A public health poster from 1952 encourages Americans to get checked for sexually transmitted diseases. Gonorrhea is the second-most-common sexually transmitted disease in the U.S., with more than 300,000 cases reported in 2011. Images from the History of Medicine hide caption

itoggle caption Images from the History of Medicine

In the U.S., doctors no longer have the option of treating gonorrhea with a pill. Instead, they are advised to use an injectable antibiotic, which is still effective against the bacteria. iStockphoto.com hide caption

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Health officials say they're worried that one day there will be no more antibiotics left to treat gonorrhea. iStockphoto.com hide caption

itoggle caption iStockphoto.com