Showing papers by "KwangCheol Casey Jeong published in 2019"
TL;DR: A combination of electron cryotomography and immunofluorescence microscopy reveals the structure of the core transmembrane subcomplex of the Legionella defective in organelle trafficking (Dot)/intracellular multiplication (Icm) type IVB secretion system (T4BSS) and an early-stage assembly process by which T 4BSS components are targeted to the bacterial poles by DotU and IcmF.
Abstract: Legionella pneumophila survives and replicates inside host cells by secreting ~300 effectors through the defective in organelle trafficking (Dot)/intracellular multiplication (Icm) type IVB secretion system (T4BSS). Here, we used complementary electron cryotomography and immunofluorescence microscopy to investigate the molecular architecture and biogenesis of the Dot/Icm secretion apparatus. Electron cryotomography mapped the location of the core and accessory components of the Legionella core transmembrane subcomplex, revealing a well-ordered central channel that opens into a large, windowed secretion chamber with an unusual 13-fold symmetry. Immunofluorescence microscopy deciphered an early-stage assembly process that begins with the targeting of Dot/Icm components to the bacterial poles. Polar targeting of this T4BSS is mediated by two Dot/Icm proteins, DotU and IcmF, that, interestingly, are homologues of the T6SS membrane complex components TssL and TssM, suggesting that the Dot/Icm T4BSS is a hybrid system. Together, these results revealed that the Dot/Icm complex assembles in an ‘axial-to-peripheral’ pattern.
69 citations
TL;DR: An in vivo model of clinical endometritis in Holstein heifers using pathogenic Escherichia coli and Trueperella pyogenes allows the isolation of effects of uterine disease on fertility from confounding factors that can occur during the postpartum period in dairy cows.
34 citations
TL;DR: The widespread of CRB into both cattle seldom treated with cephalosporin antibiotics and the surrounding environment suggests the environment is a natural source of antimicrobial resistance in beef cattle.
Abstract: Although the over-use of antibiotics during food animal production is a potential driver of antimicrobial resistant microorganisms (ARMs), a high prevalence of cefotaxime resistant bacteria (CRB) has been observed in grazing animals raised without antibiotic supplementation. In this cross-sectional study, the prevalence and concentration of CRB in beef cattle on grazing farms were investigated. Fecal samples from the recto-anal junction of cattle (n = 840) and environmental samples (n = 258) were collected from 17 farms in North and Central Florida in the United States, and a survey of farm characteristics, animal husbandry practices, and antibiotic usage was conducted. CRB were detected in fecal samples from 47.4% of all cattle, with the prevalence ranging from 21.1 to 87.5% on farms, and significantly higher (P < 0.001) in calves compared to adult cows (54.1 vs. 41.8%). Environmental samples had a higher prevalence than fecal samples (P < 0.001), with CRB detected in 88.6% of water, 98.7% of soil, and 95.7% of forage samples. Compared to the concentration (log CFU/g) of CRB in fecal samples (2.95, 95% CI: 2.89, 3.02), the concentration of CRB was higher (P < 0.001) in soil and forage samples (5.37, 95% CI: 5.16, 5.57) and lower (P < 0.001) in water samples (1.08, 95% CI: 0.82, 1.36). Soil microbiota from farms with high prevalence of CRB clustered closer together and the proportion of Phylum Proteobacteria was higher on farms with high prevalence of CRB resistance. Large farming operations were associated with a 58% higher likelihood of CRB detection in fecal samples. Regular cleaning of drinking troughs and the addition of ionophores to feed were associated with CRB reduction in fecal samples. Taken together, the widespread of CRB into both cattle seldom treated with cephalosporin antibiotics and the surrounding environment suggests the environment is a natural source of antimicrobial resistance in beef cattle.
24 citations
TL;DR: Using whole-genome sequencing and comparative genomics of 36 multidrug-resistant Escherichia coli strains isolated from beef cattle with no previous exposure to antibiotics, results are obtained suggesting that the occurrence of MDR E. coli also arises in animals with no antibiotic selective pressure.
