title: Effect of EDTA on the resistance of clinical isolates of Acinetobacter baumannii to the bactericidal activity of normal human serum.
abstract: Acinetobacter baumannii is an opportunist nosocomial pathogen of world-wide importance and produces severe infections in immunocompromised patients. However, the virulence factors contributing to its pathogenic properties are not well known. The effect of normal human serum against 18 clinical isolates of the most prevalent biotypes of A. baumannii in Chile was investigated. The effect of pre-treatment of the cells with ethylene diamine tetraacetic acid (EDTA) or bismuth subsalicylate (BSS), compounds known to decrease the amount of lipopolysaccharide (LPS) and bacterial capsular polysaccharide (CPS), respectively, in other gram-negative bacteria, was evaluated. Most isolates (16 of 18) showed resistance to normal human serum. Prior treatment with EDTA rendered nine of these isolates susceptible to serum, while seven isolates maintained their resistance. Pre-treatment with BSS did not modify the serum-resistant behaviour of the isolates. The results suggest that LPS might be involved in the resistance of A. baumannii to human serum whereas CPS does not seem to contribute to this property.
authors.affiliation: Departamento de Microbiología, Facultad de Ciencias Biológicas, Universidad de Concepción, Casilla 160-C, Concepción, Chile.
authors.forename: Apolinaria
authors.initials: A
authors.lastname: García
authors.affiliation: Departamento de Microbiología, Facultad de Ciencias Biológicas, Universidad de Concepción, Casilla 160-C, Concepción, Chile.
authors.forename: Henry
authors.initials: H
authors.lastname: Solar
authors.affiliation: Departamento de Microbiología, Facultad de Ciencias Biológicas, Universidad de Concepción, Casilla 160-C, Concepción, Chile.
authors.forename: Carlos
authors.initials: C
authors.lastname: González
authors.affiliation: Departamento de Microbiología, Facultad de Ciencias Biológicas, Universidad de Concepción, Casilla 160-C, Concepción, Chile.
authors.forename: Raúl
authors.initials: R
authors.lastname: Zemelman
mesh_terms: D000150:Acinetobacter / Q000187:drug effects* / Q000276:immunology; D016667:Bacterial Capsules / Q000187:drug effects / Q000502:physiology; D001729:Bismuth / Q000494:pharmacology; D001770:Blood Bactericidal Activity / Q000187:drug effects*; D002614:Chelating Agents / Q000494:pharmacology*; D004492:Edetic Acid / Q000494:pharmacology*; D006801:Humans; D008070:Lipopolysaccharides / Q000378:metabolism; D009942:Organometallic Compounds / Q000494:pharmacology; D012459:Salicylates / Q000494:pharmacology
chemical_list: D002614:Chelating Agents; D008070:Lipopolysaccharides; D009942:Organometallic Compounds; D012459:Salicylates; C015715:bismuth subsalicylate; D004492:Edetic Acid; D001729:Bismuth