Acinetobacter

Abstract

A.ci.ne' to.bac.ter . Gr. adj. akinetos unable to move; M.L. n. bacter the masculine form of the Gr. neut. n. bactrum a rod; M.L. masc. n. Acinetobacter nonmotile rod. Proteobacteria / Gammaproteobacteria / Pseudomonadales / Moraxellaceae / Acinetobacter Rods 0.9–1.6 × 1.5–2.5 μm, becoming spherical in the stationary phase of growth . Colonies are generally nonpigmented and are mucoid when the cells are encapsulated. Cells commonly occur in pairs and in chains of variable length. Do not form spores. Gram negative but occasionally difficult to destain. Swimming motility does not occur but the cells display “twitching motility”, presumably because of the presence of fimbriae. Aerobic, having a strictly respiratory type of metabolism with oxygen as the terminal electron acceptor. Most strains do not reduce nitrate to nitrite. Most strains grow between 20 and 37°C, having temperature optima of 33–35°C. Some strains cannot grow at 37°C. Oxidase negative. Catalase positive . Grow well on most complex media. Most strains grow in defined media containing a single carbon and energy source, such as acetate or lactate, using ammonium or nitrate salts, or one of several common amino acids, as a supply of nitrogen. Frequently amino acids such as glutamic acid or aspartic acid can serve as a single source of carbon, energy, and nitrogen in a defined mineral medium. With rare exceptions, they display no growth factor requirements. Most frequently saprophytic, occurring naturally in soil, water, sewage, and foods such as raw vegetables. Can also reside, possibly indigenously, on the human skin and in the human respiratory tract. Can cause nosocomial infections such as bacteremia, secondary meningitis, pneumonia, and urinary tract infections in humans. The mol % G + C of the DNA is : 38–47. Type species : Acinetobacter calcoaceticus (Beijerinck 1911) Baumann, Doudoroff and Stanier 1968b, 1538 emend. Bouvet and Grimont 1986, 238 ( Micrococcus calcoaceticus Beijerinck 1911,1067.)