Virginiamycin is an antibiotic effective against a number of bacteria, including Enterococcus and Staphylococcus. This medication, classified among the streptogramin antibiotics, is not available for human use and is primarily used in ethanol fermentation and management of bacterial infections in livestock. Several drug companies make virginiamycin, most commonly in a bulk powder formulation so people can mix as much as they need for a given application.
In ethanol production, antibiotics like virginiamycin can prevent contamination of the materials used for fermentation. The goal is to promote the development of healthy and beneficial yeasts to rapidly ferment materials without creating spoilage. If the fermentation vat acquires bacterial contamination, it can interfere with successful production and compromise the quality of the end product or interfere with batch production. Producers can add antibiotics to the fermenter to prevent this problem.
Farmers use antibiotics for two different reasons. Drugs like virginiamycin promote rapid growth, allowing animals to reach market weight earlier than usual, and a farmer may mix them in with the food of healthy animals as growth promoters. These drugs are also available for use in the treatment of specific infections, under the direction of a veterinarian who will prescribe an appropriate medication and monitor the animal to make sure the infection clears.
Critics of virginiamycin use in livestock argue it can put human populations at risk by contributing to the development of antibiotic resistance in infectious organisms. Contaminated meat, eggs, and dairy can cause widespread illness and it may be difficult to treat if the first line antibiotics doctors would normally turn to will not work. Some nations limit the use of antibiotics in the agricultural sector to prevent antibiotic resistance.
Like other antibiotics, virginiamycin can cause side effects. It may lead to stomach upset in animals, causing diarrhea and vomiting. It can also cause rashes and severe allergic reactions. If an animal appears to react poorly to an antibiotic, a veterinarian can try an alternate medication to see if this resolves the problem. With livestock, farmers anticipate some loss each year, and structure potential animal deaths into their budgeting and financial planning. Expected losses are part of the reason why farmers want to get animals to market quickly.
This and other agricultural antibiotics can be bought through agricultural suppliers and feed stores, without needing a specific prescription. Farmers need to store their medications appropriately to reduce the risks of contamination and unauthorized access. All drugs intended for animal use have clear labels to remind people that they are not safe for use in humans. This may be because they contain ingredients toxic to humans, or because they have not yet been studied in human populations.