Abstract
Salmonella enterica bacteria have become increasingly resistant to antimicrobial agents, partly as a result of genes carried on integrons. Clonal expansion and horizontal gene transfer may contribute to the spread of antimicrobial drug-resistance integrons in these organisms. We investigated this resistance and integron carriage among 90 isolates with the ACSSuT phenotype (resistance to ampicillin, chloramphenicol, streptomycin, sulfamethoxazole, and tetracycline) in a global collection of S. enterica isolates. Four integrons, dfrA12/orfF/aadA2, dfrA1/aadA1, dfrA7, and arr2/blaOXA30/cmlA5/aadA2, were found in genetically unrelated isolates from 8 countries on 4 continents, which supports a role for horizontal gene transfer in the global dissemination of S. enterica multidrug resistance. Serovar Typhimurium isolates containing identical integrons with the gene cassettes blaPSE1 and aadA2 were found in 4 countries on 3 continents, which supports the role of clonal expansion. This study demonstrates that clonal expansion and horizontal gene transfer contribute to the global dissemination of antimicrobial drug resistance in S. enterica.
Highlights
Salmonella enterica bacteria have become increasingly resistant to antimicrobial agents, partly as a result of genes carried on integrons
16 different integrons were found in this collection, 19 distinct integron profiles could be identified because of multiple integrons in some isolates
To better understand the dissemination of integronmediated antimicrobial drug resistance, this study characterized the class 1 integrons and genetic lineages associated with 90 multidrug-resistant isolates obtained from a global collection of nontyphoidal S. enterica
Summary
Salmonella enterica bacteria have become increasingly resistant to antimicrobial agents, partly as a result of genes carried on integrons. Clonal expansion and horizontal gene transfer may contribute to the spread of antimicrobial drug– resistance integrons in these organisms. DfrA12/orfF/aadA2, dfrA1/aadA1, dfrA7, and arr2/blaOXA30/ cmlA5/aadA2, were found in genetically unrelated isolates from 8 countries on 4 continents, which supports a role for horizontal gene transfer in the global dissemination of S. enterica multidrug resistance. Resistance may be disseminated through clonal expansion of drug-resistant strains or through horizontal transfer of genetic elements coding for resistance determinants. The global dissemination of the multidrugresistant (MDR) S. enterica serovar Typhimurim phage type DT104 clone is an example of the role of clonal expansion in the spread of antimicrobial drug resistance determinants across multiple countries and continents [8]. The location of antimicrobial drug–resistant genes on mobile genetic elements, such as plasmids, transposons, and integrons, facilitates the mobilization of resistance from one organism to another [13]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
