How Germs Learn to Live

Doctors have long been warned to go easy on antibiotics and sulfa drugs. When used with routine frequency, such germ killers may defeat their own purpose by leading to ever more resistant germs. Now comes worse news: the appearance of drug-resistant bacteria that can foil several antibiotics at once. The disturbing explanation is that certain germs "catch" this power of resistance simply by contact with one another. As a result, some infections of the intestinal and genitourinary tracts are becoming tougher than ever to treat.

Contagious Cuddling. The germs in question comprise the bacteria Shigella and Salmonella along with Escherichia coli, a common cause of infant diarrhea. Since these organisms reproduce slowly by cell division, microbiologists used to think that it would take a long time for drug-resistant strains to multiply and populate a hospital. Not so, indicates recent research. In addition to cell divi sion, these bacteria have a second way of passing on their "R factor" (drug resistance). When they cuddle up close to other bacteria, the R factor is transmitted by means of DNA (deoxyribonucleic acid), which bears chemical instructions on how to survive in the presence of antibiotics. After that, the newly resistant bacteria reproduce the usual way, by cell division.

Transfer of drug resistance was first detected in Japan. Confirmed in Israel and Europe, it has now appeared in the U.S. At Chicago's Michael Reese Hospital and Medical Center, 35% of Shigella strains have proved resistant to sulfadiazine and 21% to tetracycline; at Children's Hospital Medical Center in Boston, no fewer than 65% of the E. coli and 92% of Proteus vulgaris resisted at least one important drug. Equally sobering, researchers note that antibiotics are now routinely put in livestock feed to suppress bacteria and stimulate the animals' growth. This procedure may well produce animal bacteria that transmit drug resistance to bacteria that infect humans; indeed, such new strains may be resistant to all penicillins and tetracyclines.

Calm Assurance. All this has alarmed the usually restrained New England Journal of Medicine, which describes the resistance-transfer process as "intellectually fascinating and therapeutically frightening." The journal gloomily suggests that "unless drastic measures are taken very soon, physicians may find themselves in the pre-antibiotic Middle Ages in the treatment of infectious diseases."

Though fascinated, other experts calmly argue that laboratories are producing new antibiotics too fast for germs to catch up. Moreover, they suggest a preventive for the animal-to-man transfer problem--feed livestock different antibiotics from those given to humans. There are plenty of other drugs suitable for hogs, steers and chickens.

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