antibiotic A germ-killing substance prescribed as a medicine (or sometimes as a feed additive to promote the growth of livestock). It does not work against viruses.
bacterium (plural bacteria) A single-celled organism. These dwell nearly everywhere on Earth, from the bottom of the sea to inside animals.
binary Something having two parts, or something based on the number two.
Centers for Disease Control and Prevention, or CDC An agency of the U.S. Department of Health and Human Services, CDC is charged with protecting public health and safety by working to control and prevent disease, injury and disabilities. It does this by investigating disease outbreaks, tracking exposures by Americans to infections and toxic chemicals, and regularly surveying diet and other habits among a representative cross-section of all Americans.
Clostridium difficile A bacterium that releases a toxin, which attacks the lining of the intestines. It can trigger colitis and severe diarrhea — conditions that can kill. In just the United States, C. difficile infections kill an estimated 14,000 people each year.
epidemiologist Like health detectives, these researchers figure out what causes a particular illness and how to limit its spread.
gene (adj. genetic) A segment of DNA that codes, or holds instructions, for producing a protein. Offspring inherit genes from their parents. Genes influence how an organism looks and behaves.
germ Any one-celled microorganism, such as a bacterium, fungal species or virus particle. Some germs cause disease. Others can promote the health of higher-order organisms, including birds and mammals. The health effects of most germs, however, remain unknown.
gut Colloquial term for an organism’s stomach and/or intestines. It is where food is broken down and absorbed for use by the rest of the body.
infection A disease that can spread from one organism to another.
microbe Short for microorganism. A living thing that is too small to see with the unaided eye, including bacteria, some fungi and many other organisms such as amoebas. Most consist of a single cell.
mutation Some change that occurs to a gene in an organism’s DNA. Some mutations occur naturally. Others can be triggered by outside factors, such as pollution, radiation, medicines or something in the diet. A gene with this change is referred to as a mutant.
strain (in biology) Organisms that belong to the same species that share some small but definable characteristics. For example, biologists breed certain strains of mice that may have a particular susceptibility to disease. Certain bacteria may develop one or more mutations that turn them into a strain that is immune to the ordinarily lethal effect of one or more drugs.
superbug A popular term for a disease-causing germ that can withstand medicines.
toxic Poisonous or able to harm or kill cells, tissues or whole organisms. The measure of risk posed by such a poison is its toxicity
toxin A poison produced by living organisms, such as germs, bees, spiders, poison ivy and snakes.
virulence (in medicine) The potency of a virus, bacterium or other agent in causing infectious disease. Among a given species, some strains may cause disease with very little exposure (such as infection with a few cells). Less virulent strains may take massive exposures to create disease.