Certain scientific discoveries, once proved, seem so obvious that it’s hard to imagine that anyone ever opposed them. The notion that specific bacteria cause infectious diseases provides a striking example.

Although Robert Koch isolated the bacterium that causes cholera in 1877, his discovery was long resisted. Max von Pettenkofer, designer of the Munich sewer system and Germany’s first “Professor of Hygiene,” went so far as to gulp down a beaker of tainted water to disprove Koch. Either the water wasn’t tainted enough or von Pettenkofer had the immune system of a bratwurst, for he survived without ill effect. And in 1886, the British Cholera Commission, established to investigate cholera in India, issued a report that was an outright attack on Koch’s “germ theory.” This was not simple ignorance but something more sinister. Sir Joseph Frayer, president of the Medical Board of the India Office, worried in an official memo about “the effects of this so-called discovery on our sea traffic and international communication.” While blockheads dithered, people died.

The story above is told by Alistair Lax in “Toxin: The Cunning of Bacterial Poisons” (Oxford University Press, 208 pages, $24.95), a fascinating account of the rise of microbiology and of the extraordinary array of stratagems by which bacteria work to undo us. Human beings have become so accustomed to dominance over the natural world that it’s a bit shocking to realize that for a huge class of organisms — no less deadly for being microscopic — we are little more than prey, and ripe for the picking.

Mr. Lax begins the historical part of his account with Antoni Van Leeuwenhoek, who in 1676 turned his homemade microscope on a solution of peppercorns — he hoped to discover what gave pepper its taste — only to find “many very little living animalcules, very prettily a-moving.” But it was not until the 19th century and the pioneering work of Louis Pasteur, Joseph Lister, and Robert Koch that microbiology entered its “golden age.”

Mr. Lax, who is Professor of Cellular Microbiology at King’s College London, provides informed, sometimes rather technical appraisals of the work that both Pasteur and Koch, along with many others, accomplished on anthrax and cholera, as well as rabies (Pasteur’s crowning achievement). But Mr. Lax isn’t given to hero worship. He points out how often Pasteur was downright dishonest and he notes that late in life, at the height of his renown, Koch ran away with a 17-year-old actress, much to the scandal of Prussian society. The two men, both geniuses, detested each other mightily.

For all the gossip that enlivens this part of Mr. Lax’s account, his true fascination is with bacteria and the poisons they produce. These toxins “display a surprising subtlety” and “an extraordinary intricacy.” They are deployed by the attacking bacterium to overwhelm the cellular defenses of a host but they do so by stealth and mimicry. They breach cell membranes by injection or the creation of “pores.” They sabotage the communications between groups of cells.

In Mr. Lax’s affectionate description, normal healthy cells are both clannish and gregarious. Skin cells want to be with skin cells, liver cells with liver cells — and a good thing, too. But through continual signaling they seek constant reassurance that they are the right cells in the right places. In cells, as in real estate, location is everything. Bacterial toxins subvert these cozy communities of cells. The most successful of them are “cleverly designed molecules that are manufactured in one type of life form for use in another, and they act as if they have a detailed knowledge of how our bodies work.” They are, in effect, cellular pirates.

It was through investigation of diphtheria, less than a century ago a prime killer of children, that the existence of bacterial toxins became known. This dreadful disease, beginning with a sore throat and ending, sometimes within a week, with death by suffocation or major organ failure, puzzled doctors. The bacteria were found only in the throat but the damage to heart, liver, kidneys and muscles was extensive and suggested the effects of a systemic poison. This proved to be the case.

In 1937, Harvard researcher Alwin Pappenheimer managed to isolate six grams of pure toxin, equivalent, as Mr. Lax says, “to almost a million lethal doses.” Although an effective vaccine (still in use today) had become available in 1925, the disease wasn’t fully understood until after 1958. By a nice twist, the very virulence of diphtheria toxin may prove beneficial in the treatment of certain cancers, turning the bacterium’s cell-killing potential to positive use.

Mr. Lax ranges from the 6th century C.E., and the Plague of Justinian, to more recent acts of bioterror, yet shows that for all their horrific side effects, bacterial toxins are in a way paradoxical substances: Botulinum toxin is the deadliest known — a few billionths of a gram can kill a person — but it also is the source of Botox, with its anesthetic and wrinkle-smoothing properties. Nothing is simple in the cruel but elegant realm of our most intimate adversaries.

eormsby@nysun.com