Virginiamycin as an Antibiotic for Poultry Feeds

Yates, J. D.; Schaible, P. J.

doi:10.1038/194183b0

Cited by 16 publications

(13 citation statements)

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“…Resistance was significantly higher among retail chicken and turkey products than among beef or pork products (P Ͻ 0.0001) ( Table 1). The streptogramin combination drug virginiamycin has been used in veterinary medicine for decades, with its use in animal feed for growth promotion in both chickens and turkeys potentially contributing to the greater prevalence of resistance in those meat commodities (22).…”

Section: Resultsmentioning

confidence: 99%

Prevalence and Antimicrobial Resistance of Enterococci Isolated from Retail Meats in the United States, 2002 to 2014

Tyson

Nyirabahizi

Crarey

et al. 2018

Appl Environ Microbiol

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Bacteria of the genus are important human pathogens that are frequently resistant to a number of clinically important antibiotics. They are also used as markers of animal fecal contamination of human foods and are employed as sentinel organisms for tracking trends in resistance to antimicrobials with Gram-positive activity. As part of the National Antimicrobial Resistance Monitoring System (NARMS), we evaluated several retail meat commodities for the presence of enterococci from 2002 to 2014, and we found 92.0% to be contaminated. The majority of isolates were either (64.0%) or (28.6%), and the antimicrobial resistance of each isolate was assessed by broth microdilution. The resistance prevalences for several drugs, including erythromycin and gentamicin, were significantly higher among poultry isolates, compared to retail beef or pork isolates. None of the isolates was resistant to the clinically important human drug vancomycin, only 1 isolate was resistant to linezolid, and resistance to tigecycline was below 1%. In contrast, a majority of both (67.5%) and (53.7%) isolates were resistant to tetracycline. Overall, the robust NARMS testing system employed consistent sampling practices and methods throughout the testing period, with the only significant trend in resistance prevalence being decreased resistance to penicillin. These data provide excellent baseline levels of resistance that can be used to measure future changes in resistance prevalence that may result from alterations in the use of antimicrobials in food animal production. Enterococci, including and, are present in the guts of food-producing animals and are used as a measure of fecal contamination of meat. We used the large consistent sampling methods of NARMS to assess the prevalence of strains isolated from retail meats, and we found over 90% of meats to be contaminated with enterococci. We also assessed the resistance of the strains, commonly used as a measure of resistance to agents with Gram-positive activity, in foods. Resistance prevalence was over 25% for some antimicrobials and sample sources but was less than 1% for several of the most important therapeutic agents used in human medicine.

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Section: Resultsmentioning

confidence: 99%

Prevalence and Antimicrobial Resistance of Enterococci Isolated from Retail Meats in the United States, 2002 to 2014

Tyson

Nyirabahizi

Crarey

et al. 2018

Appl Environ Microbiol

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“…This antibiotic is active only against Gram-positive bacteria. Its growth-promoting effect has been described previously (4,5).…”

Section: Methodsmentioning

confidence: 92%

The Mode of Action of Antibiotics in Stimulating Growth of Chicks

Eyssen

Somer

1963

The Journal of Experimental Medicine

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A study was made of the effect of antibiotics on growth of chicks and on intestinal absorption of fats and carbohydrates. Around the 8th day of life, chicks fed an antibiotic-free casein-sucrose diet developed a transitory syndrome of malabsorption of fats and carbohydrates, associated with disturbance of the efficiency of feed utilization and poor weight increase. Administration of virginiamycin, at a level of 20 ppm, suppressed this period of malabsorption and resulted in improved feed conversion and increased weight gain. The temporary growth depression and malabsorption were not observed in disinfected rooms in new quarters. Under these conditions virginiamycin did not stimulate growth nor was the efficiency of feed utilization improved by the antibiotic. However, the growth-depressing flora could be introduced to the new quarters by feeding each bird 50 mg of fresh feces collected from chicks in old quarters. Both the intestinal absorption and the growth-promoting effect of virginiamycin were influenced by the type of carbohydrate in the basal diet, and have been found to be most pronounced when sucrose was fed as the sole source of carbohydrate. The malabsorption was less obvious when cornstarch was substituted for sucrose. In this case virginiamycin had only a limited effect on growth and on feed conversion. The present investigations suggest that antibiotics stimulate growth of chicks by their antibacterial action against Gram-positive microorganisms which interfere with the absorption of nutrients. Furthermore, the growth-promoting effect seems to be most pronounced during a limited period of a few days around the 8th day of life.

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“…Use ofvirginiamycin-like antibiotics as growth promoters started soon after the discovery of these antibiotics (12,347). In one work, the improvement of feed utilization in chickens by virginiamycin was compared to that caused by oxytetracycline and bacitracin, antibiotics possessing "broad" (i.e., inhibition of gram-positive and gram-negative bacteria) and "narrow" (i.e., activity on gram-positive bacteria only) spectra, respectively, and currently used in commercial feeds.…”

Section: Domestic Animalsmentioning

confidence: 99%