This little cartoon, courtesy of xkcd, highlights a problem we have had for some time, but which is getting worse–highly antibiotic-resistant bacteria. Soon after the first antibiotics appeared, especially penicillin, doctors noticed the phenomenon of developing bacterial resistance to them. The cause is evolution in action. The replication time for bacteria is extremely fast, as short as twenty minutes in some cases. So the process of evolution, of random mutation and passing new traits on to offspring, happens in minutes rather than years.
Say a population of bacteria is 99.99% susceptible to being killed by an antibiotic, or sensitive. When the antibiotic has done its work there are 0.01% of the bacteria left. If their resistance to the antibiotic is heritable, they will pass that on to their offspring. Before too long, if the antibiotic is still present in the system and nothing else intervenes, all of the bacteria will be resistant. An important thing that can intervene is that the body has its own ways of killing bacteria on its own without the help of antibiotics. If the burden of infection is low, as when antibiotics kill nearly all the bacteria, our natural infection-fighting system can do the rest.
It’s been known for a long time how to at least slow down the process of bacteria acquiring antibiotic resistance — limit the use of antibiotics to when they are really needed, and use the ordinary, simple antibiotics whenever possible. So if a germ is sensitive to many antibiotics, which is often the case, use the simple one. This reserves our newest, most powerful drugs for when we really need them, which is when they are the only ones to which the germ is sensitive. In addition, don’t use antibiotics when they don’t do any good, such as with viral infection.
A recent article in the New England Journal of Medicine, “Preventing lethal hospital outbreaks of antibiotic-resistant bacteria,” describes how we are doing. It is a vital question, because bacteria resistant to many, and sometimes all, antibiotics are killers. It’s a particular problem in hospitals, which you can think of as gathering together many sick and vulnerable people in one spot. It’s a set-up for disaster if a highly resistant bacterial strain gets loose, and is why hospitals themselves can be dangerous places — you can acquire an infection there you didn’t come in with, called nosocomial infections. Reducing the problem means limiting the use of antibiotics only to those cases in which they are really necessary and choosing the correct antibiotic. It also means strict isolation and handwashing techniques for caregivers of patients infected with these bacteria to limit the spread to others.
This problem is not going to go away. It will probably get worse. Although researchers are always working to develop new antibiotics to stay one jump ahead of the bacteria, we can’t count on this approach, either.
Antibiotics have been miracle drugs since the 1940s, saving millions of lives. If we are complacent about the issue of resistance, we will be back in the dark days before that.
Christopher Johnson is a pediatric intensive care physician and author of Your Critically Ill Child: Life and Death Choices Parents Must Face, How to Talk to Your Child’s Doctor: A Handbook for Parents, and How Your Child Heals: An Inside Look At Common Childhood Ailments. He blogs at his self-titled site, Christopher Johnson, MD.