Residual antibiotics

Residual antibiotics. With the widespread use of antibiotics in feeds the occurrence of residuals in milk, meat and eggs becomes inevitable. These residuals result primarily from failure by the producer to adhere to adequate withdrawal periods following the use of the antibiotics. In a review by Katz ( ), residual antibiotics were found in all animal species marketed in 1976 - 1978. 

Residue depletion studies in pigs fed 330 mg kitasamycin/kg feed for 14 days showed that at zero withdrawal only liver (100 ppb) and kidney (60 ppb) contained detectable residues. One day after withdrawal of the treatment, residual antibiotic activity was detectable only in the liver. Residue depletion studies in chickens fed 500 mg kitasamycin/kg feed for 14 days showed that at zero withdrawal only liver (70 ppb) contained detectable residues. One day after withdrawal, residual antibiotic activity could not be detected in any tissue. 

Results of a national survey conducted by the Ministry of Health and Welfare on residual antibiotics in domestic meat and fish in Japan for the fiscal years 1990-1992 are presented in Table 13.25. Samples were collected at the urban... 

Helicobacter pylori, which is associated with stomach ulcers, forms a 38-residue antibiotic that may help protect infected persons from other bacteria.116 This peptide forms a simple two-helix structure and is one of a large number of simple helical antimicrobial polypeptides 40 residues or less in length. Among them... 

DG Kennedy, RJ McCracken, A Cannavan, SA Kewitt. Use of liquid chromatography-mass spectrometry in the analysis of residue antibiotics in meat and milk. J Chromatogr 812 77-98, 1998. 

The selection of transformed cells is achieved using a conferred selectable trait, most commonly antibiotic resistance. Only transformed cells with the conferred resistance trait are able to survive and reproduce. However, the use of antibiotics as a media component for commercial protein production is problematic for at least two reasons. First, residual antibiotic would be a highly undesirable contaminant in the final product. Second, the recurrent use of antibiotics increases the likelihood that antibiotic-resistant pathogen strains will develop. Recent studies indicate that antibiotic selection is not necessary during every passage (or generation). 

Gramicidin A. Gramicidin A (gA) is a small 15-residue antibiotic peptide formed as a dimer in a head-to-head (HH) or a double-helical (DH) conformation. " Because of its simplicity and reduced dimensions, the gA structure has been studied extensively and simulated as a model for ion channels,and has emerged as a benchmark for simulation approaches. " The structure exposes its hydrophobic sidechains to the lipid membrane that embeds the protein. The molecular structure of gA has been known for three decades,and has been recently resolved with NMR spectroscopyThe relation of the structure seen spectroscopically to that... 

B. Z. Haznedaoglu, M. V. Yates, M. F. Maduro and S. L. Walker, Effects of residual antibiotics in groundwater on Salmonella typhimurium changes in antibiotic resistance, in vivo and in vitro pathogenicity, J. Environ. Monit., 2012, 14, 41-47. 

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