When my son Clark was little, he was prone to upper respiratory infections. I used to call him over, pull out my handkerchief, and tell him to blow. Now and then, I commented, "Wow, you're leaking a lot of brain lubricant." The poor guy. Years later, he told me he had taken me at my word. As a result, he'd gone around sniffing to keep his brain from losing all its lubricant. I wonder what would have become of him if I'd told the truth about the teeming masses of bacteria in his runny nose.

Clark, now age 19, has long ago forgiven, if not forgotten, my doctor humor. He was recently home on his college break when I received for review Jessica Snyder Sachs' Good Germs, Bad Germs: Health and Survival in a Bacterial World. Before I get to the book, I'll digress a bit more. Over Clark's school break, he asked me to go see the movie I Am Legend, starring Will Smith. As it turns out, Clark's movie choice was rather providential. Next fall my son will start medical school. I'm not sure his generation of doctors has more to learn from Good Germs, Bad Germs or I Am Legend.

The film begins with a scene from a TV newsroom. Karen at the health desk is interviewing Dr. Alice Krippen about her medical invention. "Give it to me in a nutshell," Karen prompts. "The premise is quite simple," Dr. Krippen begins. "Take something that is designed by nature and reprogram it to make it work for the body rather than against it." We learn that Dr. Krippen's team has done clinical trials on 10,009 patients using a genetically altered measles virus. In follow-ups, all are cancer free. The doctor is asked if she has found the cure for cancer. "Yes. Yes. Yes, we have," she says—as the scene shifts to a post-apocalyptic world a few years later.

Will Smith, in the role of virologist Robert Neville, is the last human inhabitant of Manhattan Island, except for a bunch of ghoulish, bloodthirsty cancer-vaccine "survivors." It seems the cancer cure has left everybody dead—or "undead"—except for Neville, who is immune to the vaccine's side effects. About thirty minutes into the film, Neville injects a captive, unconscious vampire girl. She lunges toward him, and that's when I told Clark I had to leave the theater.

In my first year of residency, I'd been surgically inserting a right subclavian line on a comatose, near-death patient when my needle must have hit a nerve. The unconscious patient sat bolt upright, opened his eyes, and stared at me just like the zombie Neville injects. Decades later, the memory of this patient still undoes my composure.

Now to Sachs' fine book. It begins with a real-life prologue about a college student who is well one day, and the next day rapidly goes into septic shock and dies. Throughout her narrative, Sachs interjects stories such as this, and herein lies much of the book's hold on the reader.

In Part 1, "The War on Germs," we meet the Renaissance physician Girolamo Fracastoro, whose 1530 text on "the French disease" was composed in Latin hexameter. His poetic treatise on syphilis was ahead of its time, correctly postulating a microbial vector and setting the stage for a branch of modern medicine.

Sachs does not mention that one of the early cures for syphilis was to have patients contract malaria—the subsequent high fever proved too much for the pesky spirochete—but she does trace other toxic cures, and then pauses at Paul Ehrlich's 1908 introduction of Salvarsan, which was effective against syphilis. From there she moves to the modern antibiotic era with Alexander Fleming's 1928 serendipitous observation of Penicillium mold, which had contaminated and thus inhibited the growth of colonies of Staphylococcus aureus.

In the chapter "Life on Man," Sachs provides a fascinating description of the bacterial colonization of the human landscape. Just 24 hours after birth, our skin sports one thousand bacteria per square centimeter. At 48 hours, the number jumps to ten thousand. We hit the hundred thousand mark by six weeks. It is this dense forest of one hundred billion friendly bacteria on our skin that guards us from the rare, unfriendly sorts. Fifteen trillion essential bacteria line and protect our empty digestive tracts. We learn that the type and count of bacteria are affected by emotional states and, even more intriguing, that the bacteria can, and do, signal our cells to enhance these symbiotic relationships.

One of the book's strong points is its blend of the highly technical with the everyday. There is enough of the nonscientific to keep all but the most unrepentant technophobes slogging along. Hang on through some subjects that just cannot be made any simpler, and you will be rewarded with stories that no one taught us in med school. For example, in 1959, while filming Cleopatra, Liz Taylor fell ill with a deadly, resistant form of staph pneumonia. An experimental batch of methicillin saved her life. Thousands of her fans and dozens of her husbands owe a debt of thanks to the antibiotic maker. If that's not enough to pique your interest, there is even a lurid description of how bacteria, once thought to be asexual in their reproductive life, have sex. This is one of the mechanisms whereby bacteria transfer antibiotic resistance from one to another and— shockingly—from one species to another.

