DRUG SENSITIVITY OF HEMOPHILUS-SP AND TRANSFER OF RESISTANCE INTO

Abstract

From June 1973 to July 1976, 742 strains of H. influenzae and H. parainfluenzae, isolated from clinical specimens, were routinely tested for in vitro sensitivity to 12 antibiotics: penicillin, ampicillin, cephalothin, streptomycin, kanamycin, gentamicin, chloramphenicol, tetracycline, minocycline, erythromycin, sulfamethoxazole and trimethoprim. Of the strains, 61 were resistant to 1 or more of these antibiotics (ampicillin, kanamycin, chloramphenicol and tetracycline. The MICs [minimum inhibitory concentrations] of 23 antibiotics were determined by the agar dilution method on most of the resistant strains and on 60 sensitive strains isolates during the same period and considered as control. Of the strains, 21 transferred their resistance determinants into E. coli K12; 23 plasmids were obtained isolated from these strains ; 2 strains contained 2 different plasmids. Of the transconjugants, 90% were stable after repeated subcultures.