[Interpretation of the influence of immunoglobulins and glycine on bacterial sensitivity to antibiotics in vitro].

The effect of human immunoglobulins (Ig) and of glycine, often added to commercial preparations as a stabilizer, have been examined in vitro on the growth of E. coli strains in the absence or presence of antibiotics in subminimal inhibitory concentrations (subMic). The Ig's (= 7S or 5S = F(ab')2 as well as glycine had no effect by themselves on bacterial growth at concentrations up to 32 mg and 4.5 mg per ml respectively. In contrast, in the presence of ampicillin, glycine induced a concentration dependent increase of bacterial sensitivity to antibiotics. This is apparently more pronounced in serosensitive than in seroresistant E. coli strains. Such a synergism could equally be shown with cefadroxil and fosfomycin, i.e. with other antibiotics interacting with cell wall synthesis, but not with those of another mode of action, as ciprofloxacin, polymyxin B or chloramphenicol.