| Abstract: | From June 1973 to July 1976, 742 strains of Haemophilus influenzae and parainfluenzae, isolated from clinical specimens, were routinely tested for in vitro sensitivity to twelve antibiotics: penicillin, ampicillin, cephalothin, streptomycin, kanamycin, gentamicin, chloramphenicol, tetracyclin, minocyclin, erythromycin, sulfamethoxazol, trimethoprim. 61 strains were found resistant to one or more of these antibiotics (ampicillin, kanamycin, chloramphenicol and tetracyclin). The MICs of 23 antibiotics were determined by the agar dilution method on most of the resistant strains and on 60 sensitive strains isolated during the same period and considered as control. 21 strains transferred their resistance determinants into E. coli K12; 23 plasmids were obtained isolated from these strains: 2 strains contained two different plasmids. 90% of the transconjugants were stable after repeated subcultures. |
