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J Infect Dis. 2009 Feb 15;199(4):513-21. doi: 10.1086/596317.

Penicillin-binding protein 7/8 contributes to the survival of Acinetobacter baumannii in vitro and in vivo.

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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.



Acinetobacter baumannii is a bacterial pathogen of increasing medical importance. Little is known about genes important for its survival in vivo.


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.


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.

[Indexed for MEDLINE]

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