Antimicrob Agents Chemother. 1981 Jun;19(6):997-1003.
Transferable tetracycline resistance in Clostridium difficile.

Smith CJ, Markowitz SM, Macrina FL.

The transfer of tetracycline resistance among strains of Clostridium difficile is described. Transfer occurred by a conjugation-like event that was insensitive to deoxyribonuclease, could not be mediated by donor culture filtrates or chloroform-treated donor cultures, and required cell-to-cell contact. Tetracycline-resistant progeny recovered from matings displayed a resistance phenotype identical to that of the donor in level of resistance, constitutive expression, and transmissibility. Although the original tetracycline-resistant donor contained 5 x 10(6)- and 22 x 10(6)-dalton plasmids, standard physical analyses of antibiotic-resistant transconjugants revealed no plasmid deoxyribonucleic acid molecules in common with the donor strain. Furthermore, tetracycline-susceptible derivatives of the original donor always possessed a plasmid complement identical to that of the resistant parental strain as determined by restriction endonuclease digestion analysis. The results indicate that the tetracycline resistance determinant(s) was not encoded by readily detectable plasmid deoxyribonucleic acid and may be chromosomally located.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=7271279&dopt=Abstract antibiotics, tetracycline




Appl Environ Microbiol. 1993 May;59(5):1467-72.
Detection of tetracycline resistance determinants in pig isolates from three herds with different histories of antimicrobial agent exposure.

Lee C, Langlois BE, Dawson KA.

Department of Agricultural Chemistry, National Taiwan University, Taipei, Republic of China.

A total of 114 gram-negative fecal isolates from domestic pigs in herds with different histories of antimicrobial agent exposure were screened for the presence of plasmid DNA and specific tetracycline resistance determinants. More than 84% of the isolates harbored plasmid DNA, which ranged in size from 2.1 to 186 kb. A total of 78 isolates (68.4%) were resistant to tetracycline at concentrations greater than 4 micrograms/ml. Plasmid DNAs from about 56% of the tetracycline-resistant isolates hybridized with DNA probes for class A, B, C, and D tetracycline resistance determinants. The class B determinant was the most common determinant (35% of the isolates), followed by the class C determinant (12%) and the class A determinant (1%). About 9% of the isolates contained two determinants on plasmids. None of the plasmids from isolates hybridized with the class D determinant probe. The class C determinant was the most prevalent determinant on plasmids in isolates from pigs not exposed to antimicrobial agents for more than 146 months, while the class B determinant was more prevalent on plasmids in isolates from pigs exposed to either subtherapeutic or therapeutic levels of antimicrobial agents. Most tetracycline resistance determinants were localized on plasmids which were more than 30 kb long. A great number of wild-type tetracycline-resistant Escherichia coli strains were found with the class E determinant on their chromosomes. This study revealed a high prevalence of tetracycline resistance determinants in the fecal flora of pig herds whether or not they were fed with antibiotics.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8517740&dopt=Abstract antibiotics, tetracycline




Clin Exp Pharmacol Physiol. 1982 Mar-Apr;9(2):139-44.
Influence of dietary restriction and protein deficiency on plasma half-life and tissue distribution of tetracycline in rats.

Raghuram TC, Krishnaswamy K, Rao KV.

1. The effects of dietary restriction and protein deficiency on plasma half-life and tissue distribution of tetracycline were studied in rats by feeding either a 20% protein diet in restricted quantity or a 9% protein diet ad lib and compared with rats given a 20% protein diet ad lib (control group). 2. It was observed that half-life of tetracycline was shortened and that plasma and tissue Cmin levels at steady-state were lower in undernourished rats. Tissue concentrations in liver, kidney, muscle and bone correlated well with plasma levels. A high degree of correlation was also observed between plasma and tonsillar concentrations of tetracycline in human subjects. 3. These studies indicate that undernourished subjects may require an altered dosage regimen of tetracycline to maintain effective steady-state concentrations of the drug.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=7127914&dopt=Abstract antibiotics, tetracycline




J Chromatogr B Biomed Appl. 1996 Mar 3;677(2):291-7.
Application of reversed-phase liquid chromatography and prepacked C18 cartridges for the analysis of oxytetracycline and related compounds.

Fedeniuk RW, Ramamurthi S, McCurdy AR.

Department of Applied Microbiology and Food Science, University of Saskatchewan, Saskatoon, Canada.

The reversed-phase (RP) chromatographic separation of oxytetracycline (OTC) 4-epioxytetracycline (4-epiOTC), alpha-apooxytetracycline (alpha-apoOTC), and beta-apooxytetracycline (beta-apoOTC) has been accomplished on an Inertsil C8 column at ambient temperature. Using the simplex method of solvent optimization, a 0.1 M ammonium acetate buffer (pH 3.0)-acetonitrile-tetrahydrofuran (72.5:12.5:15, v/v/v) mobile phase was found to give excellent separation of the compounds. OTC, 4-epiOTC, alpha-apoOTC and beta-apoOTC were resolved in 35 min with calculated detection limits of 40, 20, 50 and 140 ng/ml, respectively. Solid-phase extraction (using RP C18 cartridges) of OTC and OTC degradation compounds from distilled water and porcine muscle was tested at four concentration levels ranging from 200 to 2000 ng/ml (g); overall mean recovery of OTC from distilled water and porcine tissue was greater than 90% and 70%, respectively.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8704932&dopt=Abstract antibiotics, tetracycline




Appl Environ Microbiol. 2003 Jul;69(7):4151-8.
Identification of a new ribosomal protection type of tetracycline resistance gene, tet(36), from swine manure pits.