Transferring and developing resistance to antibiotics is what much of Sachs' book is about. It is a frightening subject that has made many a headline. But the untold side of the story is that many bacteria simply stop being harmful. Strep throat no longer carries the death sentence of resulting rheumatic heart disease and glomerular nephritis that it once did. Smallpox has been eradicated and, for the most part, tuberculosis is no longer the scourge of European cities. For unknown reasons, the plague ceased to be the threat it was even before the advent of antibiotics. There is some good news.

Sherlock Holmes, the fictional invention of a physician, was a clever investigator. He taught his pupils to look for clues; he also taught them that some clues were telling by their absence. If I have one criticism of Good Germs, Bad Germs, it is that one of the great infectious disease tales is missing—that of HIV/AIDS. The disease, the introduction of antiretroviral drugs, emergent resistance to them, and the use of antibiotics in treating immuno-compromised patients: this story, so apt for Sachs' theme, is mysteriously absent from her book.

We come now to what I believe is the single most important story in Good Germs, Bad Germs. In 1986, Michael Zasloff, a researcher at the nih, stumbled upon a chemical that helps frogs fight off bacteria. The substance consists of short chains of amino acids. These antimicrobial peptides also are made by humans. They bathe our eyes and skin with their protective activity. Zasloff realized that the amphibian version of these chemicals was particularly potent.

It seemed that Zasloff had found a safe new form of antibiotic that bacteria could not adapt or mutate to resist. The New York Times lauded the discovery and pronounced, "Dr. Zasloff will have produced a fine successor to penicillin." Zasloff and investors rushed to license the new wonder drug. Despite the approval of the Times editorial staff, the FDA demanded more clinical trials.

Enter two heroes: biologists Graham Bell and Pierre-Henri Gouyon. They published an opinion piece calling for restraint. Bacteria have the habit of becoming resistant to antibiotics once those drugs are in widespread use. They reasoned that, even though antimicrobial peptides operate differently than penicillin or other antibiotics, resistance could happen again. (In the United States alone, 25 million pounds of antibiotics are given to animals and three million pounds to humans annually.)

Zasloff replied in the press, calling Bell and Gouyon's logic "fundamentally wrong." What ensued was the equivalent of a wrestling match. Zasloff dared Bell to grow bacteria that could develop resistance to his patent medicine. Bell took up the challenge and, with his tag-team assistant, grew 22 colonies of resistant E. coli and pseudomonas.

What is so significant about this? If Zasloff, Smithkline Beecham, or others interested in the peptides had brought the drugs to market, the result might well have been bacteria resistant to our natural lines of defense. A "boo-boo" on the knee could have become an almost certain "bye-bye." To his credit, Zasloff admitted the error of his own thinking and the validity of Bell and Gouyon's.

Zasloff meant well. But, as my maternal grandmother was fond of saying, "The road to hell is paved with good intentions." Today's technology has the capacity to do great harm. Genetic engineering and the development of microbial, antimicrobial, and chemotherapeutic agents already have met with disaster and near disaster. If the past has anything to teach us, it is this: "First, do no harm."

I've passed out many prescriptions for antibiotics. Some, I'm sure, were not needed, but in the er setting, I could not be confident that the infection would go away without medicine, and I worked for individual patients. The role of those who regulate new therapies is to protect society in general. They cannot be swayed by anecdotal sentiment, no matter how compelling.

Good Germs, Bad Germs and books like it have something to teach a society dizzy with the hubris of science. I was able to walk out on I Am Legend when it got too scary, but if a Pandora escapes from the gene-splicing lab, it will not be so simple. May God grant the next generation of doctors and scientists—including my son—a greater wisdom than ours.

Matthew Sleeth, a physician, is director of Blessed Earth (www.servegodsavetheplanet.org). He is the author of Serve God, Save the Planet (Chelsea Green/Zondervan).

Copyright © 2008 by the author or Christianity Today/Books & Culture magazine.
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