The U.S. Centers for Disease Control and Prevention (CDC) warns the public Monday against an antibiotic-resistant gonorrhea, a 'superbug' deemed to be an urgent public health threat in the United States, according to Fox News.

Called a "nightmare" by the CDC, the 'superbug' causes diarrhea and is considered to belong to a group of fast-growing killer bacteria. The CDC has also added other bacteria in the list of urgent threats, which includes Clostridium difficile, or C. difficile and Enterobacteriaceae, or CRE.

A CDC report reveals that at least 2 million people become affected with serious bacterial infections each year in the United States. Among these patients, at least 23,000 die from fatal infections, according to Fox News.

In a telephone interview, CDC Director Dr. Thomas Frieden explained that bugs are becoming resistant against antibiotics and the worst part is that there are no new drugs to fight them. Frieden explains that, "For organism after organism, we're seeing this steady increase in resistance rates; we don't have new drugs about to come out of the pipeline. If and when we get new drugs, unless we do a better job of protecting them, we'll lose those, also," as reported by Fox News.

One primary cause of antibiotic resistance is overprescribing of the drug, giving pathogens the opportunity to develop resistance against treatment. Very few new antibiotics have been introduced and released in the market in the past years, and drug companies are not looking to replace or upgrade the old ones already out there for public consumption.

The three 'superbugs' -- antibiotic-resistant gonorrhea,  C. difficile and CRE-- are considered to be deadly mainly because their resistance have steadily increased over the years, and the strongest antibiotics are no longer effective in treating them.

According to Fox News, the CDC report says the drug-resistant 'superbug' Neisseria gonorrhea, affects 820,000 people each year and if left with no treatment, the sexually-transmitted disease may develop into infertility in both men and women, ectopic pregnancy, pelvic inflammatory disease, stillbirths, and  severe eye infections in babies.The bacteria CRE  meanwhile, is responsible for 9,300 healthcare-associated infections, and causes over 600 deaths per year. C. difficile, on the other hand, is a common infection in hospitals, and causes life-threatening diarrhea. Each year, this bacteria affects 250,000 people and kills 14,000.