Question

Many bacteria are now resistant to Penicillin, because

• A. Penicillin cause gene mutations.
• B. Previously resistant forms survived and reproduced better than non-resistant forms.
• C. Hospital environment inhibits competition among bacteria.
• D. Penicillin triggers the synthesis of resistant proteins.

Answer 1

The correct option is B Previously resistant forms survived and reproduced better than non-resistant forms.

Only a few decades ago, antibiotics were considered to be wonder drugs because they worked so well to cure deadly diseases. Ironically, though, many antibiotics have become less effective, precisely because they have worked so well and have been used so often. The antibiotic era began in 1929 with Alexander Fleming's observation that bacteria would not grow near colonies of the mold Penicillium. In the decades that followed this breakthrough discovery, molecules produced by fungi and bacteria have been successfully used to combat bacterial diseases such as tuberculosis and pneumonia. Antibiotics drastically reduced death rates associated with many infectious diseases. Antibiotics kill bacteria, not viruses. If you take antibiotics for a viral infection (like a cold or the flu), you will not kill the viruses, but you will introduce a selective pressure on bacteria in your body, inadvertently selecting for antibiotic-resistant bacteria. Basically, you want your bacteria to be antibiotic virgins, so that if they someday get out of hand and cause an infection that your immune system can't handle, they can be killed by a readily available antibiotic. Many bacteria are now resistant to penicillin, because, previously resistant forms survived and reproduced better than nonresistant forms. This is one of the best examples of natural selection as the nature picked up those strains which could fight for their existence. It has been worked upon broadly by Lederberg in their famous replica experiment.

Therefore, the correct answer is option B.