While a new FDA report shows antibiotic resistance remains low among many food-borne bacteria, some pathogens are increasingly showing multidrug resistance.
A new report from the US Food and Drug Administration (FDA) details antimicrobial resistance patterns in food-borne pathogens, offering some good news as well as some new concerns regarding multidrug-resistant Salmonella.
The link between antibiotic use in agriculture and the growing problem of antibiotic-resistant bacteria has taken center stage as global health officials have sought to tackle the public health threat caused by “superbugs.” Overuse of antimicrobials in the raising of farm animals has driven the evolution of drug resistance in bacteria such as Salmonella, Campylobacter coli, and Escherichia coli. Hard-to-treat infections from such pathogens will lead to an estimated 10 million deaths each year around the world by 2050, according to a report by the Food and Agriculture Organization of the United Nations. Last year, the Centers for Disease Control and Prevention (CDC) published a report showing that antibiotic-resistant Salmonella causes an estimated 6,200 illnesses each year in the United States. That report detailed findings on Salmonella isolates collected from 2004 to 2012 and their resistance and susceptibility to the drugs ceftriaxone, ampicillin, and ciprofloxacin.
On October 23, 2017, the FDA, the National Antimicrobial Resistance Monitoring System (NARMS), the US Department of Agriculture’s (USDA) Food Safety and Inspection Service, and the CDC released the 2015 NARMS Integrated Report. The report details antibiotic resistance in food-borne bacteria found in isolates from humans, raw retail meat, and animals at slaughter. “While overall resistance remains low for most human infections and there have been measurable improvements in resistance levels in some important areas, NARMS is closely monitoring a few areas of concern,” note authors of the report.
The agencies found that 76% of Salmonella isolates collected from humans showed no resistance to any of the 14 antibiotic drugs tested. However, of the Salmonella samples that were not susceptible to antibiotics, multidrug resistance (MDR) went up from 9% to 12%, which the report notes was mostly driven by an increase in combined resistance to ampicillin, streptomycin, sulfonamides, and tetracycline among Salmonella serotype I 4,,12:i:-. In addition, resistance to ceftriaxone among nontyphoidal Salmonella samples either showed further decline or continued to be low except for in turkey samples, which has held steady at 15.7% resistance since 2010. Also, while azithromycin resistance remains rare, some Salmonella isolates did show resistance to the drug, in some cases along with resistance to other antibiotics.
The report notes an area of concern regarding erythromycin resistance in Campylobacter coli, which increased three-to five-fold from 2011 to 2015 in isolates collected from humans (2.7% to 12.7%) and from chicken carcasses (3.4% to 12.8%). Campylobacter bacteria cause an estimated 1.3 million illnesses and 120 deaths in the United States each year, according to the report, though C. jejuni is much more prevalent and only 10% of those illnesses are due to C. coli. “Historically, C. coli are more commonly resistant to erythromycin and other agents than C. jejuni,” notes the report. “So far, it does not appear that this rapid rise in resistance is due to a transmissible macrolide gene.”
The FDA recommends that consumers protect themselves from exposure to food-borne pathogens such as antibiotic-resistant bacteria by following food safety guidelines.