There are not many data available on antibiotics used solely in animals and almost exclusively for growth promotion. These products include bambermycin, avilamycin, efrotomycin, and the ionophore antibiotics (monensin, salinomycin, narasin, and lasalocid). Information is also scarce for bacitracin used only marginally in human and veterinary medicine and for streptogramin antibiotics. The mechanisms of action of and resistance mechanisms against these antibiotics are described. Special emphasis is given to the prevalence of resistance among gram-positive bacteria isolated from animals and humans. Since no susceptibility breakpoints are available for most of the antibiotics discussed, an alternative approach to the interpretation of MICs is presented. Also, some pharmacokinetic data and information on the influence of these products on the intestinal flora are presented.

/pdf/antimicrobial-growth-promoters-used-in-animal-feed-effects-2m4hg3uiz3.pdf

Antimicrobial Growth Promoters Used in Animal Feed: Effects of Less Well Known Antibiotics on Gram-Positive Bacteria

https://febs.onlinelibrary.wiley.com/doi/pdf/10.1016/0014-5793%2874%2980689-7

Inhibitors of protein synthesis

Biosynthesis of polyketides by trans-AT polyketide synthases

Kirromycin, a new inhibitor of protein synthesis, is shown to interfere with the peptide transfer reaction by acting on elongation factor Tu (EF-Tu). All the reactions associated with this elongation factor are affected. Formation of the EF-Tu·GTP complex is strongly stimulated. Peptide bond formation is prevented only when Phe-tRNAPhe is bound enzymatically to ribosomes, presumably because GTP hydrolysis associated with enzymatic binding of Phe-tRNAPhe is not followed by release of EF-Tu·GDP from the ribosome. This antibiotic also enables EF-Tu to catalyze the binding of Phe-tRNAPhe to the poly(U)·ribosome complex even in the absence of GTP. EF-Tu activity in the GTPase reaction is dramatically affected by kirromycin: GTP hydrolysis, which normally requires ribosomes and aminoacyl-tRNA, takes place with the elongation factor alone. This GTPase shows the same Km for GTP as the one dependent on Phe-tRNAPhe and ribosomes in the absence of the antibiotic. Ribosomes and Phe-tRNAPhe, but not tRNAPhe or Ac-Phe-tRNAPhe, stimulate the kirromycin-induced EF-Tu GTPase. These results indicate that the catalytic center of EF-Tu GTPase that is dependent upon aminoacyl-tRNA and ribosomes is primarily located on the elongation factor. In conclusion, kirromycin can substitute for GTP, aminoacyl-tRNA, or ribosomes in various reactions involving EF-Tu, apparently by affecting the allosteric controls between the sites on the EF-Tu molecule interacting with these components.

https://www.pnas.org/content/pnas/71/12/4910.full.pdf

Kirromycin, an inhibitor of protein biosynthesis that acts on elongation factor Tu.

Poultry meat and eggs are important sources of human pathogens. Salmonella is a major cause of human foodborne infections following consumption of poultry products. The original ambition of the EU to eradicate zoonotic agents from the animal production chain has been tempered to reducing the infection pressure of specified zoonotic agents at all levels of the production chain. This can be done by a combination of pre-harvest, harvest and post-harvest measures. Feed additives constitute an important group of pre-harvest measures which can help in controlling Salmonella on the farm. Feed additives used for the control of Salmonella can be of different types, including antibiotics, prebiotics, probiotics and synbiotics. Public concerns regarding possible antibiotic resistance transfer lead to the ban of antibiotics as growth promoters in monogastric diets within the EU. Experimental and practical use of pre-, pro- and synbiotics, as well as volatile fatty acids as feed additives are discussed in this review. The effects of these additives on resistance to infection, on the extent of excretion and on the persistence of infection are reviewed. Attention is paid also to possible undesirable effects of some of these products. Taking into consideration the underestimated high level of contamination of poultry, the feed additives reviewed in this article can certainly play a valuable part in control strategies during the pre-harvest phase aiming at reducing the infection pressure and thus limiting the risk of contamination of poultry products.

Feed additives to control Salmonella in poultry

https://febs.onlinelibrary.wiley.com/doi/pdf/10.1016/0014-5793%2873%2980364-3

Kirromycin, an inhibitor of the 30 S ribosomal subunits function.

https://febs.onlinelibrary.wiley.com/doi/pdf/10.1016/0014-5793%2878%2981091-6

H. Wolf

Papers

Kirromycin, an inhibitor of the 30 S ribosomal subunits function.

Action of pulvomycin and kirromycin on eukaryotic cells