NARMS whole-genome sequencing (WGS) analysis indicates an increase in multidrug-resistant (MDR) strains of Salmonella I 4,[5],12:i:- (i.e., monophasic Salmonella serovar Typhimurium) in the United States.
These strains have predicted azithromycin resistance (AZM-R) due to presence of the mph(A) gene. These strains of AZM-R I 4,[5],12:i:- have been isolated from 112 ill people from 34 states between 2017 and 2024, with the majority identified in 2023. Of the 15 ill people with available information, 9 were hospitalized. No deaths have been reported. The median age of ill people is 26 years (interquartile range 8-53.5 years) and 60% are male. These strains of AZM-R I 4,[5],12:i:- have also been isolated from 6 ill animals (1 calf, 1 horse, and 4 pigs) as a part of the Vet-LIRN antimicrobial resistance monitoring program, 3 animals at slaughter (swine cecal samples), and 6 food product (pork) samples from 2019 to 2024.
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[Source: NARMS 30 May 2024