Acinetobacter baumannii is a bacterial pathogen increasingly identified in the clinical microbiology laboratory as a cause of infection in humans. Upon microscopic examination, A. baumannii appears as a Gram-negative coccobacillus, and it produces clear colonies when grown on MacConkey agar, indicating its inability to ferment lactose. The taxonomy of Acinetobacter genus, part of the γ subclass of the Proteobacteria phylum, is complex and currently comprises 43 species (http://www.bacterio.net/acinetobacter.html), defined mostly by genomic DNA–DNA hybridization.