Antibiotics: 5 Myths Debunked

Brad Spellberg, MD

Disclosures

October 20, 2016

Myths Surrounding Antibiotics

After 80 years of experience, much is known about antibacterial agents. Unfortunately, some of what is "known" is incorrect. To paraphrase Osler, half of everything we're taught is wrong—the problem is, which half?

Here, we seek to debunk five widely believed myths about antibiotics and resistance.

Myth 1: Humans Invented Antibiotics in the 20th Century

The first clinically useful antibacterial agent that was safe and effective was prontosil rubrum, a sulfa drug synthesized in 1931.[1] However, prontosil was not the first antibacterial agent to be invented, and humans were not the initial inventors.

Genetic analysis indicates that bacteria invented antibiotics and an antibiotic-resistance mechanism somewhere between 2 and 2.5 billion years ago.[2,3,4] Bacteria have been killing each other with these weapons, and using resistance mechanisms to protect themselves against these weapons, for 20 million times longer than we have even known that antibiotics exist.

To underscore the point, in 2011, a study[5] was published in which investigators explored a deep cave in the Carlsbad Caverns system in New Mexico, a geological formation that has been isolated from the surface of the planet for 4 million years. The section of the cave that they explored had never before been accessed by humans.

The investigators cultured many different types of bacteria from the walls of the caves. Every strain of bacteria was resistant to at least one modern antibiotic; most were multidrug-resistant. Not only was resistance found to naturally occurring antibiotics, it was also found to synthetic drugs that were not created until the 1960s-1980s (including fluoroquinolones, daptomycin, and linezolid).

Implications of busting this myth. After 2 billion years of microbial evolutionary warfare, microbes have already invented antibiotics to poison every possible biochemical pathway, and resistance mechanisms to protect every one of those pathways.[4] Thus, resistance mechanisms to antibiotics that have not yet been invented are already widespread in nature. Resistance is inevitable.

Myth 2: Inappropriate Antibiotic Use Causes the Development of Resistance

This myth is often repeated, with the implication that if we could eliminate inappropriate antibiotic use, resistance would no longer develop. However, all antibiotic use causes selective pressure by killing off bacteria. Appropriate use applies the same selective pressure as does inappropriate use. The difference is that we can and should stop inappropriate use because it offers no benefit. In contrast, appropriate antibiotic use is necessary to reduce mortality and morbidity from bacterial infections.

Implications of busting this myth. We accept that there will always be emergence of resistance from appropriate antibiotic use, but the benefit of appropriate antibiotic use to patients and society outweighs the collective harm. In contrast, without a benefit attached to inappropriate use, there is no "pro" to offset the "con" of selective pressure for antibiotic resistance.

In essence, we must seek to eliminate inappropriate antibiotic use not because this will end emergence of resistance, but because it will slow it down without forgoing any meaningful benefit of antibiotic use.

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