Dataset Information

A transferable 20-kilobase multiple drug resistance-conferring R plasmid (pKL0018) from a fish pathogen (Lactococcus garvieae) is highly homologous to a conjugative multiple drug resistance-conferring enterococcal plasmid.

ABSTRACT: Lactococcus garvieae, the causative agent of lactococcosis, has evolved strains that are highly resistant to antibiotics. Here, the 20,034-bp sequence of L. garvieae conjugative plasmid pKL0018 was determined. It contained two ermB genes and one tetS gene and a backbone more than 96% identical to that of pRE25, an Enterococcus faecalis plasmid from dry sausage.

SUBMITTER: Maki T

PROVIDER: S-EPMC2681645 | biostudies-literature | 2009 May

REPOSITORIES: biostudies-literature

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A transferable 20-kilobase multiple drug resistance-conferring R plasmid (pKL0018) from a fish pathogen (Lactococcus garvieae) is highly homologous to a conjugative multiple drug resistance-conferring enterococcal plasmid.

Maki Takeshi T Santos Mudjekeewis D MD Kondo Hidehiro H Hirono Ikuo I Aoki Takashi T

Applied and environmental microbiology 20090213 10

Lactococcus garvieae, the causative agent of lactococcosis, has evolved strains that are highly resistant to antibiotics. Here, the 20,034-bp sequence of L. garvieae conjugative plasmid pKL0018 was determined. It contained two ermB genes and one tetS gene and a backbone more than 96% identical to that of pRE25, an Enterococcus faecalis plasmid from dry sausage. ...[more]

PMID: 19218406

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Project description:UnlabelledEnterococcus faecalis, a common causative agent of hospital-acquired infections, is resistant to many known antibiotics. Its ability to acquire and transfer resistance genes and virulence determinants through conjugative plasmids poses a serious concern for public health. In some cases, induction of transfer of E. faecalis plasmids results from peptide pheromones produced by plasmid-free recipient cells, which are sensed by the plasmid-bearing donor cells. These plasmids generally encode an inhibitory peptide that competes with the pheromone and suppresses self-induction of donors. We recently demonstrated that the inhibitor peptide encoded on plasmid pCF10 is part of a unique quorum-sensing system in which it functions as a "self-sensing signal," reducing the response to the pheromone in a density-dependent fashion. Based on the similarities between regulatory features controlling conjugation in pAD1 and pAM373 and those controlling conjugation in pCF10, we hypothesized that these plasmids are likely to exhibit similar quorum-sensing behaviors. Experimental findings indicate that for both pAD1 and pAM373, high donor densities indeed resulted in decreased induction of the conjugation operon and reduced conjugation frequencies. This effect was restored by the addition of exogenous inhibitor, confirming that the inhibitor serves as an indicator for donor density. Donor density also affects cross-species conjugative plasmid transfer. Based on our experimental results, we propose models for induction and shutdown of the conjugation operon in pAD1 and pAM373.ImportanceEnterococcus faecalis is a leading cause of hospital-acquired infections. Its ability to transfer antibiotic resistance and virulence determinants by sharing its genetic material with other bacteria through direct cell-cell contact via conjugation poses a serious threat. Two antagonistic signaling peptides control the transfer of plasmids pAD1 and pAM373: a peptide pheromone produced by plasmid-free recipients triggers the conjugative transfer in plasmid-containing donors, and an inhibitor peptide encoded on the plasmid and produced by donor cells serves to modulate the donor response in accordance with the relative abundance of donors and recipients. We demonstrate that high donor density reduces the conjugation frequency of both of these plasmids, which is a consequence of increased inhibitor concentration in high-donor-density cultures. While most antibiotic strategies end up selecting resistant strains and disrupting the community balance, manipulating bacterial signaling mechanisms can serve as an alternate strategy to prevent the spread of antibiotic resistance.

Project description:The appearance of transferable oxazolidinone resistance genes poses a major challenge to public health and environmental safety. These genes not only lead pathogenic bacteria to become resistant to linezolid but also reduce sensitivity to florfenicol, which is widely used in the veterinary field. To verify the dissemination of oxazolidinone resistance genes in enterococcal isolates from pigs at different production stages in a swine farm in China, we collected 355 enterococcal isolates that were resistant to florfenicol from 600 (150 per stage) fresh fecal swabs collected from a swine farm. Through initial PCR screening and whole-genome sequencing, 175 isolates harboring different oxazolidinone resistance genes were identified. All isolates carried the optrA gene. A total of 161 (92%, 161/175) isolates carried only the optrA gene. Three (1.71%, 3/175) isolates carried both the optrA and poxtA genes, and 11 (3.1%, 11/175) isolates contained the optrA gene and poxtA2 and cfr(D) variants. A total of 175 isolates that harbored oxazolidinone resistance genes included 161 E. faecalis, 6 E. faecium, and 8 E. hirae. By sequencing the whole genomes, we found that the 161 isolates of E. faecalis belonged to 28 different STs, including 8 new STs, and the 6 isolates of E. faecium belonged to four different STs, including one new ST. The phylogenetic tree based on SNPs of the core genome showed that both clonal spread and horizontal transfer mediated the diffusion of oxazolidone resistance genes in enterococcal isolates at specific stages in pig farms. Moreover, enterococcal isolates carrying oxazolidone resistance genes could spread from breeding pigs to fattening pigs, while transferable oxazolidone resistance genes in enterococcal isolates could persist on a pig farm throughout all production stages. Representative enterococcal isolates with different oxazolidinone resistance genes were further studied through Nanopore sequencing. We identified a novel plasmid, pM4-80 L4 (15,008 bp), carrying the poxtA2 and cfr(D) genes in enterococcal isolates at different stages. We also found three different plasmids harboring the poxtA gene with high genetic variation, and all poxtA genes were flanked by two copies of IS1216E elements. In addition, four genetically distinct plasmids carrying the optrA gene were identified, and Tn554 was found to mediate chromosome-localized optrA gene transfer. Our study highlighted that transferable oxazolidinone resistance genes in enterococcal isolates could persist throughout all production stages on a pig farm, and the prevalence and dissemination of oxazolidinone resistance genes in enterococcal isolates from animal farms should be continually monitored.

Dataset Information

A transferable 20-kilobase multiple drug resistance-conferring R plasmid (pKL0018) from a fish pathogen (Lactococcus garvieae) is highly homologous to a conjugative multiple drug resistance-conferring enterococcal plasmid.

Publications

A transferable 20-kilobase multiple drug resistance-conferring R plasmid (pKL0018) from a fish pathogen (Lactococcus garvieae) is highly homologous to a conjugative multiple drug resistance-conferring enterococcal plasmid.

Similar Datasets

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