(RNN) - The Centers for Disease Control and Prevention released preliminary data Tuesday that shows nearly 2.3 million cases of chlamydia, gonorrhea and syphilis were diagnosed in 2017.
The CDC released its data at the National Sexually Transmitted Disease Prevention Conference in Washington, D.C.
After analyzing STD cases reported for 2013 and preliminary data for 2017, the CDC found four straight years of sharp increases in these specific STDs.
The 2017 numbers outpaced the 2016 record by more than 200,000 cases.
Gonorrhea cases are up 67 percent. Primary and secondary syphilis diagnoses are up 76 percent.
Chlamydia remained the most common condition, with more than 1.7 million reported cases last year.
"We are sliding backward," said Dr. Jonathan Mermin, director of the CDC's National Center for HIV/AIDS, Viral Hepatitis, STD and TB Prevention. "It is evident the systems that identify, treat, and ultimately prevent STDs are strained to near-breaking point."
Even though chlamydia, gonorrhea and syphilis are curable with antibiotics, experts say most cases go undiagnosed and untreated. That can lead to infertility, ectopic pregnancy, stillbirth and an increased HIV risk.
Doctors have found success in treating gonorrhea with the antibiotic Ceftriaxone. Gonorrhea has shown resistance to every other class of antibiotics.
The antibiotic Azithromycin can delay the development of resistance to Ceftriaxone, so in 2015, the CDC instructed doctors to prescribe a single shot of Ceftriaxone and an oral dose of Azithromycin to gonorrhea patients.
Even so, the CDC said new findings show the emerging resistance to Azithromycin in laboratory testing. A portion of samples showed emerging resistance increase from one percent in 2013 to four percent in 2017.
There is concern that a strain of gonorrhea may someday surface that does not respond to Ceftriaxone.
"We expect gonorrhea will eventually wear down our last highly effective antibiotic, and additional treatment options are urgently needed," said Dr. Gail Bolan, director of the CDC's Division of STD Prevention. "We can't let our defenses down — we must continue reinforcing efforts to rapidly detect and prevent resistance as long as possible."