Acne has long been a struggle for teens--nearly 80 percent of them  have some form of it. To make matters worse, doctors have found that the bacteria that cause acne have become increasingly resistant to antibiotics.

What is acne?

Acne is caused by oil and skin cells that become clogged in hair follicles, which then become infected with bacteria and causes swelling. A pimple forms when the plug begins to break down. Several types of pimples and acne exist, but most people will experience a combination of whiteheads, blackheads, papules and pustules. In less common acne, people will develop nodules or cysts, which are deep below the skin and can be very painful.

Mild acne can be treated with over-the-counter medications, which contain substances like benzoyl peroxide and salicylic acid.  For more severe cases, a visit to the dermatologist is necessary. Typically a patient would be prescribed an oral or topical antibiotic, which combats the growth of bacteria and reduces inflammation. Specifically, Erythromyocin and Tetracycline are often prescribed.

          [SLIDESHOW: 6 Strategies for Taming Teenage Acne]

What is antibiotic-resistant acne?

Over the years, antibiotics have become less effective at treating acne. This likely is occurring for several reasons. One is that the bacteria is mutating so that the antibiotic is not effectively killing it. The second is that the bacteria is banding together to produce biofilms, which slows down penetration of antibiotics. Research shows that antibiotic-resistant acne cases have tripled over the past few decades, which is leaving a gap in treatment.

Sore throats are another strike against oral antibiotics. Research has found that taking oral antibiotics for acne can raise the risk of developing sore throat symptoms. The study, published in the Archives of Dermatology found that college students taking oral antibiotics for acne were three times more likely to develop a sore throat than those not taking oral antibiotics.

How is this type of acne being treated?

Currently, antibiotic-resistant acne is being treated most commonly with combination therapy. This includes using an antibiotic with benzoyl peroxide or retinoids. Benzoyl peroxide decreases bacteria through a different mechanism than antibiotics, and this combination clears acne better than an antibiotic alone. Retinoids are derivatives of vitamin A, but studies have not shown the same effectiveness as benzoyl peroxide.

Another option is intense-pulsed laser and light treatments, which is used when other acne treatments fail. Laser and light treatments last for 15 to 20 minutes and take several treatments before improvements are seen. Studies show that the blue light destroys the bacteria and reduces inflammation. Unfortunately light therapy is expensive and usually is not covered by insurance. It also does not work for everyone.