(CBC) — Untreatable cases of “superbug gonorrhoea” have occurred, the World Health Organization says, as it calls for new drugs to treat the bacterial infection.

WHO and a global team of researchers published a study in the journal PLoS Medicine July 6 highlighting increases in drug-resistant gonorrhea, calling it a “serious situation.”

The United Nations health agency now advises doctors to prescribe two antibiotics called ceftriaxone and azithromycin for the sexually transmitted disease.

“We are starting to see resistance emerging to these drugs and even, as we say, superbug gonorrhea,”  Dr. Manica Balasegaram, director of the Global Antibiotic Research and Development Partnership, told reporters from Geneva.