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Animals : An Open Access Journal From... Mar 2023Non-antibiotic alternatives to antimicrobial growth promoters (AGPs) are required, and understanding the mode of action of AGPs may facilitate the development of...
Non-antibiotic alternatives to antimicrobial growth promoters (AGPs) are required, and understanding the mode of action of AGPs may facilitate the development of effective alternatives. The temporal impact of the conventional antibiotic AGP, virginiamycin, and an AGP alternative, ceragenin (CSA-44), on the structure and function of the broiler chicken cecal microbiota was determined using next-generation sequencing and H-nuclear magnetic resonance spectroscopy (NMR)-based metabolomics. To elucidate the impact of enteric bacterial diversity, oral transplantation (±) of cecal digesta into 1-day-old chicks was conducted. Microbiota transplantation resulted in the establishment of a highly diverse cecal microbiota in recipient chicks that did not change between day 10 and day 15 post-hatch. Neither virginiamycin nor CSA-44 influenced feed consumption, weight gain, or feed conversion ratio, and did not affect the structure of the cecal microbiota in chicks possessing a low or high diversity enteric microbiota. However, metabolomic analysis of the cecal contents showed that the metabolome of cecal digesta was affected in birds administered virginiamycin and CSA-44 as a function of bacterial community diversity. As revealed by metabolomics, glycolysis-related metabolites and amino acid synthesis pathways were impacted by virginiamycin and CSA-44. Thus, the administration of AGPs did not influence bacterial community structure but did alter the function of enteric bacterial communities. Hence, alterations to the functioning of the enteric microbiota in chickens may be the mechanism by which AGPs impart beneficial health benefits, and this possibility should be examined in future research.
PubMed: 36978538
DOI: 10.3390/ani13060997 -
Journal of AOAC International May 2023Antibiotics are used in ethanol production to discourage undesirable bacteria growth. To determine if antibiotic residues remain in the distillers grain (DG) byproduct,...
BACKGROUND
Antibiotics are used in ethanol production to discourage undesirable bacteria growth. To determine if antibiotic residues remain in the distillers grain (DG) byproduct, which is used as an animal food ingredient, the U.S. Food and Drug Administration/Center for Veterinary Medicine previously developed an LC-MS/MS method to detect residues of erythromycin A, penicillin G, virginiamycin M1, and virginiamycin S1 in DG to enable regulatory decision-making.
OBJECTIVE
Erythromycin and penicillin G were quantitated using the stable isotope dilution technique with their isotopically labeled compounds, which are considered optimal internal standards (ISTDs) for quantitative mass spectrometry. With the commercial availability of virginiamycin M1-d2 since then, the objectives of this study were to evaluate the feasibility of its use as it is only doubly deuterated, and to incorporate it in the method to enhance method performance.
METHOD
Antibiotic residues were solvent-extracted from DG; the extract was cleaned up by a hexane wash and solid phase extraction (SPE) and analyzed by LC-MS/MS.
RESULTS
We established suitability of virginiamycin M1-d2 as an ISTD and incorporated it in the method. For all analytes, accuracy and precision ranged 90 to 102% and 3.8 to 6.8, respectively.
CONCLUSIONS
We modified a previously developed LC-MS/MS method that uses virginiamycin M1-d2 as an ISTD to support surveillance studies to determine several drugs in DG.
HIGHLIGHTS
Virginiamycin M1-d2 was successfully incorporated into the method for better virginiamycin M1 quantitation. This addition also allowed calibration curves for all analytes to be constructed in solvent, thereby simplifying the method.
Topics: Animals; Anti-Bacterial Agents; Streptogramin A; Chromatography, Liquid; Tandem Mass Spectrometry; Penicillin G; Erythromycin; Solvents; Edible Grain; Solid Phase Extraction; Drug Residues
PubMed: 36975613
DOI: 10.1093/jaoacint/qsad032 -
Nature Communications Mar 2023During biosynthesis by multi-modular trans-AT polyketide synthases, polyketide structural space can be expanded by conversion of initially-formed electrophilic...
During biosynthesis by multi-modular trans-AT polyketide synthases, polyketide structural space can be expanded by conversion of initially-formed electrophilic β-ketones into β-alkyl groups. These multi-step transformations are catalysed by 3-hydroxy-3-methylgluratryl synthase cassettes of enzymes. While mechanistic aspects of these reactions have been delineated, little information is available concerning how the cassettes select the specific polyketide intermediate(s) to target. Here we use integrative structural biology to identify the basis for substrate choice in module 5 of the virginiamycin M trans-AT polyketide synthase. Additionally, we show in vitro that module 7, at minimum, is a potential additional site for β-methylation. Indeed, analysis by HPLC-MS coupled with isotopic labelling and pathway inactivation identifies a metabolite bearing a second β-methyl at the expected position. Collectively, our results demonstrate that several control mechanisms acting in concert underpin β-branching programming. Furthermore, variations in this control - whether natural or by design - open up avenues for diversifying polyketide structures towards high-value derivatives.
