A MOLECULAR ANALYSIS OF GREEK AND UK HAEMOPHILUS-INFLUENZAE CONJUGATIVE RESISTANCE PLASMIDS

Antibiotic resistance in Haemophilus influenzae has been associated wi th the presence of large, chromosomally integrated, conjugative plasmi ds. The plasmids of 10 beta-lactamase-positive, ampicillin-resistant s trains, two from the UK and eight from Greece, were investigated. Plas mids were detected and isolated after transfer to a rec-deficient reci pient. Purified whole plasmid was used as probe. In addition a 12 kb P stI fragment containing the putative point of recircularization in one plasmid, p1056, was cloned and used as a probe. All plasmids shared a high degree of sequence homology suggesting that plasmids of diverse geographical origin are highly related. All plasmids also shared seque nce homology with the 12 kb Pstl fragment containing the point of reci rcularization, suggesting that the sequences involved in excision and recircularization are conserved.