Diverse and Flexible Transmission of <i>fosA3</i> Associated with Heterogeneous Multidrug Resistance Regions in Salmonella enterica Serovar Typhimurium and Indiana Isolates

Abstract

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