Effect of Tetracycline on Transfer and Establishment of the Tetracycline-Inducible Conjugative Transposon Tn
            <i>916</i>
            in the Guts of Gnotobiotic Rats

Bahl, Martin Iain; Sørensen, Søren J.; Hansen, Lars Hestbjerg; Licht, Tine Rask

doi:10.1128/aem.70.2.758-764.2004

Cited by 59 publications

(39 citation statements)

References 41 publications

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“…Tn916 confers resistance to tetracycline in the host cell. The results obtained by using these strains were reported previously (2).…”

Section: Methodssupporting

confidence: 71%

“…1) indicates a homogeneous expression of gfp in all E. coli MC4100/pTGFP2 cells. Simultaneous colonization studies of two isogenic E. faecalis OG1 strains, one of which was tetracycline resistant, were performed with the animals used in the present study and were reported previously (2). The results of that study showed that the two isogenic E. faecalis strains were able to coexist in the intestines of rats receiving up to 50 g of tetracycline/ml of drinking water, which is well above the inhibitory concentration for the sensitive strain and suggests the existence of tetracycline-depleted microhabitats in the intestinal environment.…”

Section: Discussionmentioning

confidence: 99%

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In Vivo Detection and Quantification of Tetracycline by Use of a Whole-Cell Biosensor in the Rat Intestine

Bahl

Hansen

Licht

et al. 2004

Antimicrob Agents Chemother

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An Escherichia coli biosensor strain, harboring the plasmid pTGFP2, was introduced into the gastrointestinal tract of gnotobiotic rats that continuously received drinking water containing tetracycline. Plasmid pTGFP2 contains a transcriptional fusion between a green fluorescent protein (GFP) gene and a tetracyclineregulated promoter and was shown to produce a proportional GFP signal in response to exposure to various tetracycline concentrations when harbored by an E. coli strain. The plasmid was highly unstable in the host bacteria colonizing the intestinal system of the animals, and rapid plasmid loss was observed. Reintroduction of the E. coli MC4100/pTGFP2 strain into animals already colonized by the plasmid-free E. coli strain the day before euthanasia made it possible to extract and analyze the biosensors from intestinal samples. The induction of GFP in the biosensor cells extracted from the animals was estimated on a single-cell basis by use of flow cytometry, and the mean induction of GFP in the samples was compared to a standard curve prepared from known tetracycline concentrations. The results showed that the bioavailable tetracycline concentration within the bacterial growth habitat of the intestine was proportional to the concentration of tetracycline in drinking water but represented only approximately 0.4% of the intake concentration. This is a significant finding which will help to clarify antimicrobial therapy in the intestinal environment.Since their discovery in the 1940s, tetracyclines have been very useful antibiotics for the treatment of a whole range of bacterial infections in humans and animals and have also seen widespread use as growth promoters in animal husbandry (5). However, the emergence and characterization of some 36 different genes (17) conveying tetracycline or oxytetracycline resistance to the host bacteria by a number of different mechanisms have raised some concerns regarding the future usefulness of the tetracyclines. It is believed that subinhibitory concentrations of tetracycline have a positive selective effect on the dissemination and accumulation of tetracycline resistance genes in bacteria colonizing the gastrointestinal tract of mammals. This belief is based partly on molecular evidence, which indicates the tetracycline-induced transfer of mobile elements containing tetracycline resistance determinants (4), and partly on the observed increase in prevalence of various resistance determinants after therapeutic or prophylactic treatment with the drug (3, 9). To investigate this effect further it is important to be able to determine the actual in situ bioavailable concentration of the antibiotic in the microhabitats hosting bacterial activity. The traditional methods for measuring in situ antibiotic concentrations are based on an extraction of the compound from its natural matrix, followed by analysis by either chromatographic methods, such as high-pressure liquid chromatography (19), microbiological methods, such as bacterial inhibition assays (15), or in vitro biosensor ...

