The mechanisms of Acinetobacter virulence are becoming increasingly clear, providing new insights into their pathogenic role in community acquired infections. It is apparent the time is appropriate for detailed review of the increasing knowledge concerning important new information, both clinical and therapeutic, especially information concerning virulence, resistance mechanisms and typing of Acinetobacter spp. Many new findings are accumulating in almost an exponential manner since publication of previous books on this subject in 1991 and 1996.