Acinetobacter baumannii is a Gram negative bacteria. It is typically a short, almost round, rod-shape (coccobacillus). It can be an opportunistic pathogen in humans, affecting people with compromised immune systems and is becoming increasingly important as a hospital derived infection (nosocomial). It has also been isolated from soil and water samples in the environment. Bacteria of this genus lack flagella, whip-like structures many bacteria use for locomotion, but exhibit twitching or swarming motility. This may be due to the activity of type IV pili (TFP), a pole-like structure that can be extended and retracted. Motility in A. baumannii may also be due to the excretion of exopolysaccharide, creating a film of high molecular weight sugar chains behind the bacterium in order to move forward. Clinical microbiologists typically differentiate members of the Acinetobacter genus from other Moraxellaceae by performing an oxidase test, as Acinetobacter spp. are the only members of the Moraxellaceae that lack cytochrome C oxidases. A. baumannii is part of the ACB complex (A. baumannii, A. calcoaceticus, and Acinetobacter genomic species 13TU). Members of the ACB comlex are difficult to speciate (to determine the specific species of) and comprise the most clinically relevant members of the genus. A. baumannii has also been identified as an ESKAPE pathogen (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species; a group of pathogens with a high rate of antibiotic resistance that are responsible for the a majority of nosocomial infections. Colloquially, A. baumannii is referred to as 'Iraqibacter' due to its seemingly sudden emergence in military treatment facilities during the Iraq War. It has continued to be an issue for veterans and soldiers who serve in Iraq and Afghanistan. Multidrug resistant (MDR) A. baumannii has spread to civilian hospitals in part due to the transport of infected soldiers through multiple medical facilities.