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“…Tn916 confers resistance to tetracycline in the host cell. The results obtained by using these strains were reported previously (2).…”

Section: Methodssupporting

confidence: 71%

Section: Discussionmentioning

confidence: 99%

In Vivo Detection and Quantification of Tetracycline by Use of a Whole-Cell Biosensor in the Rat Intestine

Bahl

Hansen

Licht

et al. 2004

Antimicrob Agents Chemother

Self Cite

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“…Thus, in our studies, in vivo conjugal transfer of the tet(M) gene from L. lactis donor strains was also observed. In other studies, no secondary conjugal transfer from transconjugants was detected (5,29). The subtherapeutic administration of tetracycline to rats was intended to promote the spread of antibiotic resistance genes, as this effect has been reported earlier (5,34,47).…”

Section: Discussionmentioning

confidence: 99%

Intra- and Interspecies Conjugal Transfer of Tn 916 -Like Elements from Lactococcus lactis In Vitro and In Vivo

Bogusławska

Zycka-Krzesinska

Wilcks

et al. 2009

Appl Environ Microbiol

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Tetracycline-resistant Lactococcus lactis strains originally isolated from Polish raw milk were analyzed for the ability to transfer their antibiotic resistance genes in vitro, using filter mating experiments, and in vivo, using germfree rats. Four of six analyzed L. lactis isolates were able to transfer tetracycline resistance determinants in vitro to L. lactis Bu2-60, at frequencies ranging from 10 ؊5 to 10 ؊7 transconjugants per recipient. Three of these four strains could also transfer resistance in vitro to Enterococcus faecalis JH2-2, whereas no transfer to Bacillus subtilis YBE01, Pseudomonas putida KT2442, Agrobacterium tumefaciens UBAPF2, or Escherichia coli JE2571 was observed. Rats were initially inoculated with the recipient E. faecalis strain JH2-2, and after a week, the L. lactis IBB477 and IBB487 donor strains were introduced. The first transconjugants were detected in fecal samples 3 days after introduction of the donors. A subtherapeutic concentration of tetracycline did not have any significant effect on the number of transconjugants, but transconjugants were observed earlier in animals dosed with this antibiotic. Molecular analysis of in vivo transconjugants containing the tet(M) gene showed that this gene was identical to tet(M) localized on the conjugative transposon Tn916. Primer-specific PCR confirmed that the Tn916 transposon was complete in all analyzed transconjugants and donors. This is the first study showing in vivo transfer of a Tn916-like antibiotic resistance transposon from L. lactis to E. faecalis. These data suggest that in certain cases food lactococci might be involved in the spread of antibiotic resistance genes to other lactic acid bacteria.

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“…Chee-Sanford et al 8) also suggested that the fact that several species of Enterococcus possessed the same allele of tet(M) indicated the likelihood of the transfer of tet(M) among species. Although we did not measure the concentration of OTC in this study, Baul et al 4) demonstrated that low concentrations of tetracycline promote the transfer of tet(M) mediated by Tn916. The administered drug may not only apply selective pressure to retain the resistance gene but also may force the transfer of the resistance gene in the aquaculture environment.…”

Section: Discussionmentioning

confidence: 99%

Distribution of Tetracycline Resistance Gene, tet(M), in Gram-Positive and Gram-Negative Bacteria Isolated from Sediment and Seawater at a Coastal Aquaculture Site in Japan

2007

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We found increased numbers of oxytetracycline (OTC)-resistant bacteria in sediment and seawater around a marine aquaculture site after OTC therapy. Samples were collected at an aquaculture site along the coast of the Seto Inland Sea, Japan in 2004. In April, the percentage of bacteria resistant to 60 µg mL −1 OTC in the surface sediment was 6.8%-20.0%. The percentages increased during OTC therapy in the summer reaching 53.3%-60.7% in September. Ninety-two days after drug cessation, the percentages decreased to below 22.9%. Tet(M)-positive bacteria were detected in the sediment and seawater samples. Tet(M) was evident in both Gram-positive and Gram-negative bacteria from various genera, and was newly identified in Paenibacillus, Sporosarcina, Shewanella, and Pseudoalteromonas. The dominant tet(M)-positive isolates were strains of Vibrio suggesting that this genus is an important reservoir for tet(M) in the marine environment. Two different alleles were found, tet(M)-A and tet(M)-B, each in isolates from five genera. The data suggests drug therapy used in the aquaculture acted as a selective pressure promoting increased numbers of resistant bacteria.

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Effect of Tetracycline on Transfer and Establishment of the Tetracycline-Inducible Conjugative Transposon Tn 916 in the Guts of Gnotobiotic Rats

Cited by 59 publications

References 41 publications

In Vivo Detection and Quantification of Tetracycline by Use of a Whole-Cell Biosensor in the Rat Intestine

In Vivo Detection and Quantification of Tetracycline by Use of a Whole-Cell Biosensor in the Rat Intestine

Intra- and Interspecies Conjugal Transfer of Tn 916 -Like Elements from Lactococcus lactis In Vitro and In Vivo

Distribution of Tetracycline Resistance Gene, tet(M), in Gram-Positive and Gram-Negative Bacteria Isolated from Sediment and Seawater at a Coastal Aquaculture Site in Japan

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