Both increasing and decreasing trends in antimicrobial resistance are reported in the National Antimicrobial Resistance Monitoring System (NARMS) 2011 Executive Report released by the FDA in August.
NARMS is an ongoing collaborative effort by the FDA, the CDC, USDA, and state health laboratories in 14 states. The surveillance program monitors the prevalence and trends of antimicrobial resistance among foodborne isolates of Salmonella, Campylobacter, Enterococcus, and E. coli based on samples collected from humans, food-producing animals, and retail meat sources.
The report summarizes data previously released by each of the three agencies and focuses on resistance to antibiotics important in human medicine and multidrug resistance. Among the positive trends is a decline in the five-drug resistance pattern called ACSSuT (resistance to ampicillin, chloramphenicol, streptomycin, sulfonamide, tetracycline) in Salmonella Typhimurium. From its peak of 35.1 percent in 1997, resistance had declined to 19.5 percent in 2011. Also 85 percent of nontyphoidal Salmonella collected from humans had no resistance to any of the antibiotics tested, according to the report.
Resistance has also increased in some cases. Since 2005, Campylobacter resistance to the fluoroquinolone ciprofloxacin increased slightly in isolates from humans. Resistance to third-generation cephalosporins, a class of drugs used to treat Salmonella infections, increased between 2008 and 2011 among isolates from retail ground turkey and between 2009 and 2011 among certain Salmonella serotypes in cattle. The FDA took action in 2012 to prohibit certain uses of cephalosporin drugs in cattle, swine, chickens, and turkeys.
The report noted that multidrug resistance in Salmonella from humans, slaughtered chicken, and slaughtered swine was the lowest since NARMS testing began, but that resistance in Salmonella from retail poultry meats has increased, with slight fluctuations.
The FDA announced on June 30 that it has received support for its strategy to promote judicious use of antimicrobials in food-producing animals. The 26 drug manufacturers affected by this initiative (Guidance for Industry #213) have agreed to phase out the use of medically important antimicrobials in food-producing animals for food production purposes and to phase in the oversight of a veterinarian for the remaining therapeutic uses of such drugs.
According to FDA spokesperson Megan Bensette, in the Office of Foods and Veterinary Medicine, implementation of this initiative “is an important step. … Antimicrobial drugs should be used only for treating, controlling, or preventing disease in these animals in order to protect human and animal health.”