Topics: Methylation; Virginiamycin; Streptomyces; Protein Binding; Models, Molecular; Protein Structure, Tertiary; Substrate Specificity
PubMed: 36899003
DOI: 10.1038/s41467-023-36974-3 -
Biology Feb 2023() has been considered to be an effective probiotic to maintain gut health and boost productivity in the pig industry, but there is no complete understanding of its...
() has been considered to be an effective probiotic to maintain gut health and boost productivity in the pig industry, but there is no complete understanding of its mechanisms. We determined whether weaned piglets exposed to -S6 (probiotic) had altered intestinal barrier function or microbiota composition. In our study, 108 weaned piglets (54 barrows and 54 gilts) were divided equally into three groups, each with six pens and six piglets/pen, and fed a basal diet supplemented without or with antibiotic (40 g/t of Virginiamycin and 500 g/t of Chlortetracycline) or probiotic (1000 g/t of ) for a 14-day trial. On day 14, one piglet was chosen from each pen to collect blood and intestinal samples. Compared with the control group, dietary supplementation with a probiotic promoted body weight (BW) gain and average daily gains (ADG) while reducing diarrhea incidence ( < 0.05). Probiotics enhanced superoxidase dismutase (SOD) activity and decreased malondialdehyde (MDA) levels in serum ( < 0.05), and increased the level of mRNA expression of , and ( < 0.05) in the jejunum mucosa. Moreover, supplementation with probiotics improved intestinal mucosal integrity as evidenced by higher villus heights and a higher ratio of villus heights to crypt depths (duodenum and jejunum) and higher mRNA and protein levels of occludin and ZO-1 in jejunum mucosa ( < 0.05). The intestinal sIgA levels ( < 0.05) were elevated in the probiotic group, and that of serum immunoglobulin A (IgA) tended to be higher ( = 0.09). Furthermore, weaning piglets who were given probiotics had a better balance of the cecum microbiota, with abundance increased and abundance decreased. In conclusion, dietary supplementation with the probiotic -S6 promoted intestinal integrity, which was associated, in part, with modulating intestinal barrier function and microbial diversity in weaned piglets; it may offer a promising alternative to antibiotics to prevent diarrhea.
PubMed: 36829515
DOI: 10.3390/biology12020238 -
Frontiers in Veterinary Science 2023Feed additives such as monensin (MON) and virginiamycin (VM) are widely used in feedlots diets to maximize rumen fermentation. However, the knowledge about the effects...
Withdrawal of sodium monensin when associated with virginiamycin during adaptation and finishing periods on feedlot performance, feeding behavior, carcass, rumen, and cecum morphometrics characteristics of Nellore cattle.
Feed additives such as monensin (MON) and virginiamycin (VM) are widely used in feedlots diets to maximize rumen fermentation. However, the knowledge about the effects of MON and VM combinations in specifics feedlot periods and the benefits of this association are still unclear. This study aimed to evaluate the effects of withdrawal of MON when associated with VM during the adaptation and finishing periods on feedlot performance of Nellore cattle. The experiment was designed as a completely randomized block replicated six times (four animals/pen) in which 120 Nellore bulls (378.4 ± 24.4 kg) were allocated in 30 pens and fed for 112 days according to the following treatments: (T1) MON during the entire feeding period; (T2) VM during the entire feeding period; (T3) MON+VM during the adaptation period and only VM during the finishing period 1 and 2; (T4) MON+VM during the entire feeding period; (T5) MON+VM during the adaptation and finishing period 1 and only VM during the finishing period 2. After 112 days on feed, no treatment effect was observed for DMI ( ≥ 0.12). However, bulls fed T5 had greater ( = 0.05) final BW and ADG when compared to T1, T2, and T4. Cattle from T3 and T5 groups presented heavier HCW ( = 0.05) than that fed T1, T2, and T4. Nellore bulls fed T1 and T5 had lower ( < 0.01) DMI variation than those receiving T2. The withdrawal of MON when associated with VM during the final third of the feedlot period improved overall final BW, ADG, and HCW when compared to bulls fed either MON or VM, but did not positively impact feedlot performance when compared to cattle that had MON withdrawn at the end of the adaptation period.
PubMed: 36761886
DOI: 10.3389/fvets.2023.1067434 -
Frontiers in Veterinary Science 2022A study was conducted to evaluate performance, eggshell quality, nutrient metabolizability, and incubation traits of laying breeder hens fed diets supplemented with an...
