RESUMO
Cephalosporin antimicrobials can be utilized for the treatment of sepsis in neonatal foals, particularly when an aminoglycoside is contraindicated. Some cephalosporins, however, are not utilized because of cost, sporadic availability, or uncertainty about efficacy. The plasma disposition of ceftazidime, a third-generation cephalosporin with a broad spectrum of activity against a wide variety of gram-negative bacteria and minimal renal side effects has not been reported in neonatal foals. In this study, the plasma disposition of single intravenous (IV) and intramuscular (IM) doses of ceftazidime in neonatal foals was determined. Six healthy one to two-day-old foals were given 25 mg/kg of ceftazidime by IV and IM routes in a cross-over design, with a 48-h washout period between doses. Non-compartmental analysis was used to estimate plasma pharmacokinetic parameters. Median t1/2 was 2 h and median AUC0-last was 364 µg h/ml for both IV and IM administration. Median Cmax after IM administration was 101 µg/ml, with a median Tmax of 0.7 h. Relative bioavailability of IM injection was 90%. There were no statistically significant differences between estimated IV and IM pharmacokinetic parameters. Plasma concentrations remained above the human CLSI susceptible breakpoint for Enterobacteriaceae for over 8 h following IV and IM administration.
Assuntos
Antibacterianos/administração & dosagem , Cavalos , Administração Intravenosa/veterinária , Animais , Ceftazidima , Cefalosporinas , Cavalos/sangue , Injeções Intramusculares/veterináriaRESUMO
Conjugation is one of the main mechanisms involved in the spread and maintenance of antibiotic resistance in bacterial populations. We recently showed that the emerging macrolide resistance in the soilborne equine and zoonotic pathogen Rhodococcus equi is conferred by the erm(46) gene carried on the 87-kb conjugative plasmid pRErm46. Here, we investigated the conjugal transferability of pRErm46 to 14 representative bacteria likely encountered by R. equi in the environmental habitat. In vitro mating experiments demonstrated conjugation to different members of the genus Rhodococcus as well as to Nocardia and Arthrobacter spp. at frequencies ranging from â¼10-2 to 10-6 pRErm46 transfer was also observed in mating experiments in soil and horse manure, albeit at a low frequency and after prolonged incubation at 22 to 30°C (environmental temperatures), not 37°C. All transconjugants were able to transfer pRErm46 back to R. equi Conjugation could not be detected with Mycobacterium or Corynebacterium spp. or several members of the more distant phylum Firmicutes such as Enterococcus, Streptococcus, or Staphylococcus Thus, the pRErm46 host range appears to span several actinobacterial orders with certain host restriction within the Corynebacteriales All bacterial species that acquired pRErm46 expressed increased macrolide resistance with no significant deleterious impact on fitness, except in the case of Rhodococcus rhodnii Our results indicate that actinobacterial members of the environmental microbiota can both acquire and transmit the R. equi pRErm46 plasmid and thus potentially contribute to the maintenance and spread of erm(46)-mediated macrolide resistance in equine farms.IMPORTANCE This study demonstrates the efficient horizontal transfer of the Rhodococcus equi conjugative plasmid pRErm46, recently identified as the cause of the emerging macrolide resistance among equine isolates of this pathogen, to and from different environmental Actinobacteria, including a variety of rhodococci as well as Nocardia and Arthrobacter spp. The reported data support the notion that environmental microbiotas may act as reservoirs for the endemic maintenance of antimicrobial resistance in an antibiotic pressurized farm habitat.
Assuntos
Antibacterianos/farmacologia , Farmacorresistência Bacteriana/genética , Transferência Genética Horizontal , Genes Bacterianos , Macrolídeos/farmacologia , Rhodococcus equi/genética , Actinobacteria/genética , Plasmídeos/genéticaRESUMO
The soil-dwelling, saprophytic actinomycete Rhodococcus equi is a facultative intracellular pathogen of macrophages and causes severe bronchopneumonia when inhaled by susceptible foals. Standard treatment for R. equi disease is dual-antimicrobial therapy with a macrolide and rifampin. Thoracic ultrasonography and early treatment with antimicrobials prior to the development of clinical signs are used as means of controlling endemic R. equi infection on many farms. Concurrently with the increased use of macrolides and rifampin for chemoprophylaxis and the treatment of subclinically affected foals, a significant increase in the incidence of macrolide- and rifampin-resistant R. equi isolates has been documented. Previously, our laboratory demonstrated decreased fitness of R. equi strains that were resistant to macrolides, rifampin, or both, resulting in impaired in vitro growth in iron-restricted media and in soil. The objective of this study was to examine the effect of macrolide and/or rifampin resistance on intracellular replication of R. equi in equine pulmonary macrophages and in an in vivo mouse infection model in the presence and absence of antibiotics. In equine macrophages, the macrolide-resistant strain did not increase in bacterial numbers over time and the dual macrolide- and rifampin-resistant strain exhibited decreased proliferation compared to the susceptible isolate. In the mouse model, in the absence of antibiotics, the susceptible R. equi isolate outcompeted the macrolide- or rifampin-resistant strains.
