Can you really become immune to antibiotics or build a resistance to them? Are certain bacteria just stronger than antibiotics? And if so, what might a doctor do if you have a bacterial infection that is not harmed by antibiotics?
Your letter reflects a common misconception about antibiotics and resistance, because antibiotic resistance is an increasingly serious problem around the world.
First, here are a few basic principles: People do not become immune or resistant to antibiotics, bacteria do. People may have side effects or allergic reactions to antibiotics, such as penicillin allergies, but they do not become immune or resistant to the antibiotics.
Second, bacteria become resistant to antibiotics by various means, all of which require that the bacteria be exposed to the antibiotic. (Actually, we are now seeing some examples of bacterial resistance being passed from one type of bacteria to another without exposure to the antibiotic, but at some point the original bacteria developed the resistance because of such an exposure.)
Most bacteria reproduce very rapidly, with dividing times of minutes to hours. They also have frequent mutations to their genetic material. When a person takes an antibiotic, all of the bacteria in his or her body will be exposed to it. Many bacteria will be killed or their growth stopped by the antibiotic, but a few who may have undergone a mutation that makes them resistant will not. These few mutant bacteria will grow within a matter of hours to be the dominant strain of that bacteria in the person’s body, and the antibiotic will no longer be effective.
The problem of bacterial resistance to antibiotics is made much worse by doctors prescribing them inappropriately, or by people taking them inappropriately or incorrectly. For example, when you have a viral cold, no antibiotic will help you, since no antibiotic works against the cold viruses. If you take an antibiotic, all of the bacteria in your body will be affected by it, and some will become resistant to it. If you then develop an illness caused by one of those bacteria — let’s say pneumonia — the antibiotic will not be effective, and different antibiotics may have to be used.
The bacteria staph aureus has been notorious for years because of its ability to develop resistance to antibiotics, but for years one antibiotic, vancomycin, remained effective for severe staph infections, probably because it was seldom used. Disturbing reports from many hospitals now show that strains of staph resistant to vancomycin are turning up, and infections by those strains are becoming untreatable, since no antibiotic remains effective against them.
Trying to prevent the development of this antibiotic resistance is one of the major reasons why medical authorities urge doctors not to prescribe antibiotics except when they are really needed and will help. Colds and many other viral infections such as mono or flu (some types) will not respond to antibiotics, and taking them will simply convert sensitive bacteria in one’s body into resistant ones.