immune reaction, immune response, immunologic response - a bodily defense reaction that recognizes an invading substance (an antigen: such as a virus or fungus or bacteria or transplanted organ) and produces antibodies specific against that antigen

bioremediation - the act of treating waste or pollutants by the use of microorganisms (as bacteria) that can break down the undesirable substances

microorganism - any organism of microscopic size

acidophil, acidophile - an organism that thrives in a relatively acid environment

bacteroid - a rodlike bacterium (especially any of the rod-shaped or branched bacteria in the root nodules of nitrogen-fixing plants)

Calymmatobacterium, genus Calymmatobacterium - a genus of bacterial rods containing only the one species that causes granuloma inguinale

Francisella, genus Francisella - a genus of gram-negative aerobic bacteria that occus as pathogens and parasite in many animals (including humans)

gonococcus, Neisseria gonorrhoeae - the pus-producing bacterium that causes gonorrhea

legionella, Legionella pneumophilia - the motile aerobic rod-shaped Gram-negative bacterium that thrives in centralheating and air conditioning systems and can cause Legionnairs' disease

nitrobacterium - any of the bacteria in the soil that take part in the nitrogen cycle; they oxidize ammonium compounds into nitrites or oxidize nitrites into nitrates

penicillin-resistant bacteria - bacteria that are unaffected by penicillin

rod - any rod-shaped bacterium

diplococcus - gram-positive bacteria usually occurring in pairs

Rickettsia - any of a group of parasitic bacteria that live in arthropods (as ticks and mites) and can cause disease if transmitted to human beings

resistance - the degree of unresponsiveness of a disease-causing microorganism to antibiotics or other drugs (as in penicillin-resistant bacteria)

microphage - a neutrophil that ingests small things (as bacteria)

microbiology - the branch of biology that studies microorganisms and their effects on humans

gram-positive - (of bacteria) being or relating to a bacterium that retains the violet stain used in Gram's method

gram-negative - (of bacteria) being or relating to a bacterium that does not retain the violet stain used in Gram's method