Assuntos
Infecções por Actinomycetales/tratamento farmacológico , Antibacterianos/farmacologia , Claritromicina/farmacologia , Macrófagos Alveolares/microbiologia , Rhodococcus equi/efeitos dos fármacos , Rifampina/farmacologia , Infecções por Actinomycetales/imunologia , Infecções por Actinomycetales/microbiologia , Animais , Contagem de Colônia Microbiana , Farmacorresistência Bacteriana , Aptidão Genética/efeitos dos fármacos , Aptidão Genética/fisiologia , Cavalos , Fígado/efeitos dos fármacos , Fígado/microbiologia , Pulmão/efeitos dos fármacos , Pulmão/microbiologia , Macrófagos Alveolares/efeitos dos fármacos , Masculino , Camundongos , Camundongos Nus , Testes de Sensibilidade Microbiana , Cultura Primária de Células , Rhodococcus equi/fisiologia , Baço/efeitos dos fármacos , Baço/microbiologiaRESUMO
Rhodococcus equi is a leading cause of severe pneumonia in foals. Standard treatment is dual antimicrobial therapy with a macrolide and rifampin, but the emergence of macrolide- and rifampin-resistant R. equi isolates is an increasing problem. The objective of this study was to determine the effect of macrolide and/or rifampin resistance on fitness of R. equi Three unique isogenic sets were created, each consisting of four R. equi strains, as follows: a susceptible parent isolate, strains resistant to macrolides or rifampin, and a dual macrolide- and rifampin-resistant strain. Each isogenic set's bacterial growth curve was generated in enriched medium, minimal medium (MM), and minimal medium without iron (MM-I). Bacterial survival in soil was analyzed over 12 months at -20°C, 4°C, 25°C, and 37°C, and the ability of these strains to retain antimicrobial resistance during sequential subculturing was determined. Insertion of the mobile element conferring macrolide resistance had minimal effect on in vitro growth. However, two of three rpoB mutations conferring rifampin resistance resulted in a decreased growth rate in MM. In soil, macrolide- or rifampin-resistant R. equi strains exhibited limited growth compared to that of the susceptible R. equi isolate at all temperatures except -20°C. During subculturing, macrolide resistance was lost over time, and two of three rpoB mutations reverted to the wild-type form. The growth of rifampin-resistant R. equi colonies is delayed under nutrient restriction. In soil, possession of rifampin or macrolide resistance results in decreased fitness. Both macrolide and rifampin resistance can be lost after repeated subculturing.IMPORTANCE This work advances our understanding of the opportunistic environmental pathogen Rhodococcus equi, a disease agent affecting horses and immunocompromised people. R. equi is one of the most common causes of severe pneumonia in young horses. For decades, the standard treatment for R. equi pneumonia in horses has been dual antimicrobial therapy with a macrolide and rifampin; effective alternatives to this combination are lacking. The World Health Organization classifies these antimicrobial agents as critically important for human medicine. Widespread macrolide and rifampin resistance in R. equi isolates is a major emerging problem for the horse-breeding industry and might also adversely impact human health if resistant strains infect people or transfer resistance mechanisms to other pathogens. This study details the impact of antimicrobial resistance on R. equi fitness, a vital step for understanding the ecology and epidemiology of resistant R. equi isolates, and will support development of novel strategies to combat antimicrobial resistance.
