The new strain, dubbed H041, is resistant to all cephalosporins, the researchers said.
"This is both an alarming and a predictable discovery," said study researcher Dr. Magnus Unemo, of the Swedish Reference Laboratory for Pathogenic Neisseria. "Since antibiotics became the standard treatment for gonorrhea in the 1940s, this bacterium has shown a remarkable capacity to develop resistance mechanisms to all drugs introduced to control it," Unemo said.
"While it is still too early to assess if this new strain has become widespread, the history of newly emergent resistance in the bacterium suggests that it may spread rapidly unless new drugs and effective treatment programs are developed," he said.
Unemo's study will be presented this week at the International Society for Sexually Transmitted Disease Research (ISSTDR) conference, in Quebec City.
Gonorrhea can cause a burning sensation when urinating and pus discharge from the genitals, though it causes no symptoms in about 50 percent of infected women and approximately 2 percent to 5 percent of men. If left untreated, gonorrhea can lead to serious and irreversible health complications.
In women, the infection can cause chronic pelvic pain and fertility problems. In 3 percent to 4 percent of cases, untreated infections spread to the skin, blood, joints or the heart and can cause potentially fatal infections.
The CDC said experts are working on strategies to prevent antibiotic resistance, including treating the disease with several antibiotics at once. The agency said protected sex and STD screening could reduce the spread of gonorrhea.