Characterization of Resistance Genes and Plasmids from Outbreaks and Illness Clusters Caused by Salmonella Resistant to Ceftriaxone in the United States, 2011-2012.
Salmonella is an important cause of foodborne illness; however, quickly identifying the source of these infections can be difficult, and source identification is a crucial step in preventing additional illnesses. Although most infections are self-limited, invasive salmonellosis may require antimicrobial treatment. Ceftriaxone, an extended-spectrum cephalosporin, is commonly used for treatment of salmonellosis. Previous studies have identified a correlation between the food animal/retail meat source of ceftriaxone-resistant Salmonella and the type of resistance gene and plasmid it carries. In this study, we examined seven outbreaks of ceftriaxone-resistant Salmonella infections, caused by serotypes Typhimurium, Newport, Heidelberg, and Infantis. All isolates were positive for a plasmid-encoded blaCMYgene. Plasmid incompatibility typing identified five IncI1 and two IncA/C plasmids. Both outbreaks containing blaCMY-IncA/C plasmids were linked to consumption of cattle products. Three of five outbreaks with blaCMY-IncI1 (ST12) plasmids were linked to a poultry source. The remaining IncI1 outbreaks were associated with ground beef (ST20) and tomatoes (ST12). In addition, we examined isolates from five unsolved clusters of ceftriaxone-resistant Salmonella infections and used our plasmid-encoded gene findings to predict the source. Overall, we identified a likely association between the source of ceftriaxone-resistant Salmonella outbreaks and the type of resistance gene/plasmid it carries.
1 Enteric Diseases Laboratory Branch, Centers for Disease Control and Prevention , Atlanta, Georgia .
Jason P
JP
Folster
2 Enteric Diseases Epidemiology Branch, Centers for Disease Control and Prevention , Atlanta, Georgia .
Julian E
JE
Grass
3 IHRC, Inc. , Atlanta, Georgia .
Amelia
A
Bicknese
3 IHRC, Inc. , Atlanta, Georgia .
Julia
J
Taylor
2 Enteric Diseases Epidemiology Branch, Centers for Disease Control and Prevention , Atlanta, Georgia .
Cindy R
CR
Friedman
1 Enteric Diseases Laboratory Branch, Centers for Disease Control and Prevention , Atlanta, Georgia .
Jean M
JM
Whichard
D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002443:Ceftriaxone / Q000494:pharmacology*; D002511:Cephalosporins / Q000494:pharmacology; D004269:DNA, Bacterial / Q000235:genetics; D004196:Disease Outbreaks; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D005517:Foodborne Diseases / Q000382:microbiology; D008460:Meat / Q000382:microbiology; D010957:Plasmids / Q000235:genetics*; D012475:Salmonella / Q000187:drug effects* / Q000235:genetics*; D012480:Salmonella Infections / Q000188:drug therapy / Q000382:microbiology; D014481:United States
D000900:Anti-Bacterial Agents; D002511:Cephalosporins; D004269:DNA, Bacterial; D002443:Ceftriaxone
Salmonella; antimicrobial; plasmid; resistance