Assuntos
Farmacorresistência Bacteriana/efeitos dos fármacos , Macrolídeos/farmacologia , Rhodococcus equi/efeitos dos fármacos , Rhodococcus equi/crescimento & desenvolvimento , Rifampina/farmacologia , Animais , Antibacterianos/farmacologia , Proteínas de Bactérias/genética , RNA Polimerases Dirigidas por DNA/genética , Farmacorresistência Bacteriana/genética , Doenças dos Cavalos/microbiologia , Cavalos , Humanos , Testes de Sensibilidade Microbiana , Rhodococcus equi/genéticaRESUMO
Rhodococcus equi is a common cause of pneumonia in foals and an opportunistic pathogen in immunosuppressed people. The ability of R. equi to survive and replicate in macrophages is the basis of its pathogenicity. Limited knowledge about the role of cytokines in host defense against R. equi comes from studies in mice and the role of cytokines in intracellular survival of R. equi in equine macrophages is unknown. The objectives of this study were to determine the effect of priming with interferon (IFN)-γ, interleukin (IL)-1ß, IL-4, IL-6, IL-10, or tumor necrosis factor (TNF)-α at various concentrations on intracellular survival of virulent R. equi in equine monocyte-derived macrophages (MDM), and to determine the effects of various combinations of the same cytokines on intracellular survival of R. equi. MDM from 10 adult horses were primed with recombinant equine cytokines at doubling concentrations ranging from 25 to 200â¯ng/mL prior to infection with virulent R. equi. Priming with IFN-γ, TNF-α, or IL-6 significantly decreased intracellular replication of R. equi compared to unprimed monolayers. In contrast, priming with IL-10 or IL-1ß significantly increased intracellular replication of R. equi. Pairwise combinations of the cytokines listed above did not results in synergism or antagonism. This study demonstrated that IFN-γ, TNF-α, or IL-6 improved equine MDM function against R. equi whereas IL-1ß or IL-10 were detrimental.
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Infecções por Actinomycetales/microbiologia , Interferon gama/farmacologia , Interleucinas/farmacologia , Macrófagos/microbiologia , Rhodococcus equi/efeitos dos fármacos , Fator de Necrose Tumoral alfa/farmacologia , Animais , Células Cultivadas , Interações Medicamentosas , Cavalos , Rhodococcus equi/crescimento & desenvolvimentoRESUMO
Treatment of mice with the combination of clarithromycin with rifampin resulted in a significantly lower number of Rhodococcus equi CFU in the organs of mice than treatment with either drug alone or placebo. There was no significant difference in the number of R. equi CFU between mice treated with clarithromycin monotherapy, rifampin monotherapy, or placebo. The combination of clarithromycin with rifampin conferred a clear advantage over either drug as monotherapy in this model of chronic R. equi infection.
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Infecções por Actinomycetales/tratamento farmacológico , Antibacterianos/uso terapêutico , Claritromicina/uso terapêutico , Rhodococcus equi/efeitos dos fármacos , Rhodococcus equi/patogenicidade , Rifampina/uso terapêutico , Animais , Combinação de Medicamentos , Masculino , Camundongos , Camundongos Nus , Testes de Sensibilidade MicrobianaRESUMO
MICs of erythromycin, clarithromycin, azithromycin, rifampin, gentamicin, and doxycycline against 101 isolates of Rhodococcus equi were determined by broth macrodilution, disk diffusion, and Etest. Categorical agreement ranged between 85.1 and 100%. Overall, the agreement between Etest and disk diffusion was better than the agreement between broth macrodilution and the agar-based methods.
Assuntos
Antibacterianos/farmacologia , Testes de Sensibilidade Microbiana/métodos , Rhodococcus equi/efeitos dos fármacos , Infecções por Actinomycetales/microbiologia , Infecções por Actinomycetales/veterinária , Animais , Testes de Sensibilidade a Antimicrobianos por Disco-Difusão , Doenças dos Cavalos/microbiologia , CavalosRESUMO
OBJECTIVES: The objective of this study was to identify the molecular mechanism of macrolide resistance in the actinomycete Rhodococcus equi, a major equine pathogen and zoonotic agent causing opportunistic infections in people. METHODS: Macrolide-resistant (nâ=â62) and macrolide-susceptible (nâ=â62) clinical isolates of R. equi from foals in the USA were studied. WGS of 18 macrolide-resistant and 6 macrolide-susceptible R. equi was performed. Representative sequences of all known macrolide resistance genes identified to date were used to search the genome assemblies for putative homologues. PCR was used to screen for the presence of the identified resistance determinant in the rest of the isolates. Mating experiments were performed to verify mobility of the gene. RESULTS: A novel erm gene, erm(46), was identified in all sequenced resistant isolates, but not in susceptible isolates. There was complete association between macrolide resistance and the presence of erm(46) as detected by PCR screening of all 124 clinical isolates of R. equi. Expression of erm(46) in a macrolide-susceptible strain of R. equi induced high-level resistance to macrolides, lincosamides and streptogramins B, but not to other classes of antimicrobial agents. Transfer of erm(46) to macrolide-susceptible R. equi was confirmed. The transfer frequency ranged from 3â×â10(-3) to 1â×â10(-2). CONCLUSIONS: This is the first molecular characterization of resistance to macrolides, lincosamides and streptogramins B in R. equi. Resistance was due to the presence of a novel erm(46) gene mobilizable likely by conjugation, which has spread among equine isolates of R. equi in the USA.
