Letter to the Editor

Antimicrobial resistance

In reading the case study by Fraile et al1 in the January-February 2009 issue of the Journal of Swine Health and Production, I noted the statements "Antibiotics are used as prevention, therapeutic treatment, or both in swine medicine. This use has been associated with a significant increase in the resistance pattern of some microorganisms to antibiotics used in human and veterinary medicine" attributed to Drs Henry and Apley2 in Diseases of Swine. I have just read that whole chapter, some of it twice, and, beyond references to the means by which resistance might develop for some of the general groupings of antibacterials, I find no reference that makes valid the inflammatory statement as written in the article by Fraile, et al.1

The potential political ramifications that may arise from the phrase "significant increase" in a year when a resolution before the AVMA House of Delegates seeks to disallow all non-prescription, nontherapeutic agents from food animal use are too great to ignore if its roots can truly be traced to our "Bible" and two of our most esteemed authors.

Assistance and proof, please.


Dave Madsen


1. Fraile LJ, Crisci E, Weenberg J, Armadan M, Mendoza L, Ruiz L, Bernaus S, Montoya MM. Effect of treatment with phytosterols in three herds with porcine respiratory disease complex. J Swine Health Prod. 2009;17:32-41.

2. Henry SC, Apley MD. Therapeutics. In: Straw BE, D’Allaire S, Mengling WL, Taylor DJ, eds. Diseases of Swine. 8th ed. Ames, Iowa: Iowa State University Press; 1999:1155-1163.


First, I would like to say that it was not my intention to generate a debate about the use of antibiotics in livestock with my article. In fact, the statement concerning increasing antimicrobial resistance was meant to justify research on and use of alternatives to the use of antibiotics in swine.

I have been involved for many years in the European Medicine Agency in Europe and I strongly defend the correct use of antibiotics in any species. In fact, I had to struggle very hard to maintain groups of antibiotics (such as quinolones) available in veterinary medicine in Europe.

I apologize for not selecting the most suitable reference to support the following statement that appears in the paper: “This use has been associated with a significant increase in the resistance pattern of some microorganisms to antibiotics used in human and veterinary medicine.” Nevertheless, in many references, similar statements concerning increasing antimicrobial resistance can be found, for example, in the 2007 review article by Mathew et al.1 Other authors have also addressed this issue.2,3

Very best regards

Lorenzo Fraile


1. Mathew AG, Cissell R, Liamthong S. Antibiotic resistance in bacteria associated with food animals: A United States perspective of livestock production. Foodborne Pathog Dis. 2007;4:115-133.

2. Johnson AP. Veterinary use of antimicrobial agents and problems of resistance in human bacterial infections [Correspondence]. J Antimicrob Chemoth. 1997;39:285-286.

3. Piddock LJ. Does the use of antimicrobial agents in veterinary medicine and animal husbandry select antibiotic-resistant bacteria that infect man and compromise antimicrobial chemotherapy [Leading Article]? J Antimicrob Chemoth. 1996;38:1-3.