Rapid Communication: 16S ribosomal ribonucleic acid characterization of liver abscesses in feedlot cattle from three states in the United States1

Abstract

Liver abscesses are a major economic burden to beef producers. Although a few causative organisms have been cultured from purulent material, the full polymicrobial diversity of liver abscesses has not been reported. The objective of this study was to characterize purulent material collected from liver abscess in beef cattle produced in different production systems in 3 cattle producing states in the United States using 16S rRNA gene sequencing. Differences between purulent material microbial communities among geographic region of feeding and application of a common antimicrobial were also investigated. Cattle included in the study were fed in California (dairy type) and Colorado and Texas (both beef type). Liver abscesses from a cross section of feedlots, geographic areas, and tylosin phosphate-administered groups were collected at harvest; DNA from 34 liver abscess samples was extracted; and the V4 region of the 16S rRNA gene was amplified and sequenced. Sequences were classified into 5 phyla, 13 classes, and 17 orders in the domain Bacteria. The phyla identified included Bacteroidetes (35.2% of reads), Proteobacteria (28.6%), Fusobacteria (18.2%), Firmicutes (12.4%), and Actinobacteria (5.5%). Sequences matching the genera and , which have previously been identified as causative agents in liver abscesses, were both present in the abscess bacterial communities at a relative abundance of 15.1 and 3.2%, respectively, of the overall relative abundance. Furthermore, 3 of the most common phyla were Gram-negative bacteria. An analysis-of-similarities test was conducted on Euclidean distances to assess differences between cattle treated and not treated with tylosin as well as to assess differences between geographic regions. Geographical region and treatment with tylosin did affect the microbiome ( = 0.002 and = 0.026 respectively); however, a more robust sample scheme is needed to explore these differences. To our knowledge, this is the first publication describing the complex community of liver purulent material using next generation sequencing in cattle. These data provide a framework for research on a more targeted approach to liver abscess prevention and treatment.

An Advanced Understanding of Uterine Microbial Ecology Associated with Metritis in Dairy Cows

“…These uterine pathogens were also found in the gut and blood of dairy cows, indicating hematogenous transmission of bacteria towards the uterus [34]. This is supported by the fact that bacteremia was detected in more than ~50% of postpartum dairy cows [67], and that uterine pathogens were found in other body sites causing liver abscess [68, 69] and foot rot [40, 70]. Because uterine pathogens were even present in healthy and non-pregnant cows without causing inflammation [71, 72], it is possible that uterine pathogens are normal residents of the bovine uterus, and uterine disease may develop in postpartum cows with high abundance of uterine pathogens by alteration of uterine microbiota.…”

Characterization of bacterial DNA identified in abscessed and non-abscessed bovine hepatic tissue at the time of harvest

“…In the current study, although the same five phyla accounted for the largest share of reads, Fusobacteria was the prevailing phylum (51% of reads), followed by Bacteroidetes (11% of reads), and then distantly by Firmicutes , Actinobacteria , and Proteobacteria (< 3% of reads, collectively). Potentially, this difference in rank order of the dominant phyla is associated with the decision to analyze by liver abscess score in the current study ( Figure 2 ), rather than the pooled analysis of purulent tissue and abscess wall material from various abscess scores discussed by Weinroth et al, (2017) and Amachawadi et al, (2021) . In the current study, scarred and non-abscessed livers exhibited greater Proteobacteria (31.2% of reads) than the abscessed liver scores which is numerically similar to the proportion observed by Weinroth et al, (2017) .…”

“…Potentially, this difference in rank order of the dominant phyla is associated with the decision to analyze by liver abscess score in the current study ( Figure 2 ), rather than the pooled analysis of purulent tissue and abscess wall material from various abscess scores discussed by Weinroth et al, (2017) and Amachawadi et al, (2021) . In the current study, scarred and non-abscessed livers exhibited greater Proteobacteria (31.2% of reads) than the abscessed liver scores which is numerically similar to the proportion observed by Weinroth et al, (2017) . Furthermore, the alpha diversity ( Figure 4 a–c ) and nMDS plots ( Figure 5 ) indicate no difference in the means of observed OTU between the livers with scores of Sc and A−.…”

“…Within abscessed livers, the predominant phyla were somewhat dissimilar in their proportions to that observed in other recent research. Weinroth et al (2017) sampled abscessed livers of both beef and dairy type cattle and found that Bacteroidetes and Proteobacteria were the dominate phyla followed by Fusobacteria , Firmicutes , and Actinobacteria . More recently, Amachawadi et al (2021) showed that Fusobacteria was the dominant phylum obtained from purulent liver abscess material followed by Proteobacteria .…”

“…Research efforts have been largely focused on eliminating the causative agent of infection or reducing the infective agent’s ability to gain entry to the liver ( Fox et al, 2009 ; Reinhardt and Hubbert, 2015 ; Huebner et al, 2019 ). Liver abscesses are, however, a polymicrobial environment as evidenced by both culture and culture-independent methods ( Nagaraja and Chengappa, 1998 ; Weinroth et al, 2017 ). More recent culture-independent methods have also focused on the effect of current in-feed therapeutics on the effect of liver abscess bacterial community ( Amachawadi et al, 2021 ) and the association of epimural bacterial communities of the rumen wall of cattle with or without liver abscesses ( Abbas et al, 2020 ).…”