A potpourri of issues

November 2001

This month I wish to touch on 3 subjects: last month’s editorial on “Thinking the unthinkable,” the 39th Annual IDSA meeting and antibiotics in poultry and animal feeds.

Thinking the unthinkable

Last month’s editorial was, in a sense, a masterpiece of poor timing. From the writer’s point of view, it was very timely, considering the events of the last several weeks. From the reader’s point of view, it was badly dated, since the issue arrived only in the last several days of October, a time when the current anthrax bioterror event was already widespread, and may in fact be continuing.

Already some of our most cherished and reassuring beliefs about the epidemiology, prophylaxis and treatment of inhalation anthrax are being questioned. For example, what really are the lower limits of the ID₅₀ for inhalation anthrax? What is the upper limit of the incubation period for inhalation anthrax, once an infectious dose of spores is inhaled? Would penicillin work just as well for prophylaxis? Then there are the more technical and bioengineering questions about how spores are disseminated within the postal system and mail delivery locations. And how can the fatal case in a hospital worker in New York City be explained?

Just as troubling are the many questions related to ciprofloxacin prophylaxis; how much damage to people are we causing by such widespread use of ciprofloxacin, and equally important, how much damage are we doing to our bacterial ecology and our already severe problems of antimicrobial drug resistance? Answers will come eventually, but probably not soon.

Infectious disease physicians find themselves in the distinctly unaccustomed position of being “media darlings,” much sought after by television, radio and print journalists as well. Few of us are wholly comfortable in that role, and fewer still enjoy it, but it is virtually a societal obligation at this time. Accurate and honest information is critical for a jittery population. In addition, health care personnel at all levels need to be educated.

Anthrax is the bioterror du jour; it will probably not be the whole story. We must stay alert to the possibility of encountering other agents from the “Class A” list, as noted on the CDC Web site.

The 39th Annual IDSA Meeting

After using this space last year to criticize the structure and content of the 38th Annual Meeting of the IDSA, it is now appropriate to give credit where credit is surely due. The program committee for the this year’s meeting undoubtedly heard concerns expressed by many others in addition to this editorialist. Certainly many of the concerns that I expressed a year ago were resolved. Whatever the process, the program committee put together an excellent program. Evidently, the IDSA membership thought so too, since attendance at this meeting substantially exceeded that at last year’s meeting. Congratulations to Tom Quinn and Julie Gerberding as the cochairs of the committee.

As might have been anticipated, the entire proceeding was somewhat clouded by national events. Julie Gerberding, for example, could not attend to enjoy the fruits of the program committee’s deliberations, her presence being required at home in Atlanta. A closed-circuit television link was used on the last day of the meeting, Oct. 28, to update the membership on the most recent activities at CDC.

Finally, in retrospect about the meeting, the “venue factor” cannot be overlooked, even though it cannot be measured directly. New Orleans in early September vs. San Francisco in late October: that’s a no brainer!

Antibiotics in poultry and animal feeds

The larger part of an entire issue of The New England Journal of Medicine (Oct. 18, 2001) was devoted to this topic, covered in 3 original articles and an accompanying editorial by Sherry Gorbach, who also happens to be the new editor of Clinical Infectious Diseases. His editorial is entitled – simply and unemotionally – “Antimicrobial use in animal feed – Time to stop.”

In truth, it’s probably long past time to stop. As much as 50% of the total antibiotic production in the United States is devoted to veterinary use. Most of this use is nontherapeutic, that is – growth promotion and enhancement of feed efficiency. The antimicrobials used have usually not been identical with those used in humans, though there have been notable exceptions. They are, however, drawn in large part from the same classes of drugs used in humans. These include, for example, penicillins, cephalosporins, tetracyclines, glycopeptides, fluoroquinolones and streptogramins.

The major argument supporting the use of antimicrobials in animal husbandry is the economic one, and this is indeed a formidable argument. Without such antimicrobial use, it is claimed, the meat and poultry in our national diet would be manyfold more expensive than it is. The major argument against such use is the increasing burden of antimicrobial drug resistance in human pathogens, as detailed in the 3 research articles in the Oct. 18 NEJM, as well as many previous studies.

This debate has gone on now for over 3 decades and remains unresolved. It has been the topic of 3 expert committees of the National Academies – Institute of Medicine, carried out at approximately 10-year intervals. The first, reporting in the 1970s, concluded that although there were concerns, there was not really a significant problem. The second, reporting in 1988, concluded that “the committee was unable to find a substantial body of direct evidence that established the existence of a definite human health hazard in the use of subtherapeutic use of penicillin and the tetracyclines in animal feeds” (I had the pleasure of serving on that committee, chaired by Morton Swartz).

The third expert committee, reporting in 1999, introduced its conclusions with the following sentence: “The committee concluded that the use of drugs in the food-animal production industry is not without some problems and concerns, but it does not appear to constitute an immediate public health concern; additional data might alter this conclusion.” There is now additional data, and the data do alter that conclusion; there is now an immediate public health concern. Add to that the fact that such use of antibiotics in Europe has been abandoned without grave economic consequences and it is clear that — in Dr. Gorbach’s words — it’s time to stop.