Assuntos
Antibacterianos/farmacologia , Farmacorresistência Bacteriana , Transferência Genética Horizontal , Genes Bacterianos , Macrolídeos/farmacologia , Rhodococcus equi/efeitos dos fármacos , Rhodococcus equi/genética , Infecções por Actinomycetales/microbiologia , Infecções por Actinomycetales/veterinária , Animais , Animais Recém-Nascidos , Conjugação Genética , DNA Bacteriano/química , DNA Bacteriano/genética , Doenças dos Cavalos/microbiologia , Cavalos , Lincosamidas/farmacologia , Rhodococcus equi/isolamento & purificação , Análise de Sequência de DNA , Estreptogramina B/farmacologia , Estados UnidosRESUMO
Background: Anatomical location-dependent differences in transdermal opioid penetration are well described in human patients. Although this has been investigated in horses with fentanyl, there is no literature available on location-dependent plasma buprenorphine concentrations when administered as a transdermal matrix-type patch. Objective: This study aims to compare the plasma concentrations achieved from the matrix-type transdermal buprenorphine patches placed at different anatomical sites (metacarpus, gaskin, and ventral tail base) in healthy adult horses. Study design: This is a randomized experimental study with a Latin square design. Methods: Six adult horses were given each of three treatments with a minimum 10-day washout period. For each treatment, two 20â µg h-1 matrix-type buprenorphine patches were applied to the ventral aspect of the tail base (TailTDP), metacarpus region (MetacarpusTDP), or gaskin region (GaskinTDP). Whole blood samples (for determination of buprenorphine concentration) and physiological variables were collected before (0â h) and at 0.5, 2, 4, 6, 8, 10, 12, 16, 24, 32, 48, 56, 72, 96 and 120â h after patches were applied. The patches were removed 96â h following placement and were analyzed for residual buprenorphine content. Buprenorphine concentrations were measured in plasma by LC-MS/MS. A mixed-effects model was used to analyze the physiological variables. Results: Between the three treatment groups, there was no change in physiological variables across timepoints as compared to baseline and when compared to each other in a single horse and between horses (p > 0.3). When comparing all three locations, the buprenorphine uptake was observed to be more consistent with respect to measurable plasma concentrations >0.1â ng ml-1 when applied to the ventral aspect of the tail base. In the TailTDP group, the mean plasma buprenorphine concentrations were >0.1â ng ml-1 from 2 to 32â h. The highest group mean was 0.25â ng ml-1 noted at 4â h. Conclusions: The metacarpal and gaskin regions presented more erratic and inconsistent buprenorphine uptake and plasma concentrations as compared to the ventral aspect of the tail base. Further research must be directed at investigating the optimal dose, achievable duration of analgesia, change in measurable plasma concentrations, and behavioral and systemic effects.
RESUMO
Background: Matrix type transdermal buprenorphine patches have not been investigated in horses and may provide an effective means of providing continuous pain control for extended period and eliminating venous catheterization. Objective: Assessment of the physiological variables (heart rate, respiratory rate, body temperature) and thermal nociceptive threshold testing, and describing the pharmacokinetic profile of transdermal buprenorphine matrix-type patch (20â µg h-1 and 40â µg h-1 dosing) in healthy adult horses. Study design: Randomised experimental study with a Latin-square design. Methods: Six adult healthy horses received each of the three treatments with a minimum 10 day washout period. BUP0 horses did not receive a patch (control). BUP20 horses received one patch (20â µg h-1) applied on the ventral aspect of the tail base resulting in a dose of 0.03-0.04â µg kg-1 h-1. BUP40 horses received two patches placed alongside each other (40â µg h-1) on the tail base resulting in a dose of 0.07-0.09â µg kg-1 h-1. Whole blood samples (for determination of buprenorphine concentration), physiological variables and thermal threshold testing were performed before (0â h) and at 2, 4, 8, 12, 16, 24, 32, 40, 48, 56, 64, 72, and 96â h after patch application. The patches were removed 72â h following placement and were analyzed for residual buprenorphine content. Results: Between the three groups, there was no change in physiological variables across timepoints as compared to baseline (p > 0.1). With the higher dose, there was a significant increase in thermal thresholds from baseline values from 2â h until 48â h and these values were significantly higher than the group receiving the lower patch dose for multiple timepoints up to 40â h. 40â µg h-1 patch led to consistent measurable plasma concentrations starting at 2â h up to 96â h, with the mean plasma concentrations of > 0.1â ng/ml from 4â h to 40â h. Conclusions: 20â µg h-1 and 40â µg h-1 patch doses were well tolerated by all horses. At higher dose, plasma buprenorphine concentrations were more consistently measurable and blunted thermal thresholds for 48â h vs. 32â h with 20â µg h-1 dosing as compared to control.
