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FSI FY 99 ANNUAL ACCOMPLISHMENTS REPORT
WHO Holds an Informal Information Meeting on Antimicrobial Resistance Surveillance in Food-borne Pathogens
The World Health Organization (WHO) held a meeting March 30 April 2, 1999, in Geneva, Switzerland, on Antimicrobial Resistance Surveillance in Food-borne Pathogens. In attendance from the FDA/Center for Veterinary Medicine, was Dr. Linda Tollefson. This meeting followed an October 1997 WHO meeting held in Berlin on the medical impact of the use of antimicrobials in food animals. Based on the recommendations from the 1997 meeting, a number of national and international groups began projects to strengthen antimicrobial resistance surveillance of food-borne pathogens. Dr. Tollefson remarked that the “1999 meeting provided an informal exchange of information between ongoing and planned programs.” A primary goal was to encourage international collaboration and possible convergence of surveillance activities. A total of 24 scientists from l0 countries participated in the meeting. Participants presented reports on l l national and international antimicrobial resistance surveillance projects including the U.S. National Antimicrobial Resistance Monitoring System for Enteric Bacteria (NARMS-EB). Discussions followed each of the presentations to identify both characteristics of successful programs and limitations of other programs. The participants were encouraged to continue discussions and identify possibilities for collaboration. In March 2000, WHO will assess the need for a future meeting.
U.S. Representatives Visit Mexico to Discuss NARMS
In June, National Antimicrobial Resistance Monitoring System Enteric Bacteria (NARMS EB) representatives from FDA, Drs. Linda Tollefson and Kathy Hollinger, and Dr. Paula Cray from USDA ARS visited Mexico to help start a monitoring system for antimicrobial resistance in Salmonella and Campylobacter. The U.S. representatives described the NARMS-EB and presented current data on multiple drug resistance in Salmonella from poultry slaughter isolates and on antimicrobial resistance in Campylobacter from poultry.
Dr. Tollefson reported that “the project will begin with participation by sites in five Mexican states, organized by Dra Mussaret Zaldi of O’Horan General Hospital in Yucatan, with significant food animal agriculture in close proximity to the monitoring centers.” The participating states are Durango, Michoacan, Guanajuato, Mexico City and Yucatan. These sites are among fifteen collaborating laboratories situated throughout Mexico, Costa Rica, and Guatemala associated with the World Health Organization (WHO) Resistnet group. This group was organized in 1996 to monitor resistance among the human nosocomial pathogens Salmonella, Shigella, Staph aureus, E. coli, and P. aeruginosa.
Dr. Tollefson noted that “the new project will first collect isolates from children in daycare settings to characterize the carriage rates of Salmonella in children and identify the antimicrobial resistance patterns of the isolates.” A proposal to obtain animal isolates from retail poultry and swine markets in coordination with the School of Veterinary Medicine in Yucatan is planned for the future. Plans to exchange advanced training in isolation methodology for surveillance purposes and susceptibility testing are also in progress.
This collaboration between the U.S. NARMS-EB and the Mexican antimicrobial surveillance group represents the initiation of the first international human and animal monitoring system for food-borne antimicrobial drug susceptibility surveillance in the Americas.
National Antimicrobial Resistance Monitoring System
The United States now has in place a system that allows the Food and Drug Administration (FDA) to tell when food-borne bacteria that cause disease in humans begin to develop resistance to antimicrobials used in food animals. The system is called National Antimicrobial Resistance Monitoring System Enteric Bacteria (NARMS EB). It combines the resources of FDA, the Centers for Disease Control and Prevention (CDC), and the U.S. Department of Agriculture (USDA) to create a nationwide monitoring system. Dr. Tollefson, FDA/Center for Veterinary Medicine explains “under NARMS, isolates of E. coli, Salmonella, Enterococci, and Campylobacter from humans and food animals are collected and tested to determine whether the bacteria are beginning to lose their susceptibility to antimicrobial drugs.” The program alerts Department of Health and Human Services employees at CDC and FDA to any change in bacterial response to antibiotics used in people. Informed public health officials, responsible animal producers and drug manufacturers, and veterinarians can use this information to control and prevent harm from the use of antimicrobials in food animals through prudent antibiotic use practices. The system tests the three gram -negative bacteria for susceptibility to 17 different antibiotics and the susceptibility of gram -positive Enterococci to 27 antibiotics. The human isolates are tested by CDC, and the animal isolates by the Agricultural Research Services of USDA. FDA initiated the program in 1996 and significantly expanded it under the Food Safety Initiative in 1999 to collect more isolates from more locations and more types of bacteria from animals and humans.
