GENETIC-TRANSFORMATION IN HAEMOPHILUS-PARAINFLUENZAE CLINICAL ISOLATES

Haemophilus parainfluenzae isolates recovered from patients with respi ratory diseases were studied for their ability to undergo genetic tran sformation by isogenic DNA. Two chromosomal markers, streptomycin resi stance and nalidixic acid resistance, were tested for transformation e fficiencies in H. parainfluenzae recipients from three biotypes. Most efficient in transformation was biotype II, followed by biotype I, whi le biotype III was nontransformable. Lack of transformation was not ow ing to poor donor activity of DNA, but to inability of the cells to de velop competence. Strains that formed clumps in liquid media were nont ransformable. Since the transformable biotype II is one of the prevale nt biotypes world wide, one can speculate that DNA transformation prob ably plays a major role in the spread of drug resistance in H. parainf luenzae.