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Accounts of Chemical Research Apr 2021Continued, rapid development of antimicrobial resistance has become worldwide health crisis and a burden on the global economy. Decisive and comprehensive action is...
Continued, rapid development of antimicrobial resistance has become worldwide health crisis and a burden on the global economy. Decisive and comprehensive action is required to slow down the spread of antibiotic resistance, including increased investment in antibiotic discovery, sustainable policies that provide returns on investment for newly launched antibiotics, and public education to reduce the overusage of antibiotics, especially in livestock and agriculture. Without significant changes in the current antibiotic pipeline, we are in danger of entering a post-antibiotic era.In this Account, we summarize our recent efforts to develop next-generation streptogramin and lankacidin antibiotics that overcome bacterial resistance by means of modular chemical synthesis. First, we describe our highly modular, scalable route to four natural group A streptogramins antibiotics in 6-8 steps from seven simple chemical building blocks. We next describe the application of this route to the synthesis of a novel library of streptogramin antibiotics informed by in vitro and in vivo biological evaluation and high-resolution cryo-electron microscopy. One lead compound showed excellent inhibitory activity in vitro and in vivo against a longstanding streptogramin-resistance mechanism, virginiamycin acetyltransferase. Our results demonstrate that the combination of rational design and modular chemical synthesis can revitalize classes of antibiotics that are limited by naturally arising resistance mechanisms.Second, we recount our modular approaches toward lankacidin antibiotics. Lankacidins are a group of polyketide natural products with activity against several strains of Gram-positive bacteria but have not been deployed as therapeutics due to their chemical instability. We describe a route to several diastereomers of 2,18--lankacidinol B in a linear sequence of ≤8 steps from simple building blocks, resulting in a revision of the C4 stereochemistry. We next detail our modular synthesis of several diastereoisomers of -lankacidinol that resulted in the structural reassignment of this natural product. These structural revisions raise interesting questions about the biosynthetic origin of lankacidins, all of which possessed uniform stereochemistry prior to these findings. Finally, we summarize the ability of several - and -lankacidins to inhibit the growth of bacteria and to inhibit translation in vitro, providing important insights into structure-function relationships for the class.
Topics: Anti-Bacterial Agents; Drug Resistance, Bacterial; Escherichia coli; Gram-Negative Bacteria; Gram-Positive Bacteria; Macrolides; Microbial Sensitivity Tests; Molecular Conformation; Molecular Dynamics Simulation; Ribosomes; Streptogramins; Virginiamycin
PubMed: 33792282
DOI: 10.1021/acs.accounts.0c00894 -
Journal of AOAC International Sep 2021Antibiotics are used in ethanol production to discourage the growth of bacteria that would lower the yield of the product. Any antibiotic residues remaining in...
BACKGROUND
Antibiotics are used in ethanol production to discourage the growth of bacteria that would lower the yield of the product. Any antibiotic residues remaining in distillers grain (DG) co-product could lead to antimicrobial resistance, which is a public health concern. The U.S. Food and Drug Administration (FDA) Center for Veterinary Medicine (CVM) previously developed an LC-MS/MS analytical method to detect residues of erythromycin A, penicillin G, virginiamycin M1, and virginiamycin S1 in DG to enable regulatory decision making.
OBJECTIVE
The objective of this study was to ensure the method's robustness by carrying out a multi-laboratory validation of the method.
METHOD
Test portions were extracted with a mixture of acetonitrile and buffer. The extract was cleaned by solid phase extraction. The concentrated eluant was reconstituted and analyzed by LC-MS/MS. Eight laboratories participated in the study.
RESULTS
Average accuracies for the combined three matrixes for all four compounds at all fortification levels ranged from 83->109% with repeatability relative standard deviation (RSDr; within laboratory) ≤17% and reproducibility relative standard deviation (RSDR; between laboratory) ≤21%. The Horwitz ration (HorRat) values ranged 0.4-1.0 indicating that method reproducibility is acceptable.
CONCLUSIONS
An interlaboratory study was successfully conducted to evaluate an LC-MS/MS method for the determination of the drugs of interest in DG. The results demonstrate that the method is fit for purpose to determine the drugs in DG and could serve as a regulatory method capable of being used for compliance actions for DG containing these antibiotic contaminants.
