Three of the most common sexually transmitted infections are growing increasingly resistant to antibiotics, according to a new report by the World Health Organization (WHO). In response, the U.N. health agency has updated the international treatment guidelines for chlamydia, gonorrhea and syphilis to help ensure the problem doesn’t get any worse, CBS News reports.

Combined, chlamydia, gonorrhea and syphilis infect more than 200 million people worldwide every year. But WHO authorities said many doctors around the world don’t prescribe the right type or correct doses of antibiotics, and they often miss prescribing treatment within the window of time needed to properly treat and prevent these bacterial infections. What’s more, international health authorities warned that because of these slip-ups, the germs that cause these illnesses are able to adapt to fight off current antibiotics used to treat them. Doctors fear the problem will escalate if proper steps aren’t taken to stave off widespread resistance to these meds.

For gonorrhea, one of the most resistant infections today, experts cautioned that quinolones (an older, cheaper class of antibiotics) should no longer be used, because of widespread high levels of resistance around the world. The new WHO STI treatment guidelines also urged doctors to closely track the prevalence of antibiotic-resistant strains of gonorrhea in their communities and prescribe appropriately based on local patterns of resistance.

The most effective form of treatment for syphilis today, according to the new guidelines, is a single dose of benzathine penicillin, an antibiotic doctors inject into a patient’s buttock or thigh. For chlamydia, the most common bacterial STI, several treatments are available. But to remain effective against antibiotic-resistant strains of the bacteria that cause this infection, doctors have adjusted dosing patterns.

The WHO guidelines also state that when used correctly and consistently, condoms are still one of the most effective methods of protection against sexually transmitted infections.

Click here to learn more about STIs and antibiotic resistance.