A national shortage of penicillin is threatening a simple treatment for syphilis, prompting Baltimore health officials to reserve the drugs for infected pregnant women.

All others with the sexually transmitted disease are getting another antibiotic, doxycycline, which is effective if taken properly, said Dr. Kathleen Page, the Baltimore Health Department's director of STD/HIV/TB clinical services. But it requires more treatments and more follow-up — a challenge for the population most affected.

“A major concern about treating syphilis with doxy is compliance, as patients need to take the medication for two weeks,” said Page, who is also an assistant professor of medicine and infectious disease at the Johns Hopkins University.

Penicillin is injected in a clinic in one or three weekly doses, depending on the state of infection, she said, “so we can confirm completion of treatment.”

The greatest concern, however, is for pregnant women. Without treatment, babies born to mothers with syphilis can die or suffer complications such as blindness and brain damage.

The type of penicillin in short supply, penicillin G benzathine, is made only by Pfizer, which is experiencing a manufacturing delay, according to the U.S. Food and Drug Administration, which tracks drug shortages.

Pfizer says it informed customers at the end of April of a short-term shortage.

“Pfizer recognizes the importance of Bicillin L-A to our customers and patients and has taken remedial action to minimize the duration of the supply shortage,” the company said in a statement. “As a result, Pfizer has been allocating shipments to help avoid a stock out, and recommends customers prioritize requests for Bicillin L-A in cases where it is the only choice for the patient's treatment. Pfizer expects to commence resupplying the market for Bicillin L-A in July 2016.”

Such shortages, particularly of injectable drugs, have become an acute problem.

The FDA cites no one reason. The industry has blamed natural disasters, raw materials shortages and changes to FDA protocols, among other reasons.

The FDA and health caretrade groups say industry consolidation is a factor, as are makers who discontinue less profitable generic drugs or whose plants fail safety inspections. Maintaining sterility during the manufacturing of injectable drugs can be particularly difficult, industry officials have said.

Officials at the state Department of Health and Mental Hygiene report that the penicillin shortage is already affecting some of Maryland's local health departments, hospital systems, community practitioners and pharmacies.

The University of Maryland Medical Center also is restricting penicillin use to pregnant women with syphilis.

“For the time being, we are in good shape at UMMC but are taking measures to protect our penicillin supply,” spokeswoman Karen Lancaster said. “The pharmacy and infectious disease teams closely track information about potential shortages to help mitigate any issues that may arise.

“Other second-line regimens, including doxycycline and ceftriaxone, are being utilized in place of Bicillin L-A in nonpregnant patients with syphilis.”

Officials at the Baltimore County Health Department believe they have supplies to last through July and plan to continue using penicillin to treat all cases of syphilis.

Penicillin is used for other bacterial infections, such as streptococcal infections. The U.S. Centers for Disease Control and Prevention are now recommending clinicians use other antibiotics if possible.

The CDC also instructed clinicians to request emergency supplies from Pfizer when they have doses lasting three weeks or less.

Penicillin is the CDC's recommended treatment for syphilis, which has been a persistent problem in Maryland, and particularly Baltimore, for years.

The infection rate in 2014 in the city was 31 per 100,000 people. The state infection rate was 7.5. The national rate was 6.3.

State health officials say Maryland ranked eighth in the nation for rates of syphilis in 2014 and consistently ranks among the top 10 nationwide. Infection rates also rose significantly in 2015, to 509 cases recorded statewide, up 13.4 percent from the year before.

After a period of decline, congenital cases have ticked up in the past few years. There were 16 instances of the of the disease being passed on to babies born in Baltimore City and in Baltimore, Anne Arundel, Prince George's and Montgomery counties in 2014, according to state health data. Health officials said 18 babies were born with syphilis in 2015.

National data show a 25 percent jump in syphilis cases among pregnant women across the country from 2012 to 2014, according to the CDC. Nearly one in four women with the disease was pregnant, and there was a 37 percent jump in the number of infants born with syphilis and a 67 percent increase in syphilis-related stillbirths in that time.

There are many more cases of other sexually transmitted diseases, such as gonorrhea and chlamydia, recorded both locally and nationally. But theytypically aretreated with other antibiotics, for which no shortages are reported.

Syphilis, whichis characterized by sores on the mouth or genitals, isoften mistaken for other diseases or ignored, according to the CDC.

The early stage is when it's most easily transmitted through sexual contact.

The sores are usually painless but, if untreated, can lead to rashes on the hand and feet, or elsewhere on the body.

The symptoms usually go away but the disease can remain latent in the body, and decades later cause serious problems such as difficulty with muscle movement, paralysis, numbness, blindness and dementia.

meredith.cohn@baltsun.com