Outbreaks Associated with Antibiotic-resistant Foodborne Pathogens

Introduction: Antibiotic-resistant foodborne pathogens are a natural consequence of antibiotic usage in food animals. Sixty-five percent of antibiotics that are sold for use in animal agriculture are similar or identical to antibiotics sold for use in human medicine, and whenever an antibiotic is used, its efficacy diminishes as certain bacterium, under selective pressure, will go on to survive and proliferate.  When people consume food items that are contaminated with antibiotic-resistant pathogens, they develop infections that are more likely to lead to hospitalization and an increased risk of death. Keeping track of antibiotic-resistant foodborne illness outbreaks is a critical first step in understanding overall disease burden. 

Purpose: Limited information exists on outbreaks of foodborne illness due to antibiotic-resistant bacteria.  CSPI has developed a database to document the link between food products and associated human cases.

Methods: Outbreaks were compiled based on comprehensive literature review. The outbreak database catalogues illnesses, hospitalization, and death, based on etiology, state, food source (when available), food commodity category, antibiotic-resistance profile, WHO and FDA classifications of antimicrobial pharmaceuticals. 

Results: A total of 55 outbreaks, in which bacterial infections were resistant to at least one antimicrobial agent, have been identified between 1973 and 2012, causing 20,571 documented illnesses, 3155 hospitalizations, and 27 deaths. Outbreaks from associated food commodity categories include: beef (causing 10 outbreaks), dairy (13), eggs (1), multi-ingredient foods (3), poultry (6), pork (1), produce (3), seafood (2), and unknown items (13). Salmonella spp. were identified as causative agents in 48 of 55 outbreaks, with S. Typhimurium implicated in 19 and S. Newport 15 outbreaks. E. coli caused 5 outbreaks, and Campylobacter jejuni and Staphylococcus aureus were each responsible for 1 outbreak. Responsible bacteria displayed resistance to a total of 15 different antibiotics and to at least one sulfonamide. 

Significance: Prevention efforts are needed to combat the problem of antibiotic-resistant foodborne illnesses. These illnesses are more likely to cause longer hospital stays, and an increase in risk of death. Database development and analysis provides public health officials with the evidence to construct more effective mitigation efforts.