The paradox of Hemophilus infuenzae type B bacteremia in the presence of serum bactericidal activity.

摘要: Abstract We investigated the role of serum bactericidal activity in Hemophiplus influenzae type b infections infants with meningitis and a rat model. In infected infants, 13/22 admission sera had against infecting strain, bacteremia was as frequent those (54%) without (56%). The coexistence reproduced studied experimentally weanling rats. Serum from such rats kills vitro 95% conventionally broth-grown bacteria within 10 min, but does not kill organisms obtained animals. Thus determined for H. may have no relevance vivo, Incubation normal 30 min at 37 degrees C produces resistance like that vivo organisms. This phenotypic conversion depends on factors are molecular weight less than 1,000, stable to 100 C, destroyed by ashing. When injected intravenously into nonimmune animals, quickly cleared, while serum-preincubated not. latter, however, cleared when bacteremic (half-life min). Bacteremia persist despite this capacity clearance because entering blood extravascular fluids, which contain greater 90% total bacterial burden.