Seventy-three syphilis patients at public clinics in Montgomery and Prince George's counties mistakenly were treated with a type of penicillin that was too weak to cure them, setting off a scramble to locate them before they became more seriously ill or infected their sex partners, Maryland health officials said yesterday.

None of the patients--including five pregnant women--suffered any other ill effects from taking the wrong drug. Four infants were given penicillin treatments as a precaution because the discovery that their mothers had been given the wrong drug was made shortly before their births. None of the babies tested positive for congenital syphilis.

However, officials have not located two adult patients who would be urged to undergo an extra round of injections with the more potent form of penicillin. Eleven others declined additional treatment.

Some of the syphilis patients treated from January to October 1998 had resumed sexual activity, raising the possibility that they would pass on the disease to their partners. That risk increased pressure on public health officials to find them and offer the appropriate drug treatment.

"That's what took so much manpower," said Carol Jordan, Montgomery's senior nurse administrator for communicable diseases. "We had to reinterview the patients to make sure no other partners were out there who needed to be checked as well. It took three months."

The county said it spent about $24,000 in overtime and other expenses to extend the search to nighttime and weekend hours and to track down everyone who had sexual contact with the patients.

Syphilis is a sexually transmitted disease that is easily cured but can cause severe consequences if untreated. After the initial phase of the infection, when a variety of symptoms appear over much of the body, it can be silent for 20 years. Then, without warning, it can inflict irreversible and severe damage to the heart, brain, eyes, knee joints and nasal tissues.

In an article in today's edition of Morbidity and Mortality Weekly, published by the U.S. Centers for Disease Control and Prevention, Maryland chief epidemiologist Diane M. Dwyer and federal officials said confusion over the drug, Bicillin, has caused similar medication errors all over the country for years.

The article did not identify Montgomery and Prince George's counties as places where the problem occurred, but local officials confirmed it. The publication warned public health workers across the nation to place written orders for new supplies of the drug and to carefully review incoming shipments.

The penicillin drug is manufactured by Wyeth-Ayerst Laboratories in two injectable forms: a short-acting preparation called Bicillin C-R used for strep throat and the longer-lasting Bicillin L-A, which is recommended for treating syphilis patients. Both have been on the market since the early 1950s.

The color scheme, typography and contents of packages seem virtually identical, except for the different letters after the product name, public health officials said.

"The labeling was so close that I think it was an easy error to make, and obviously we're not the only ones to make it," Jordan said. Her staff had been unaware that there was more than one type of Bicillin, she said.

"We ordered a drug for 30 years and they always sent us the right one, and suddenly they're sending us the wrong one," she said. The confusion apparently began when someone locally placed an order without specifying which form of Bicillin was wanted, and someone at Wyeth-Ayerst interpreted the order to mean the less potent form, she said.

No one on her staff has been disciplined, she said.

After Montgomery officials complained to the U.S. Food and Drug Administration, discussions began with Wyeth-Ayerst about packaging changes. FDA officials said yesterday they are investigating the matter.

Philip de Vane, the firm's North American medical director, said Wyeth-Ayerst would review the situation. "As a physician I think any prescription error is regrettable," he said. "I take this report very seriously. But I think it's only fair to point out that these products have been available since the early 1950s."

The problem came to light last fall when Prince George's health officials ran out of the stronger form of Bicillin and borrowed some from Montgomery.

Ten patients were treated by a doctor before he realized that he had been provided with the less potent form.