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U.S. Department of Health and Human Services

Animal & Veterinary

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FDA Veterinarian Newsletter September/October 2000 Volume XV, No. V

Drs. Marcia Headrick, Charlotte Spires, Kathy Hollinger, Charles Eastin (Division of Epidemiology) and Linda Tollefson (OSC), attended the recent International Conference on Emerging Infectious Diseases (ICEID). The conference was hosted by the Centers for Disease Control (CDC) and the American Society of Microbiology (ASM) in Atlanta, Georgia. There were several presentations and posters at the conference using National Antimicrobial Resistance Monitoring Program (NARMS) data. Oral presentations were given by Shannon Rossiter of CDC on "High prevalence of fluoroquinolone-resistant Campylobacter jejuni in the FoodNet sites" and by Fred Angulo of CDC on "Enterococci study: monitoring for the seeds of antimicrobial resistance in the food supply."

Posters on NARMS data included:

  • Emergence of a multidrug-resistant strain of Salmonella serotype Newport in the United States -- NARMS 1997-1999
  • Antimicrobial resistance patterns of Escherichia coli O157:H7 - NARMS 1996-1999
  • Fluoroquinolone-resistance in Campylobacter from chicken and the human health impact: a quantitative risk assessment using data from FoodNet and NARMS
  • Fluoroquinolone-resistant Campylobacter causes longer duration of diarrhea than fluoroquinolone-susceptible Campylobacter strains in FoodNet sites
  • High prevalence of antimicrobial resistance among Shigella isolates to agents commonly used for treatment - NARMS 1999
  • Phage type and antimicrobial resistance trends among human Salmonella serotype Typhimurium isolates in NARMS 1997-1998 - continued dominance of DT-104 R-type ACSSuT
  • Emerging antimicrobial resistance among human Salmonella isolates to clinically important antimicrobial agents -- NARMS 1996-1999

Following is an abstract presented by Dr. Katherine Hollinger:

Fluoroquinolone Resistance in Campylobacter from Chickens and Human Health Impact; A Quantitative Risk Assessment using FoodNet and other sources of Data

K. Hollinger1, M. Bartholomew1, D. Vose2, M. Miller1, S. Thompson1, D. Vugia3, T. Fiorentino4, J. Benson5, J. Johnson6, K. Smith7, E. DeBess8, F. Angulo9, and the EIP FoodNet Working Group9

1FDA, Rockville, MD; 2D. Vose Consultancy, Ltd., Dordogne, FRANCE; 3California Dept. of Health Services, Berkeley, CA; 4Connecticut Emerging Infections Program, New Haven, CT; 5Georgia Emerging Infections Program, Decatur, GA; 6Maryland Dept. of Health and Mental Hygiene, Baltimore, MD; 7Minnesota Dept. of Health, Minneapolis, MN; 8Oregon Health Div., Portland, OR; 9CDC, Atlanta, GA

Background: Emerging antimicrobial resistance, due to use of antimicrobials, is a public health concern in human and animal medicine worldwide. Animals serve as reservoirs for many foodborne pathogens, including Salmonella and Campylobacter. Antibiotic resistant organisms may be present in or on animals as a result of drug use. These resistant foodborne pathogens can contaminate a carcass during slaughter or processing. When these resistant bacteria cause illness in a person who needs treatment, medical therapy may be compromised if the pathogenic bacteria are resistant to the drug(s) used for treatment. Fluoroquinolones are effective against most bacterial enteric pathogens and are often used to treat Campylobacter infections. Campylobacter is the predominant bacterial cause of enteric infections. Fluoroquinolones were approved for treatment of colibacillosis in poultry in 1995. The FDA Center for Veterinary Medicine (CVM) developed a risk assessment model that evaluates the risk of fluoroquinolone resistant Campylobacter infections from consumption of chicken that are attributed to use of fluoroquinolones in chickens.

Methods: A mathematical model was developed to relate the prevalence of resistant Campylobacter infections in humans, due to consumption of chicken, to the prevalence of resistant Campylobacter in chickens. The model uses data from recently initiated surveillance systems (FoodNet and NARMS) that monitors incidence of foodborne disease, and prevalence of fluoroquinolone resistance, as well as data from the published literature.

Results: The model estimates a mean of 2 million cases of Campylobacter for 1998 in the US. Approximately 50 to 70 percent of Campylobacter infections were attributed to exposure to chicken. Of these chicken associated infections seeking care and receiving treatment, 55 percent received a fluoroquinolone. An estimated 5000 people (5 –95 percent confidence interval 2600 to 8600) became ill with a fluoroquinolone resistant Campylobacter infection associated with consuming chicken and received fluoroquinolones for their illness. The risk assessment also described data gaps and data limitations and gives detailed assumptions where data were lacking.

Conclusions: This risk assessment indicates that approximately five thousand people who are ill with fluoroquinolone resistant infections could be treated with a fluoroquinolone and that treatment is potentially compromised due to resistance. Surveillance data can be used to update the model annually and will indicate changes in level of resistance and incidence of campylobacteriosis. These changes may reflect alterations in food animal production, processing or may indicate changes in bacterial virulence or a change in the susceptibility of the human population. Forecasting potential changes in level of resistance in chickens could provide a means to mitigate the human health impact.

Dr. Katherine Hollinger is an Epidemiologist in CVM’s Division of Epidemiology.