The sexually transmitted disease gonorrhea may be turning into a superbug.

Researchers have discovered a strain of gonorrhea that is resistant to all antibiotics currently available to treat it.

This new strain could transform a common and once easily treatable infection into a global threat to public health, the researchers said.

Since the 1970s, gonorrhea has become increasingly resistant to traditional antibiotics , including penicillin and tetracycline, and, in 1991, it became resistant to fluoroquinolone. Antibiotics called cephalosporins are the only type left that doctors recommend to treat the disease.

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 is caused by the bacterium Neisseria gonorrhea, and is spread through sexual activity. It is one of the most common sexually transmitted diseases in the world. In the United States alone, there are an estimated 700,000 cases annually, according to the Centers for Disease Control and Prevention (CDC).

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.

Pass it on: A new strain of gonorrhea has been discovered that is resistant to all the antibiotics currently available to treat it.

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