Whittle G, Whitehead TR, Hamburger N, Shoemaker NB, Cotta MA, Salyers AA.

Department of Microbiology, University of Illinois, 601 S. Goodwin Avenue, Urbana, IL 61801, USA.

Previously, only one ribosome protection type of a tetracycline resistance gene, tetQ, had been identified in Bacteroides spp. During an investigation of anaerobic bacteria present in swine feces and manure storage pits, a tetracycline-resistant Bacteroides strain was isolated. Subsequent analysis showed that this new Bacteroides strain, Bacteroides sp. strain 139, did not contain tetQ but contained a previously unidentified tetracycline resistance gene. Sequence analysis showed that the tetracycline resistance gene from Bacteroides sp. strain 139 encoded a protein (designated Tet 36) that defines a new class of ribosome protection types of tetracycline resistance. Tet 36 has 60% amino acid identity over 640 aa to TetQ and between 31 and 49% amino acid identity to the nine other ribosome protection types of tetracycline resistance genes. The tet(36) region was not observed to transfer from Bacteroides sp. strain 139 to another Bacteroides sp. under laboratory conditions. Yet tet(36) was found in other genera of bacteria isolated from the same swine manure pits and from swine feces. Phylogenetic analysis of the tet(36)-containing isolates indicated that tet(36) was present not only in the Cytophaga-Flavobacter-Bacteroides group to which Bacteroides sp. strain 139 belongs but also in gram-positive genera and gram-negative proteobacteria, indicating that horizontal transfer of tet(36) is occurring between these divergent phylogenetic groups in the farm environment.

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Kidney Int. 1977 Nov;12(5):366-72.
Tetracycline fluorescence in uremic and primary hyperparathyroid bone.

Teitelbaum SL, Hruska KA, Shieber W, Debnam JW, Nichols SH.

Twenty-five patients with end-stage renal disease, nine of whom were receiving pharmacologic doses of vitamin D, and seventeen patients with primary hyperparathyroidism underwent bone biopsy following a three-day course of tetracycline administration. The mean width of the fluorescent tetracycline bands were significantly greater in the bones of patients with uremia than in those with primary hyperparathyroidism. This difference was due to wide labels present in the patients with uremia who had not been treated with vitamin D, as no differences existed in mean label widths of patients with uremia who had received this compound and the patients with primary hyperparathyroidism. Comparison of the maximum label widths distinguished not only primary hyperparathyroid patients from those with uremia, but uremic patients who had recieved vitamin D from those who had not been so treated. Quantitative microscopy of standard, nonfluorescent histologic features failed to make this latter distinction. These data are consistent with the presence of a wide zone of instantaneously fluorescing material in uremic bone following tetracycline administration, which does not relate to bone apposition occurring during antibiotic administration. This phenomenon probably represents a delay in mineral maturation which is normalized by vitamin D. Furthermore, it is apparent that the use of a continuously administered (single) tetracycline label will result in an overestimation of bone formation rates, particularly in osteomalacic states.

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Contrib Microbiol Immunol. 1979;6:178-88.
The persistence of R-plasmid-carrying E. coli in a married couple, one of whom was receiving antibiotics.

Petrocheilou V, Richmond MH, Bennett PM.

The aerobic Gram-negative intestinal flora of two individuals, husband and wife, has been followed for about 20 months. The wife was receiving prolonged tetracycline treatment for acne during the first year of the study and was found to carry a large proportion of tetracycline resistant E. coli in her faecal flora even after the tetracycline treatment had ended. A brief therapeutic course of ampicillin during the period when no tetracycline was being taken resulted in the temporary disappearance of the tetracycline resistant flora, but this returned, even though no tetracycline was being taken, as soon as the ampicillin ended. The husband took no antibiotics during the period under study but was frequently found to excrete the same resistant E. coli as his wife. Moreover, the plasmids carried by the tetracycline resistant strains in the wife and the husband were often indistinguishable. This suggests that R-plasmids may spread from people under treatment to close relatives who have not been treated.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=394928&dopt=Abstract antibiotics, tetracycline

plantsci.cam.ac.uk

The effects of five tetracycline analogues, anhydrotetracycline, doxycycline, minocycline, oxytetracycline, and tetracycline, on Top10 promoter activity in NT1 tobacco tissue culture cells have been analysed. The concentration that repressed Top10 promoter activity, the level of transgene repression and the kinetics of transgene de-repression were determined for each analogue, and could not be predicted from in vitro binding affinity to the tetracycline repressor or from comparison with animal cells. Doxycycline had the most potent effect on the Top10 promoter and completely inhibited transgene expression at 4 nmol l(-1). Tetracycline was the most versatile of the analogues tested; tetracycline inhibited the Top10 promoter at 10 nmol l(-1) and was easily washed out to restore Top10-driven expression in 12-24 h. A study was also made of the suitability for plant research of a novel tetracycline analogue, GR33076X. In animal cells, GR33076X de-repressed Top10 promoter activity in the presence of inhibitory concentrations of anhydrotetracycline. In NT1, it is shown that GR 33076X can antagonize repression of the Top10 promoter in the presence of tetracycline, but not of anhydrotetracycline or of doxycycline. Different tetracycline analogues can therefore be used to regulate the Top10 promoter in plant cells and this property may be exploited in planning an optimum course of transgene regulation.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12177125&dopt=Abstract antibiotics, tetracycline