A study was conducted to evaluate performance, eggshell quality, nutrient metabolizability, and incubation traits of laying breeder hens fed diets supplemented with an additive containing polyphenols and saponins of a proprietary blend from and (QY) biomass. Hens were fed 4 feeds in 5 periods of 28 days each from 30 to 49 weeks of age. Experimental feeds were a Control diet; Control + virginiamycin (33 g/ton); Control + QY (250 g/ton) and Control + virginiamycin + QY. A total of 40 White Plymouth Rock and 44 Rhode Island Red breeder hens were allocated in individual cages using a completely randomized block design with 21 replicates. Performance parameters, evaluated per period, were egg production, egg weight, FCR, egg mass, and culled eggs. All eggs were collected in the last 4 days of each period to evaluate specific egg weight, percentage of albumen, yolk and shell, and Haugh unit as well as cuticle quality, shell strength, and shell thickness. At the end of the experiment, nutrient metabolizability assessment and four incubations were conducted. There were no interactions between diet and period in all evaluated responses ( > 0.05). Experimental diets did not affect daily egg production, egg weight, and egg mass as well as Haugh unit, yolk and albumen percentage, and yolk color ( > 0.05). However, hens fed Control + QY produced eggs with better shell strength, shell thickness, and cuticle quality than hens fed the Control ( < 0.05). Hens fed Control + QY or Control + virginiamycin + QY had lower culled eggs, better FCR and higher egg specific weight, shell percentage, and yolk strength compared to breeder hens fed the Control ( < 0.05). In general, hens fed QY achieved enhanced performance and egg quality compared to virginiamycin. In conclusion, laying breeder hens fed diets supplemented with Quillaja and Yucca additive, from 30 to 49 weeks of age, maintained their productive performance, had improved eggshell and cuticle quality and reduced culled, dirty and contaminated eggs.
PubMed: 36744222
DOI: 10.3389/fvets.2022.1069295 -
Translational Animal Science Oct 2022Monensin and virginiamycin are included in beef cattle finishing diets as prophylaxis to minimize the incidence of ruminal acidosis and liver abscesses. Due to different...
Monensin and virginiamycin are included in beef cattle finishing diets as prophylaxis to minimize the incidence of ruminal acidosis and liver abscesses. Due to different and probably complementary modes of action, this study aimed to determine the effects of a combination of monensin and virginiamycin, both included in the diet at recommended doses, on ruminal health, the occurrence of liver abscesses, and growth performance of feedlot-finished cattle. One hundred and forty-four steers (6 animals/pen) were fed 1 of 3 corn-based finishing diets containing 30 mg of monensin (), 25 mg of virginiamycin (), or 30 and 25 mg of monensin and virginiamycin (), respectively, per kilogram of dry matter. Ruminal pH probes were inserted into two animals per pen and set to record pH every 10 min. On d 100, animals were slaughtered, and rumens and livers were recovered, on which occurrence and degree of ruminal damage, prevalence and number of liver abscesses, and liver scores (A-: livers with no more than two small abscesses; A+: livers with at least one large abscess or more than four medium abscesses; A: any other abscessed liver) were determined. Simultaneous inclusion of monensin and virginiamycin resulted in a 4.3% decrease ( < 0.04) in dry matter intake (; 8.8, 9.2, and 9.2 ± 0.19 kg/d for MN + VM, MN, and VM-fed animals, respectively) and similar ( > 0.13) average daily body weight gain (; 1.49 ± 0.021 kg/d) and hot carcass weight (; 269 ± 1.7 kg), compared with feeding diets containing one additive or the other. Therefore, in terms of ADG, a 9.4% improvement ( < 0.01) in feed efficiency was observed in MN + VM-fed animals. Backfat thickness (5.6 ± 0.08 mm) and ribeye area (69.9 ± 0.53 cm) remained unaffected ( ≥ 0.74), as well as the minimum (4.98 ± 0.047), mean (6.11 ± 0.037), and maximum ruminal pH (7.23 ± 0.033) values and the time (125 ± 22.3 min/d), area (57.67 ± 12.383 pH × h), and episodes (22 ± 3.8 bouts) of pH below 5.6 ( ≥ 0.12). Overall, prevalence (24 ± 3.4%) and the number of liver abscesses (1.6 ± 0.14 abscesses/abscessed liver), liver scores (20 ± 3.1% of A- and 4 ± 1.8% of A livers), and prevalence (67 ± 3.5%) and degree of damage to the ruminal epithelium (2.5 ± 0.22% affected surface) were similar ( ≥ 0.18) across treatments; however, the occurrence of ruminal lesions tended ( ≤ 0.07) to be associated with that of liver abscesses and reduced ADG when feeding monensin alone.
PubMed: 36601062
DOI: 10.1093/tas/txac154 -
European Journal of Medicinal Chemistry Jan 2023New therapeutic strategies for glioblastoma treatment, especially tackling the tumour's glioblastoma stem cell (GSC) component, are an urgent medical need. Recently,...
