multidrug Resistance IncP-2 Megaplasmid, pPAG5, from a Clinical Pseudomonas
Meng Li1,2, Congcong Guan1,2, Gaoyu Song1,2
1Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, Northwest Universitygrid.412262.1, Xi'an, People's Republic of China.
Abstract:
The spread of resistance genes via horizontal plasmid transfer plays a significant role in the formation of multidrug-resistant (MDR) Pseudomonas aeruginosa strains. Here, we identified a megaplasmid (ca. 513 kb), designated pPAG5, which was recovered from a clinical multidrug-resistant P. aeruginosa PAG5 strain. The pPAG5 plasmid belonged to the IncP-2 incompatibility group. Two large multidrug resistance regions (MDR-1 and MDR-2) and two heavy metal resistance operons (merEDACPTR and terZABCDE) were identified in the pPAG5 plasmid. Genetic analysis demonstrated that the formation of MDR regions was mediated by several homologous recombination events. Further conjugation assays identified that pPAG5 could be transferred to P. aeruginosa but not Escherichia coli. Antimicrobial susceptibility testing on transconjugants demonstrated that pPAG5 was capable of transferring resistance genes to transconjugants and producing a multidrug-resistant phenotype. Comparative analysis revealed that pPAG5 and related plasmids shared an overall similar backbone, including genes essential for replication (repA), partition (par), and conjugal transfer (tra). Further phylogenetic analysis showed that pPAG5 was closely related to plasmids pOZ176 and pJB37, both of which are members of the IncP-2-type plasmid group. IMPORTANCE The emergence and spread of plasmid-associated multidrug resistance in bacterial pathogens is a key global threat to public health. It is important to understand the mechanisms of the formation and evolution of these plasmids in patients, hospitals, and the environment. In this study, we detailed the genetic characteristics of a multidrug resistance IncP-2 megaplasmid, pPAG5, and investigated the formation of its MDR regions and evolution. To the best of our knowledge, plasmid pPAG5 is the largest multidrug resistance plasmid ever sequenced in the Pseudomonas genus. Our results may provide further insight into the formation of multidrug resistance plasmids in bacteria and the molecular evolution of plasmids.
Insights
Researchers identified pPAG5, the largest multidrug resistance plasmid in Pseudomonas. This IncP-2 megaplasmid transfers resistance genes, contributing to multidrug-resistant Pseudomonas aeruginosa strains and posing a public health threat.
Area of Science:
- Microbiology
- Genetics
- Molecular Biology
Background:
- Horizontal plasmid transfer is a key driver of multidrug resistance (MDR) in bacterial pathogens.
- Pseudomonas aeruginosa is an opportunistic pathogen frequently associated with hospital-acquired infections and MDR.
Purpose of the Study:
- To characterize the genetic makeup and functional properties of a novel, large MDR plasmid, pPAG5, from a clinical MDR P. aeruginosa strain.
- To investigate the mechanisms underlying the formation of MDR regions within pPAG5.
- To understand the evolutionary context and transferability of pPAG5.
Main Methods:
- Whole-genome sequencing and assembly of the megaplasmid pPAG5.
- Bioinformatic analysis to identify resistance genes, operons, and plasmid backbone genes.
- Conjugation assays to determine plasmid transferability between bacterial species.
- Antimicrobial susceptibility testing of transconjugants.
Main Results:
- Identification of pPAG5, a ~513 kb IncP-2 megaplasmid, carrying two large MDR regions and heavy metal resistance operons.
- Homologous recombination events were identified as key mechanisms in the formation of MDR regions.
- pPAG5 demonstrated efficient transfer to P. aeruginosa but not to Escherichia coli, conferring an MDR phenotype to transconjugants.
- Comparative analysis revealed pPAG5 shares a conserved backbone with other IncP-2 plasmids, suggesting a common evolutionary origin.
Conclusions:
- pPAG5 represents the largest MDR plasmid sequenced in the Pseudomonas genus to date.
- The study provides insights into the formation and evolution of MDR plasmids, crucial for understanding the spread of antimicrobial resistance.
- Understanding such large MDR plasmids is vital for combating the global public health threat posed by MDR bacterial pathogens.
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