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Introduction: Understanding the pharmacokinetics and pharmacodynamics of fentanyl in horses is crucial for optimizing pain management strategies in veterinary medicine. Methods: Six adult horses were enrolled in a randomized crossover design. Treatments included: placebo, two 100â mcg/h patches (LDF), four 100â mcg/h patches (MDF), and six 100â mcg/h patches (HDF). Patches were in place for 72â h. Blood was obtained for fentanyl plasma concentration determination, thermal threshold, mechanical threshold, heart rate, respiratory rate, and rectal temperature were obtained prior patch placement and at multiple time points following patch placement for the following 96â h. Fentanyl plasma concentration was determined using LC-MS/MS. Data were analyzed using a generalized mixed effects model. Results: Mean (range) maximum plasma concentration (Cmax), time to Cmax, and area under the curve extrapolated to infinity were 1.39 (0.82-1.82), 2.64 (1.21-4.42), 4.11 (2.78-7.12)â ng/ml, 12.7 (8.0-16.0), 12.7 (8.0-16.0), 12 (8.0-16.0)â h, 42.37 (27.59-55.56), 77.24 (45.62-115.06), 120.34 (100.66-150.55)â hâ ng/ml for LDF, MDF, and HDF, respectively. There was no significant effect of treatment or time on thermal threshold, mechanical threshold, respiratory rate, or temperature (p > 0.063). There was no significant effect of treatment on heart rate (p = 0.364). There was a significant effect of time (p = 0.003) on heart rate with overall heart rates being less than baseline at 64â h. Conclusions: Fentanyl administered via transdermal patch is well absorbed and well tolerated but does not result in an anti-nociceptive effect as measured by thermal and mechanical threshold at the doses studied.
RESUMO
Macrolide and rifampin resistance developed on a horse breeding farm after widespread use was instituted for treatment of subclinical pulmonary lesions in foals. Resistance occurred in 6 (24%) of 25 pretreatment and 8 (62%) of 13 (62%) posttreatment isolates from affected foals. Drug-resistant isolates formed 2 distinct genotypic clusters.
Assuntos
Infecções por Actinomycetales/veterinária , Farmacorresistência Bacteriana Múltipla , Doenças dos Cavalos/microbiologia , Macrolídeos/farmacologia , Pneumonia Bacteriana/veterinária , Rhodococcus equi/efeitos dos fármacos , Rifampina/farmacologia , Infecções por Actinomycetales/diagnóstico por imagem , Infecções por Actinomycetales/tratamento farmacológico , Infecções por Actinomycetales/microbiologia , Animais , Infecções Assintomáticas , Cruzamento , Genes Bacterianos , Doenças dos Cavalos/diagnóstico por imagem , Doenças dos Cavalos/tratamento farmacológico , Cavalos , Kentucky , Tipagem Molecular , Filogenia , Pneumonia Bacteriana/diagnóstico por imagem , Pneumonia Bacteriana/tratamento farmacológico , Sequências Repetitivas de Ácido Nucleico/genética , Rhodococcus equi/genética , Rhodococcus equi/isolamento & purificação , UltrassonografiaRESUMO
BACKGROUND: Donkeys with clinical signs of pituitary pars intermedia dysfunction are treated with oral pergolide mesylate despite the lack of species-specific pharmacokinetic data. OBJECTIVE: To evaluate the pharmacokinetics of intragastric and oral pergolide mesylate in healthy donkeys (Equus asinus). STUDY DESIGN: Pharmacokinetic study. METHODS: Six healthy donkeys were administered pergolide mesylate (Prascend®) at 2 µg/kg bodyweight (bwt) intragastrically once, then once daily per os (PO) for 5 days. Blood samples were collected at 0, 10, 20, 30 and 45 min and 1, 1.5, 2, 3, 4, 6, 8, 12, 24, 36 and 48 h after the single intragastric dose, once daily immediately before the PO dose, and then again at the above times after Day 5 of once daily oral dosing. Plasma pergolide concentration was quantified via ultra-performance liquid chromatography-tandem mass spectrometry. Pergolide concentration versus time data after the first and last doses were analysed based on noncompartmental pharmacokinetics using commercial software. Paired t-tests were used to compare single and multiple doses (p < 0.05). In a follow-up study, a single oral dose was then administered to two donkeys followed by concurrent blood sampling from the jugular and cephalic veins to evaluate the effect of route of administration on pergolide pharmacokinetics. RESULTS: Cmax , Tmax AUC, and t½λz differed significantly (p ≤ 0.03) after single and multiple doses, with significantly lower Cmax (0.16 ± 0.16 ng/ml) and t½λz (9.74 ± 1.35 h) after intragastric dosing on Day 1 than after 5 days of oral dosing (3.74 ± 2.26 ng/ml and 16.35 ± 5.21 h, respectively). Pergolide plasma concentrations were higher in jugular vein samples compared to cephalic vein samples after a single oral dose. MAIN LIMITATIONS: Small sample size; varied administration routes. CONCLUSIONS: Pergolide mesylate (dosed at 2 µg/kg bwt) is bioavailable in donkeys after intragastric and PO administration. Differences in pharmacokinetics were noted after multiple doses, related to different routes of administration and sublingual absorption of pergolide.
