STUDY ON THE BACTERICIDAL ACTIVITY AND SYNERGISTIC EFFECT OF NEUTROPENIC RAT SERUM WITH GENTAMICIN

It is well known that normal rat serum (NRS) shows an antibacterial ac tivity because of the presence of endogenous substances that are able to express a defence against pathogenic microorganisms. Moreover, in f ormer studies, we observed that NRS presents a synergistic activity wi th some antibiotics (thus able to lower minimum inhibitory concentrati on values). The aim of this research was to study the antibacterial ac tivity and synergistic effect of neutropenic rat sera (NPRS) with gent amicin. The animals were made neutropenic by the i.p. injection of cyc lophosphamide (100 mg/kg on day 0 and 75 mg on day 4). At all tested c oncentrations (from 0.25% to 5%) NPRS showed lower antibacterial activ ity than NRS with differences which were always statistically signific ant. The synergistic activity of NPRS with gentamicin was still presen t and quite similar to that of NRS, in spite of many altered blood par ameters showing evident immunodepression. Some possible interpretation s of these results are discussed.