Antibiotics, as the name implies, work against life, or more specifically against living cells. Since our bodies are also made up of living cells, the antibiotics have to distinguish between the cells in our bodies and the cells of the bacteria causing the infection or disease. To see how antibiotics recognize bacterial cells, we have to know something about the difference between those cells and the cells in our own bodies. One of the differences between bacterial cells and animal cells is that a bacterial cell is surrounded by a strong “cell wall.” When a bacterial cell reproduces, the cell wall stretches and grows until the single cell is big enough to divide in two.