1 Virginiamycin
Virginiamycin (virginiamycin) is also known as puremycin, virginiamycin, verimycin, virgimycin, staphylomycin, staphylomycin resistance and so on. The molecular formula of virginiamycin M1 (factor M1): C28 H35 N307; the molecular formula of virginiamycin S1 (factor S1): C43H49N7O10. The structural formula of virginiamycin is red-yellow powder with a peculiar odor. The solubility in water is 563μg/ml, and it is easily soluble in methanol, ether and chloroform. It is isolated from the fermentation product of Streptomyces virginiae of the genus Streptomyces.
This product does not contain fermentation residues and other metabolic toxins, and the quality is stable. But it is not a single component, mainly containing 70% to 80% of the M1 component (M1 factor), and 20% to 30% of the S1 component (S1 factor). M1 is a macrolide and S1 is a cyclic polypeptide. Their respective antibacterial ranges are different. Virginiamycin is a complex of factor M1 and factor S1, and they have a good synergistic effect. The minimum inhibitory concentration (MIC) of the M1 component against Staphylococcus aureus is 0.25μg/ml, the S1 component is 4μg/ml, but the combination of the two is 0.125μg/ml, which improves the bactericidal effect1 ~ 30 times. The M1 component is named because it is most effective against Micrococcus aureus. The S1 component is named because it is most effective against Sarcina lutea. M1: S1=70:30, when this ratio is composed, the antibacterial activity is the highest. Because of the different structures of the two components, bacteria that are resistant to the S1 component are still very sensitive to the M1 component, so virginiamycin hardly develops resistance.
2 role
It only has an inhibitory effect on Gram-positive bacteria. The mechanism of action is to inhibit the ribosome of the bacteria and prevent it from achieving a bactericidal effect on protein synthesis. After oral administration, it only stays and acts on the intestinal tract, mainly excreted by feces, and the residual amount is small. Oral LD50 for rats is 7 500 mg per kilogram of body weight, and one-time oral administration. When the dose for mice reaches 1,550 mg per kilogram of body weight, no harmful reactions are found. The maximum safe dose for pigs is 800 mg per kilogram of body weight. The pigs were fed with a dose of 500 mg for 3 months without adverse reactions.
Virginiamycin has good stability, and its potency remains unchanged for 3 years at room temperature. When added to feed, it can maintain a stable potency after crushing, mixing, high temperature (70-90°C), steaming, and granulating for about 30 minutes. It can be stored in broiler feed for more than 6 months. The carrier of the premix can be calcium carbonate, broken rice bran (containing 2% oil for dust removal), soybean meal, corn meal, etc. When there is a lot of fish meal in the feed, the general antibiotics are destroyed quickly (chlortetracycline decreases by 20%-40% in 6 months), and the potency of virginiamycin is basically not stored in the high-protein feed containing fish meal for 6 months. change. The Ministry of Agriculture of the People's Republic of China stipulates that the amount of feed for chickens under 16 weeks of age is 2-5 mg/kg; for pigs, it is 10-20 mg/kg. The withdrawal period for pigs and chickens is 1d. Laying hens are forbidden.