Efficacy of passive immunotherapy in experimental postsplenectomy sepsis due to Haemophilus influenzae type B

In an effort to develop a more effective therapy for postsplenectomy sepsis, ceftriaxone and human intravenous immunoglobulin (IVIG), alone and in combination, were evaluated for their efficacy against experimental Haemophilus influenzae type B (Hib) bacteremia in splenectomized and sham-operated infant rats. Five-day-old animals had either a splenectomy or sham operation. At 12 days of age, they were challenged intraperitoneally with Hib. Fifteen hours later blood specimens were obtained for quantitative bacterial cultures, and immediately thereafter therapy was started with ceftriaxone, IVIG, combination of ceftriaxone and IVIG, or albumin (control). Quantitative blood cultures were repeated 24 and 48 hours after the treatment. Prior to the treatments, splenectomized animals had significantly higher bacterial counts in blood when compared with sham-operated animals (P < .001). Splenectomized animals receiving IVIG, ceftriaxone, or the combination of IVIG and ceftriaxone had significantly increased bacterial clearance from blood when compared with the controls (P < .01). In addition, animals treated with ceftriaxone or the combination of IVIG and ceftriaxone had significantly increased bacterial clearance compared with the IVIG alone treatment group (P < .01). Overall, the mortality was significantly higher in splenectomized animals compared with the sham-operated animals (P < .05). The control animals had significantly higher mortality compared with the IVIG, ceftriaxone, and combined ceftriaxone and IVIG treatment groups (P < .05). There were no detrimental effects of combining IVIG and ceftriaxone together.