New therapeutic strategies for glioblastoma treatment, especially tackling the tumour's glioblastoma stem cell (GSC) component, are an urgent medical need. Recently, mitochondrial translation inhibition has been shown to affect GSC growth, clonogenicity, and self-renewal capability, therefore becoming an attractive therapeutic target. The combination of streptogramins B and A antibiotics quinupristin/dalfopristin (Q/D), which inhibits mitochondrial ribosome function, affects GSCs more effectively in vitro than the standard of care temozolomide. Here, docking calculations based on the cryo-EM structure of the Q/D-bound mitochondrial ribosome have been used to develop a series of streptogramin A derivatives. We obtained twenty-two new and known molecules starting from the dalfopristin and virginiamycin M1 scaffolds. A structure-activity relationship refinement was performed to evaluate the capability of these compounds to suppress GSC growth and inhibit mitochondrial translation, either alone or in combination with quinupristin. Finally, quantitative ultra HPLC-mass spectrometry allowed us to assess the cell penetration of some of these derivatives. Among all, the fluorine derivatives of dalfopristin and virginiamycin M1, (16R)-1e and (16R)-2e, respectively, and flopristin resulted in being more potent than the corresponding lead compounds and penetrating to a greater extent into the cells. We, therefore, propose these three compounds for further evaluation in vivo as antineoplastic agents.
Topics: Humans; Streptogramins; Streptogramin A; Glioblastoma; Anti-Bacterial Agents; Protein Biosynthesis; Protein Synthesis Inhibitors; Microbial Sensitivity Tests
PubMed: 36495628
DOI: 10.1016/j.ejmech.2022.114979 -
Antibiotics (Basel, Switzerland) Nov 2022The timely implementation of antimicrobial stewardship interventions could delay or prevent the development of higher levels of antimicrobial resistance in the future....
The timely implementation of antimicrobial stewardship interventions could delay or prevent the development of higher levels of antimicrobial resistance in the future. In food-producing animals in Australia, high-importance antimicrobials, as rated by the Australian Strategic and Technical Advisory Group (ASTAG), include virginiamycin and third-generation cephalosporins (in individual pigs or cattle). The use of high-importance antimicrobials in companion animals is more widespread and less regulated. There is no national antimicrobial use surveillance system for animals in Australia. Consequently, there is a gap in the knowledge about reasonable use across all sectors of veterinary practice. This study explored attitudes towards the use in veterinary medicine of antimicrobials with high importance to human health, and determined levels of agreement about the introduction of restrictions or other conditions on this use. An online survey was distributed via social media and email from June to December 2020 to veterinarians working in Australia. Of the 278 respondents working in clinical practice, 49% had heard of the ASTAG rating system, and 22% used a traffic light system for antimicrobial importance in their practice. Overall, 61% of participants disagreed that veterinarians should be able to prescribe high-importance antimicrobials without restrictions. If there were to be restrictions, there was most agreement amongst all respondents for only restricting high-importance antimicrobials (73%). There is a need for education, guidance, and practical support for veterinarians for prescribing high-importance antimicrobials alongside any restrictions.
PubMed: 36358244
DOI: 10.3390/antibiotics11111589 -
Applied Microbiology and Biotechnology Sep 2022Antibiotic resistance genes are usually tightly controlled by transcription factors and RNA regulatory elements including sRNAs, riboswitches, and attenuators, and their...
Antibiotic resistance genes are usually tightly controlled by transcription factors and RNA regulatory elements including sRNAs, riboswitches, and attenuators, and their expression is activated to respond to antibiotic exposure. In previous work, we revealed that the rppA gene is regulated by attenuator LRR and two mistranslation products in Bacillus thuringiensis BMB171. However, its function and promoter regulation is still not precise. In this study, we demonstrated that the encoding product of the rppA gene acts as an ARE1 ABC-F protein and confers resistance to antibiotics virginiamycin M1 and lincomycin when overexpressed. Besides the reported attenuator LRR, the expression of the rppA gene is controlled by the sigma factor SigA and a global transcription factor CcpA. Consequently, its promoter activity is mainly maintained at the stationary phase of cell growth and inhibited in the presence of glucose. Our study revealed the function and regulation of the rppA gene in detail. KEY POINTS: • The RppA protein acts as an ARE1 ABC-F protein • The rppA gene confers resistance to antibiotics virginiamycin M1 and lincomycin when overexpressed • The expression of the rppA gene is regulated by the sigma factor SigA and the pleiotropic regulator CcpA.
Topics: Anti-Bacterial Agents; Bacillus thuringiensis; Bacterial Proteins; Drug Resistance, Microbial; Gene Expression Regulation, Bacterial; Immunoglobulin A, Secretory; Lincomycin; Sigma Factor; Streptogramin A; Transcription Factors; Transcription, Genetic
PubMed: 35906441
DOI: 10.1007/s00253-022-12090-y