Intergeneric Transfer of a β-Lactamase Gene between Ps. aeruginosa and E. coli

THE transfer of antibiotic resistance genes between strains of enteric bacteria by cell-to-cell contact was first detected 1 in 1959, and much effort has now been directed towards the understanding of this genetic process, particularly in relation to the ecology of man and his domestic animals 2–4 . It is now clear that the problems raised by this phenomenon are world-wide, and the recent publication of the Swann report 5 , with its recommendations for the restriction in the use of antibiotics in animal husbandry, has also underlined many gaps in our knowledge. One of these is undoubtedly an understanding of the range of bacterial species that can accept antibiotic resistance genes by cell-to-cell contact and harbour the R -factors involved. We report here that antibiotic resistance markers, particularly for resistance to carbenicillin, can be transferred freely between strains of Pseudomonas aeruginosa isolated from burns, and various enteric bacteria.