Susceptibility of isolates ofAcinetobacter anitratusandAcinetobacter lwoffiito the bactericidal activity of normal human serum

The bactericidal activity of normal human serum against the Gram-negative coccobacilli Acinetobacter anitratus and Acinetobacter lwoffii was studied; 12% and 84%, respectively, of the tested strains appeared to be sensitive. Thus, serum resistance may be an important factor contributing to the pathogenic potential of A. anitratus strains. Three types of bactericidal action were shown. In the first, the strains were killed when the alternative complement pathway was activated. In the second, some strains required both the classical and alternative pathways. In the third variant, the strains needed either the alternative or classical activation pathway.