The National Antimicrobial Resistance Monitoring System for Enteric Bacteria (NARMS) was established in 1996. NARMS is a collaboration between state and local public health departments, CDC (Centers of Disease Control and Prevention), the U.S. Food and Drug Administration (FDA), and the U.S. Department of Agriculture (USDA). This national public health surveillance system tracks changes in the antimicrobial susceptibility of certain enteric (intestinal) bacteria found in ill people (CDC), retail meats (FDA), and food animals (USDA) in the United States. The NARMS program at CDC helps protect public health by providing information about emerging bacterial resistance, the ways in which resistance is spread, and how resistant infections differ from susceptible infections.
NARMS monitors antibiotic resistance among the following four major foodborne bacteria.
Non-typhoidal Salmonella enterica is widely dispersed in nature. It can be found in intestinal tracts of vertebrates including wildlife, livestock, domestic pets, and also in environmental sources such as pond water. It is spread through the fecal oral route and through contact with contaminated foods. An estimated 1.2 million people get sick from Salmonella infection in the United States each year. Of these, about 23,000 are hospitalized, and 450 die from their infections. Symptoms include nausea, vomiting, abdominal cramps, diarrhea, fever, headache generally lasting 4 to 7 days with acute symptoms lasting 1-2 days. Serious disease can develop in the very young, the elderly and the immunocompromised. Fluoroquinolones and cephalosporins are used as first-line therapies for the treatment of serious Salmonella infection in adults. Cephalosporins are recommended for the treatment of pediatric infections.
Campylobacter is part of the natural gut flora of most food-producing animals such as chickens, turkeys, swine, cattle and sheep. It is estimated to cause over 1.3 million illnesses and 76 deaths in the United States each year. More than 80% of Campylobacter infections are caused by C. jejuni. However, other Campylobacter species, such as C. coli and C. fetus can cause disease in humans. C. coli and C. jejuni cause similar disease symptoms including fever, diarrhea, abdominal cramps, and vomiting lasting anywhere from 2 to 10 days. Most cases of Campylobacter gastroenteritis are self-limited and typically, antibiotic therapy is not needed. When antibiotic therapy is indicated, macrolides and fluoroquinolones are most commonly prescribed. Major food sources linked to C. jejuni infections include improperly handled or undercooked poultry products, raw milk and cheeses made from raw milk, and contaminated water.
Escherichia coli Escherichia coli is one of the predominant enteric species in the normal intestinal flora of vertebrates. However, some serotypes of E. coli can cause severe diarrheal diseases in humans. One of these pathogenic strains is E. coli O157, which is monitored for antibiotic resistance by CDC in the human population. More information can be found on the CDC website. USDA and FDA monitor resistance among generic (non-serotyped) E. coli from food animals and retail meats. Generic E. coli are used by NARMS as an indicator organism to detect both emerging resistance patterns and specific resistance genes that could potentially be transferred to other pathogenic gram-negative bacteria, like Salmonella.
Enterococcus is ubiquitous in nature and can be found in the gastrointestinal tracts, genitourinary tracts, oral cavities, and skin of humans and animals, as well as in insects, plants, soil, and water. Enterococcus is the only gram-positive organism that NARMS routinely monitors. Because it is consistently present in both types of meat and food animals, NARMS uses Enterococcus as an indicator organism to track resistance to antibiotics with activity against gram-positive organisms that may result from antimicrobial use. Enterococcus infection is notable largely as a hospital or community-acquired illness, and not much information is known about its role as a direct cause of foodborne illness. However, it is known that poorly processed meat and milk are among the foods that can transmit it.