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OBJECTIVE: To evaluate effects of black walnut extract (BWE) on equine mononuclear cells and determine whether BWE has direct proinflammatory effects. SAMPLE: Mononuclear cells separated from blood samples from 8 horses. PROCEDURES: Aqueous BWE was prepared and processed to eliminate contamination with particulates and microbes. A Limulus amoebocyte lysate assay was used to detect lipopolysaccharide (LPS) contamination in the BWE. Mononuclear cells were incubated in minimal essential medium with or without the addition of 0.6% to 10% (vol/vol) BWE. These mononuclear cells were assessed for viability, activities of caspases 3 and 7, nitric oxide production, procoagulant activity, and tumor necrosis factor-α production. The effect of LPS on cellular responses induced by BWE was assessed by coincubation with 13 U of polymyxin B/mL; mononuclear cells incubated with LPS were used as a reference. RESULTS: BWE did not cause loss of cell membrane integrity in mononuclear cells but did induce a dose-dependent increase in activities of caspases 3 and 7. Neither BWE nor LPS significantly induced production of nitric oxide. Both BWE and LPS induced comparable amounts of procoagulant activity and tumor necrosis factor-α production; coincubation with polymyxin B reduced the activity for BWE and LPS by 50% and approximately 100%, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: Addition of BWE induced inflammatory activation of equine mononuclear cells, a portion of which was independent of the effects of LPS. Furthermore, BWE and LPS may work in concert to induce systemic inflammatory responses that contribute to the development of acute laminitis in horses.
Assuntos
Doenças do Pé/veterinária , Doenças dos Cavalos/etiologia , Juglans/química , Leucócitos Mononucleares/imunologia , Extratos Vegetais/química , Animais , Fatores de Coagulação Sanguínea/metabolismo , Caspase 3/metabolismo , Caspase 7/metabolismo , Doenças do Pé/induzido quimicamente , Doenças do Pé/imunologia , Doenças dos Cavalos/induzido quimicamente , Doenças dos Cavalos/imunologia , Cavalos , Abrigo para Animais , Leucócitos Mononucleares/efeitos dos fármacos , Leucócitos Mononucleares/enzimologia , Lipopolissacarídeos/imunologia , Óxido Nítrico/metabolismo , Polimixina B/imunologia , Polimixina B/metabolismo , Fator de Necrose Tumoral alfa/biossínteseRESUMO
OBJECTIVE: To assess the in vitro capability of aqueous black walnut extracts (BWEs) to generate reactive oxygen species in water-based media ranging in makeup from a simple buffer solution to a complex solution containing serum. SAMPLE: 3 BWEs. PROCEDURES: Production of reactive oxygen species by BWEs prepared in water or N-hexane was tested in PBS solution, PBS solution containing 0.5% bovine serum albumin and 5mM glucose (PBG), and RPMI-1640 medium (RPMI) containing 10% fetal bovine serum or 10% donor horse serum. Reactive oxygen species production was measured as conversion of nonfluorescent dihydrorhodamine 123 by reactive oxygen species to its fluorescent product, rhodamine-123. Hydrogen peroxide was used as a standard for reactive oxygen species activity. RESULTS: BWEs prepared in water generated reactive oxygen species in a dose-dependent manner over a 4-hour period, with peak activity detected when the BWEs were added as 10% (vol/vol) of the RPMI. The BWE prepared in N-hexane generated maximal reactive oxygen species activity after incubation for 3 to 4 hours when added at concentrations ranging from 0.3% to 0.5% (vol/vol) of the RPMI. The BWE prepared in water generated the highest fluorescent signal in PBS solution, whereas the BWE prepared in N-hexane generated the highest fluorescent signal in PBG. CONCLUSIONS AND CLINICAL RELEVANCE: The BWEs prepared in water generated a dose-dependent induction of fluorescence in all the water-based solutions tested. These findings indicated that the BWEs, which are used to induce laminitis in horses, generate reactive oxygen species.
