E-Letter responses to:

reports: Morten O. A. Sommer, Gautam Dantas, and George M. Church Functional Characterization of the Antibiotic Resistance Reservoir in the Human Microflora Science 2009; 325: 1128-1131 [Abstract] [Full text] [PDF]

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Published E-Letter responses:

Are Human Microflora Influenced by Environmental Exposure to Antibiotics?

Peter Oelschlaeger, Jeffrey H. Toney   (13 October 2009)

Are Human Microflora Influenced by Environmental Exposure to Antibiotics? 13 October 2009
Peter Oelschlaeger, Assistant Professor Department of Chemistry, California State Polytechnic University, Pomona, CA 91768, USA, Jeffrey H. Toney Respond to this E-Letter: Re: Are Human Microflora Influenced by Environmental Exposure to Antibiotics?	The Report by M. O. Sommer et al. describes an extensive array of antibiotic resistance genes found in the human microflora ("Functional characterization of the antibiotic resistance reservoir in the human microflora," 28 August 2009, p. 1128), including the discovery of 95 unique inserts containing functional antibiotic resistance genes. More than one out of four of these genes encode beta-lactamases that inactivate beta-lactams, such as penicillin and amoxicillin, by hydrolysis—consistent with the wide use of these antibiotics. On average, an adult in the United States makes two outpatient visits per year and 15.3% of these visits result in the prescription of an antibiotic (1). To avoid potential influence of antibiotics on the study of human microfloral genes, these investigators chose two unrelated healthy subjects who had not been exposed to antibiotics for at least one year. This would allow sufficient time for the elimination of bacterial subpopulations that may have been exposed to antibiotics while the individual was undergoing treatment. However, it is highly unlikely that an individual living in a developed country could escape any exposure to antibiotics; detectable levels can be found in water, agricultural products and meat. In the United States, an estimated 8,600 to 13,000 tons of antibiotics (about half of the total consumption) are used for nontherapeutic purposes, including agriculture and animal husbandry (2). A host of antibiotics have been detected in wastewater at levels of 1.7 to 1.9 micrograms/liter (3). A clearer picture of the reported "immense diversity of antibiotic resistance machinery in the human microbiome" will emerge if comparative studies can be done with individuals from environments naïve to industrial exposure. Peter Oelschlaeger Department of Chemistry, California State Polytechnic University, Pomona, CA 91768, USA. Jeffrey H. Toney College of Natural, Applied and Health Sciences, Kean University, Union, NJ 07083, USA. References 1. C. L. Roumie et al., J. Gen. Intern. Med. 20, 697 (2005). 2. K. Kuemmerer, in Pharmaceuticals in the Environment: Sources, Fate, Effects and Risks, K. Kuemmerer, Ed. (Springer, Berlin - Heidelberg, 2004), pp. 27–44. 3. A. Alder et al., in Pharmaceuticals in the Environment: Sources, Fate, Effects and Risks, K. Kuemmerer, Ed. (Springer, Heidelberg - Berlin, 2004), pp. 55–66.