Transfer of beta-lactamase plasmids by conjugation in Neisseria gonorrhoeae

Conjugation experiments in vitro have been used in an attempt to explain certain epidemiological phenomena seen amongst penicillinase producing Neisseria gonorrhoeae (PPNG) isolated at St Mary's Hospital, London. These include changes in plasmid profiles, a lack of beta-lactamase encoding plasmids in PAOU-requiring strains and a difference in the serological classification of strains of PPNG and non-PPNG isolated from the same clinic. It was shown that acquisition of the conjugative plasmid by beta-lactamase producing transconjugants does vary, but is not related to the auxotype/serovar (A/S) class of, or type of beta-lactamase plasmid carried by the donor. It was not possible to transfer either the 3.2MDa or 4.4MDa plasmids to PAOU-requiring strains of N gonorrhoeae. The conjugation frequency from a single donor to different recipients was shown to be variable, but was not influenced by the serovar of the recipients. It was shown that the transfer and acceptance of beta-lactamase encoding plasmids is variable but it was not possible to identify the factors responsible.