Cipro Overview

If you have read How Cells Work, then you are familiar with the inner workings of a typical bacterium and might want to skip this section. Here's a quick summary to highlight the most important points in How Cells Work -- we'll use the common E. coli cell as an example:

You can see that, in any living cell, DNA helps create enzymes, and enzymes create the chemical reactions that are "life."

You can now see that the life of a cell is dependent on a rich soup of enzymes that float in the cell's cytoplasm.

An antibiotic is a poison that works to destroy bacterial cells while leaving human cells unharmed. All antibiotics take advantage of the fact that there are many differences between the enzymes inside a human cell and the enzymes inside a bacterium. If a toxin is found, for example, that affects a particular E. coli enzyme that does not even exist in human cells, then it may be an effective antibiotic. Streptomycin, for example, is an antibiotic that can gum up the ribosome in a bacterium but leaves human ribosomes unharmed (a ribosome is a large enzyme that helps to turn DNA information into new enzymes).

Penicillin was one of the first antibiotics. It gums up certain bacteria's ability to build cell walls. Since bacterial cell walls and human cell walls are very different, penicillin has a big effect on certain species of bacteria but no effect on human cells. The sulfa drugs work by disabling an enzyme that manages the creation of nucleotides in bacteria but not in humans. Without nucleotides, the bacteria cannot reproduce.

Antibiotics only work on living cells. Bacteria are living cells. Antibiotics have no effect on viruses. See How Viruses Work for details.

You can see that the search for new antibiotics occurs down at the enzyme level, hunting for differences between the enzymes in human and bacterial cells that can be exploited to kill bacteria without affecting human cells.

The problem with any antibiotic is that it becomes ineffective over time. Bacteria reproduce so quickly that the probability for mutations is high. In your body, there may be millions of bacteria that the antibiotic kills. But if just one of them has a mutation that makes it immune to the antibiotic, that one cell can reproduce quickly and then spread to other people. Most bacterial diseases have become resistant to some of the antibiotics used against them through this process.

Cipro is an antibiotic that happens to be effective against anthrax bacteria, as well as many other types of bacteria. For example, it will kill E. coli bacteria. It is helpful in treating bacterial infections that cause everything from bronchitis to gonorrhea.

According to the Bayer site, Cipro works in the following way:

In other words, inside E. Coli bacteria and anthrax bacteria is an enzyme, called topoisomerase II, that helps the cell to wind DNA into a compact structure and then unwind it when needed. Cipro blocks topoisomerase II and prevents it from doing its job. A bacterial cell that has Cipro in it can no longer uncoil its DNA in order to create enzymes or reproduce. The bacteria containing Cipro eventually die.

There are reports that Soviet scientists created antibiotic-resistant strains of anthrax. One easy way to accomplish this would be to grow large quantities of anthrax and then treat it with Cipro to see if any of the cells lived. Then you would allow those few living cells to reproduce. These would be Cipro-resistant cells. However, they would not be resistant to other antibiotics that happen to work against anthrax.

For more information on Cipro, anthrax and related topics, check out the links on the next page.