It is difficult to classify all bacteria into clear-cut categories. Various classification methods are used, depending in part, on the purpose.
- Bacteria are given 2 names (usually Latin) denoting their genus and species
- Ex. Escherichia coli
- The name is italicized or underlined because it’s Latin.
- The first name refers to the genus (plural: genera) and is capitalized,
- The last name refers to the species (plural: species) and is not
- Phenotypic Classification—usually presumptive
- Macroscopic morphology
- Colonial appearance
- Microscopic appearance
- Gram stain: Gram-positive vs. Gram-negative, Gram-variable
- Influences choice of antibiotic—in general, Gram-positive bacteria are
more susceptible to penicillin G than Gram-negative bacteria. Why?