The Acinetobacter baumannii Biofilm-Associated Protein Plays a Role in Adherence to Human Epithelial Cells

Abstract

Acinetobacter baumannii is a significant source of nosocomial infections worldwide. This bacterium has the ability to survive and persist on multiple abiotic surfaces in health care facilities, and once a focus has been established, this opportunistic pathogen is difficult to eradicate. This paper demonstrates that the A. baumannii biofilm-associated protein (Bap) is necessary for mature biofilm formation on medically relevant surfaces, including polypropylene, polystyrene, and titanium. Scanning electron microscopy analyses of biofilms show that Bap is required for three-dimensional tower structure and water channel formation. In conjunction with persistence on abiotic surfaces, adherence to eukaryotic cells is an important step in bacterial colonization resulting in infection of the host. We have described Bap as the surface structure involved in adherence of A. baumannii to both normal human bronchial epithelial cells and normal human neonatal keratinocytes. However, Bap is not involved in internalization of the bacterium in these two cell lines. Furthermore, this study shows that the presence of Bap increases the bacterial cell surface hydrophobicity. The results of this study are pertinent, as the data lead to a better understanding of the role of Bap in biofilm formation on medical surfaces and in colonization of the host.

Molecular Analysis of the Acinetobacter baumannii Biofilm-Associated Protein

“…Additionally, affinity-purified Bap-specific antibodies blocked Bap-mediated biofilm formation by A. baumannii strains MS3009, MS3011, and MS3014. Taken together, our results demonstrate a role for Bap in biofilm formation that is consistent with previous literature examining other A. baumannii strains (13,16). Our results should provide the basis for more detailed studies to examine the translocation and function of Bap in A. baumannii, including other common multidrug-resistant sequence types associated with hospital infection outbreaks.…”

“…baumannii 307-0294 resulted in decreased biofilm growth and decreased adherence to human bronchial epithelial and neonatal keratinocyte cells (13,16). Bap homologues have also been identified and characterized in other bacteria, including members of other genera typically associated with hospital-acquired infection, such as Staphylococcus (17), Enterococcus (18,19), and Pseudomonas (20,21).…”

Study of the Response Regulator Rrp1 Reveals Its Regulatory Role in Chitobiose Utilization and Virulence of Borrelia burgdorferi

“…Cells were then resuspended in fresh PBS. SEM determinations were performed as described before (47,48). Briefly, 10 l of cell suspensions was settled on poly-L-lysine-coated round coverslips (BD BioSciences, San Jose, CA).…”

Co-Colonization with <i>Neisseria species</i> Is a Risk Factor for Prolonged Colonization with Multidrug-Resistant <i>Acinetobacter baumannii</i> in the Respiratory Tract

“…The precise mechanism by which Neisseria co-colonization induced prolongation of MDRAB colonization was not determined. One of the molecules that contributes to adherence of A. baumannii in human epithelial cells is biofilm-associated protein (Bap) (12), although no report has described the potential environmental factors that can control the differential expression of the bap gene. Another factor that can control the formation of biofilms by A. baumannii is the presence of metal cations, such as iron.…”