Excerpted from: How is antibiotic immunity acquired? (Tony Mazzull, Scientific American, 05/10/04) Bacteria have a variety of mechanisms by which they become resistant to antibiotics, depending on the particular antibiotic (or class of antibiotic) and the type of bacteria involved... First, the cell wall of a bacterium can be altered so that an antibiotic cannot penetrate it. Second, some bacteria produce enzymes that can destroy antibiotics before they can work. Third, certain bacteria have developed mechanisms known as efflux pumps, which are able to "eject" antibiotics from the bacterial cell before they have a chance to exert any effect. Finally, the antibiotic target site within the bacteria can be altered. In this situation, when an antibiotic enters the bacterial cell it must bind to its intended target in order to have an effect on the bacteria. If the target within the bacteria has been changed to make this binding impossible, the bacteria will be resistant to the medicine's effects... The hope is that with more appropriate use of antibiotics and thus a reduction in antibiotic selection pressure, we can stem the tide of resistance and maintain a useful armamentarium of antibiotics for treating all types of bacterial infections. Patients should thus avoid taking antibiotics for things such as the common cold (which is caused by viruses and not bacteria), complete their courses of antibiotics as prescribed and not share their antibiotics with others. ACTIVITY Part 1: Restate, in your own words, the four mechanisms bacteria use to help themselves resist the effects of antibiotic medicine. 1. 2. 3. 4. ICTiviTY Part 2: Choose one of the four mechanisms described above and draw a simple diagram lustrating how it works. Label components of your diagram as necessary (e.g., cell wall, antibiotic olecule(s)) and use arrows or other symbols to show actions/effects..

1. Excerpted from: How is antibiotic immunity acquired? (Tony Mazzull, Scientific American,
05/10/04) Bacteria have a variety of mechanisms by which they become resistant to antibiotics,
depending on the particular antibiotic (or class of antibiotic) and the type of bacteria involved...
First, the cell wall of a bacterium can be altered so that an antibiotic cannot penetrate it. Second,
some bacteria produce enzymes that can destroy antibiotics before they can work. Third, certain
bacteria have developed mechanisms known as efflux pumps, which are able to "eject"
antibiotics from the bacterial cell before they have a chance to exert any effect. Finally, the
antibiotic target site within the bacteria can be altered. In this situation, when an antibiotic enters
the bacterial cell it must bind to its intended target in order to have an effect on the bacteria. If
the target within the bacteria has been changed to make this binding impossible, the bacteria will
be resistant to the medicine's effects... The hope is that with more appropriate use of antibiotics
and thus a reduction in antibiotic selection pressure, we can stem the tide of resistance and
maintain a useful armamentarium of antibiotics for treating all types of bacterial infections.
Patients should thus avoid taking antibiotics for things such as the common cold (which is
caused by viruses and not bacteria), complete their courses of antibiotics as prescribed and not
share their antibiotics with others. ACTIVITY Part 1: Restate, in your own words, the four
mechanisms bacteria use to help themselves resist the effects of antibiotic medicine. 1. 2. 3. 4.
ICTiviTY Part 2: Choose one of the four mechanisms described above and draw a simple
diagram lustrating how it works. Label components of your diagram as necessary (e.g., cell wall,
antibiotic olecule(s)) and use arrows or other symbols to show actions/effects.