Opinon: Antibiotics and the Great Microbial War

Daniel Sprockett

Daniel Sprockett

Daniel Sprockett is a researcher in the KSU Department of Anthropology and a columnist at the Daily Kent Stater. Contact him at [email protected]

A sore throat, cough and fever—these symptoms are enough to send most people running to the doctor’s office. But if your doctor prescribes you unnecessary antibiotics, you might end up worse off.

Alexander Fleming’s accidental discovery of penicillin in 1928 allowed him to become privy to the constantly raging war between microbial superpowers and commandeer one of the most potent weapons in the their arsenal—the antibiotic.

“Antibiotic” is actually a generic term for a substance that kills microbes, but antibiotics can work in a variety of ways. For example, penicillin inhibits the construction of the bacterial cell wall. Penicillin molecules bind to the enzyme that strings together the peptidoglycan struts of the cell wall and prevent it from doing its job.

Tetracycline, another common antibiotic, accomplishes the same goal via different means. It targets the molecular machinery that bacteria use to translate their genetic blueprint into functional proteins. Tetracycline binds to what is known as the 30S ribosomal subunit, preventing it from building new proteins that are essential to microbial life. The fact that these molecules are able to target uniquely microbial structures, while avoiding the destruction of human cells, is what makes them so medically useful to us.

Over the last three billion years, bacteria’s direct competitors—archaea, fungi and viruses—have also evolved their own powerful tool sets. The resulting microbial arms race has escalated into an extremely sophisticated armory of molecular weapons. The war for limited resources rages on.

But now the rules have changed. Human hosts use bacteria’s own molecular weapons against them. Despite losses, prolific microbial reproduction rates allow their armies to stay fully manned. Then in 1959, we uncovered their secret weapon— a process known as HGT, or horizontal gene transfer. Evolving microbial defenses against antibiotics are an inefficient, but effective, process of trial and error. But what makes them so valuable to microbes is their ability to transmit these new antibiotic-beating tactics not just to their offspring, but across the entire range of bacterial life through HGT.

It’s like the movie “Independence Day,” when the Americans discover a way to defeat the alien warships, and transmit that information to armies across the world. Only instead of using Morse code, bacteria transfer bits of DNA. This sharing of military secrets has been a major cause of the recent explosion of antibiotic resistance in human pathogens.

But some scientists are investigating ways to hijack this process and use it against our microbial invaders. Researchers at the University of Wisconsin have proposed using one of bacteria’s own DNA transfer mechanisms, bacterial conjugation, to deliver genetic instructions, telling the bacterium to continually copy a series of useless genes instead of replicating its own genome. This will eventually lead to its death. This would allow doctors to kill pathogens while avoiding the development of further antibiotic resistance. Of course, even with these new techniques in the works, it won’t be long before the slow, unyielding march of bacterial evolution finds a way to outmaneuver us again.