title: Adherence of Acinetobacter baumannii strains to human bronchial epithelial cells.
abstract: Acinetobacter baumannii is an important nosocomial pathogen, but the mechanisms contributing to its epidemicity and virulence are largely unknown. The organism is able to colonize skin and mucosal surfaces of the human host. Adherence of microorganisms to host cells is an important virulence factor as it is the initial step of the colonization process. In the present study, adherence of A. baumannii to human bronchial epithelial NCI-H(292) cells was examined by light and scanning electron microscopy. Thirty-seven strains were investigated including 18 from outbreaks, 16 not associated with outbreaks, and three for which an epidemic implication was unknown. Eight and 11 isolates belonged to European clone I and II, respectively. Two types of adherence were observed, dispersed adherence of bacteria to the cell, and adherence of clusters of bacteria at localized areas of the cells. Bacteria with dispersed adherence interacted with the epithelial cells through fimbriae, but were also entrapped by protrusions extending from the epithelial cells. Quantitative adherence varied considerably among strains but there was no significant correlation of the outbreak-associated strains with the percentage of infected cells. There was, however, a correlation between the clonal lineage and the percent of infected cells, with clone II being more adherent than clone I (P<0.05). Ten consecutive isolates from one outbreak were investigated to test whether adherence increased during passage among patients, but this appeared not to be the case. This study showed that A. baumannii adheres to human bronchial epithelial cells in vitro and that A. baumannii strains of clone II had a relatively high capacity for adhering to these cells.
authors.affiliation: Department of Microbiology, School of Medicine, Kyungpook National University, Daegu, #101, Dongin 2-ga, Jung-gu, Daegu 700-422, South Korea.
authors.forename: Je Chul
authors.initials: JC
authors.lastname: Lee
authors.forename: Henk
authors.initials: H
authors.lastname: Koerten
authors.forename: Peterhans
authors.initials: P
authors.lastname: van den Broek
authors.forename: Henry
authors.initials: H
authors.lastname: Beekhuizen
authors.forename: Ron
authors.initials: R
authors.lastname: Wolterbeek
authors.forename: Maria
authors.initials: M
authors.lastname: van den Barselaar
authors.forename: Tanny
authors.initials: T
authors.lastname: van der Reijden
authors.forename: Joke
authors.initials: J
authors.lastname: van der Meer
authors.forename: Joke
authors.initials: J
authors.lastname: van de Gevel
authors.forename: Lenie
authors.initials: L
authors.lastname: Dijkshoorn
mesh_terms: D000151:Acinetobacter Infections / Q000382:microbiology; D040981:Acinetobacter baumannii / Q000502:physiology* / Q000648:ultrastructure; D001422:Bacterial Adhesion; D001980:Bronchi / Q000166:cytology; D002460:Cell Line; D004847:Epithelial Cells / Q000382:microbiology / Q000502:physiology* / Q000648:ultrastructure; D006801:Humans; D008855:Microscopy, Electron, Scanning; D020545:Respiratory Mucosa / Q000166:cytology*