Food Safety Message Taken to Trade Shows
This year, the Center for Veterinary Medicine started an exhibit program designed to bring the food safety message to livestock producers and veterinarians at their trade shows. The focus is on preventing the risk to public health from bacteria that have grown resistant to antimicrobials following the use of the drugs in food animals. Mr. Jon Scheid, coordinator of Food Safety Initiative Education program, describes the exhibit program as “a layout of posters depicting key aspects of the Center's approach to food safety, including its program to monitor the emergence of resistant pathogens in food animals.” In addition, literature presented at the booth fully explains the Center's programs and how they involve livestock producers and veterinarians. Staff at the booth respond to questions from trade show participants. To date the exhibit program has been well received by a variety of audiences including livestock producers and veterinarians. The exhibit program gives these individuals a chance to ask questions in person and get timely responses.
BSE Educational Activities Gain Vice Presidential Award
On May 14, the Food and Drug Administration (FDA)/Association of American Feed Control Officials (AAFCO) Bovine Spongiform Encephalopathy (BSE) Feed Regulation Team was honored with Vice President Al Gore's Hammer Award. The Hammer Award honors Federal employees and their partners who have joined forces to streamline procedures, put consumers first, and help build a better and more cost effective government. The award citation reads “For making a significant contribution to reducing the possibility of bovine spongiform encephalopahty (BSE/Mad Cow Disease) becoming established and spread in the U.S.” The BSE Feed Regulation Team used an innovative education-oriented partnership program to enforce a FDA regulation designed to control BSE.
The BSE regulation, now in effect for two years, restricts the use of mammalian protein in feeds for cattle and other ruminants. The regulation requires protein renderers, protein blenders, feed manufacturers, and distributors to label feeds that contain prohibited material with the following warning statement: "Do not feed to cattle or other ruminants." FDA developed the regulation to prevent the establishment and amplification of BSE through feed.
Ms. Gloria Dunnavan, FDA/CVM, Director Division of Compliance, reports “the data shows that compliance rates for the first inspections of all but one industry segment equaled or exceeded 75 percent. Compliance rates at follow up inspections should approach the goal of 100 percent, based on the enforcement strategy developed and updated jointly by the partners. Independent research has shown that major industry adjustments have been made to facilitate compliance with the regulations. FDA and State inspectors have conducted an unprecedented number of education oriented inspections; a reinvented approach to doing inspections that has resulted in 70 percent savings in the cost of inspections.”
The Fairmont Hotel in Dallas, Texas was the setting for another initiative conducted by the BSE Feed Regulation Team. The FDA sponsored workshop held for state veterinarians and feed control officials from all fifty states, Puerto Rico, the U.S. Virgin Islands and Canada provided a briefing on the latest developments with the BSE feed regulation. More than 170 state and federal regulators took part in the two day workshop that featured speakers from FDA's Center for Veterinary Medicine (CVM), and Office of Regulatory Affairs (ORA), USDA's Animal and Plant Health Inspection Service (APHIS) and Canada's Food Inspection Agency.
Dr. John Honstead, a veterinary medical officer with FDA/Center for Veterinary Medicine briefed participants on the current science on BSE and its impact on human health. Dr. John Honstead reported that “although the BSE epidemic in the United Kingdom continues to abate, there are growing concerns that the incidence of a similar disease in humans called new variant Creutzfeldt-Jakob disease (CJD) is increasing.” The states played an important role in the presentation of this workshop. The states and FDA provided detailed accounts of their perspectives and experience with inspections for compliance with the regulation. The session concluded with a look at similar efforts “north of the border” from our regulatory counterpart, Mr. Sergio Tolussa with the Canadian Food Inspection Agency.
Other topics included import activities, future initiatives and the use of a problem solving breakout session to deal with several scenarios involving the use of prohibited materials. Finally, Dr. Linda Detwiler from USDA/APHIS discussed a Memorandum of Understanding with USDA and provided some insight into USDA's role in the prevention of BSE in this country. This workshop generated a great deal of interaction among the participants including many questions, solutions to problems, ideas for inspectional techniques, educational initiatives and enforcement approaches.
Thanks to the development of the BSE regulation, we can continue to say that there has not been a single case of BSE reported in the United States. Educational efforts such as this with our regulatory partners will help assure that we can continue to make that claim.
Research on Food Safety
The Office of Research has developed research programs in two distinct thematic areas; 1) antibiotic resistance in the pre and post approval animal production environments, and 2) the microbial quality of animal feeds. Antibiotic resistance as it relates to zoonotic pathogens is directly related to the Center for Veterinary Medicine's (CVM) mission regulating the safe and effective use of drugs for use in food producing animals. "Development of antibiotic resistance in zoonotic pathogens is a critical human food safety issue impinging on the safe use of antimicrobials," noted Dr. Michael Myers, Acting Director of CVM's Division of Animal and Food Microbiology. CVM also regulates animal food. "As many feed components for food producing animals harbor foodborne pathogens such as Salmonella, it is important to understand the potential role feed may play in transmission of zoonotic pathogens to man," states Dr. David Wagner, a Research Animal Scientist at FDA/CVM. Dr. Wagner also noted that "it is also important to understand how microbes associated with feed commodities influence the development and dissemination of antibiotic resistance within the environment."
