FDA NARMS Retail Meat Interim Report for Salmonella Shows Encouraging Early Trends Continue; Includes Whole Genome Sequencing Data for the First Time

May 4, 2016 — 

The U.S. Food and Drug Administration has released a new interim report that measures antimicrobial resistance in Salmonella isolated from raw retail meat and poultry collected through the National Antimicrobial Resistance Monitoring System (NARMS). The 2014-2015 Retail Meat Interim Report contains data from January 2014 – June 2015. It focuses only on Salmonella, a major pathogen of concern in foodborne disease outbreaks. Information includes serotype distribution, prevalence by food source and state, selected resistance patterns, and a list of all the identified antimicrobial resistance genes. To provide data in a timelier manner, the FDA intends to issue retail meat interim reports twice per year. In this report FDA also includes, for the first time, whole-genome sequencing data for Salmonella as a new component of routine NARMS surveillance practices and has placed all the isolate-level data on its website. [Source: FDA CVM, April 26, 2016]

Encouraging Trends
In many important categories, encouraging improvements found in 2011 continued to be evident in the latest data.

• The prevalence of Salmonella in retail poultry is at its lowest level since testing began in 2002. In ground turkey, the prevalence of Salmonella has declined from a high of 19% in 2008 to 6% in 2014. In retail chicken over the same time period, it has dropped from 15% to 9%.
• Salmonella resistance to ceftriaxone (an important antibiotic used to treat seriously ill patients) from chicken sources continued to decline steadily from a high of 38% in retail chicken meats in 2009 to 18% in 2014, and 5% during the first half of 2015. In ground turkey isolates, ceftriaxone resistance was detected in 7% of 2014 isolates and 4% of 2015 isolates collected through June, which represents an 80% decline since 2011 when resistance peaked at 22%.
• Fluoroquinolones like ciprofloxacin are classified as critically important for the treatment of Salmonella infections. Ciprofloxacin resistance was absent in Salmonella from poultry and beef, although a single isolate was found in pork.
• All Salmonella from retail meats were susceptible to azithromycin, another important antibiotic recommended for the treatment of Salmonella and other intestinal pathogens.
• Multidrug resistance in Salmonella continued to show a downward drift in chicken and turkey from 2011 levels of 45% and 50%, respectively, to 20% and 36% in June 2015.

Findings of Concern

• FDA identified the first instance of ciprofloxacin resistance in an isolate from retail pork, and identified the genes associated with this resistance for future tracking (see below).
• One ceftriaxone-resistant retail chicken isolate from 2014 had the extended-spectrum β-lactamase (ESBL) gene blaCTX-M-65. This is the first time this important class of resistance gene was detected in the U.S. This ESBL gene causes resistance to β-lactam antibiotics, including third generation cephalosporins, resulting in fewer treatment options for infected patients.
• While only three isolates of Salmonella serotype Dublin were recovered from meats (ground beef) in 2014, they exhibited extensive resistance patterns as in the past, showing resistance to 9-12 of 14 drugs tested.