The U.S. Food & Drug Administration has released its 2014 National Antimicrobial Resistance Monitoring System (NARMS) Integrated Report, highlighting antimicrobial resistance patterns in bacteria isolated from humans, retail meats and animals at slaughter.

Specifically, FDA said the report focuses on major foodborne bacteria that are resistant to antibiotics that are considered important to human medicine and on multi-drug-resistant organisms (described as resistant to three or more classes of antibiotics).

NARMS was established in 1996 as a partnership among FDA, the Centers for Disease Control & Prevention and the U.S. Department of Agriculture to track antibiotic resistance in foodborne bacteria. NARMS is critically important for monitoring trends in antimicrobial resistance among foodborne bacteria collected from humans, retail meats and food-producing animals. In particular, it assists FDA in making data-driven decisions on the approval of safe and effective antimicrobial drugs for animals.

The agency said NARMS will also be critical in evaluating the effectiveness of FDA’s Guidance for Industry #213 and the agricultural objectives in the Administration’s National Action Plan for Combating Antibiotic-Resistant Bacteria.

Findings

FDA listed the following points to summarize important observations from the 2014 NARMS Integrated Report. There are few changes from the 2012-13 NARMS Integrated Report. Overall resistance continues to remain low for most human infections, and there have been measurable improvements in resistance levels in some important areas.

Moving in the right direction:

1. The prevalence of salmonella in both retail chicken meat (9.1%) and retail ground turkey (5.5%) was at its lowest level since retail meat testing began in 2002. The prevalence of campylobacter in retail chicken meat samples has gradually declined over time to 33%, the lowest level since testing began.

2. Approximately 80% of human salmonella isolates are not resistant to any of the tested antibiotics. This has remained relatively stable over the past 10 years, FDA said. Resistance for three critically important drugs -- ceftriaxone, azithromycin and ciprofloxacin -- in human non-typhoidal salmonella isolates remained below 3%.

3. Overall, ceftriaxone resistance continued to decline in non-typhoidal salmonella from all NARMS sources, with the exception of retail turkey meat isolates, where it rose slightly. This was paralleled by a decline in ceftriaxone-resistant Escherichia coli from retail chicken meat (from 13% in 2011 to 6.6% in 2014). In cattle, salmonella isolates from carcasses collected at processing plants as part of pathogen reduction/hazard analysis critical control point (PR/HACCP) testing, ceftriaxone resistance reached its lowest level (7.6%) since 1999. In 2014, ceftriaxone resistance in human Salmonella Heidelberg isolates was 8.5%, down from a peak of 24% in 2010.

4. Among all salmonella serotypes, the percentage of human isolates resistant to at least ampicillin, chloramphenicol, streptomycin, sulfonamides and tetracyclines (ACSSuT) continued a steady decline to 3.1%, the lowest since testing began in 1996 (8.7%). Similarly, ACSSuT resistance in cattle PR/HACCP Salmonella typhimurium isolates declined sharply from 67% in 2009 to 7% in 2014, the lowest level since this testing began in 1997.

5. With the exception of five isolates in the past 10 years, no resistance has been detected in enterococcus bacteria isolates to three important drugs: daptomycin, linezolid and vancomycin.

Still of concern:

While a majority of the observations in the 2014 NARMS Integrated Report show desirable trends, FDA said there are a few findings of potential concern, including:

1. Decreased susceptibility to ciprofloxacin has increased in human and cattle (PR/HACCP) salmonella serotype Dublin isolates since 2003, with slight declines since 2012. While the incidence of human Salmonella Dublin infections is relatively low, can cause invasive disease with more severe outcomes and ranks among the top four serotypes isolated from retail ground beef and cattle PR/HACCP samples.

2. Multi-drug-resistant salmonella from turkey PR/HACCP samples has increased from approximately 27% to 41% over the past 10 years.

3. High and increasing levels of ciprofloxacin resistance were detected in Campylobacter jejuni from human (26.7%) and chicken PR/HACCP (28%) samples in 2014 and remained above 35% in Campylobacter coli from humans.

The NARMS Integrated report covers a time period before the full implementation of FDA's Guidance for Industry #213, which 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 the end of December 2016.