HIGHLIGHTS
The method was posted to the FDA/Foods Program Compendium of Analytical Laboratory Methods.
Topics: Anti-Bacterial Agents; Chromatography, Liquid; Penicillin G; Reproducibility of Results; Tandem Mass Spectrometry
PubMed: 33774675
DOI: 10.1093/jaoacint/qsab026 -
Translational Animal Science Jan 2021The objective of this experiment was to determine the effects of narasin (NAR; Skycis®; Elanco Animal Health, Greenfield, IN) or virginiamycin (VIR; Stafac®; Phibro...
The objective of this experiment was to determine the effects of narasin (NAR; Skycis®; Elanco Animal Health, Greenfield, IN) or virginiamycin (VIR; Stafac®; Phibro Animal Health Corporation, Teaneck, NJ) on finishing pig growth performance and carcass characteristics. Two separate experiments were conducted at the same site in 2013 and 2014. A total of 576 pigs (initial BW = 23.2 ± 0.19 kg) were housed in 24 pens with 8 pigs per pen in Exp. 1. In Exp. 2, a total of 888 pigs (initial BW = 26.2 ± 0.12 kg) were housed in 39 pens with 8 pigs per pen. Treatments consisted of a series of unmedicated corn-soybean meal diets (CON), CON + NAR (15 mg/kg), or CON + VIR (11 mg/kg) fed for 108 d (Exp. 1) or 109 d (Exp. 2). Pen was the experimental unit in both studies. Data were analyzed as a randomized complete block design with the main effects of block and treatment (Exp. 1) and as an incomplete block design with the fixed effect of treatment and the random effects of barn and barn within block (Exp. 2). In Exp.1, NAR and VIR increased ( < 0.05) ADG and ADFI from days 0 to 28, and BW on days 28, 56, 76, and 97 as compared to pigs fed CON. During days 0-28, pigs fed NAR had a greater ( < 0.05) G:F than those fed CON or VIR. Also, during days 28-56 pigs fed VIR had a greater ( < 0.05) ADFI than pigs fed CON. Pigs fed NAR or VIR had greater ( < 0.05) carcass yield than those fed CON. In Exp.2, feeding NAR increased ( < 0.05) pig BW from days 54 through 96 compared to pigs fed CON or VIR. No differences ( > 0.05) in ADG were detected between pigs fed VIR and CON through the first 74 day, but ADG of pigs fed VIR was similar to ( > 0.05) those fed NAR from days 26 to 54. From day 0 to 109, NAR improved ADG compared to pigs fed VIR, which also had similar gain to those consuming CON ( = 0.04). Feed efficiency was similar between pigs fed NAR and VIR with pigs fed CON intermediate ( = 0.05). Pigs fed NAR had a greater ( < 0.05) HCW and loin depth than those fed CON or VIR. A subtherapeutic dose of VIR showed improvements in growth performance that were similar to NAR in one experiment. Although there were differences in the magnitude of growth and carcass effects of NAR between the two studies, pigs fed NAR showed at least a tendency to have greater G:F and in some cases increased carcass weight and yield compared to pigs consuming nonmedicated feed.
