Transfer of beta-lactamase plasmids from Neisseria gonorrhoeae to Neisseria meningitidis and commensal Neisseria species by the 25.2-megadalton conjugative plasmid

Abstract

Two highly tetracycline-resistant, ,-lactamase-producing Neisseria gonorrhoeae strains were used as donors for conjugation with Neisseria meningitidis and commensal Neisseria species. We found that both strains were able to transfer the 4.4-and 3.2-megadalton ,-lactamase plasmids to the recipients tested, with frequencies between 10-' and 10-9.The gonococcal P-lactamase plasmids were first described in 1977 (19). Since that time, they have become endemic in North America, and they are common in other parts of the world (4, 8). They can be mobilized by the 24.5-megadalton (MDa) indigenous conjugative gonococcal plasmid, conjugative Haemophilus plasmids, and enteric plasmids (9,10,14,15,19). The 3.2-MDa 3-lactamase plasmid has also been associated with strains of Haemophilus ducreyi and urogenital Haemophilus parainfluenzae (1, 13). In contrast, the ,-lactamase plasmid was maintained in only a few strains of Neisseriaflava, Neisseria cinerea, Neisseria subflava, Neisseria mucosa, and N. subflava-N. sicca but not in strains of Neisseria meningitidis under laboratory conditions (8). Two reports (5, 16) indicated that ,-lactamase-producing N. meningitidis can be isolated, but this is a rare event. More recently, Ikeda et al. (10) found that 3 of 20 Neisseria gonorrhoeae strains (15%) carrying the 24.5-and 4.4-MDa plasmids mobilized the ,B-lactamase plasmid to N. meningitidis strains. In contrast, the 24.5-MDa gonococcal conjugative plasmid that mobilizes the P-lactamase plasmids has a narrow host range.The recent identification of the 25.2-MDa tetracycline plasmid in clinical isolates of N. gonorrhoeae, N. meningitidis, Kingella denitrificans, and Eikenella corrodens led to renewed concerns about the spread of the P-lactamase plasmids to N. meningitidis (11,15,20). Unlike the ancestral 24.5-MDa plasmid (8) occurring strains exist that carry the 25.2-and 4.4-MDa plasmids. Therefore, we created one by transferring a 25.2-MDa plasmid into a Proto/IB-3 recipient which carried the 4.4-MDa 3-lactamase and 2.6-MDa cryptic plasmids (CDC6). Both donors were naturally streptomycin resistant.The donor and recipient strains were grown in supplemented GCK broth for 4 h to a concentration of 108 CFU/mI, as previously described (19). Matings were performed by the filter-mating technique (19). Transconjugants were selected on GCK agar (Difco Laboratories, Detroit, Mich.) supplemented with rifampin (1 ,ug/ml) alone; rifampin (1 j,g/ml) and penicillin (10 ,ug/ml); rifampin (1 ,ug/ml) and tetracycline (10 jig/ml); or rifampin (1 jig/ml), penicillin (10 ,ug/ml), and tetracycline (10 ,ig/ml). Plates were incubated at 36.5°C in 4% CO2 and examined for the growth of the transconjugants at 24 and 48 h. The colonies that grew on the antibioticcontaining media were scored for nalidixic acid resistance. Colonies that were resistant to nalidixic acid and rifampin were considered to be true transconjugants.To verify the plasmid content of the transconjugants, selected isolates were screened by agarose gel electrophoresis, and plasmid profiles ...

Plasmid-mediated Tet M in Haemophilus ducreyi

“…Thus, plasmid pMR9418 is similar to other conjugative Haemophilus R plasmids in this characteristic and differs from the cryptic H. ducreyi conjugative plasmid described previously (7). This, along with the fact the 25.2-MDa plasmid retained its ability to mobilize 13-lactamase plasmids (25,26), suggests that the ancestor of pMR9418 may not be the cryptic H. ducreyi plasmid described previously, but more work is needed to confirm this hypothesis.…”

Plasmids of Neisseria gonorrhoeae and other Neisseria species

“…In all cases, the ,B-lactamase plasmid was associated with the 25.2-MDa plasmids in the transconjugants. We found that the N. cinerea transconjugants were exceptions to this generalization because when they were used as recipients, the ,-lactamase plasmids were found without the 25.2-MDa plasmids (36). Recently, P-lactamaseproducing N. meningitidis strains have been described (3,9).…”

“…When introduced into the commensal Neisseria spp., the P-lactamase plasmids were very unstable and were quickly lost from most of the recipient strains. In a later study, Ikeda et al (21) Recently, using strains containing both the P-lactamase plasmid and the 25.2-MDa tetracycline resistance conjugative plasmid, we mobilized the 4.4-and 3.2-MDa P-lactamase plasmids into a variety of Neisseria spp., including N. meningitidis (36). A number of the transconjugants maintained the P-lactamase plasmids in the absence of selective antibiotic pressure.…”

Neisseria meningitidis: an overview of the carriage state

“…A plasmid containing the resistance gene to tetracycline, tetM, identified in N. gonorrhoeae, has shown the capability to be transferred in vitro to N. meningitidis (Roberts & Knapp, 1988). Since both species can occasionally co-exist in the genitourinary tract or in the nasopharynx, it has been speculated that transfer of resistance plasmids may also occur in vivo (Dillon et al, 1983).…”