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Doenças do Pé/veterinária , Doenças dos Cavalos/etiologia , Juglans/química , Extratos Vegetais/química , Espécies Reativas de Oxigênio/metabolismo , Animais , Doenças do Pé/imunologia , Doenças dos Cavalos/imunologia , Cavalos , Lipopolissacarídeos/metabolismoRESUMO
OBJECTIVE: To assess IgE response and cytokine gene expressions in pulmonary lymph collected from bovine respiratory syncytial virus (BRSV)-infected calves after ovalbumin inhalation. ANIMALS: Thirteen 7- to 8-week-old calves. PROCEDURES: The efferent lymphatic duct of the caudal mediastinal lymph node of each calf was cannulated 3 or 4 days before experiment commencement. Calves were inoculated (day 0) with BRSV (n = 7) or BRSV-free tissue culture medium (mock exposure; 6) via aerosolization and exposed to aerosolized ovalbumin on days 1 through 6 and day 15. An efferent lymph sample was collected daily from each calf on days -1 through 16; CD4+ and CD8+ T lymphocyte subsets in lymph samples were enumerated with a fluorescence-activated cell scanner. Expressions of several cytokines by efferent lymphocytes and lymph ovalbumin-specific IgE concentration were measured. Each calf was euthanized on day 16 and then necropsied for evaluation of lungs. RESULTS: Mean fold increase in ovalbumin-specific IgE concentration was greater in BRSV-infected calves than in mock-infected calves. At various time points from days 4 through 10, percentages of T lymphocyte subsets and CD4+:CD8+ T lymphocyte ratios differed between BRSV-infected calves and day -1 values or from values in mock-infected calves. On days 3 through 5, IL-4 and IL-13 gene expressions in BRSV-infected calves were increased, compared with expressions in mock-infected calves. Lung lesions were consistent with antigen exposure. CONCLUSIONS AND CLINICAL RELEVANCE: In response to the inhalation of aerosolized ovalbumin, BRSV infection in calves appeared to facilitate induction of a T helper 2 cell response and ovalbumin-specific IgE production.
Assuntos
Citocinas/metabolismo , Imunoglobulina E/imunologia , Ovalbumina/toxicidade , Infecções por Vírus Respiratório Sincicial/veterinária , Vírus Sincicial Respiratório Bovino , Animais , Anticorpos Antivirais , Bovinos , Citocinas/genética , Regulação da Expressão Gênica/fisiologia , Pulmão/patologia , Linfa/química , Linfa/metabolismo , Subpopulações de Linfócitos/fisiologia , Masculino , Ovalbumina/administração & dosagem , Infecções por Vírus Respiratório Sincicial/imunologia , Infecções por Vírus Respiratório Sincicial/patologia , Infecções por Vírus Respiratório Sincicial/virologiaRESUMO
Pneumonia caused by the intracellular bacterium Rhodococcus equi is an important cause of disease and death in immunocompromised hosts, especially foals. Antibiotics are the standard of care for treating R. equi pneumonia in foals, and adjunctive therapies are needed. We tested whether nebulization with TLR agonists (PUL-042) in foals would improve innate immunity and reduce the severity and duration of pneumonia following R. equi infection. Neonatal foals (n = 48) were nebulized with either PUL-042 or vehicle, and their lung cells infected ex vivo. PUL-042 increased inflammatory cytokines in BAL fluid and alveolar macrophages after ex vivo infection with R. equi. Then, the in vivo effects of PUL-042 on clinical signs of pneumonia were examined in 22 additional foals after intrabronchial challenge with R. equi. Foals infected and nebulized with PUL-042 or vehicle alone had a shorter duration of clinical signs of pneumonia and smaller pulmonary lesions when compared to non-nebulized foals. Our results demonstrate that host-directed therapy can enhance neonatal immune responses against respiratory pathogens and reduce the duration and severity of R. equi pneumonia.
