Diverse and Flexible Transmission of fosA3 Associated with Heterogeneous Multidrug Resistance Regions in Salmonella enterica Serovar Typhimurium and Indiana Isolates.

We identified fosA3 at a rate of 2.6% in 310 Salmonella isolates from food animals in Guangdong province, China. The fosA3 gene was genetically linked to diverse antibiotic resistance genes (ARGs), including mcr-1, bla CTX-M-14/55, oqxAB, and rmtB These gene combinations were embedded in heterogeneous fosA3-containing multidrug resistance regions on the transferable ST3-IncHI2 and F33:A-:B- plasmids and the chromosome. This indicated a great flexibility of fosA3 cotransmission with multiple important ARGs among Salmonella species.