Analyst. 1994 Dec;119(12):2713-6.
Sensitive spectrofluorimetric determination of tetracycline residues in bovine milk.

Croubels S, Van Peteghem C, Baeyens W.

Laboratory of Food Analysis, Faculty of Pharmaceutical Sciences, University of Ghent, Belgium.

A novel, sensitive, high-performance liquid chromatographic method for the residue determination of tetracyclines in bovine milk has been developed. Clean-up of the sample extracts is performed with metal chelate affinity chromatography. Detection is based upon the measurement of fluorescence induced by complexation of tetracyclines with the zirconium cation, which is added post-column to the high-performance liquid chromatographic eluate. The method has been validated for oxytetracycline, tetracycline and chlortetracycline. Calibration curves using 'blank' milk fortified at the 10-200 ng ml-1 level showed good linear correlation. Accuracy was measured at the 100 ng ml-1 level and was found to be within acceptable limits using a t-test (alpha = 0.05). At this level both within- and between-day precision, as measured by relative standard deviation (S(r)), were less than 16% for oxytetracycline and chlortetracycline, and less than 20% for tetracycline. The most striking advantages of the proposed method, over previously reported methods, are the higher sensitivity and specificity achieved. Using a signal-to-noise ratio of 4:1, the detection limits of the assay were 1 ng ml-1 for oxytetracycline, 2 ng ml-1 for tetracycline and 4 ng ml-1 for chlortetracycline.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=7879882&dopt=Abstract antibiotics, tetracycline




Pharmazie. 1980 Jan;35(1):24-6.
Studies on spectrophotometric determination of tetracycline and its degradation products.

Regosz A, Zuk G.

The spectrophotometric method was employed for determination of tetracycline (1) and its degradation products epitetracycline (2), anhydrotetracycline (3) and anhydroepitetracycline (4). The determination has been based on the difference in the molar absorptivities (epsilon) of 1 and 2 at 254 and 267 nm, as well as of 3 and 4 at 260 and 272 nm, respectively. The difference in epsilon at 357 and 390 nm has also been employed for the determination of 1 and 3. On the basis of these dependences, the compounds were determined both in synthetic mixtures and in some solid dosage forms.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=7384172&dopt=Abstract antibiotics, tetracycline




J Assoc Off Anal Chem. 1988 Jul-Aug;71(4):768-72.
First derivative spectrophotometric determination of anhydrotetracyclines in tetracyclines.

Wahbi AA, Al-Khamees HA, Yousef AM.

King Saud University, College of Pharmacy, Pharmaceutical Chemistry Department, Riyadh, Saudi Arabia.

A rapid method is presented for detection and determination of anhydrotetracycline-HCl (ATC-HCl) and 4-epianhydrotetracycline-HCl (4-EATC-HCl) in tetracycline-HCl (TC-HCl). The method determines the 2 compounds as a sum, not individually. The first derivative absorption curve has a trough (D1) at 460 nm which is linearly related to concentration (1-10 mg/mL). ATC-HCl + 4-EATC-HCl content was determined in TC-HCl powder and capsules by the D1 and the compensation D1 spectrophotometric methods. The results were compared with those obtained using U.S. Pharmacopeia and British Pharmacopoeia methods.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=3417597&dopt=Abstract antibiotics, tetracycline




Food Addit Contam. 1998 Aug-Sep;15(6):645-50.
Effects of extraction and spiking procedures on the determination of incurred residues of oxytetracycline in cattle kidney.

Cooper AD, Tarbin JA, Farrington WH, Shearer G.

Ministry of Agriculture, Fisheries & Food, CSL Food Science Laboratory, Norwich, UK.

The effects of different extraction and spiking procedures on the determination of incurred oxytetracycline residues in animal tissues have been investigated. The extraction procedures investigated--direct aqueous or organic solvent extraction, enzymic digestion or sonication--all gave similar results for incurred oxytetracycline concentration in cattle kidney after correction for spike recovery. There was therefore no evidence for binding or conjugation of oxytetracycline in this tissue. Highest recovery from spiked tissue was obtained using ethyl acetate as extractant. The effects of spiking procedure (spike contact time, spike solvent and tissue state) on recovery from spiked cattle kidney were also small, indicating that added oxytetracycline spike does not interact with the tissue.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10209574&dopt=Abstract antibiotics, tetracycline




Z Allg Mikrobiol. 1984;24(2):119-24.
[Formation of plasmid pBR322 oligomers as depending on a tetracycline concentration]

[Article in German]

Wiehle W, Hecker M, Reichstein B, Mach F.

Escherichia coli K12 strains containing the plasmid pBR322 often show varying contents of plasmid oligomers, in which the monomer units are arranged in tandem. When the concentration of the plasmid-selective antibiotic tetracycline in the medium becomes increased selection of cells containing largely higher oligomers occurs. The number of monomer units organized in the oligomers increases with tetracycline concentration. recA- mutants are unable to generate oligomers under the same conditions and show lower tetracycline resistance. This observations suggest a selective advantage of oligomer containing cells in the presence of tetracycline as a result of higher gene dosage. But E. coli cells transformed with monomers, dimers, trimers, as well as tetramers of pBR322 are characterized by roughly the same plasmid DNA content as well as plasmid coded beta-lactamase and resistance to tetracycline.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=6372270&dopt=Abstract antibiotics, tetracycline




Am J Vet Res. 1990 Dec;51(12):2015-8.
Antimicrobial resistance in streptococcal species isolated from bovine mammary glands.

