The Path of Most Resistance
Every child has colonies of helpful and harmful bacteria living in his body. Within those colonies, a few individual strains of bacteria may have a natural ability to resist certain antibiotics. So whenever your child takes an antibiotic, the germs that are susceptible to that drug die, leaving more room for the drug-resistant microbes to reproduce and become dominant. The same thing can happen when your child doesn't finish his whole course of antibiotics. Either way, the strong survive.
If your child develops a sizable population of resistant bacteria after taking an antibiotic, it doesn't necessarily mean she'll become ill. The new bugs may simply live in her body—in which case, she's said to be "colonized"—or they may disappear over time. Under the right circumstances, though, she could get sick with a tough-to-treat infection. One of the great mysteries of medical science is why bacterial infections develop in one case and not another; it probably depends on a variety of factors, such as the strength and number of bacteria, and the child's own immune system.
However, even if your child doesn't have any symptoms, she can still pass along those resistant bacteria to others. That's how a child who's never even taken antibiotics can become infected with drug-resistant bacteria. "Young kids in child-care centers share germs better than they share toys," says Sarah Long, M.D., a pediatric infectious-disease specialist at St. Christopher's Hospital for Children, in Philadelphia.
In fact, kids play a key role in the development of resistant bacteria—not only do they spread germs easily, but they take more antibiotics than adults do. While many of those prescriptions are crucial for their health, others are unnecessary. "Antibiotics are important for treating bacterial infections, but more than 90 percent of children's illnesses are actually viral infections that can't be cured with antibiotics," says Dr. Long. Asking for antibiotics when your child has a bad cold, for example, can wind up doing more harm than good.