Canadian Medical Guide > Organisms > Bacteria Terms and Definitions
Bacteria
Medical Definition: | One of the three domains of life (the others being Eukarya and ARCHAEA), also called Eubacteria. They are unicellular prokaryotic microorganisms which generally possess rigid cell walls, multiply by cell division, and exhibit three principal forms: round or coccal, rodlike or bacillary, and spiral or spirochetal. Bacteria can be classifed by their response to OXYGEN: aerobic, anerobic, or facultatively anerobic; by the mode by which they obtain their energy: chemotrophic (via chemical reaction) or phototrophic (via light reaction); for chemotrophs by their source of chemical energy: lithotrophic (from inorganic compounds) or organotrophic (from organic compounds); and by where they get their CARBON: heterotrophic (from organic sources) or autotrophic (from CARBON DIOXIDE). They can also be classifed by whether or not they stain (based on the structure of their CELL WALLS) with CRYSTAL VIOLET dye: gram-negative or gram-positive. |
Guide Notes: | GEN; prefer specifics; relation to bact disease: Manual 22.12-22.16; presence of bacteria in organs vs infection: Manual 22.11; note many precoord BACT- terms (BACTERIAL PROTEINS, ANTIBODIES, BACTERIAL, etc); "coliform bacteria" = COLIFORM BACILLI see ENT |
Atypical Bacterial Forms - Microorganisms that have undergone greater changes than normal in morphology, physiology, or cultural characteristics. | |
Bacteria, Aerobic | |
Bacteria, Anaerobic | |
Bacteroidetes - A phylum of bacteria comprised of three classes: Bacteroides, Flavobacteria, and Sphingobacteria. | |
Biofilms - Films of bacteria or other microbial organisms, usually embedded in extracellular polymers such as implanted medical devices, which adhere to surfaces submerged in, or subjected to, aquatic environments (From Singleton & Sainsbury, Dictionary of Microbiology and Molecular Biology, 2d ed). Biofilms consist of multilayers of microbial cells glued together to form microbial communities which are highly resistant to both phagocytes and antibiotics. | |
Chlorobi - A phylum of anoxygenic, phototrophic, CHLOROBI including the family Chlorobiaceae. They occur in aquatic sediments, sulfur springs, and hot springs and utilize reduced sulfur compounds instead of oxygen. | |
Chloroflexi - Phylum of green nonsulfur bacteria including the family Chloroflexaceae, among others. | |
Cyanobacteria - A subgroup of the oxygenic photosynthetic bacteria comprised of unicellular to multicellular photosynthetic bacteria possessing CHLOROPHYLL a and carrying out oxygenic PHOTOSYNTHESIS. Cyanobacteria are the only known organisms capable of fixing both CARBON DIOXIDE (in the presence of light) and NITROGEN. Formerly called blue-green algae, cyanobacteria were traditionally treated as ALGAE. By the late 20th century, however, it was realized that the blue-green algae were unique and lacked the traditional NUCLEUS and CHLOROPLASTS of the green and other algae. The comparison of nucleotide base sequence data from 16S and 5S rRNA indicates that cyanobacteria represent a moderately deep phylogenetic unit within the GRAM-NEGATIVE BACTERIA. | |
Endospore-Forming Bacteria - A group of rods or cocci whose taxonomic affinities are uncertain. They form endospores, thick-walled bodies formed within the vegetative cells of certain bacteria, able to withstand adverse environmental conditions for prolonged periods. | |
Fusobacteria - A phylum of anaerobic, gram-negative bacteria with a chemoorganotrophic heterotrophic metabolism. They are resident flora of the OROPHARYNX. | |
Gram-Negative Bacteria - Bacteria which lose crystal violet stain but are stained pink when treated by Gram's method. | |
Gram-Positive Bacteria - Bacteria which retain the crystal violet stain when treated by Gram's method. | |
Proteobacteria - A phylum of bacteria consisting of the purple bacteria and their relatives which form a branch of the eubacterial tree. This group of predominantly gram-negative bacteria is classified based on homology of equivalent nucleotide sequences of 16S ribosomal RNA or by hybridization of ribosomal RNA or DNA with 16S and 23S ribosomal RNA. | |
Spirochaetales - An order of slender, flexuous, helically coiled bacteria, with one or more complete turns in the helix. | |
Sulfur-Reducing Bacteria - A group of gram-negative, anaerobic bacteria that is able to oxidize acetate completely to carbon dioxide using elemental sulfur as the electron acceptor. |
Bacteria Medical Definitions and Terms
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