Brown MB, Scasserra AE.

Department of Infectious Diseases, College of Veterinary Medicine, University of Florida, Gainesville 32610.

Streptococcal species isolated from dairy cows with clinical mastitis were obtained from mastitis research workers in Florida, Louisiana, New York, Vermont, Washington, and West Virginia. Seventy-one streptococcal isolates were tested, including 39 strains of Streptococcus agalactiae, 21 strains of S dysgalactiae, and 11 strains of S uberis. The minimal inhibitory concentration of erythromycin, lincomycin, oxytetracycline, penicillin, spectinomycin, streptomycin, and tetracycline was determined for each isolate. Differences were not detected among strains with respect to geographic origin. None of the strains was resistant to penicillin. Lincomycin was the next most effective antimicrobial, with only 2 resistant strains of each streptococcal species. There were no differences among the streptococcal species with respect to resistance to either penicillin or lincomycin. Streptococcus uberis was more likely to be resistant to erythromycin than were S agalactiae and S dysgalactiae (P less than 0.02). Streptococcus agalactiae and S uberis had similar distributions for resistance to oxytetracycline, tetracycline, spectinomycin, and streptomycin. Strains of S dysgalactiae were more likely to have intermediate resistance to oxytetracycline and streptomycin than were strains of S agalactiae and S uberis, which were highly resistant to oxytetracycline and streptomycin (P less than 0.001). Differences were not detected among the streptococcal species with respect to resistance to spectinomycin. Resistance to multiple antimicrobials was observed in all streptococcal species tested. Although S dysgalactiae appeared to have a greater percentage of strains (73%) that were resistant to multiple antimicrobials than did S agalactiae (31%) or S uberis (45%), differences were not statistically significant.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=2085229&dopt=Abstract antibiotics, tetracycline




J Clin Microbiol. 1989 Dec;27(12):2767-71.
Screening of type Ia and Ib Streptococcus agalactiae strains with high sialic acid levels by determination of susceptibility to tetracyclines.

Nagano Y, Nagano N, Takahashi S, Suzuki A, Okuwaki Y.

Department of Environmental Hygiene, Faculty of Hygiene, Kitasato University, Japan.

The type-specific capsular polysaccharide antigen of Streptococcus agalactiae is recognized to be an antiphagocytic factor in strains having large amounts of it. In the present study, it was indicated that vaginal isolates of types Ia and Ib could be classified into two groups on the basis of both their levels of the sialic acid, which occupies the terminal side chains of the polysaccharide, and their susceptibility to tetracyclines: one group comprised strains with low sialic acid levels (less than 9 micrograms/mg of cell dry weight) as well as with susceptibility to tetracyclines (MIC, less than or equal to 0.5 micrograms/ml), and the other comprised strains with higher sialic acid levels (greater than or equal to 9 micrograms/mg) and resistance to tetracyclines (MIC, greater than or equal to 8 micrograms/ml). A few isolates were found to have low levels of sialic acid and to be resistant to tetracyclines, but no isolates that were both relatively high in sialic acid and susceptible to tetracyclines were ever detected. Among strains of those serotypes, the MICs of tetracyclines were not in proportion to the sialic acid levels and were not affected when the sialic acid levels of each strain were altered by using Todd-Hewitt broth with various concentrations of Na2HPO4 and glucose. It was, therefore, apparent that the correlation of sialic acid levels with susceptibility to tetracyclines was not related directly to the sialic acid content or to the amount of the capsular polysaccharide. Since no plasmid DNAs were detected among representative strains that were tetracycline resistant, it was apparent that at least for the strains tested, resistance was chromosomal gene associated. In strains of S. agalactiae of types of Ia and Ib, the determination of susceptibility to tetracyclines was considered to be useful for screening strains with higher sialic acid levels.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=2687321&dopt=Abstract antibiotics, tetracycline




J Trop Med Hyg. 1987 Dec;90(6):301-5.
Penicillin and tetracycline susceptibility of gonococci from Addis Ababa and incidence of penicillinase-producing strains.

Gedebou M, Tassew A.

Department of Medical Microbiology and Parasitology, Faculty of Medicine, Addis Ababa University, Ethiopia.

One hundred and nine Neisseria gonorrhoeae strains were isolated from urethral discharge of male patients in a health centre in Addis Ababa, identified following conventional procedures, and tested for penicillin and tetracycline susceptibility by the agar dilution technique. World Health Organization reference strains were also tested as controls. Penicillinase producing N. gonorrhoeae (PPNG) were identified using Oxoid beta-lactamase detection papers. Minimal inhibitory concentration (MIC) values of penicillin varied between less than 0.01 mg l-1 and greater than 10.24 mg l-1 while those of tetracycline, between less than 0.25 mg l-1 and 4.0 mg l-1. About 64% of isolates were resistant to penicillin, requiring MICs of greater than or equal to 0.64 mg l-1: 26% were resistant to tetracycline, requiring greater than or equal to 2 mg l-1 for inhibition. The rate of simultaneous resistance to both antibiotics was 18%. PPNG comprised 49% of isolates, of which 23% were resistant also to tetracycline. Of 70 penicillin-resistant strains, 17 (24%) were non-PPNG.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=3123709&dopt=Abstract antibiotics, tetracycline