Bacillus anthracis bacterial colonies, showing a clear space where a bacteria-killing virus has been used. (CDC/ Megan Mathias and J. Todd Parker)

Viruses that kill bacteria -- otherwise known as bacteriphages -- are being investigated as an alternative to traditional antibiotics, The Scientist magazine reports. It may sound like swallowing a fly and then sending a spider in after it, but so-called phage therapy could actually save us from our growing dependence on increasingly useless antibiotics.

Antibiotics work by killing off the microbes that make us sick, but the organisms left behind after a course of treatment can breed further generations of increasingly resistant bacteria. Antibiotic resistance already causes at least 23,000 deaths a year in the United States alone, and just last week President Obama called on federal agencies to help fix the problem.

The issue is that developing new antibiotics isn't very cost effective -- if people only take them when they're really necessary, sales stay low, and if they're over-prescribed to increase profit, then bacteria are more likely to develop resistance to them.

For that same reason, phage therapy -- which was actually used as a treatment before antibiotics existed -- has been slow to come up in the world. But a shout-out from the National Institute of Allergy and Infectious Diseases has phage therapy back in the hot seat.

Studies have examined the use of phage therapy in treating ear and lung infections (specifically those that are common in cystic fibrosis patients). Phages also show promise for treating the bacterial films that plague bone wounds and prosthetic infections.  In some parts of Europe, phage therapy never really fell out of style -- and now the doctors who support it may have an edge in treating their patients.

Phages, a group of researchers recently argued in a Nature Outlook article, are an attractive alternative to the antibiotics prescribed today: The viruses are highly specific, so unlike antibiotics they could treat pathogens without killing off our helpful bacteria. It's also relatively simple to combat resistance by adding new viruses to the treatment cocktail as needed. And while some may cringe at the idea of infecting themselves with a virus when they're already sick, researchers are able to select viruses (or tweak existing ones) that won't activate an immune response.

Scientists still need to work on getting phage therapy approved for treatment of human illnesses in the United States. But in the agricultural industry, where the over-use of antibiotics in livestock has lead to the rise of dangerous organisms on farms and in slaughterhouses, phages are already being used.

It's not as if phage therapy can kick antibiotics to the curb overnight: Scientists still aren't clear on the mechanisms by which these viruses target their bacterial nemeses. And in some cases, viruses that are expert bacterial killers in the lab just don't work when they encounter the microbes inside of a sick cow. But as federal agencies knuckle down for a fight with dangerous bacteria, phage therapy will no doubt find a place in their tool kits.