Life-saving antibiotics are increasingly losing their disease-fighting power because of flagrant worldwide overuse, 150 doctors and medical scientists in 25 nations charged yesterday.

In news conferences in Boston, Mexico City, Sao Paulo, and Santo Domingo in the Dominican Republic, the group issued a joint statement urging international action to curb "global drug abuse."

Misuse of the so-called "miracle drugs" has led to their "becoming increasingly ineffective in curing and controlling bacterial infections," said Dr. Stuart Levy of Tufts Univeristy, one of the group's organizers. Unless corrective steps are taken, the group said, "we may find a time when such agents are no longer useful to combat disease."

The abuse and overuse, they said, consist of:

Over-prescribing everywhere, for example, prescribing antibiotics for ailments like the common cold, for which they are ineffective.

Putting antibiotics in animal feed to promote livestock growth, a common use in this country.

Three practice common in less developed countries: indiscriminate sale of powerful and sometimes dangerous antibiotics without prescriptions, exaggerated advertising to uninformed consumrs, and sale by some American or European drugmakers or local subsidiaries for uses forbidden in nations with stricter regulation.

Among well-known signers were Drs. Walter Gilbert of Harvard; Ananda Chakrabarty of the University of Illinois, developer of an organism to consume oil spills; Irving Delappe of the National Institutes of Health in Bethesda and Louis Baron and Dennis Kopecko of the Walter Reed Army Institute of Research.

The joint effort grew out of a five-day scientific meeting in Santo Domingo last January on bacterial plasmids.

Plasmids are bits of DNA or genetic material used in new genetic engineering techniques to carry genes from one species to another. But many plasmids also carry genes for drug resistance, and the scientists in Santo Domingo concluded that there is now "a worldwide public health problem "in the way they are doing so.

What gives them the opportunity, they said, are abuses "at all levels . . . consumers, prescribers, dispensers, manufacturers and government regulatory agencies."

"As a first step," they said, "we urge . . . uniform practice in prescription and distribution of antibiotics" at least in areas where medical expertise permits it, and "proper standards of advertising and dispensing" in all nations.

Also, said the group, "Let on one suppose that widespread use of antibiotics is in any way a substitute for good sanitation and personal hygiene." The politicians and health officers of some developing countries have sometimes claimed disease would be a greater problem for them if they did not permit easy purchase of antibiotics.

Dr. Yankel Kupersztoch of Mexico City's National Polytechnic Institute -- who, with Levy, led the Institute -- who, with Levy, led the new appeal -- reported a dramtic link between growing antibiotic use and emergence of resistant bacteria in Mexico.

Dr. Levy presented data showing large numbers of antibiotic-resistant bacteria in the intestinal tracts of ordinary non-hospitalized Americans, "the result, I think, of antibiotic use in all areas, in medicine and veterinary medicine and animal feeds." Fifty per cent of all antibiotics used in this country, he pointed out, are used in feeds.

"If we continue to use drugs" in the same indiscriminate way, he warned grimly, "the resistant strains of bacteria will replace all sensitive strains."