The “Tragedy of the Commons” is a familiar problem to economists. The concept was originally penned in 1833 by economist William Forster Lloyd who felt it was imperative for landowners to understand that the decisions of individuals can harm the collective. In his essay, Lloyd theorized that uncoordinated animal grazing on collective lands (the “commons”) would ultimately destroy the richness of the resources (the “tragedy”). In his example, one producer could increase personal revenue by adding an extra cow or two to the collective land. However, if every producer utilizing the shared lands acted in the same manner, the resources of the collective lands would more quickly be depleted with the lack of resources felt by all. More formally, the “Tragedy of the Commons” is about how individually rational economic decisions can lead to suboptimal social outcomes.
There are several examples of “Tragedies of the Commons” in agriculture. These examples range from aquifer extractions for crop irrigation to fish density in cultivation ponds. The example that I will flesh out in this article, however, is that of antimicrobial resistance. The “commons” in this example is antimicrobial effectiveness in food animal production. It is in the best interest of all producers to maintain the effectiveness of currently marketed antimicrobials. This can be achieved by judiciously medicating animals. However, mass antimicrobial therapeutic programs (e.g. metaphylaxis, prophylaxis) have become popular options to reduce sickness and death from infectious diseases in certain production systems. Mass therapy with non-medically important antimicrobials may be used for production purposes other than treating, controlling, or preventing disease, such as to enhance growth and improve feed efficiency. However, it is illegal in the United States to use medically important antimicrobial drugs for anything but therapeutic purposes.
Mass medication programs, if used properly, have been shown to benefit individuals and society. However, overuse or misuse can lead to increased selection pressure on susceptible organisms to become resistant to antimicrobial therapy. Therefore, the “tragedy” in the example is the rise of resistant organisms and the loss of antimicrobial effectiveness. In this example, the producer, who may be focused on short-term individual profit maximization, may be tempted to overuse antimicrobials in order to achieve better health performance. The collective (societal) cost of this individually rational decision is the eventual degradation of antimicrobial effectiveness.
Viewing the issue of antimicrobial resistance as a “tragedy of the commons” can help all interested parties understand the resource of concern, the potential solutions (and limits of potential solutions), and identify policy approaches. Proper antimicrobial stewardship could potentially lessen the magnitude and speed of the potential tragedy of the commons. Antimicrobial stewardship is used to describe a multi-tiered approach to maintain the effectiveness of antimicrobials and reduce the emergence of resistance. All parties associated with antimicrobial use including government agents, veterinarians, and producers must be involved in the various facets of stewardship.