A genus of nonmotile, aerobic bacteria (family Neisseriaceae) containing Gram-negative or -variable coccoid or short rods, or cocci, often occurring in pairs. Spores are not produced. These bacteria grow on ordinary media without the addition of serum. They are oxidase-negative and catalase-positive; carbohydrates are oxidized or not attacked at all, and arginine dihydrolase is not produced. They are a frequent cause of nosocomial infections and can also cause severe primary infections in immunocompromised people. The type species is Acinetobacter calcoaceticus. Syn: Lingelsheimia.