Researchers have identified three new antibiotic regimens to treat gonorrhea, offering options for a serious and common infectious disease that has become all but untreatable.
The sexually transmitted disease often called "the clap" infects an estimated 800,000 people a year in the U.S. It can have serious consequences, such as infertility and ectopic pregnancy, and it can increase the risk of infection with HIV, the virus that causes AIDS.
Worse, the bacteria that cause gonorrhea have become resistant to all but one class of antibiotics, and they are gradually outsmarting even that one. The Centers for Disease Control and Prevention says only one antibiotic may now safely be used on a regular basis, and it has to be injected. That makes treatment difficult, because many doctors don't stock the injection, meaning patients have to come back for treatment. And many patients prefer pills to shots.
Researchers now say they have options: two new antibiotic regimens that use existing drugs, and another one with a new drug. "An encouraging development in a discouraging field," Gail Bolan, director of the division of STD Prevention at the CDC, calls it. The researchers released results of two clinical trials at a meeting in Vienna Monday.
Public-health officials are warning that deadly bacteria are outwitting medicines, spawning new drug-resistant forms of disease that few, if any, medicines can treat. At the same time, few new antibiotics are being developed to overcome the evolving organisms; one problem is they aren't lucrative for drug companies, Dr. Bolan said.
Gonorrhea is particularly challenging because the bacteria hoard mutated genes, while some other organisms can mutate back to a more drug-susceptible strain, Dr. Bolan said. "Gonorrhea is a very smart organism," she said.
Two of the new regimens are combinations of existing antibiotics. In a clinical trial involving 401 patients conducted by the CDC and the National Institutes of Health, both combinations cured all of the infections of the throat and rectum, the researchers said. Many participants reported side effects like diarrhea, vomiting and abdominal pain.
The first regimen involves an injectable antibiotic called gentamicin. The second uses an oral drug called gemifloxacin. Both will be considered fallback options for the current treatment, which is effective and has limited side effects, Dr. Bolan said. It consists of an injectable form of the drug ceftriaxone, along with one of two oral antibiotics.
A third possible treatment with a single oral dose of a new-generation drug called solithromycin also cured the gonorrhea infections of all 42 patients in a Phase II trial, said Edward W. Hook, the study's principal investigator and professor and director of the division of infectious diseases at the University of Alabama at Birmingham.
While the new drug regimens will help, "the arsenal is still very small," said Dr. Bolan. "We are still calling for better antimicrobials to help outsmart gonorrhea."
Prabha Fernandes, president and chief executive officer of Cempra Pharmaceuticals, which licensed solithromycin and funded the study, now hopes the government will fund a Phase III clinical trial.
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