Examining the role ofAcinetobacter baumanniiPlasmid Types in Disseminating Antimicrobial Resistance

Abstract

Acinetobacter baumanniiis a Gram-negative pathogen responsible for hospital-acquired infections with high levels of antimicrobial resistance (AMR). The spread of multidrug-resistantA. baumanniistrains, particularly those resistant to carbapenems, has become a global concern. Spread of AMR inA. baumanniiis primarily mediated by the acquisition of AMR genes through mobile genetic elements, such as plasmids. Thus, a comprehensive understanding of the role of different plasmid types in disseminating AMR genes is essential. In this study, we analysed the distribution of plasmid types, sampling sources, geographic locations, and AMR genes carried onA. baumanniiplasmids. A collection of 814 complete plasmid entries was collated and analysed. Most plasmids were identified in clinical isolates from East Asia, North America, South Asia, West Europe, and Australia.We previously devised anAcinetobacterPlasmid Typing (APT) scheme whererep/Rep types were defined using 95% nucleotide identity and updated the scheme in this study by adding 13 novelrep/Rep types (93 types total). The APT scheme now includes 178 Rep variants belonging to three families: R1, R3, and RP. R1-type plasmids were mainly associated with global clone 1 strains, while R3-type plasmids were highly diverse and carried a variety of AMR determinants including carbapenem, aminoglycoside and colistin resistance genes. Similarly, RP-type and rep-less plasmids were also identified as important carriers of aminoglycoside and carbapenem resistance genes. This study provides a comprehensive overview of the distribution and characteristics ofA. baumanniiplasmids, shedding light on their role in the dissemination of AMR genes. The updated APT scheme and novel findings enhance our understanding of the molecular epidemiology ofA. baumanniiand provide valuable insights for surveillance and control strategies.IMPORTANCEA. baumanniihas emerged as a major cause of nosocomial infections, particularly in intensive care units, posing a substantial challenge to patient safety and healthcare systems. Plasmids, which carry antimicrobial resistance (AMR) genes, play a crucial role in the multidrug resistance exhibited byA. baumanniistrains, necessitating a comprehensive understanding of plasmid spread, and how to track them. This study provides important insights intoA. baumanniiplasmid epidemiology, and the extent of their role in spreading clinically significant AMR genes and how they are differentially distributed across different clones i.e. sequence types (STs) and geographical regions. These insights are important for identifying high-risk areas or clones implicated in plasmid transmission, in the context of the spread of multidrug-resistantA. baumanniistrains. It also highlights the involvement of R3-type, RP-type and rep-less plasmids in the acquisition and spread of significant AMR genes including those conferring resistance to carbapenems, aminoglycosides and colistin.