Assuntos
Infecções por Actinomycetales , Doenças dos Cavalos , Cavalos , Imunidade Inata/efeitos dos fármacos , Lipopeptídeos/farmacologia , Oligodesoxirribonucleotídeos/farmacologia , Pneumonia Bacteriana , Rhodococcus equi/imunologia , Receptor 2 Toll-Like/agonistas , Receptor 6 Toll-Like/agonistas , Receptor Toll-Like 9/agonistas , Infecções por Actinomycetales/tratamento farmacológico , Infecções por Actinomycetales/imunologia , Infecções por Actinomycetales/patologia , Infecções por Actinomycetales/veterinária , Animais , Doenças dos Cavalos/tratamento farmacológico , Doenças dos Cavalos/imunologia , Doenças dos Cavalos/patologia , Cavalos/imunologia , Cavalos/microbiologia , Macrófagos Alveolares/imunologia , Macrófagos Alveolares/patologia , Pneumonia Bacteriana/tratamento farmacológico , Pneumonia Bacteriana/imunologia , Pneumonia Bacteriana/patologia , Pneumonia Bacteriana/veterinária , Índice de Gravidade de DoençaRESUMO
PROBLEM: Minimal evidence exists supporting therapeutic selections for equine placentitis. The goal of this study was to characterize the anti-inflammatory effects of firocoxib when administered to mares with placentitis. METHODS: Mares (gestation D270-300) were assigned to: INFECT (n = 6; placentitis, no treatment), FIRO (n = 6; placentitis, firocoxib, 0.1 mg/kg, PO, daily), and NORM (n = 6; no infection/treatment). Allantoic fluid (8 hours, 24 hours, birth) and amniotic fluid (birth) were collected from mares after infection. Concentrations of IL-1ß, IL-6, TNF-α, IL-10, PGF2α , and PGE2 in fluids were measured by ELISA. mRNA expression of IL-1ß, IL-6, TNF-α, IL-8, IL-10, matrix metalloproteinases (MMPs) -1, 3, and 9 in fetal membranes/fetuses was quantified using real-time PCR. RESULTS: Allantoic TNF-α concentrations were lowest in FIRO at 8 hours and 24 hours post-infection; IL-6 concentrations were lower in FIRO than NORM at 8 hours, lower in FIRO than INFECT at 24 hours post-inoculation, and lower in NORM than FIRO or INFECT at birth. Marginal mean allantoic IL-ß and IL-10 concentrations were lower in FIRO and NORM than INFECT. Amniotic fluid cytokines were lowest in NORM with all measurements in that group being below the limit of detection. Allantoic PGF2α concentrations were lower in FIRO and INFECT than NORM at 8 hours post-inoculation, and lower in FIRO than INFECT or NORM at 24 hours post-inoculation. Allantoic PGE2 concentrations were lower in FIRO than INFECT. Amniotic PGF2α and PGE2 concentrations were lower in NORM than INFECT. In fetal membranes, group differences with respect to IL-1ß, IL-6, IL-8, and MMP1 were dependent on tissue type. CONCLUSIONS: Data suggest a suppressive effect of firocoxib administration on cytokine and prostaglandin production in mares with placentitis.
Assuntos
4-Butirolactona/análogos & derivados , Anti-Inflamatórios/uso terapêutico , Inibidores de Ciclo-Oxigenase 2/uso terapêutico , Doenças dos Cavalos/tratamento farmacológico , Inflamação/tratamento farmacológico , Doenças Placentárias/tratamento farmacológico , Placenta/metabolismo , Sulfonas/uso terapêutico , 4-Butirolactona/uso terapêutico , Animais , Feminino , Cavalos , Interleucina-6/metabolismo , Metaloproteinase 1 da Matriz/metabolismo , Placenta/patologia , Gravidez , Prostaglandinas/metabolismo , Fator de Necrose Tumoral alfa/metabolismoRESUMO
BACKGROUND: Rhodococcus equi (R. equi) infections are endemic in many horse facilities in the United States resulting significant economic loses annually. Currently, there is no commercial vaccine available and the emergence of isolates that are resistant to the current treatment and prophylaxis using antibiotics prompts closer surveillance of this pathogen. OBJECTIVE: This study compares three different genotyping techniques, Pulsed Field Gel Electrophoresis (PFGE), Multilocus Sequence Typing (MLST) and whole genome SNP-based phylogeny to determine the most accurate method to monitor the spread of macrolide-and-rifampin-resistant R. equi. METHODS: 16 macrolide and rifampin-resistant and 6 susceptible R. equi and their Illumina Miseq whole genome sequences were used in this study. The isolates were sub-typed by PFGE with VspI and a dendrogram based on their similarities generated. Additionally, three phylogenetic trees were constructed using CSI phylogeny on (i) whole genome sequences (WGS), (ii) in silico MLST sequences and (iii) MLST sequences obtained after PCR-amplification and Sanger sequencing. RESULTS: PFGE identified 18 different genetic profiles and grouped the 22 isolates into 3 clusters independently of their susceptibilities. The phylogenetic trees built from WGS and MLST data showed similar topology, separating the isolates into 2 major clades in accordance with their susceptibility profiles (susceptible and resistant). However, only the trees generated with next generation sequencing data could detect the clonality of the resistant isolates.