Transfer of Plasmid-Borne Beta-Lactamase in Neisseria gonorrhoeae

Abstract

Neisseria gonorrhoeae strain GC82 contains a plasmid specifying a 8-lactamase (,3-Lam+}. Mixed incubation of strain GC82 with a penicillin-susceptible (X-Lam-), streptomycin-resistant mutant of strain GC9 results in the expression of f8-lactamase activity and streptomycin resistance in the transcipients. The frequency of transfer of the plasmid-specified resistance to penicillin seems to be proportional to the initial input ratio of the mating mixture of donor to recipient and to correlate positively with bacterial density. Cell-to-cell transmission of the deoxyribonucleic acid (DNA) appears to be by a conjugal mechanism or, alternatively, by an as yet undescribed transducing phage. Additionally, whole-cell DNA from a f8-lactamase-producing strain could be used to transform streptomycin-resistant recipients, resulting in the expression of both 8-lactamase activity and streptomycin resistance in the transformants, and purified gonococcal plasmid DNA transformed Escherichia coli but not the gonococcus. Circular DNA extracted from donor GC82 comprised three molecular species (approximately 2.7, 4.8, and 25 megadaltons [Mdal]), whereas the recipients GC9-S (Ste) contained only the 2.7-Mdal cryptic DNA species. DNA from the GC9-S82 (StrW, ,8-Lam+) transcipient contained a 4.8-Mdal species in addition to the cryptic molecular species (2.7 Mdal). The finding that the transcipient will not retransfer f8-lactamase is consistent with the hypothesis that the 25-Mdal plasmid promotes mobilization of the smaller 4.8-Mdal R plasmid.Although Neisseria gonorrhoeae has been traditionally thought of as a susceptible organism, the occurrence of gonococcal strains that are relatively resistant to penicillin and other antibiotics has gradually become an important clinical problem during the past 15 years, necessitating the use of elevated dosages of penicillin. It should be noted that there have been recent indications that the minimal inhibitory concentration (MIC) for penicillin of clinical isolates has decreased somewhat (24, 31).Resistance to penicillin in bacteria is frequently associated with the presence of 18-lactamase. The literature on 83-lactamase in gramnegative bacteria has been reviewed extensively (33). A number of these resistances have been specified by R plasmids. Previously, no /8-lactamase has been reported in N. gonorrhoeae, and resistance of the gonococcus was occasioned by a change in the binding site for penicillin (34). In the last several years the isolation of /3-lactamase-producing strains ofN. gonorrhoeae has been reported (1,2,5,28,30). Recent reports have indicated the presence of plasmid-specified, /8-lactamase-containing gonococci presumably associated with very high levels of resistance in these strains (13) and conjugal transfer of the gonococcal /8-lactamase plasmid (12).Evidence for plasmid deoxyribonucleic acid (DNA) in N. gonorrhoeae strain 2686 type 1 has been presented by Engelkirk and Schoenhard (14) and Maness and Sparling (24). The presence of plasmid DNA in each of the colonial types of...

Antibiotic Susceptibility of Beta-Lactamase-Producing Strains of Branhamella ( Neisseria ) catarrhalis

“…The first procedure was essentially as described by Baron et al (2). In the second technique, a modification of the Hirt lysis procedure was employed (7).…”

Plasmid-Mediated Ampicillin Resistance in Haemophilus ducreyi

“…Three strains were resistant to ampicillin (minimal inhibitory concentration > 128 ,ug/ml) and produced /8-lactamase as determined by hydrolysis of a chromogenic cephalosporin (23). Since plasmid-mediated 83-lactamase production had been documented in Haemophilus influenzae (10) and Neisseria gonorrhoeae (2,11,26), we wondered if f8-lactamase production might also be plasmid mediated in H. ducreyi and whether there might be any relationship between such a plasmid and the previously characterized plasmids of N. gonorrhoeae and H. influenzae.…”

The Role of the Transcription Factors MtrR and MtrA in the Fitness of the Pathogen Neisseria gonorrhoeae

“…To date,~-lactamase is the most potent mechanism of penicillin resistance in N. gonorrhoeae, and it increases the MIC of strains 16-fold (13,95,155).…”

“…Members of the MFS family of bacterial efflux pumps are identified by [12][13][14] transmembrane spanning regions within the large protein that makes up the pump.…”