Abstract: The effectiveness of antibiotics has been challenged by the increasing frequency of antimicrobial resistance (AMR), which has emerged as a major threat to global health. Despite its negative impact on the development of AMR, there are few effective strategies for reducing AMR in food-producing animals. Using whole-genome sequencing and comparative genomics of 36 multidrug-resistant (MDR) Escherichia coli strains isolated from beef cattle with no previous exposure to antibiotics, we obtained results suggesting that the occurrence of MDR E. coli also arises in animals with no antibiotic selective pressure. Extended-spectrum-β-lactamase-producing E. coli strains with enhanced virulence capacities for toxin production and adherence have evolved, which implies important ramifications for animal and human health. Gene exchanges by conjugative plasmids and insertion elements have driven widespread antibiotic resistance in clinically relevant pathogens. Phylogenetic relatedness of E. coli strains from various geographic locations and hosts, such as animals, environmental sources, and humans, suggests that transmission of MDR E. coli strains occurs intercontinentally without host barriers.IMPORTANCE Multidrug-resistant (MDR) Escherichia coli isolates pose global threats to public health due to the decreasing availability of treatment options. To better understand the characteristics of MDR E. coli isolated from food-producing animals with no antibiotic exposure, we employed genomic comparison, high-resolution phylogenetics, and functional characterization. Our findings highlight the potential capacity of MDR E. coli to cause severe disease and suggest that these strains are widespread intercontinentally. This study underlines the occurrence of MDR E. coli in food-producing animals raised without antibiotic use, which has alarming, critical ramifications within animal and human medical practice.
20 citations
TL;DR: It is suggested that LPS dosing does not affect pH alone, however, LPS could drive the development of SARA by affecting bacteria and bacterial fermentation.
15 citations
TL;DR: Evaluated effects of single and combined supplementation of calcium and manganese on sporulation of common pathogenic and food spoilage Bacillus species: B. licheniformis, B. subtilis and B. coagulans revealed that B. cereus displayed the weakest sporulation capabilities on media with minimal supplementation levels of calcium-manganese.
Abstract: Spores are resistant against many extreme conditions including the disinfection and sterilization methods used in the food industry. Selective prevention of sporulation of Bacillus species is an ongoing challenge for food scientists and fermentation technologists. This study was conducted to evaluate the effects of single and combined supplementation of calcium and manganese on sporulation of common pathogenic and food spoilage Bacillus species: B. cereus, B. licheniformis, B. subtilis and B. coagulans. Sporulation of Bacillus vegetative cells was induced on sporulation media supplemented with diverse concentrations of the minerals. Under the various mineral supplementation conditions, the degree of sporulation was quantified with colonies formed by the Bacillus spores. The results revealed that B. licheniformis and B. cereus displayed the weakest sporulation capabilities on media with minimal supplementation levels of calcium and manganese. The lowest sporulation of B. subtilis and B. coagulans was observed on media supplemented with the highest level of calcium and low levels of manganese. Depending on effect of supplementation on sporulation, the Bacillus species were divided into two distinct groups: B. licheniformis and B. cereus; and B. subtilis and B. coagulans. The information provides valuable insight to selectively reduce sporulation of Bacillus species undesirable in the food industry.
14 citations
TL;DR: It is shown that animal genetics is associated with the hindgut microbiome, which is related to fat deposition and beta-lactam resistance in the gastrointestinal tract, and potentially a factor affecting the gut antimicrobial resistance.
Abstract: Antibiotics have been widely used in livestock to treat and prevent bacterial diseases. However, use of antibiotics has led to the emergence of antibiotic resistant microorganisms (ARMs) in food animals. Due to the decreased efficacy of antibiotics, alternatives to antibiotics that can reduce infectious diseases in food animals to enhance animal health and growth performance are urgently required. Here, we show that animal genetics is associated with the hindgut microbiome, which is related to fat deposition and beta-lactam resistance in the gastrointestinal tract. We investigated the hindgut microbiota structure in 95 postweaning heifers belonging to the unique multibreed Angus-Brahman herd with breed composition ranging from 100% Angus to 100% Brahman. The hindgut microbial composition of postweaning heifers differed among breed groups. The mucin-degrading bacterium Akkermansia known for promoting energy expenditure was enriched in Brahman calves that contained less intramuscular fat content, while butyrate-producing bacterium Faecalibacterium was linearly positively correlated with Angus proportion. Moreover, the higher relative abundance of beta-lactam resistant genes including ampC gene and arcA gene was associated with the greater Brahman proportion. As the first study aimed at understanding changes in hindgut microbiota among beef cattle with linear gradient of breed composition and its association with marbling in meat, our results suggest that the effects of animal genetics on the gut microbiota structure is associated with fat deposition and potentially a factor affecting the gut antimicrobial resistance.