Intramural research efforts on antibiotic resistance have centered on development of research to monitor, or identify, the patterns and types of antibiotic resistant zoonotic pathogens at the retail and animal production levels and studies focusing on development and dissemination of antibiotic resistance within the animal production environment. "This two pronged approach is designed to provide information about the types of resistant pathogens reaching the consumer, which when coupled with the other research results, will help to formulate prudent use strategies to minimize or mitigate resistance development," noted Dr. David White, a Research Microbiologist at FDA/CVM. Current monitoring activities are focused on characterizing the microbial quality of animal feeds and the types of antibiotic susceptibility patterns among E. coli, Salmonella, and Enterococcus ssp isolates obtained from retail ground beef, ground turkey, ground pork and farm raised fish. Additional monitoring activities are focused on characterizing susceptibility patterns to veterinary E. coli, Salmonella, and Enterococcus isolates from swine and poultry production facilities. Another surveillance activity is Center for Veterinary Medicine’s (CVM) participation in the PulseNet program sponsored by CDC. "CVM’s involvement with this epidemiological surveillance tool provides a critical link to the animal production environment for traceback studies during outbreaks of foodborne illness," noted Dr. Shaohau Zhao, who is CVM's laison to PulseNet. Research efforts on development and dissemination of antibiotic resistance in shiga toxin producing Escherichia coli (STEC), Enterococci, and Salmonella ssp as a consequence of antibiotic use in aquaculture, swine and poultry facilities are also underway.
Our extramural research program is designed to complement and augment our intramural research plan. Six of the current projects are designed to elucidate the prevalence and risk factors associated with the dissemination of antibiotic resistant Salmonella, E. coli O157:H7, and Enterococci within the animal production environment. Another study seeks to adapt and validate microbial detection methods developed for food in the animal production environment.
Evaluating the Risk to Human Health from Resistant Food-borne Pathogens and Resistant Determinants Associated with the Use of Antimicrobials in Food Producing Animals
Evidence of increasing resistance to antimicrobial drug treatment in bacteria that infect humans has raised questions about the role that antimicrobial drug use in food producing animals plays in the emergence of antimicrobial drug resistant bacteria.
Food animals receive antimicrobials for growth promotion, and control or treatment of infectious diseases. Food animals can carry organisms that are pathogenic to humans and these organisms may develop resistance when the animal is exposed to the antibiotics. These resistant organisms can contaminate food products at slaughter and then infect humans who ingest the food.
FDA's goal is to protect public health by ensuring that significant human antimicrobial therapies are not compromised due to the use of antimicrobials in food animals, while providing for the safe use of antimicrobials in animals.
In December 1998, FDA released a document entitled "A Proposed Framework for Evaluating and Assuring the Human Safety of the Microbial Effects of Antimicrobial New Animal Drugs Intended for Use in Food Producing Animals." This document sets out a conceptual risk based process for evaluating the microbial safety of antimicrobial drugs intended for use in food producing animals. In the document, FDA proposes that pre-approval data be required to show that the level of resistance transfer from animals to humans associated with the use of drugs in food animals will be safe for consumers of food products derived from treated animals. Depending on a drug’s category, FDA may require post approval monitoring, either through NARMS-EB, or possibly on-farm testing.
Dr. Sharon Thompson, FDA/Center for Veterinary Medicine (CVM), Associate Director for Veterinary Medical and International Affairs noted that “CVM is in the process of conducting a risk assessment that evaluates the risk to human health from resistant food-borne pathogens associated with the use of antimicrobials in food producing animals. CVM will use this formula to model the risk of increased duration of illness due to resistant Campylobacter infections attributable to the use of fluoroquinolones in chickens.” A mathematical model was derived to relate the prevalence of resistant Campylobacter infections in humans from chickens to the prevalence of resistant Campylobacter in chickens. In deriving the model, the risk assessment expert contracted by CVM for the project incorporated the uncertainties in the data that had been gathered. To develop the risk assessment on fluoroquinolone resistant Campylobacter, data on the prevalence of Campylobacter in both chickens and humans were needed. CVM used prevalence data in chickens from the National Antimicrobial Resistance Monitoring System (NARMS) database, noted Dr. Thompson. The FoodNet, an active surveillance system for food-borne pathogens maintained by the Centers for Disease Control and Prevention (CDC), and associated databases and published journal articles were sources for the human prevalence and other epidemiologic data.
Dr. Sharon Thompson, further states “this risk assessment is the first of several that will be done by CVM. The model used in this assessment is a prototype for assessing risk due to the transfer of resistant food-borne pathogens from animals to humans. CVM will be developing a second risk assessment model to assess the transfer of resistance determinants to human pathogens from enterococci originating in animals.” These risk assessments will ensure that the Agency is making sound science-based regulatory decisions.
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