title: Penicillin-binding protein 7/8 contributes to the survival of Acinetobacter baumannii in vitro and in vivo.
abstract: BACKGROUND
  Acinetobacter baumannii is a bacterial pathogen of increasing medical importance. Little is known about genes important for its survival in vivo.
  
  
  RESULTS
  Screening of random transposon mutants of the model pathogen AB307-0294 identified the mutant AB307.27. AB307.27 contained its transposon insertion in pbpG, which encodes the putative low-molecular-mass penicillin-binding protein 7/8 (PBP-7/8). AB307.27 was significantly killed in ascites (P<.001), but its growth in Luria-Bertani broth was similar to that of its parent, AB307-0294 (P=.13). The survival of AB307.27 was significantly decreased in a rat soft-tissue infection model (P<.001) and a rat pneumonia model (P=.002), compared with AB307-0294. AB307.27 was significantly killed in 90% human serum in vitro, compared with AB307-0294 (P<.001). Electron microscopy demonstrated more coccobacillary forms of AB307.27, compared with AB307-0294, suggesting a possible modulation in the peptidoglycan, which may affect susceptibility to host defense factors.
  
  
  CONCLUSIONS
  These findings demonstrate that PBP-7/8 contributes to the pathogenesis of A. baumannii. PBP-7/8 either directly or indirectly contributes to the resistance of AB307-0294 to complement-mediated bactericidal activity. An understanding of how PBP-7/8 contributes to serum resistance will lend insight into the role of this low-molecular-mass PBP whose function is poorly understood.
authors.affiliation: Veterans Administration Western New York Healthcare System, The Witebsky Center for Microbial Pathogenesis, Department of Medicine, State University of New York-Buffalo, Buffalo, New York 14214, USA. trusso@acsu.buffalo.edu
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Russo
authors.forename: Ulrike
authors.initials: U
authors.lastname: MacDonald
authors.forename: Janet M
authors.initials: JM
authors.lastname: Beanan
authors.forename: Ruth
authors.initials: R
authors.lastname: Olson
authors.forename: Ian J
authors.initials: IJ
authors.lastname: MacDonald
authors.forename: Shauna L
authors.initials: SL
authors.lastname: Sauberan
authors.forename: Nicole R
authors.initials: NR
authors.lastname: Luke
authors.forename: L Wayne
authors.initials: LW
authors.lastname: Schultz
authors.forename: Timothy C
authors.initials: TC
authors.lastname: Umland
mesh_terms: D000151:Acinetobacter Infections / Q000276:immunology* / Q000382:microbiology*; D040981:Acinetobacter baumannii / Q000235:genetics / Q000254:growth & development* / Q000472:pathogenicity; D000595:Amino Acid Sequence; D000818:Animals; D001770:Blood Bactericidal Activity; D003165:Complement System Proteins / Q000276:immunology; D003198:Computer Simulation; D004251:DNA Transposable Elements; D003627:Data Interpretation, Statistical; D004195:Disease Models, Animal; D006801:Humans; D046529:Microscopy, Electron, Transmission; D008969:Molecular Sequence Data; D009154:Mutation; D046915:Penicillin-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D018410:Pneumonia, Bacterial / Q000276:immunology / Q000382:microbiology; D051381:Rats; D018461:Soft Tissue Infections / Q000276:immunology / Q000382:microbiology; D014556:Urine / Q000382:microbiology
chemical_list: D004251:DNA Transposable Elements; D046915:Penicillin-Binding Proteins; D003165:Complement System Proteins