New antibiotic for gonorrhea advances in trials

Computer-generated image of drug-resistant Neisseria gonorrhoeae bacteria. CDC

In recent years, the sexually transmitted disease known as gonorrhea has become more common. Last year, more than 550,000 people were diagnosed in the U.S. The bacterium that causes this infection, Neisseria gonorrhoeae, is becoming harder to treat. More people are developing infections that are resistant to multiple classes of antibiotics. If not cured, gonorrhea can cause infertility and other problems.

To combat this public health threat, scientists have been searching for compounds that kill the bacterium by novel mechanisms. They discovered a new type of antibiotic called zoliflodacin that can inhibit the bacterium’s DNA synthesis in a different way than current antibiotics.

A research team led by Dr. Stephanie N. Taylor of Louisiana State University Health Sciences Center tested zoliflodacin in people with gonorrhea. Their trial was designed to evaluate the drug’s safety and assess whether to proceed to larger studies. The trial was supported by NIH’s National Institute of Allergy and Infectious Diseases (NIAID). Results were published on November 8, 2018, in the New England Journal of Medicine.

The investigators recruited men and women, ages 18 to 55, from sexual health clinics in several U.S. cities. Participants either had untreated genital gonorrhea, signs and symptoms of gonorrhea, or a sexual partner with gonorrhea. They were randomly assigned to receive either 2 grams or 3 grams of zoliflodacin by mouth, or 500 milligrams of ceftriaxone, a currently recommended antibiotic, by injection.

About one week after treatment, nearly all of the gonorrhea infections of the genitals were cured: 48 of 49 people (98%) who received 2 grams of zoliflodacin, all 47 people who received 3 grams, and all 21 people who got ceftriaxone. Similarly, all 13 rectal infections were cured no matter which treatment the person received.

However, throat infections were more persistent. Throat infections were cured in 4 of 6 people (67%) receiving 2 grams of zoliflodacin and 7 of 9 people (78%) receiving 3 grams. All 4 people in the ceftriaxone group were cured.

Participants were asked about side effects. Overall, the people tolerated both types of treatment well. A mild upset stomach was the most common side effect.

“The rate of reported gonorrhea cases in the United States has increased 75% since the historic low in 2009, and antibiotic resistance has considerably reduced the number of treatment options for this disease,” says NIAID Director Dr. Anthony S. Fauci. “These encouraging research findings published today suggest that zoliflodacin has the potential to be a useful and easy-to-administer oral antibiotic for treating gonorrhea.”

The FDA awarded zoliflodacin with fast track status for development as an oral treatment for gonorrhea. Plans are now underway for testing in the U.S., Netherlands, South Africa, and Thailand.