ANTIBIOTICS

Antibiotics represent a class of drugs used in the treatment of infections and infectious diseases caused by bacteria. These bacteria possess unique features (e.g., a cell wall, proteins, enzymes) that differentiate them from animal cells. Antibiotics interfere with the production of these bacterial characteristics, resulting in selective killing or growth inhibition of susceptible microorganisms. For example, prior to 1990, infections caused by Streptococcus pneumoniae (e.g., pneumonia, bronchitis, ear infections), were usually treated with penicillin or amoxicillin. Streptococcus pneumoniae possess a cell wall that acts as a protective barrier— a unique feature not found on animal or human cells. Penicillin or amoxicillin, two common antibiotics, bind to that cell wall as it is produced, causing it to weaken and "leak," eventually killing the bacteria without harming the animal host cells.

Antibiotics can be further described by the number of bacteria covered (narrow-spectrum antibiotics versus broad-spectrum antibiotics), and by how strongly the antibiotics work against the bacteria (bactericidal activity versus bacteriostatic activity). Narrow-spectrum antibiotics are used to treat infections limited to a few families and types of bacteria, while broad-spectrum antibiotics are useful to treat infections caused by multiple families of bacteria. An antibiotic that exhibits bactericidal activity will kill bacteria when it comes into contact with it (e.g., S. pneumoniae). Bacteriostatic activity, on the other hand, occurs when an antibiotic inhibits the growth of bacteria, without necessarily killing it.