10 citations
25 Apr 2019
TL;DR: The draft genomes of two Fusobacterium necrophorum isolates from the uterus of dairy cows with metritis are presented to allow for future comparative genome studies.
Abstract: A commensal in the gastrointestinal tract, Fusobacterium necrophorum is involved in the pathogenicity of abscesses, foot rot, and metritis in cattle. Here, we present the draft genomes of two Fusobacterium necrophorum isolates from the uterus of dairy cows with metritis to allow for future comparative genome studies.
5 citations
30 May 2019
TL;DR: The first draft genome sequences of four Helcococcus ovis isolates from the uterus of dairy cows with metritis are reported to enable a better understanding of the bacterium’s pathogenicity and antimicrobial resistance.
Abstract: Helcococcus ovis is an emerging pathogen implicated in the pathogenesis of metritis in dairy cows. Herein, we report the first draft genome sequences of four Helcococcus ovis isolates from the uterus of dairy cows with metritis. This information will enable a better understanding of the bacterium's pathogenicity and antimicrobial resistance.
4 citations
10 Oct 2019
TL;DR: The draft genome sequences of four Bacteroides pyogenes isolates obtained from the uterus of metritic cows are reported to increase the understanding of its pathogenicity, antimicrobial resistance, and differentiation across hosts.
Abstract: Bacteroides pyogenes is found in the human and animal gut and is implicated in the pathogenesis of metritis in cows. We report the draft genome sequences of four Bacteroides pyogenes isolates obtained from the uterus of metritic cows. This will increase the understanding of its pathogenicity, antimicrobial resistance, and differentiation across hosts.
3 citations
TL;DR: Transposon sequencing is defined as a gene sequencing methodology that allows for the identification of nonessential genes and the determination of gene function using a random transposon insertional mutagenesis followed by massively parallel sequencing.
Abstract: Transposons are elements widely dispersed among organisms which are able to move and replicate fragments of genomes. The extensive variability in transposons present in most organisms requires extensive identification and interpretation of the resulting transposon mutants after transposon mutagenesis. However, much of this is reliant on utilizing randomness characteristics of transposon to identify essential genes for the organism of interest. Integration of the transposon mutant approach with commercialized next-generation sequencing (NGS) technology has helped to advance transposon identification by sequencing millions of reads generated from a single run on an NGS platform. Transposon sequencing is defined as a gene sequencing methodology that allows for the identification of nonessential genes and the determination of gene function using a random transposon insertional mutagenesis followed by massively parallel sequencing. The detailed protocol will be outlined in this chapter. The genomic DNA integrated with the transposons is sequenced using an NGS platform in order to determine the location of each mutation.
29 Jan 2019
TL;DR: The authors discusses the use of antibiotics in cattle production operations and answers some common questions about antibiotics and antibiotic-resistant microorganisms in the United States each year, and discusses the benefits and risks of using antibiotics in the cattle production process.
Abstract: Antibiotic-resistant microorganisms cause millions of illnesses and cost billions of dollars in the United States each year. This 5-page fact sheet written by Chad Carr, Matt Hersom, K. C. Jeong, Nicolas DiLorenzo, Jason Scheffler, Victoria Roberts, Gina Faniola, Stephanie Miller, Haley Denney, Nahilia Williams, and Bianca McCracken and published by the UF/IFAS Department of Animal Sciences discusses the use of antibiotics in cattle production operations and answers some common questions about antibiotics and antibiotic-resistant microorganisms. http://edis.ifas.ufl.edu/an351