Correspondence/Rebuttal pubs.acs.org/est
Response to Comment on “Feather Meal: A Previously Unrecognized Route for Reentry into the Food Supply of Multiple Pharmaceuticals and Personal Care Products (PPCPs)”
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best knowledge of the composition of animal feed and may have useful insights into potential routes of entry of unwanted drug residues.
e welcome the continuing discussion of our study on pharmaceuticals and personal care products (PPCPs) in feather meal, and are encouraged by interest from the avian veterinarian community. In acknowledging the major finding of our study that feather meal does contain antimicrobial residues, Dr. Kelly suggests that the reintroduction pathway shown in Figure 11 may not apply because the detected levels of fluoroquinolones are too low to select for drug-resistant Campylobacter spp. in poultry. However, the pathway for drug deposition in feather meal we show simply provides an overview of the mechanism of drug recycling in poultry production without elaborating on the magnitude of animal body burdens or antimicrobial resistance outcomes that may result. Given the industry’s acknowledged practice of supplementing poultry feed with feather meal, the pathway thus is scientifically correct as stated. Owing to a lack of data, the question of whether drug residue levels present in feather meal are high enough to exert selective pressure on pathogenic microorganisms may not be answered conclusively at this time. Evidence exists that sublethal, yet inhibitory concentrations of fluoroquinolones can enhance selective pressure and drive emergence of resistance. The fluoroquinolone daily inclusion rate (0.03 μg/g feed) calculated by Dr. Kelly2 is similar to the enrofloxacin and ciprofloxacin minimum inhibitory concentrations (MIC) for a poultryderived strain and a laboratory strain of C. jejuni.3,4 As well, concentrations of ciprofloxacin of less than 0.03 μg/g can exert selective pressure on other clinically relevant strains of bacteria.5 We detected multiple classes of antimicrobials in each sample, so other important factors to consider are the potential for cross-selection pressure,6 the potential for additive effects of multiple types of fluoroquinolones in a sample, and how these antimicrobials in feather meal might augment what is provided in medicated feed,7 which were not discussed in the comment. Others have also raised concerns over the role of feather meal and other rendered meals as vectors for antimicrobialresistant bacteria to food animals.8,9 More broadly, experts ranked the question, “Does environmental exposure to [pharmaceuticals and personal care product (PPCP)] residues result in the selection of antimicrobial resistant microorganisms, and is this important in terms of human health outcomes?” third most important out of over 100 research questions considered.10 These issues remain relevant in the policy arena as well; the FDA acknowledges a need to limit the use of medically important antimicrobials in food animals.11 In light of our finding of previously unrecognized PPCPs in a commonly administered animal feed ingredient and the subsequent queries raised, additional research is needed on feather meal, including drug bioavailability, uptake, and antimicrobial resistance. A dialogue with animal producers and veterinarians, such as Dr. Kelly, is essential, as they have the © 2012 American Chemical Society
D. C. R. U. M. F. K. E. †
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Love†,‡,* Halden‡,§,∥,⊥ Davis†,‡ Nachman†,‡,#
Johns Hopkins Center for a Livable Future, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States ‡ Department of Environmental Health Sciences, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States § School of Sustainable Engineering and the Built Environment, Arizona State University, Tempe, Arizona, United States ∥ Center for Environmental Security, Biodesign Institute, Arizona State University, Tempe, Arizona, United States ⊥ Center for Health Information & Research, Arizona State University, Tempe, AZ, U.S. # Department of Health Policy and Management, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States
AUTHOR INFORMATION
Corresponding Author
*Phone: 443.287.4761; fax: 410-502-7579; e-mail: dlove@ jhsph.edu. Notes
The authors declare no competing financial interest.
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REFERENCES
(1) Love, D. C.; Halden, R. U.; Davis, M. F.; Nachman, K. E. Feather meal: A previously unrecognized route for reentry into the food supply of multiple pharmaceuticals and personal care products (PPCPs). Environ. Sci. Technol. 2012, 46 (7), 3795−3802. (2) Kelly, B. Comment on “Feather meal: A previously unrecognized route for reentry into the food supply of multiple pharmaceuticals and personal care products (PPCPs). Environ. Sci. Technol. 2012, DOI: 10.1021/es303433s. (3) Performance Standards for Antimicrobial Disk and Dilution Susceptibility Tests for Bacteria Isolated from Animals; Approved Standard; 3rd ed.; Clinical and Laboratory Standards Institute2008; Vol. 28 (8), pp 1−99. (4) Pasquali, F.; Lucci, A.; Manfreda, G. Mutant prevention concentration of ciprofloxacin, enrofloxacin and nalidixic acid against Campylobacter jejuni. Int. J. Antimicrob. Agents 2008, 31 (5), 500−502. (5) Tello, A.; Austin, B.; Telfer, T. C. Selective pressure of antibiotic pollution of bacteria of importance to public health. Environ. Health Perspect. 2012, 120 (8), 1100−1106. Published: October 22, 2012 13026
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(6) Wright, G. D. The antibiotic resistome: The nexus of chemical and genetic diversity. Nat. Rev. Microbiol. 2007, 5 (3), 175−186. (7) Love, D. C.; Davis, M. F.; Bassett, A.; Gunther, A.; Nachman, K. E. Dose imprecision and resistance: medicated free-choice feeds in industrial food animal production. Environ. Health Perspect. 2010, 119 (3), 279−283. (8) Hofacre, C. L.; White, D. G.; Maurer, J. J.; Morales, C.; Lobsinger, C.; Hudson, C. Characterization of antibiotic-resistant bacteria in rendered animal products. Avian Dis. 2001, 45 (4), 953− 961. (9) Cullen, P.; Mc Dermott, S. D.; Carter, P. J.; Paige, J. C.; Wagner, D. D. Prevalence and Antibiotic Susceptibility Profiles of Enterococcus spp. Recovered from Rendered Animal Feed Commodities: Results of a National Survey; U.S. Food and Drug Administration Science Forum Poster Abstract Board H-01. Washington, DC, April 24−25, 2003; http:// www.accessdata.fda.gov/scienceforums/forum03/H-01.htm (accessed October 8, 2012). (10) Boxall, A. B. A.; Rudd, M. A.; Brooks, B. W.; Caldwell, D. J.; Choi, K.; Hickmann, S.; Innes, E.; Ostapyk, K.; Staveley, J. P.; Verslycke, T.; Ankley, G. T.; Beazley, K. F.; Belanger, S. E.; Berninger, J. P.; Carriquiriborde, P.; Coors, A.; Deleo, P. C.; Dyer, S. D.; Ericson, J. F.; Gagné, F.; Giesy, J. P.; Gouin, T.; Hallstrom, L.; Karlsson, M. V.; Larsson, D. G.; Lazorchak, J. M.; Mastrocco, F.; McLaughlin, A.; McMaster, M. E.; Meyerhoff, R. D.; Moore, R.; Parrott, J. L.; Snape, J. R.; Murray-Smith, R.; Servos, M. R.; Sibley, P. K.; Straub, J. O.; Szabo, N. D.; Topp, E.; Tetreault, G. R.; Trudeau, V. L.; Van Der Kraak, G. Pharmaceuticals and personal care products in the environment: What are the big questions? Environ. Health Perspect. 2010, 120 (9), 1221− 1229. (11) U.S. Food and Drug Administration. Guidance for Industry # 209: The Judicious Use of Medically Important Antimicrobial Drugs in Food-Producing Animals, Docket No. FDA-2010-D-0094, 2012.
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