Factual errors in review article

JAC Journal of Antimicrobial Chemotherapy DOI: 10.1093/jac/dkh267 Advance Access publication 12 May 2004 Factual errors in review article Linda Tollefson* U.S. Food and Drug Administration, 7519 Standish Place, Rockville, MD 20878, USA Keywords: antimicrobial resistance, animal agriculture *Tel: +1-301-827-2943; Fax: +1-301-827-4335; E-mail: Sir, The recent article in JAC by Phillips et al.1 contains several factual errors. The authors contend that pathogens that become resistant due to the use of antimicrobial agents in food-producing animals rarely infect humans and when they do, the clinical consequences of resistance may be small. This assessment diverges from the majority of the peer-reviewed scientific literature on the subject, casting doubt on how objectively the authors reviewed the published data. The credibility of the authors’ assessment is further strained by frequent improper citation of the published literature. In the Introduction the authors state ‘. . .there has been a concerted attack on the agricultural use of antibiotics, based on the assumption that all such usage is imprudent since it might act as an important source of resistance in bacteria affecting humans’. The authors improperly cite seven references to support this statement. Although the cited references state that some agriculture uses are imprudent, the references do not say ‘all such usage is imprudent’. Phillips et al.1 state ‘. . .an independent examination of the facts, free from commercial or political influence, shows that the actual risk is extremely small and may be zero in many cases’. It is difficult to understand what ‘facts’ the authors are referring to since there is a great deal of evidence demonstrating an association between antimicrobial use in animals and antimicrobial resistance in humans. A summary of this evidence was recently published by Swartz.2 There is also accumulating evidence that antimicrobial resistance among bacteria isolated from humans resulting from the use of antimicrobial agents in food animals results in adverse human health consequences. Several studies demonstrating these effects will be published in 2004, but two articles published in 2002 are available that review evidence showing excess infections and increased morbidity are associated with the use of antimicrobial agents in food animals.3,4 Moreover, an international expert consultation in December 2003 convened by FAO, OIE and WHO concluded ‘there is clear evidence of adverse human health consequences due to resistant organisms resulting from non-human usage of antimicrobials’.5 The authors chose to ignore this evidence, instead stating ‘It might be thought that antibiotic-resistant salmonellae would have a devastating clinical effect, but this is rarely the case in developed countries.147,148. Most readers would incorrectly conclude that references 147 and 148 found no clinical effects, when in fact the authors of these studies reported that resistance in Salmonella was associated with higher hospitalization and fatality rates. The authors use several paragraphs to refute the observation that chicken is a common source of campylobacteriosis in humans, but the point of these arguments is not clear. Phillips et al.1 claim that it is eating in a restaurant rather than consumption or handling of chicken that is the cause of campylobacteriosis in humans. However, it is the poultry meat, not the non-poultry meat, at retail that has been found to be highly contaminated with Campylobacter.6,7 It follows that poultry is likely to be the primary vehicle on which Campylobacter is carried into restaurants, since in developed countries people tend not to carry Campylobacter organisms. Given the probable volume of poultry entering the restaurant and the high prevalence of Campylobacter contamination of poultry relative to other food, it is logical to conclude that the highly contaminated poultry meat could have cross-contaminated the non-poultry meat during handling and preparation at the restaurant. Although the authors’ stated goal was ‘to draw out the facts among much misinformation’, Phillips et al.1 have written an assessment of the literature on the use of antimicrobials in foodproducing animals and its effects on human health that is not ‘free from commercial or political influence’, if that phrase is a euphemism for bias. References 1. Phillips, I., Casewell, M., Cox, T. et al. (2004). Does the use of antibiotics in food animals pose a risk to human health? A critical review of published data. Journal of Antimicrobial Chemotherapy 53, 28– 52. 2. Swartz, M. (2002). Human diseases caused by foodborne pathogens of animal origin. Clinical Infectious Diseases 34, Suppl. 3, S111–22. 3. Barza, M. & Travers, K. (2002). Excess infections due to antimicrobial resistance: the attributable fraction. Clinical Infectious Diseases 34, Suppl. 3, S126– 30. 4. Travers, K. & Barza, M. (2002). Morbidity of infections caused by antimicrobial-resistant bacteria. Clinical Infectious Diseases 34, Suppl. 3, S131–4. 5. Food and Agricultural Organization, Organization of International Epizootics, World Health Organization (2003). Joint First FAO/OIE/ WHO Expert Workshop on Non-Human Antimicrobial Usage and Antimicrobial Resistance: Scientific Assessment, Geneva, 1-5 December, 2003. [Online.] (http://www.who.int/foodsafety/micro/meetings/ nov2003/en/) (10 February 2004, date last accessed.) 6. Smith, K. E., Besser, J. M., Hedberg, C. W. et al. (1999). Quinolone-resistant Campylobacter jejuni infections in Minnesota, 1992-1998. New England Journal of Medicine 340, 1525–32. 7. Zhao, C., Ge, B., De Villena, J. et al. (2001). Prevalence of Campylobacter spp., Escherichia coli, and Salmonella serovars in retail chicken, turkey, pork, and beef from the Greater Washington, D.C., area. Applied Environmental Microbiology 67, 5431– 6. 271 JAC vol.54 no.1 q The British Society for Antimicrobial Chemotherapy 2004; all rights reserved.  (...truncated)