132 - Emergence and Spread of Multidrug-resistant salmonella Serotype Infantis Infections in the United States, 2003–2018

Background: Infantis re-emerged as a leading Salmonella serotype when a multidrug-resistant (MDR) strain with a rare extended spectrum β-lactamase (ESBL) bla_CTX-M-65 gene emerged among returned travelers from Peru in 2012 and then spread domestically. This strain has been isolated from chickens at slaughter and retail, and humans in outbreaks traced to chicken. We reviewed national surveillance data to determine incidence trends and antibiotic resistance among Infantis infections.

Methods: We reviewed data from 2003–2018 from the Foodborne Diseases Active Surveillance Network to determine the incidence and epidemiology of infections in 10 sites under surveillance; PulseNet to determine pulsed-field gel electrophoresis (PFGE) patterns; and National Antimicrobial Resistance Monitoring System (NARMS) to determine antimicrobial susceptibility testing (AST) results and resistance genes of isolates identified by whole genome sequencing (WGS). We defined MDR Infantis as having ceftriaxone resistance by AST and either the bla_CTX-M-65 gene or one of 18 PFGE patterns linked to that gene by WGS.

Results: The 2,154 patients with Infantis infection had a median age of 36 years and 57% were female; 86% had isolates from stool, 9% from urine, and 3% from blood. Only 10% reported foreign travel and 27% were hospitalized. The incidence of infections began increasing in 2010 and by 2017–2018 was 2-fold higher than the average during 2003–2009. During 2003–2018, 856 (88%) of 970 NARMS isolates had PFGE or WGS data; 48 isolates were MDR Infantis, and in addition to ceftriaxone and ampicillin resistance (by definition), all 48 were resistant to 3 or more antibiotic classes, 94% had decreased susceptibility to ciprofloxacin, and 67% were resistant to cotrimoxazole. During 2012–2016, 2% of isolates were MDR Infantis; this increased to 17% during 2017–2018 (Figure).

Conclusion: During the past decade, the incidence of Infantis infections markedly increased. This was likely driven by the emergence of an ESBL-producing strain that was initially associated with travel, and is now mostly domestically acquired and associated with consuming chicken. MDR Infantis now accounts for 1 in 5 Infantis infections. Public health strategies to reduce Salmonella contamination of chicken could help prevent these infections.Figure: Number of Salmonella Infantis isolates and percentage MDR Infantis, by year—United States, 2003–2018

Presenting Author(s)

• 

  Felicita Medalla, MD, MS

  Epidemiologist
  Division of Foodborne, Waterborne, and Environmental Diseases, Centers for Disease Control and Prevention, Atlanta, GA
  Atlanta, GA

  Disclosure: I do not have any relevant financial / non-financial relationships with any proprietary interests.

  Slides Slides and Audio

Co-Author(s)

• DP

  Daniel C. Payne, PhD, MSPH

  Epidemiologist
  Centers for Disease Control and Prevention
  Atlanta, Georgia

  Disclosure: I do not have any relevant financial / non-financial relationships with any proprietary interests.
• PS

  Preethi Sundararaman, MPH

  Epidemiologist
  Division of Foodborne, Waterborne, and Environmental Diseases, Centers for Disease Control and Prevention, Atlanta, GA
  Atlanta, Georgia

  Disclosure: I do not have any relevant financial / non-financial relationships with any proprietary interests.
• MB

  Meseret Birhane, MPH, MAS

  Epidemiologist
  Division of Foodborne, Waterborne, and Environmental Diseases, Centers for Disease Control and Prevention, Atlanta, GA
  Atlanta, Georgia

  Disclosure: I do not have any relevant financial / non-financial relationships with any proprietary interests.
• AC

  Andrew Classon, MPH

  Database manager, PulseNet
  Division of Foodborne, Waterborne, and Environmental Diseases, Centers for Disease Control and Prevention, Atlanta, GA
  Atlanta, Georgia

  Disclosure: I do not have any relevant financial / non-financial relationships with any proprietary interests.
• HC

  Hayat Caidi, PhD

  Microbiologist
  Division of Foodborne, Waterborne, and Environmental Diseases, Centers for Disease Control and Prevention, Atlanta, GA
  Atlanta, Georgia

  Disclosure: I do not have any relevant financial / non-financial relationships with any proprietary interests.
• JF

  Jason Folster, PhD

  Microbiologist
  Division of Foodborne, Waterborne, and Environmental Diseases, Centers for Disease Control and Prevention, Atlanta, GA
  Atlanta, Georgia

  Disclosure: I do not have any relevant financial / non-financial relationships with any proprietary interests.
• 

  Cindy R. Friedman, MD

  Team Lead, National Antimicrobial Resistance Monitoring System for Enteric Bacteria (NARMS)
  Centers for Disease Control and Prevention
  Atlanta, Georgia

  Disclosure: I do not have any relevant financial / non-financial relationships with any proprietary interests.
• 

  Louise Francois Watkins, MD, MPH

  Medical Officer
  Division of Foodborne, Waterborne, and Environmental Diseases, Centers for Disease Control and Prevention
  Atlanta, Georgia

  Disclosure: I do not have any relevant financial / non-financial relationships with any proprietary interests.