FIG 6.

K1 capsule polysaccharide protected A. baumannii from complement-mediated bacterial killing in human ascites. AB307.30 (capsule negative) was rapidly killed in 100% human ascites fluid compared to its wild-type parent, AB307-0294. Preincubation with anti-OmpA MAb 7D4 did not enhance complement-mediated bactericidal activity against both AB307-0294 (wt; K1 capsule positive) and AB307.30 (capsule negative) in 100% human ascites fluid. Opsonization with anti-K1 capsule MAb 13D6 also did not augment the bactericidal activity of human ascites. n = 3. ****, P < 0.0001 (two-way ANOVA). The data are presented as means ± standard deviations.