ABSENCE OF HEPATIC CLEARANCE OF HAEMOPHILUS INFLUENZAE TYPE B |[lpar]|Hib|[rpar]| In RATS

In situ perfusions of livers in adult rats were performed using non-piliated (NP) & mannose-resistant piliated (MR) Hib compared to E. coli K12 NP, MR, & mannose-sensitive piliated (MS) strains. Following infusion of organisms via the portal vein, effluent was collected from the inferior vena cava during infusion of 100 ml. tissue culture medium. Total colony counts in the effluent expressed as per cent of number of organisms infused (mean values are listed where more than 1 animal was tested) were: Hib NP, 158% (3 animals); Hib MR 170% (2 animals); E. coli NP, 16% (3 animals); E. coli MR, 11% (1 animal); E. coli MS, 10% (2 animals). Similar results were obtained when whole animals (infant rats) were studied with quantitative blood cultures over a 30 min. period following IV administration of organisms. Hib MR strains recovered following in situ hepatic perfusions remained adherent to buccal epithelial cells, whereas many isolates of Hib MR strains in the live animal studies lost their pili. Adult rat livers do not effectively clear Hib NP or MR strains in this model. Further studies are needed to define the mechanisms by which Hib pili are lost or suppressed during bacteremia.