Attempted Transfer of Antibiotic Resistance between Bacteroides and Escherichia coli

Bene, Victor E. Del; Rogers, Mary; Farrar, W. Edmund

doi:10.1099/00221287-92-2-384

Cited by 6 publications

(1 citation statement)

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“…Systematic efforts to transfer well-characterized antibiotic resistance plasmids from Escherichia coli to Bacteroidesfragilis have been unsuccessful, despite the fact that the B. fragilis group of Gram-negative anaerobes contains the most numerous organisms in the human colon, where they are in close contact with E. coli (1)(2)(3). Transfer of drug resistance from Bacteroides to E. coli has been reported, but the plasmids involved have not been characterized and no further work with these strains has been published (4)(5)(6).…”

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Plasmid transfer from Escherichia coli to Bacteroides fragilis: differential expression of antibiotic resistance phenotypes.

Guiney¹,

Hasegawa²,

Davis³

1984

Proc. Natl. Acad. Sci. U.S.A.

122

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A unique shuttle plasmid, pDP1, has been constructed to mediate gene transfer between Escherichia coli and the Gram-negative anaerobe Bacteroides fragilis. pDP1 contains the pBR322 replicon and the Bacteroides clindamycin resistance plasmid pCP1 linked to the transfer origin of the broad host range plasmid RK2. pDP1 can be transferred from E. coli to B. fragilis by the RK2 conjugation system even though RK2 itself is not maintained in the Bacteroides recipients. The antibiotic resistance and replication functions of pDPl have been mapped by deletion analysis, and a 5-kilobase portion of the plasmid has been identified as the essential region for maintenance in Bacteroides. Comparison of the resistance conferred by pDPl on E. coli and B. fragilis shows that antibiotic resistance genes are expressed differently in aerobic and anaerobic bacteria. These results document the feasibility of gene transfer from E. coli to B. fragilis and demonstrate the usefulness of this conjugation system to study genetic structure and expression in Bacteroides.Studies of genetic exchange between aerobic and anaerobic bacteria have produced inconclusive results. Systematic efforts to transfer well-characterized antibiotic resistance plasmids from Escherichia coli to Bacteroidesfragilis have been unsuccessful, despite the fact that the B. fragilis group of Gram-negative anaerobes contains the most numerous organisms in the human colon, where they are in close contact with E. coli (1-3). Transfer of drug resistance from Bacteroides to E. coli has been reported, but the plasmids involved have not been characterized and no further work with these strains has been published (4-6). In an earlier study, we identified a large conjugative plasmid in Bacteroides ochraceus (subsequently renamed Capnocytophaga ochraceus) capable of transferring multiple antibiotic resistance to E. coli (7). However, this R plasmid could not be transferred into intestinal Bacteroides, a finding consistent with the subsequent classification of C. ochraceus as an oral microaerophilic organism, distinct from the strict anaerobes (2). Only one report has described transfer of antibiotic resistance from E. coli to Bacteroides, and the plasmid involved was not identified or characterized (8). We have tested plasmids from 14 different incompatibility groups in E. coli (IncA-C, B, FII, FIV, H, I, K, L, N, P, U, W, Y, and 9) for transfer to B. fragilis, but none could be detected in the Bacteroides recipients (3). We have concluded that there is a substantial barrier to plasmid transfer between E. coli and B. fragilis. This barrier could operate at the level of plasmid DNA transfer during conjugation, plasmid DNA replication in the new host, or the expression of antibiotic resistance genes in the Bacteroides recipient.To study this problem, we have constructed a unique shuttle vector to mediate gene transfer between E. coli and B. fragilis. This transfer system utilizes the conjugation functions of the broad host range plasmid RK2, a member of the P incompatibility...

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confidence: 99%