PubMed: 33748685
DOI: 10.1093/tas/txab020 -
Antimicrobial Resistance in Porcine Enterococci in Australia and the Ramifications for Human Health.Applied and Environmental Microbiology Apr 2021Enterococci are ubiquitous opportunistic pathogens that have become a major public health issue globally. The increasing prevalence of antimicrobial resistance in... (Comparative Study)
Comparative Study
Enterococci are ubiquitous opportunistic pathogens that have become a major public health issue globally. The increasing prevalence of antimicrobial resistance in hospital-adapted enterococci had been thought to originate from livestock. However, this association between livestock and hospital-adapted enterococci is currently unclear. This study investigates the antimicrobial susceptibilities of enterococci isolated from pig cecal samples and compares the genomic characteristics of from pigs to those of isolates from meat chickens and from human sepsis cases. From 200 cecal samples, antimicrobial susceptibility testing was performed for ( = 84), ( = 36), and ( = 17). Whole-genome sequencing was performed for all isolates, and the sequences were compared to those of previously studied isolates from meat chickens and human sepsis cases through bioinformatics analysis. Resistance (non-wild type) to erythromycin, gentamicin, tetracycline, ampicillin, daptomycin, virginiamycin, and quinupristin-dalfopristin was identified. More importantly, except for a single isolate harboring the operon, no resistance was observed in the three species to vancomycin, teicoplanin, and linezolid, which are critically important antimicrobials used to treat enterococcal infections in humans. The isolates from chickens were genetically distinct from human and pig isolates, which were more closely related. Human strains that were closely related to pig strains were not typical "hospital-adapted strains" as previously identified. The results of this study show that enterococci from Australian finisher pigs are not a source of resistance to critically important antimicrobials and that from pigs is not part of the current human hospital-adapted population. Resistance to the critically important antimicrobials vancomycin, teicoplanin, and linezolid is not found in enterococci collected from Australian finisher pigs. However, some antimicrobial resistance was observed. In particular, resistance to quinupristin-dalfopristin, a combination of two streptogramin class antimicrobials, was identified despite the absence of streptogramin use Australia-wide since 2005. Other observed resistance among enterococci from pigs include chloramphenicol, erythromycin, and tetracycline resistance. Genomic comparison of from Australian pigs to isolates collected from previous studies on chickens and humans indicate that from pigs are genetically more similar to those of humans than those from chickens. Despite the increased genetic similarities, strains from pigs are phylogenetically distinct and did not belong to the dominant sequence types found in hospital-adapted strains causing sepsis in humans. Therefore, the results indicate that Australian finisher pigs are not a source of hospital-adapted in Australia.
Topics: Animals; Anti-Bacterial Agents; Australia; Cecum; Chickens; Drug Resistance, Bacterial; Enterococcus; Environmental Monitoring; Genome, Bacterial; Humans; Microbial Sensitivity Tests; Sepsis; Swine
PubMed: 33712430
DOI: 10.1128/AEM.03037-20 -
Tropical Animal Health and Production Feb 2021The effect of the association of non-protein nitrogen, yeast, and bacterial probiotics on the ruminal microbiome of beef cattle intensively finished on pasture was...
The effect of the association of non-protein nitrogen, yeast, and bacterial probiotics on the ruminal microbiome of beef cattle intensively finished on pasture was evaluated. The experiment was carried out in a completely randomized design with five treatments and four replications. The treatments consisted of a group of animals kept on pasture that received low consumption supplementation (LS) and four groups that received for 98 days, 17.5 g concentrate kg body weight. The supplements were composed of the association of additives: urea (U), slow-release non-protein nitrogen (U+SRN), yeast (Saccharomyces cerevisiae; U+SRN+Y), and bacterial probiotics (live strains of bacteria; U+SRN+Y+BP). All supplements also contained salinomycin and virginiamycin. After slaughtering the animals, samples of ruminal content were collected to quantify groups of fibrolytic bacteria (Ruminococcus albus and Fibrobacter succinogenes), non-fibrolytic (Prevotella ruminicola, Selenomonas ruminantium, and Streptococcus bovis), Archaea, and ciliate protozoa, using the qPCR technique. The abundance of F. succinogenes was the same for the LS animals and those that received the supplement U+SRN+Y (1.42×10 copies mL) but higher than the other treatments. Supplementation reduced by 90% the abundance of S. bovis compared to the LS. The inclusion of yeast increased the abundance of fibrolytic bacteria by 2.2-fold. For animals that received the supplement U+SRN+Y+BP and the LS, there was no difference for non-fibrolytic bacteria (3.07×10 copies mL). The use of yeasts and sources of non-protein nitrogen in high-concentrate diets for beef cattle stimulates the growth of fibrolytic bacteria, which can contribute to the reduction of digestive disorders and metabolic diseases in animals that receive diets with high concentrate in pasture intensive termination systems.
Topics: Animal Feed; Animals; Bacteria; Cattle; Diet; Fermentation; Fibrobacter; Ionophores; Probiotics; Rumen; Ruminococcus; Saccharomyces cerevisiae
PubMed: 33598856
DOI: 10.1007/s11250-021-02617-2 -
Journal of Environmental Science and... 2021Sugarcane yeast and brewer's yeast from ethanol production are widely used as ingredients of animal feed formulations in Brazil. To avoid the contamination of the must...
