[Comparative study of the protective role of the vaccine against Haemophilus influenzae type b and partial splenectomy in an experimental model].

BACKGROUND

Although the vaccine against Haemophilus influenzae type b has demonstrated its efficacy in children, this bacteria continues to be a cause or overwhelming sepsis in splenetomized patients.

METHODS

To compare the degree of protection provided by partial splenectomy and the conjugated diptheria toxoid vaccine against H. influenzae type b, the bacteremia generated 24, 48 and 96 hours after intravenous inoculation with this bacteria at concentrations of 5 x 10(14), 5 x 10(13) and 5 x 10(12) colony-forming units was assessed in rats subjected to total splenectomy, with and without previous vaccination, to partial splenectomy or to sham operation.

RESULTS

With respect to both the proportion of positive blood cultures and the concentration of H. influenzae in the blood stream, the sham-operated control rats and those vaccinated prior to splenectomy presented similar behaviors; the widest differences with respect to the latter two groups were found in the nonvaccinated total splenectomy rats, and the results with the partial splenectomy group fell between these two extremes.

CONCLUSIONS

The protection of H. influenzae type b vaccine against infection is equivalent to that provided by the intact spleen for inoculum concentrations of 5 x 10(13) colony-forming units and less. Thus, the possibility of its systematic use in asplenic patients should be considered. The protection provided by the remnant spleen following 50% splenectomy is intermediate between those observed with eusplenia and with asplenia. These results suggest that when partial splenectomy is to be performed in normal spleen, the attempt should be made to conserve as much of the organ as possible.