What can dirty diapers teach us about medicine? That infectious bugs are cagey.
When scientists designed the first antibiotics more than 50 years ago, they called them medical marvels. The drugs cured common infections caused by bacteria in just days, slashing death rates and transforming medical care.
But through tiny genetic changes, prompted in part by our own overuse and misuse of antibiotics, super bugs now outsmart our once super drugs. Certain bacterial strains have developed resistance to antibiotics that once killed them and passed this ability to their descendants. Today, a few of these strains can even overcome every existing antibiotic.
Scientists thought that after many generations without exposure to antibiotics, the bacteria would eventually succumb to the drugs once again. Unfortunately, that doesn't seem to be the case, says Bruce Levin, a population geneticist at Emory University in Atlanta, Georgia.
Levin analyzed E. coli bacteria—the harmless kind in our colons—found in 70 dirty diapers from a day care center. One-quarter of the bacteria in the used diapers were resistant to streptomycin, an antibiotic rarely prescribed in the previous 30 years.
Levin's diaper discovery was buoyed by research led by Richard Lenski, a microbiologist at Michigan State University in East Lansing who trained in Levin's lab.
Since 1988, Lenski has monitored flasks of streptomycin-resistant E. coli. After 10 years and 20,000 bacterial generations, he flooded the bugs with streptomycin for the first time. They remained unfazed by the drug.
Levin and others have run thousands of computer simulations to come up with strategies that slow the development and spread of resistance.
Because drug-resistant bacteria will continue to plague us, Levin jokes that research on antibiotic resistance offers the perfect career opportunity. He says, "We must continually discover new ways to deal with bacterial infections. I tell students that when you graduate from school, there are plenty of things for you to do!"