Metabolome of purulent materials of liver abscesses from crossbred cattle and Holstein steers fed finishing diets with or without in-feed tylosin

Abstract

Liver abscesses in feedlot cattle are a polymicrobial infection with Fusobacterium necrophorum and Trueperella pyogenes as the primary and secondary etiologic agents, respectively. Cattle with liver abscesses do not exhibit clinical signs and the abscesses are detected only at slaughter. The objective was to conduct metabolomics analysis of purulent materials of liver abscesses to identify biochemicals. Liver abscesses from crossbred cattle (n=24) and Holstein steers (n=24), each fed high-grain finishing diet with tylosin (n=12) or no tylosin (n=12) were included in the study. Abscess purulent materials were analyzed by ultrahigh performance liquid chromatography-tandem mass spectroscopy. A total of 759 biochemicals were identified and were broadly categorized into carbohydrates, energy metabolism pathways intermediates, peptides, amino acids and their metabolites, lipids and their metabolites, nucleotides, vitamins and cofactors, xenobiotics, and partially characterized molecules. The top 50 biochemicals identified included amino acids, lipids, nucleotides, xenobiotics, peptides and carbohydrates and their metabolites. Among the 15 amino acid metabolites in the top-50 biochemicals, four were tryptophan metabolites, indoleacrylate, indolepropionate, tryptamine, and anthranilate. The 3-phenylpropionate, a product of phenylalanine metabolism, was the predominant metabolite in purulent materials. Between the four treatment groups, a two-way ANOVA analysis identified biochemicals that exhibited significant main effects for cattle type and in-feed tylosin use and their interactions. A total of 59 and 85 biochemicals were different (P < 0.05) between the cattle type (crossbred vs. Holstein steers) and in-feed tylosin use (tylosin vs. no tylosin), respectively. Succinate, an intermediate of lactate fermentation by some bacterial species, was one of the top 30 biochemicals that differentiated the four treatment groups. A number of lysophospholipids, indicative of bacterial and host cell membrane lyses, were identified in the purulent materials. In conclusion, to our knowledge this is the first report on the metabolome of liver abscess purulent materials and several biochemicals identified were related to metabolic activities of the bacterial community, particularly F. necrophorum and T. pyogenes. Biochemicals unique to liver abscesses that appear in the blood may serve as biomarkers and be of diagnostic value to detect liver abscesses of cattle before slaughter.

Characterization of Three New Outer Membrane Adhesion Proteins in Fusobacterium necrophorum

“…Antibiotic prophylaxis has effectively reduced the severity of liver abscesses [8], with the US Feed Additive Compendium listing five antimicrobials currently approved for use to prevent this disease in cattle [9]. Among these drugs, tylosin is the most effective antibiotic, but even it does not entirely prevent liver abscesses [8,10]. In addition, there has been a surge in antibiotic resistance in recent years, a process that we now know is inevitable [11].…”

“…These rising resistance rates, combined with increased public health concern about the use of antibiotics for growth promotion in food animals and the growing consumer demand for "No added antibiotics", have driven the search for viable alternatives to antibiotics. Given that liver abscess is diagnosed only at the late stages of the disease, leading to poor prognoses for infected animals [10,12], the best option is likely to be the development of a potent vaccine that effectively prevents F. necrophorum infection in cattle.…”