Antibiotics, in addition to killing or inhibiting the growth of microorganisms, may also affect the mechanism of host defence in many ways. Such effects may be clinically relevant especially in the case where an impairment of immunological function can be seen. We, therefore, decided to study the influence of penicillin G, cefotaxim, ceftazidime, streptomycin, and lincomycin on the function of phagocytes by using the macrophage adherence assay and the macrophage spreading assay. We also followed the concentrations of neopterin and interferon gamma (IFN gamma) in the plasma of mice treated with the above mentioned antibiotics. Changes in adherence of peritoneal macrophages were seen in mice treated with therapeutic doses of penicillin G and cefotaxim, after 2 h of incubation. Cefotaxim and streptomycin in the usual therapeutic dose and ceftazidime in a fourfold higher dose influenced the capacity of peritoneal macrophages to spread on a glass surface. The same was seen with lincomycin when administered in the therapeutic dose and in a fourfold higher dose. In all the mice treated with antibiotics the concentration of IFN gamma was higher than in the control mice, while the reverse was seen concerning neopterin release, with an exception in mice treated with streptomycin.

Department of Microbiology Medical Faculty University of Rijeka Rijeka Croatia