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Open Access Highly Accessed Research article

Acinetobacter baumannii invades epithelial cells and outer membrane protein A mediates interactions with epithelial cells

Chul Hee Choi1, Jun Sik Lee1, Yoo Chul Lee1, Tae In Park2 and Je Chul Lee1*

Author Affiliations

1 Department of Microbiology, Kyungpook National University School of Medicine, Daegu, 700-422, Korea

2 Department of Pathology, Kyungpook National University School of Medicine, Daegu, 700-422, Korea

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BMC Microbiology 2008, 8:216  doi:10.1186/1471-2180-8-216

Published: 10 December 2008



Acinetobacter baumannii is a nosocomial pathogen of increasing importance, but the pathogenic mechanism of this microorganism has not been fully explored. This study investigated the potential of A. baumannii to invade epithelial cells and determined the role of A. baumannii outer membrane protein A (AbOmpA) in interactions with epithelial cells.


A. baumannii invaded epithelial cells by a zipper-like mechanism, which is associated with microfilament- and microtubule-dependent uptake mechanisms. Internalized bacteria were located in the membrane-bound vacuoles. Pretreatment of recombinant AbOmpA significantly inhibited the adherence to and invasion of A. baumannii in epithelial cells. Cell invasion of isogenic AbOmpA- mutant significantly decreased as compared with wild-type bacteria. In a murine pneumonia model, wild-type bacteria exhibited a severe lung pathology and induced a high bacterial burden in blood, whereas AbOmpA- mutant was rarely detected in blood.


A. baumannii adheres to and invades epithelial cells. AbOmpA plays a major role in the interactions with epithelial cells. These findings contribute to the understanding of A. baumannii pathogenesis in the early stage of bacterial infection.