Sugarcane yeast and brewer's yeast from ethanol production are widely used as ingredients of animal feed formulations in Brazil. To avoid the contamination of the must in ethanol production refineries, the use of antibiotics is one of the main preventive treatments. Thus, there is a risk of antibiotic residues carry over from yeast to animal feed. This unintentional addition of antibiotics can produce non-compliant feed products, due to regulatory aspects and their toxicity for animals. The results of an exploratory program to assess the occurrence of over 60 antibiotics and other pharmaceuticals in 27 sugarcane yeast and brewer's yeast samples were described. Monensin was present in seven samples with concentrations ranging from 0.47 to 263.5 mg kg. Other antibiotics quantitated were virginiamycin (2.25 mg kg) and amprolium (0.25 mg kg). Monensin in sugarcane yeast may represent a risk for further feeds production, especially for those products intended for sensible species such as equines and rabbits, for which monensin has toxic effects.
Topics: Animal Feed; Anti-Bacterial Agents; Brazil; Ethanol; Food Industry; Monensin; Saccharomyces cerevisiae; Virginiamycin; Yeasts
PubMed: 33560907
DOI: 10.1080/03601234.2021.1880223 -
Journal of Animal Science Feb 2021Essential oils are plant-derived aromatic volatile oils, and they contain bioactive compounds that have been shown to improve poultry nutrition. In this study, we...
Effects of dietary oregano essential oil supplementation on growth performance, intestinal antioxidative capacity, immunity, and intestinal microbiota in yellow-feathered chickens.
Essential oils are plant-derived aromatic volatile oils, and they contain bioactive compounds that have been shown to improve poultry nutrition. In this study, we investigated the effects of oregano essential oil (OEO) on intestinal antioxidative capacity, immunity, and gut microbiota of young yellow-feathered chickens. A total of nine hundred and sixty 1-d-old female Qingyuan partridge chickens were randomly allocated to four treatment groups with six replicates of 40 birds each, and the feeding trial was lasted for 30 d. The controls were fed on a basal diet without in-feed antibiotics; the birds in the antibiotic group were fed the basal diet supplemented with 20 mg/kg virginiamycin; the remaining birds were fed the basal diet containing 150 or 300 mg/kg OEO, respectively. Dietary supplementation with 150 or 300 mg/kg OEO increased average daily feed intake (P = 0.057) and average daily gain (P < 0.05). The activities of glutathione peroxidase and total antioxidative capacity in plasma, jejuna, and ileal mucosa were increased by OEO supplementation (P < 0.05), with a trend of lower jejunal content of malonaldehyde (P = 0.062). Moreover, dietary OEO increased the content of secretory immunoglobulin A (P = 0.078) and the relative expression of Claudin 1, Mucin 2, and Avain beta-defensin 1 in ileum (P < 0.05). Sequencing data of 16S rRNA indicated that dietary OEO increased the relative abundance of Firmicutes phylum, and Clostridium and Lactobacillus genera, and decreasing that of Romboutsia. Functional analyses indicated that microbial amino sugar and nucleotide sugar metabolism, replication, and repair systems were higher in OEO groups than those of controls and antibiotic treatment. In conclusion, dietary supplementation with OEO enhanced growth performance, alleviated local oxidative stress in intestine, improved production of natural antibodies, and favorably modulated intestinal microbiota composition.
Topics: Animal Feed; Animals; Antioxidants; Chickens; Diet; Dietary Supplements; Female; Gastrointestinal Microbiome; Intestines; Oils, Volatile; Origanum; RNA, Ribosomal, 16S
PubMed: 33544855
DOI: 10.1093/jas/skab033 -
Poultry Science Mar 2021Probiotics are being developed as alternatives to antibiotic growth promoters. The aim of the study was to investigate the effects of 2 novel strains of Bacillus pumilus...
Effects of novel probiotic strains of Bacillus pumilus and Bacillus subtilis on production, gut health, and immunity of broiler chickens raised under suboptimal conditions.
