FDA finds some improvement in antibiotic resistance trends

FDA makes changes to NARMS methodology, reporting structure.

August 12, 2015

3 Min Read
FDA finds some improvement in antibiotic resistance trends

The U.S. Food & Drug Administration released its "2012-13 National Antimicrobial Resistance Monitoring System (NARMS) Integrated Report."

FDA said this report replaces its annual "NARMS Executive Summary" report and highlights antimicrobial resistance patterns in bacteria isolated from humans, retail meats and animals at slaughter. Specifically, the report focuses on major foodborne pathogens that are resistant to antibiotics that are considered important to human medicine, and on multidrug resistant pathogens (described as resistant to three or more classes of antibiotics).

NARMS monitors foodborne pathogens to determine whether they are resistant to various antibiotics used in human and veterinary medicine. Specifically NARMS screens: non-typhoidal salmonella, campylobacter, Escherichia coli and enterococcus.

Salmonella and campylobacter are the leading bacterial causes of foodborne illness. While E. coli and enterococcus may cause foodborne illness, they are included in NARMS mainly to help track the occurrence and spread of resistance.


Overall, FDA said the "2012-13 Integrated Report" reveals mostly encouraging findings, with some areas of concern.

Encouraging findings:

* About 80% of human salmonella isolates are not resistant to any of the tested antibiotics, a finding that has not changed in the past 10 years. Further, resistance to ceftriaxone, azithromycin and quinolones, three important drugs used to treat human salmonella isolates, remains below 3%.

* Salmonella multi-drug resistance (resistance to three or more classes of antibiotics) in human, cattle and chicken isolates has not changed (at about 10%) in the last decade, and the numbers of multi-drug resistant salmonella isolates in retail chicken have gone down (about 3%).

* Campylobacter jejuni resistance to the fluoroquinolone ciprofloxacin, the most common antibiotic used to treat human C. jejuni illness, was at its lowest level in retail chicken to date (11%). C. jejuni causes most human campylobacter infections.

Still of concern:

* Multidrug resistance (MDR) in human isolates of a common salmonella serotype (l 4,[5],12:i:-) continues to rise. Resistance has more than doubled from 18% in 2011 to 46% in 2013.

* An increase in MDR and ceftriaxone resistance was also observed in salmonella serotype Dublin isolated from cattle and human sources.

Note: The NARMS Integrated Report covers time periods before the FDA's publication in December 2013 of Guidance for Industry #213. The guidance announced a specific strategy for animal drug companies to voluntarily revise the labeling of their medically important antimicrobials used in the feed and water of food-producing animals to withdraw approved production uses and place the remaining therapeutic uses of these products under veterinary oversight. The affected animal drug companies have agreed to implement this strategy by December 2016.


What’s New

According to FDA, the integrated report reflects improvements in NARMS testing. Animal testing now includes cecal (intestinal) testing of food-producing animals presented for slaughter before they are exposed to in-plant processing, making them better indicators of the microbial status of animals in farm settings. Additionally, the new in-plant sampling makes it possible to distinguish market hogs and sows among swine samples and dairy and beef among cattle samples.

NARMS is also now using epidemiological cut-off values to interpret antimicrobial susceptibility data in a move toward globally harmonized methods for campylobacter surveillance, FDA said.

Unlike previous year’s reports, FDA noted that the NARMS integrated report covers multiple years (2012-13) and has a new format to help better communicate the complex information presented. The tables and graphs used to summarize collected data in previous reports are still available. However, they are enhanced by new interactive graphs designed to help the reader quickly visualize the latest antimicrobial resistance trends.

The full NARMS Integrated Report can be found at http://www.fda.gov/downloads/AnimalVeterinary/SafetyHealth/AntimicrobialResistance/NationalAntimicrobialResistanceMonitoringSystem/UCM453398.pdf

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