Antibiotics

Following the discovery of penicillin, the many new antibiotics that were discovered or made to effectively control infectious bacteria. By the 1970s, the scientific community assumed that the battle against bacterial infections had been won. Beginning in the 1980s, however, instances of bacterial resistance to previously effective antibiotics began to appear. The problem of resistance has accelerated throughout the 1990s to the present.

Altering an antibiotic slightly by adding or modifying a chemical side group can restore the effectiveness of the antibiotic. It is now clear, however, that such effectiveness may be short-lived. Resistance to the modified antibiotic can develop in a relatively short time.

An important contributor to the problem of antibiotic resistance is the overuse or misuse of antibiotics. Proper use of an antibiotic for the prescribed time either kills the target bacteria directly, or weakens the bacteria so that they are killed by the host's immune response. If the concentration of the antibiotic is too low to kill the bacteria, however, or if a patient stops taking the antibiotic before the course of the drug is complete, the surviving bacteria can then develop resistance to the drug. The resistant trait can be passed on to subsequent generations of the bacteria.

Some types of bacteria are now resistant to all but a few antibiotics. One strain of a Staphylococcus bacterium is resistant to every known antibiotic. Infections caused by this microbe are extremely difficult to treat. So far, this strain is rare, but clinical microbiologists expect that cases will become more frequent.