Emergence of Multidrug-Resistant Salmonella enterica Serovar Goldcoast Strains in Taiwan and International Spread of the ST358 Clone

Salmonella enterica serovar Goldcoast infection was rare in Taiwan; it was not detected in routine surveillance from 2004 to 2013. This serovar was first identified in 2014, but the frequency of infection remained low until 2017. From 2014 to 2016, all but one isolate was pan-susceptible. S. Goldcoast infections abruptly increased in 2018, and all isolates were multidrug-resistant (MDR). All MDR isolates harbored an IncHI2 plasmid, and the majority carried 14 antimicrobial resistance genes, aac(3)-IId, aadA22, aph(3')-Ia, aph(6)-Id, bla(TEM-1B), bla(CTX-M-55), Inu(F), floR, qnrS13, arr-2, sul2, sul3, tet(A), and dfrA14. S. Goldcoast strains recovered in Taiwan and 96 of 99 strains from Germany, the Netherlands, the United Kingdom, and the United States belonged to sequence type 358 (ST358). Whole-genome single-nucleotide polymorphism and core genome multilocus sequence type analyses revealed that all strains of the ST358 clone shared a high degree of genetic relatedness. The present study highlighted that a dramatic increase in S. Goldcoast infections followed the emergence of MDR strains and indicated that a genetically closely related S. Goldcoast ST358 clone may have widespread significance internationally.