Examples of antibiotics are penicillin, which is derived from the fungus, Penicillium, and streptomycin, the tetracyclines, erythromycin, and others, which are derived from various species of Streptomyces. A second source of antimicrobial agents are those that are produced in the laboratory. These are often referred to as synthetic drugs. The spectrum of activity of an antimicrobial drug refers to the range of bacterial species the drug can affect. Broad spectrum drugs affect a broad range while a narrow spectrum drug affects a relatively smaller range of bacteria.
Some antibiotics can cause side effects.
Some people experience an allergic reaction to antimicrobial agents. Superinfections - If the normal flora are disrupted by an antibiotic, the bacteria or fungi of the body whose growth is normally suppressed by the competing normal flora can increase in population. The increase in the population of these opportunistic bacteria or fungi as a result of the removal of competing normal flora because of the use of an antibiotic is called a superinfection. The acquisition of antibiotic resistance can be accomplished in a variety of ways. It is thought that mutations can confer resistance to a bacterium.