antibiotic resistance on the farm antibiotic use in food animals课件

Antibiotic Resistance on the Farm Antibiotic Use in Agriculture Gary A. Balsamo, DVM, MPH&TM Louisiana Department of Health and Hospitals, Office of Public Health Infectious Disease Epidemiology How much antibiotics are used in agriculture? No one knows for sure 20 million lbs per year (estimate by FDA). Estimates range from 36 % to 70 % of all antibiotics produced in the USA and over 50 % of those produced worldwide Uses of antibiotics in agriculture? Growth promotion and disease prevention (majority) Medicating diseased animals Fish farms Fruit, potatoes, tobacco and others Ornamental plants What antibiotics are used in food production? Penicillins Tetracyclines Macrolides Lincomicin Bacitracin Virginiamycin Aminoglycosides Sulfonamides Streptomycin NARMS 2002 retail food study (preliminary results): 2,513 meats analyzed for the presence of Campylobacter and Salmonella (chicken breasts, pork chops, ground beef and ground turkey) Campylobacter was recovered from 47 % of the chicken breasts. Resistance: 15 % of C. jejuni and 9 % of C. Coli were resistant to ciprofloxacin 20 % of C. Coli were resistant to erythromicin NARMS 2002 retail food study (preliminary results): 5 multi-drug resistant strains of Salmonella Newport were recovered from ground beef, ground turkey and pork chops. 1574 meat samples were analyzed for Enterococcus and E coli. 1,070 E coli isolates were recovered Resistance: 52 % to tetracycline 36% to streptomycin 28% to sulfamethoxazole 19% to ampicillin 14 % to gentamicin How does animal use of antibiotics contribute to resistance? Animals consume and excrete antibiotics (approximately 2 trillion lbs of manure generated in USA annually) Animals can transmit resistant bacteria in food Food of animal origin most common cause of food-borne infections due to: Salmonella Campylobacter Yersinia E Coli 0157,H7 Genetic transfer to human specific organisms (avoparcin in pigs and chickens). This can also occur with plant bacteria. Antibiotic resistance: A public health concern Increased cost to healthcare Development of new antibiotics is slow Prolonged illness and greater risk to death Greater risk of antibiotic resistant food- borne illness (Salmonella DT-104, fluoroquinilone resistant Campylobacter) Use of Avoparcin/ VRE Country Avoparcin used VRE in animal husbandry Belgium+ Denmark+ Finland+ France+ Germany+ Great Britain+ The Netherlands+ Norway+ Sweden United States Prevalence of vancomycin-resistant Enterococcus faecium in nursing homes No. persons investigated No. E. faecium positive No. VRE positivea,b Vegetarians42230 Nonvegetarians62326 aP0.05. bAll VRE-positive samples were E. faecium. Elements of vancomycin-resistance Source No. isolates T variant G variant Humans 4516 29 Pigs 3332 1 Poultry193 0193 Total27148223 CDC studies 1971-1983 AS Salmonella CFR 0.2% AR Salmonella CFR 4.2% CDC studies 1987 AS Salmonella outbreak cases requiring hospitalization: 57% AR Salmonella outbreak cases requiring hospitalization: 24.5%* * Other studies performed since this time have replicated these results in Salmonella and Campylobacter outbreaks History of concern Antibiotic use for disease prevention and growth promotion began in 1950s. In 1960s scientists began raising concerns with antibiotic resistance in humans 1977: FDA proposed restricting the use of penicillin and tetracycline in farm animals (overruled by Congress) 1999 NAS report concluded minimal or no risk Should antibiotics for growth promotion and disease prevention be banned? Adverse effect on animal industry reduced food supply increased cost increased disease incidence economic loss by farmers May not be totally necessary Might only require ban of specific antimicrobial drugs that could select for resistance to drugs in human medicine. AVMA recommends: Use of narrow spectrum drugs Tx only the sick or at risk Further research before imposing bans Antibiotic use in therapy: Veterinarians can use certain approved animal drugs “extra label” Certain drugs, such as fluoroquinolones, cannot be used “extra label”. Antibiotics are often not necessary in therapy AVMA recommends: Use of narrow spectrum drugs Tx only the sick or at risk for bacterial infections Further research before imposing bans Producer education Organizations recommending some type of ban or strict regulation of antibiotic use in food animals: AMA APHA CSTE American College of Preventive Medicine WHO What is being done? Presidents Council on Food Safety NARMS FDA (primary regulatory agency) CVM Proposed withdrawal of approval to use enrofloxacin in poultry water EPA (regulation of antimicrobial use on crops) USDA FSIS (tests for illegal substances) FSI FARAD NARMS (National Antimicrobial Resistance Monitoring System Not just for people Coordinated network of PH labs and Federal agencies DHHS FDA (CVM) CDC USDA (FSIS, ARS, APHIS) Specific microbes are tested for resistance Compared over time to check for changes in resistance patterns Expansion of Agricultural Surveillance Expanding to all fifty states Surveillance for resistant pathogens found on retail foods EPA is reviewing the effect of antimicrobial pesticide products Sources American Society for Microbiology K K Barnes et al. “Water-Quality Data for Pharmaceuticals, Hormones, and Other Organic Wastewater Contaminants in U.S. Streams.” USGS, Open-File Report 02-94 D W Kolpin et al. “Pharmaceuticals, Hormones, and Other Organic Wastewater Contaminants in U.S. Streams, 1999-2000: A National Reconnaissance.” Environmental Science and Technology, 36(6): 1202-1211. H C Wegener et al. “Use of Antimicrobial Growth Promo