Transfer of Infectious Drug Resistance in Microbially Defined Mice

Reed, Norman D.; Sieckmann, Donna G.; Georgi, Carl E.

doi:10.1128/jb.100.1.22-26.1969

Cited by 22 publications

(6 citation statements)

References 19 publications

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“…The in vivo transfer of the R factor ROR-1 to theX820 recipient is in agreement with the results reported by Reed et al (28) and Salzman and Klemm (30). R factor-containing clones ofX820 were detected within 6 hr after the addition of the donor strain M7-18, after which time the proportion of Tcr X820 clones slowly increased in the recipient population.…”

Section: Discussionsupporting

confidence: 91%

Genetic Exchange Between Escherichia coli Strains in the Mouse Intestine

Jones

Curtiss

1970

J Bacteriol

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Germ-free mice contaminated with selected Escherichia coli strains were used for experiments designed to demonstrate gene transfer and recombinant formation in vivo. The well-characterized conjugation system of E. coli K-12 was examined in these experiments. Contamination of germ-free mice with a polyauxotrophic Fstrain followed by the addition of isogenic Hfr, F', or F+ strains resulted in the appearance of all recombinant classes at frequencies that would be expected from an in vitro mating experiment. Inheritance of unselected donor markers occurred at frequencies that were dependent on linkage relationships established in experiments in vitro. The presence of Lactobacillus had no influence on gene transfer and recombinant formation in an F' x Fin vivo mating. The R factor ROR-1 was transferred from E. coli strain M7-18 to an E. coli F-strain in the mouse intestine.

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Section: Discussionsupporting

confidence: 91%

Genetic Exchange Between Escherichia coli Strains in the Mouse Intestine

Jones

Curtiss

1970

J Bacteriol

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“…It is generally agreed that plasmid transfer occurs readily in the gut of gnotobiotic animals which harbor only the donor and recipient bacteria involved in the reaction, but no indigenous microflora (9,22,34,36,37,47), or in newborn or very young animals in which an indigenous microflora is either absent (46) or is not well developed (40). In contrast, plasmid transfer in the gut of weaned animals or of adult humans could be demonstrated, if at all, only at extremely low rates.…”

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confidence: 99%

Experimental and Mathematical Models of Escherichia coli Plasmid Transfer In Vitro and In Vivo

1983

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Little is known about the factors that govern plasmid transfers in natural ecosystems such as the gut. The consistent finding by earlier workers that plasmid transfer in the normal gut can be detected only at very low rates, if at all, has given rise to numerous speculations concerning the presence in vivo of various inhibitors of plasmid transfer. Plasmids Rl, Rldrd-19, and pBR322 were studied in Escherichia coli K-12 and wild-type E. coli hosts in two experimental systems: (i) gnotobiotic mice carrying a synthetic indigenous microflora (F-strains) which resemble in their function the normal indigenous microflora of the mouse large intestine, and (ii) anaerobic continuous-flow cultures of indigenous large intestinal microflora of the mouse, which can simulate bacterial interactions observed in the mouse gut. Mathematical models were developed to estimate plasmid transfer rates as a measure of the "fertility," i.e., of the intrinsic ability to transfer the plasmid under the environmental conditions of the gut. The models also evaluate the effects of plasmid segregation, reduction of the growth rates of plasmidbearing bacterial hosts, repression of transfer functions, competition for nutrients, and bacterial attachment to the wall of the gut or culture vessel. Some confidence in the validity of these mathematical models was gained because they were able to reproduce a number of known phenomena such as the repression offertility of the Rl plasmid, as well as known differences in the transmission and mobilization of the plasmids studied. Interpretation of the data obtained permitted a number of conclusions, some of which were rather unexpected. (i) Fertility of plasmidbearing E. coli in the normal intestine was not impaired. The observed low rates of plasmid transfer in the normal gut can be explained on quantitative grounds alone and do not require hypothetical inhibitory mechanisms. (ii) Conditions for longterm spread and maintenance throughout human or animal populations of a diversity of conjugative and nonconjugative plasmids may be optimal among E. coli strains of low fertility, as are found among wild-type strains. (iii) E. coli strains carrying plasmid pBR322 plus Rldrd-19 were impaired in their ability to transfer Rldrd-19, but strains carrying pBR322 were significantly better recipients of Rldrd-19 than a plasmid-free recipient E. coli. (iv) Long-term coexistence of. plasmid-bearing and plasmid-free E. coli, in spite of undiminished fertility, appeared to be due to a detrimental effect of the plasmid on the growth rate of its host bacterium, rather than due to high rates of plasmid segregation. (v) Mathematical analysis of experimental data published by earlier investigators is consistent with the conclusion that plasmid transfer occurs consistently in the human gut, but that the resulting transconjugant E. coli populations are too small to be detected regularly with the culture methods used by earlier investigators. It is concluded that the long-term interactions observed were often the consequences of mi...

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“…Thus, the importance of R+ E. coli as a reservoir of resistance determinants which can be transferred to pathogenic bacteria has not been established. However, early studies in Japan, reviewed by Watanabe (17), demonstrated the transfer of multiple drug resistance in vivo in human volunteers and dogs, and recent studies in microbially defined animals (7,9) have clearly shown that R factor transfer can occur in vivo.…”

Section: Discussionmentioning

confidence: 99%

Transferable Drug Resistance Among Enterobacteriaceae Isolated from Cases of Neonatal Diarrhea in Calves and Piglets

Aden¹,

Reed²,

Underdahl³

et al. 1969

Applied Microbiology

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Fecal specimens were collected on 22 different Nebraska ranches and at the Department of Veterinary Science from young calves and pigs with neonatal diarrhea. Enxterobacteriaceae isolated from these fecal specimens were screened for resistance to tetracycline, streptomycin, sulfamethizole, kanamycin, chloramphenicol, colistin, nitrofurantoin, and nalidixic acid. Of the 92 strains studied, 57 were resistant to one or more of these antimicrobial agents. Resistant strains were obtained from all herds involved in the study. The two most common resistance patterns were tetracycline streptomycin sulfamethizole (22 of 57) and tetracycline (13 of 57). None of the strains were resistant to chloramphenicol, colistin, nitrofurantoin, or nalidixic acid. The 57 resistant strains were studied to determine whether the resistance was transferable. Forty-three of the 57 resistant strains could transfer part or all of their resistance pattern to a drug-sensitive recipient. The 43 R+ strains were obtained from 17 of the 23 herds studied. Considerable variation was observed between different R+ strains in the frequency of transfer of resistance to a particular drug. In addition, variation in the frequency of transfer of different resistance determinants in individual R+ strains was noted.

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Transfer of Infectious Drug Resistance in Microbially Defined Mice

Cited by 22 publications

References 19 publications

Genetic Exchange Between Escherichia coli Strains in the Mouse Intestine

Genetic Exchange Between Escherichia coli Strains in the Mouse Intestine

Experimental and Mathematical Models of Escherichia coli Plasmid Transfer In Vitro and In Vivo

Transferable Drug Resistance Among Enterobacteriaceae Isolated from Cases of Neonatal Diarrhea in Calves and Piglets

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