title: Deciphering the multifactorial nature of Acinetobacter baumannii pathogenicity.
abstract: BACKGROUND
  Acinetobacter baumannii is an emerging bacterial pathogen that causes a broad array of infections, particularly in hospitalized patients. Many studies have focused on the epidemiology and antibiotic resistance of A. baumannii, but little is currently known with respect to its virulence potential.
  
  
  RESULTS
  The aim of this work was to analyze a number of virulence-related traits of four A. baumannii strains of different origin and clinical impact for which complete genome sequences were available, in order to tentatively identify novel determinants of A. baumannii pathogenicity. Clinical strains showed comparable virulence in the Galleria mellonella model of infection, irrespective of their status as outbreak or sporadic strains, whereas a non-human isolate was avirulent. A combined approach of genomic and phenotypic analyses led to the identification of several virulence factors, including exoproducts with hemolytic, phospholipase, protease and iron-chelating activities, as well as a number of multifactorial phenotypes, such as biofilm formation, surface motility and stress resistance, which were differentially expressed and could play a role in A. baumannii pathogenicity.
  
  
  CONCLUSIONS
  This work provides evidence of the multifactorial nature of A. baumannii virulence. While A. baumannii clinical isolates could represent a selected population of strains adapted to infect the human host, subpopulations of highly genotypically and phenotypically diverse A. baumannii strains may exist outside the hospital environment, whose relevance and distribution deserve further investigation.
authors.affiliation: Department of Biology, University Roma Tre, Rome, Italy.
authors.forename: Luísa C S
authors.initials: LC
authors.lastname: Antunes
authors.forename: Francesco
authors.initials: F
authors.lastname: Imperi
authors.forename: Alessandra
authors.initials: A
authors.lastname: Carattoli
authors.forename: Paolo
authors.initials: P
authors.lastname: Visca
mesh_terms: D000151:Acinetobacter Infections / Q000453:epidemiology* / Q000382:microbiology; D040981:Acinetobacter baumannii / Q000254:growth & development / Q000472:pathogenicity*; D018441:Biofilms; D004196:Disease Outbreaks; D006461:Hemolysis; D006801:Humans; D006868:Hydrolysis; D010738:Type C Phospholipases / Q000378:metabolism; D014774:Virulence
chemical_list: D010738:Type C Phospholipases