Probiotics are being developed as alternatives to antibiotic growth promoters. The aim of the study was to investigate the effects of 2 novel strains of Bacillus pumilus and Bacillus subtilis on production, intestinal microbiota, gut health, and immunity of broilers raised under suboptimal conditions. Day-old chicks (Cobb 500, n = 2,073) were randomly assigned into 6 groups: Con group (group fed with basal diet), Ab group (group treated with virginiamycin), groups treated with 2 levels of B. pumilus (low dose: 3 × 10 cfu/kg of feed [BPL] and high dose: 1 × 10 cfu/kg [BPH]), and groups treated with 2 levels of B. subtilis (low dose: 3 × 10 cfu/kg [BSL] and high dose: 1 × 10 cfu/kg [BSH]). Production parameters were recorded weekly. Cecal tonsils and content as well as ileum samples were collected on day 14 and day 42. Cecal tonsils were used to sort T-regulatory cells (CD4+CD8-CD25+ and CD4+CD8+CD25+) to study expression of IL-10 and interferon gamma, whereas cecal content was used for bacterial culture. Ileum samples were used to measure gene expression of tight junction proteins, mucin, and cytokines. BW and feed intake increased in the Ab, BPL, BSL, and BSH groups compared with the Con group between day 35 and day 42. The CD4+CD8-CD25+ cells expressed high levels of IL-10 in the BSH group on day 14 and in the BPL, BSL, and BSH groups on day 42 and high levels of interferon gamma in the BPL, BSL, and BSH groups on day 14 and in the BSL and BSH groups on day 42. The expression of IL-10 and interferon gamma in CD4+CD8+CD25+ cells was higher only in the BSH group on day 14 and day 42. Cecal bacterial populations of genera, Lactobacillus (day 14 and day 42) and Clostridium (day 14), were higher in the BSH group. Expression of tight junction protein increased significantly in the ileum on day 14 in the BPL (occludin, zona occludens 1 [ZO-1]), BSL (occludin, ZO-1), and BSH (occludin, ZO-1, junctional adhesion molecule 2 [JAM-2]) groups compared with that in the Con group and declined in all groups except in the BSH group (occludin, ZO-1, JAM-2) on day 42. Expression of MUC2 and IL-17F increased in all groups on day 14 and remained high on day 42 in the BSL and BSH groups. Taken together, both Bacillus probiotics altered the intestinal and immune activities, particularly on day 14, suggesting beneficial influence of probiotics.
Topics: Animals; Bacillus pumilus; Bacillus subtilis; Chickens; Diet; Gastrointestinal Microbiome; Gastrointestinal Tract; Probiotics; Random Allocation
PubMed: 33516480
DOI: 10.1016/j.psj.2020.11.048 -
Scientific Reports Jan 2021
PubMed: 33510325
DOI: 10.1038/s41598-021-82285-2 -
Anais Da Academia Brasileira de Ciencias 2020The aim was to evaluate the use of mixture of microencapsulated carvacrol and cinnamaldehyde as a replacement for growth-promoting antibiotics in broiler diets on...
The aim was to evaluate the use of mixture of microencapsulated carvacrol and cinnamaldehyde as a replacement for growth-promoting antibiotics in broiler diets on performance, intestinal quality, organ development, carcass yields and cuts, and meat quality. In the trial were used 600 male chicks, allocated in a completely randomized design, with five treatments and eight replicates of 15 birds, reared up to 41 days of age. The treatments were: Negative Control (NC), Positive Control (PC) 30 mg/kg of virginiamycin, NC+100 mg/kg of essential oils, NC+200 mg/kg of essential oils and NC+400 mg/kg of essential oils. Essential oils were composed by a micro-encapsulated blend, with of 60% cinnamaldehyde, 30% carvacrol and 10% carrier. Birds received essential oils achieved performance equivalent to those birds received PC diets, having better development than NC broilers. No differences were found on relative organ weight, intestinal mucosa and meat quality parameters, however, higher villus:cript ratio was found in PC, NC+200 and NC+400 groups. Meat crude protein and yellowness were influenced by inclusion of carvacrol and cinnamaldehyde. It was concluded microencapsulated carvacrol and cinnamaldehyde can replace growth-promoting antibiotic in broiler diets, ensuring performance, intestinal integrity and broiler meat quality.
Topics: Acrolein; Animal Feed; Animal Nutritional Physiological Phenomena; Animals; Anti-Bacterial Agents; Chickens; Cymenes; Diet; Dietary Supplements; Male; Meat
PubMed: 33331397
DOI: 10.1590/0001-3765202020200343