New NARMS Report Shows Mixed Results on Antibiotic Resistance
The National Antimicrobial Resistance Monitoring System (NARMS), established in 1996, is a collaborative program of state and local public health departments and universities, the U.S. Food and Drug Administration (FDA), the Centers for Disease Control and Prevention (CDC), and the U.S. Department of Agriculture (USDA). NARMS gathers surveillance data from human clinical samples, slaughter samples and retail meat samples and tracks changes in the antimicrobial susceptibility of enteric (intestinal) bacteria found in ill people (CDC), retail meats (FDA), and food animals (USDA) in the U.S. NARMS data are used by FDA to make regulatory decisions designed to preserve the effectiveness of antibiotics for humans and animals.
A NARMS report issued this week (which covers data from calendar year 2015), found that certain types of resistance are on the rise. Namely, the report found that:
Seventy-six percent of Salmonella isolated from humans had no resistance to any of the 14 antimicrobial drugs tested, but among isolates showing resistance, multidrug resistance (MDR) increased from 9 percent to 12 percent driven largely by an increase in combined resistance to ampicillin, streptomycin, sulfonamides, and tetracycline among Salmonella serotype I 4,,12:i:-.
Ceftriaxone resistance either continued to decline or remained low in nontyphoidal Salmonella from all NARMS sources except turkey hazard analysis and critical control point (HACCP) samples, where the percent resistance in 2015 (15.7 percent) was the same as 2010 levels.
While still rare, azithromycin resistance occurred in Salmonella, in some cases in strains with resistance to other antibiotics.
Erythromycin resistance in Campylobacter coli increased three-to five-fold between 2011 and 2015 in isolates from humans (2.7 percent to 12.7 percent) and from chicken carcasses (3.4 percent to 12.8 percent).
Transmissible quinolone resistance in Salmonella may be increasing. The underlying resistance traits reside on mobile genetic elements and therefore have the potential to be shared, either alone or together with other resistance genes, with susceptible strains of Salmonella.
The report also found that ground turkey resistance levels continue to decline. More specifically, from 2014 to 2015, there was a decline from 73 percent to 57 percent in the proportion of retail ground turkey Salmonella isolates resistant to at least one antimicrobial. Historically, the majority of isolates from turkey sources have been resistant to at least one antimicrobial.
Of note, this report covers a time period prior to the full implementation of FDA guidance recommending the reduction of medically important antibiotics in food-producing animals. As more and more companies adopt FDA’s recommendations, it is likely that we will begin to see resistance levels decline across the board.