Doctors can give the HIV medicine Truvada as a preventative to healthy heterosexuals at high risk of the virus and should treat gonorrhea differently to hold off a drug-resistant form growing outside the country, U.S. officials said.

The new guidelines for the sexually transmitted diseases were announced today by the U.S. Centers for Disease Control and Prevention.

The CDC in January 2011 advised that Gilead Sciences Inc. (GILD)’s once-a-day pill Truvada was safe and partially effective as a preventative for homosexual men, and suggested frequent testing if the medicine was used. The gonorrhea guideline issued today urges doctors to use more potent antibiotic injections instead of cefixime, the pill that has been the standard of care.

“Action is urgently needed to prevent untreatable gonorrhea from becoming a reality,” Gail Bolan, director of the Atlanta-based CDC’s division of sexually transmitted disease prevention, in a telephone interview.

Treatment options have shrunk as every medicine starting with penicillin loses effectiveness against gonorrhea, the second-most commonly reported infectious disease in the U.S. with about 700,000 new cases a year. Cefixime and the more- potent ceftriaxone injection belong to the only class of effective drugs left to use, the agency today said in a report.

Infection ‘Canary’

“Gonorrhea is very good at picking up antibiotic resistance,” said Carlos del Rio, a professor of medicine at Emory University in Atlanta and a member of the CDC’s gonorrhea surveillance program, by telephone. “In a way, it’s the canary in the coal mine for antibiotic resistance in the STD setting.”

While gonorrhea infections often are symptomless, they can lead to infertility and other serious conditions if untreated. Screening is necessary because many infections are “silent,” with few or no symptoms, Bolan said. Less than half of new cases are diagnosed each year.

The Food and Drug Administration approved Truvada on July 16 for use by healthy heterosexuals or homosexuals who are at high risk of being infected with the AIDS virus, such as in cases in which one partner has HIV. Daily use of the pills to prevent HIV infection, known as pre-exposure prophylaxis, or PrEP, should only be used for people who are uninfected and continue to use regular testing and prevention methods, such as condoms, according to the interim guidelines.

The daily pill had already been deemed safe and partially effective for homosexual and bisexual men in a January 2011 CDC interim guidance, and the World Health Organization published initial guidelines in July suggesting that couples with one infected member could use the drug.

Another Tool

“This provides another tool that providers can use for HIV prevention,” said Dawn Smith, lead author on the guidelines and a biomedical interventions implementation officer at the CDC’s National Center for HIV and AIDS Prevention. “It will always need to be targeted at people who are very high risk. It requires a lot of work.”

An estimated 48,000 HIV infections occurred in the U.S. in 2009 and 27 percent were among heterosexual men and women who didn’t inject drugs, the guidance states. Though this could be used to drive those numbers down, the prevention method still needs development, said Mitchell Warren, executive director of AVAC: Global Advocacy for AIDS Prevention.

Early Effort

“It’s still very early days,” he said. “It’s not as if anyone is out there actively promoting it. Even with the FDA approval, the most important next steps are the demonstration projects, to really help us understand how to deliver PrEP, to whom we can best deliver and motivate adherent use, and really add public health impact.”

Two studies cited in the guidance found that the method, which prevents HIV from establishing a permanent infection by making new viruses as it enters the body, is effective for heterosexual people. Still, the prevention method’s long-term safety in adults and for pregnant users’ fetuses hasn’t been determined conclusively, a main reason those taking Truvada should be monitored closely, according to the guidance.

The CDC guidelines for gonorrhea treatment were last updated in 2007, when the bacteria demonstrated resistance to the fluoroquinolone class of medicines, and the agency recommended discontinuing their use. Cefixime and ceftriaxone are members of a family of drugs known as cephalosporins. Companies have been reluctant to invest in developing new antibiotics because they are used sparingly, and often held in reserve to prevent resistance, del Rio said.

“The industry doesn’t do work based on public health,” del Rio said. “They work based on what’s going to benefit their stockholders.”

Antibiotic Incentives

In June, the U.S. Senate reauthorized the Prescription Drug User Fee Act, adding a section called “Generating Antibiotic Incentives Now,” to encourage drugmakers to develop new antibiotics for life-threatening infections. Under the new language, qualified drugs would receive an additional five years of market exclusivity and a faster review.

The legislation “isn’t enough to fix the problem,” said Robert Guidos, vice president for public policy at the Infectious Diseases Society of America, based in Arlington, Virginia. “It’s valuable, and it’s obviously sparked a lot of attention in industry. But it isn’t enough.”

Other options that may help may be research and development tax credit, or strengthening partnerships between public health officials and private industry may also help, he said.