Nontyphoidal Salmonella enterica Nonsusceptible to Both Levofloxacin and Ceftriaxone in Nebraska, United States 2014-2015

Caitlin N. Murphy, Randal C. Fowler, Andrea J. Williams, Peter C. Iwen, Paul D. Fey

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


Nontyphoidal Salmonella enterica is a common cause of illness in humans ranging from gastroenteritis to invasive disease. National surveillance programs continually monitor trends in antimicrobial resistance patterns and mechanisms of resistance to identify emerging public health threats. Our study shows the emergence of nonsusceptibility to both levofloxacin and ceftriaxone, a concerning phenotype that threatens first-line antibiotic therapy, in Salmonella isolates recovered between 2014 and 2015. From 2010 to 2013 the rate of resistance increased from 0.0% (0/1181) to 1.5% (9/593) in 2014 and 2015. The isolates with this phenotype were found to be from multiple serotypes, including Typhimurium, Newport, and Enteritidis. Resistance to ceftriaxone was attributed to the presence of either an AmpC or extended-spectrum β-lactamase, and resistance to fluoroquinolones was attributable to the presence of mutations in the quinolone resistance-determining region or the presence of plasmid-mediated quinolone resistance genes. As this resistance pattern was seen in a variety of Salmonella serotypes harboring varied resistance mechanisms, it indicates a worrying trend in the spread of isolates resistant to both first-line treatment options.

Original languageEnglish (US)
Pages (from-to)235-238
Number of pages4
JournalFoodborne pathogens and disease
Issue number4
StatePublished - Apr 2018


  • Salmonella
  • antibiotic resistance
  • quinolones

ASJC Scopus subject areas

  • Microbiology
  • Food Science
  • Applied Microbiology and Biotechnology
  • Animal Science and Zoology


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