Antimicrobial Resistance in Salmonella in the United States from 1948 to 1995

We conducted a retrospective study of 2,149 clinical Salmonella strains to help document the historical emergence of antimicrobial resistance. There were significant increases in resistance to older drugs, including ampicillin, chloramphenicol, streptomycin, sulfamethoxazole, and tetracycline, which were most common in Salmonella enterica serotype Typhimurium. An increase in multidrug resistance was observed for each decade since the 1950s. These data help show how Salmonella evolved over the past 6 decades, after the introduction of new antimicrobial agents.