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Objectives: Pseudomonas aeruginosa has intrinsic antibiotic resistance and the strong ability to acquire additional resistance genes. However, a limited number of investigations provide detailed modular structure dissection and evolutionary analysis of accessory genetic elements (AGEs) and associated resistance genes (ARGs) in P. aeruginosa isolates. The objective of this study is to reveal the prevalence and transmission characteristics of ARGs by epidemiological investigation and bioinformatics analysis of AGEs of P. aeruginosa isolates taken from a Chinese hospital., Methods: Draft-genome sequencing was conducted for P. aeruginosa clinical isolates (n = 48) collected from a single Chinese hospital between 2019 and 2021. The clones of P. aeruginosa isolates, type 3 secretion system (T3SS)-related virulotypes, and the resistance spectrum were identified using multilocus sequence typing (MLST), polymerase chain reaction (PCR), and antimicrobial susceptibility tests. In addition, 17 of the 48 isolates were fully sequenced. An extensive modular structure dissection and genetic comparison was applied to AGEs of the 17 sequenced P. aeruginosa isolates., Results: From the draft-genome sequencing, 13 STs were identified, showing high genetic diversity. BLAST search and PCR detection of T3SS genes (exoT, exoY, exoS, and exoU) revealed that the exoS+/exoU- virulotype dominated. At least 69 kinds of acquired ARGs, involved in resistance to 10 different categories of antimicrobials, were identified in the 48 P. aeruginosa isolates. Detailed genetic dissection and sequence comparisons were applied to 25 AGEs from the 17 isolates, together with five additional prototype AGEs from GenBank. These 30 AGEs were classified into five groups -- integrative and conjugative elements (ICEs), unit transposons, Inc pPBL16 plasmids, Inc p60512-IMP plasmids, and Inc pPA7790 plasmids., Conclusion: This study provides a broad-scale and deeper genomics understanding of P. aeruginosa isolates taken from a single Chinese hospital. The isolates collected are characterized by high genetic diversity, high virulence, and multiple drug resistance. The AGEs in P. aeruginosa chromosomes and plasmids, as important genetic platforms for the spread of ARGs, contribute to enhancing the adaptability of P. aeruginosa in hospital settings., (© 2023. The Author(s).)

Pseudomonas aeruginosa is noted for its intrinsic antibiotic resistance and capacity of acquiring additional resistance genes. In this study, the genomes of nine clinical P. aeruginosa isolates were fully sequenced. An extensive genetic comparison was applied to 18  P. aeruginosa accessory genetic elements (AGEs; 13 of them were sequenced in this study and located within P. aeruginosa chromosomes) that were divided into four groups: five related integrative and conjugative elements (ICEs), four related integrative and mobilizable elements (IMEs), five related unit transposons, and two related IMEs and their two derivatives. At least 45 resistance genes, involved in resistance to 10 different categories of antibiotics and heavy metals, were identified from these 18 AGEs. A total of 10 β -lactamase genes were identified from 10 AGEs sequenced herein, and nine of them were captured within class 1 integrons, which were further integrated into ICEs and IMEs with intercellular mobility, and also unit transposons with intracellular mobility. Through this study, we identified for the first time 20 novel MGEs, including four ICEs Tn 6584 , Tn 6585 , Tn 6586 , and Tn 6587 ; three IMEs Tn 6853 , Tn 6854 , and Tn 6878 ; five unit transposons Tn 6846 , Tn 6847 , Tn 6848 , Tn 6849 , and Tn 6883 ; and eight integrons In1795, In1778, In1820, In1784, In1775, In1774, In1789, and In1799. This was also the first report of two resistance gene variants bla CARB-53 and catB3s , and a novel ST3405 isolate of P. aeruginosa . The data presented here denoted that complex transposition and homologous recombination promoted the assembly and integration of AGEs with mosaic structures into P. aeruginosa chromosomes., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Yu, Yang, Li, Chen, Hu, Jing, Luo, Yin, Zou and Zhou.)

Purpose: Pseudomonas aeruginosa is a common causative bacteria in nosocomial infections. This study aims to describe the structure and evolutionary characteristics of mobile genetic elements (MGEs) carrying antibiotic resistance genes (ARGs) from P. aeruginosa and to conduct bioinformatics and comparative genomic analysis to provide a deeper understanding of the genetic characteristics and diversity of MGEs in P. aeruginosa. Methods: Fifteen clinical isolates of P. aeruginosa from China were collected and sequenced in this study, and 15 novel MGEs were identified. Together with four MGEs from GenBank, a total of 19 MGEs were used to perform detailed modular structure dissection and sequence comparison. Then, the biological experiments were carried out to verify the biological characteristics of these isolates and MEGs. Results: The novel MGEs identified in this study displayed diversification in modular structures, which showed complex mosaic natures. The seven types of 19 MGEs included in this study were divided into three groups: i) novel MGEs (firstly identified in this study): four IncpSE5381-aadB plasmids and three Tn 7495-related integrative and mobilizable elements (IMEs); ii) newly defined MGEs (firstly designated in this study, but with previously determined sequences): four Tn 7665-related IMEs; iii) novel transposons with reference prototypes identified in this study: two Tn 6417-related integrative and conjugative elements (ICEs), two IS-based transposition units, two Tn 501-related unit transposons, two Tn 1403-related unit transposons. At least 36 ARGs involved in resistance to 11 different classes of antimicrobials and heavy metals were identified. Additionally, three novel blaOXA variants were identified. Antimicrobial susceptibility testing showed that these variants were resistant to some β-lactamase antibiotics and blaOXA-1204 was additionally resistant to cephalosporins. Conclusion: The continuous evolution of ARG-carrying MGEs during transmission, leading to the emergence of novel MGEs or ARGs, which facilitates the spread of antibiotic resistance in P. aeruginosa and enhances the diversity of transmission modes of bacterial resistance. [ABSTRACT FROM AUTHOR]