Moreover, they say, long regimens of expensive antibiotics are unnecessary, and can be even dangerous, after the infection has cleared.

Though the antibiotic Cipro has become the drug of choice among people worried about anthrax, several other widely available and less expensive antibiotics are very likely to work as well.

"So young doctors have a paucity of information about old standards like ampicillin, and are hounded to use expensive new antibiotics."

"If people need to use very expensive antibiotics for life-threatening infections, that's fine, but we don't want them used for sore throats," Dr. Atkinson said.

When a resistant bacterial infection is treated with an antibiotic, the treatment fails and the strain has free rein to multiply, so that newer, more expensive antibiotics are needed.

The report also found that amoxicillin, long a standard treatment, was about as effective as newer, more expensive antibiotics and caused fewer side effects.

With the launch of new and expensive antibiotics worldwide, the pressure to sell with little regard to the national essential drug lists or rational prescribing.

The most common examples of counterfeit drugs are malaria tablets and expensive antibiotics, such as ciprofloxacin.

The bacterium that causes shigella dysentery, S. dysenteriae type 1, has become resistant to all but very expensive antibiotics, doctors said.

While hospitals substituted more expensive antibiotics for most infections, there was no alternative for infants with congenital syphilis.