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1.
Antibacterial activity against Escherichia coli was obtained with subminimal inhibitory concentrations of oxytetracycline (OTC) and EDTA-tromethamine. Inhibitory effects were not observed using combinations of dimethyl sulfoxide and OTC or dimethyl sulfoxide and EDTA-tromethamine. Neither EDTA-tromethamine nor OTC used alone was capable of the same degree of inhibition. Using a 2-dimensional Microtiter checkerboard technique, the inhibitory activity of these combinations was studied and isobolograms were plotted. A synergistic effect was seen with combinations of OTC and EDTA-tromethamine. Kinetic studies of microbial death, using subminimal inhibitory concentrations of these agents, confirmed these findings.  相似文献   

2.
Combinations of EDTA-tromethamine and 7 antimicrobial agents (chloramphenicol, nalidixic acid, oxytetracycline, penicillin, polymyxin-B, streptomycin, and triple sulfa) were tested for synergistic activities against Pseudomonas aeruginosa. Three in vitro tests were used, including minimal inhibitory concentrations of the drugs, a 2-dimensional Microtiter checkerboard technique, and bacterial inhibition studies. A synergistic inhibitory action was observed with combinations of EDTA-tromethamine plus penicillin and EDTA-tromethamine plus oxytetracycline. When chloramphenicol, streptomycin, nalidixic acid, polymyxin-B, or triple sulfa was mixed with EDTA-tromethamine, synergistic action did not occur.  相似文献   

3.
Thein vitro synergistic effects of combinations of EDTA-tromethamine and six antimicrobial agents (ampicillin, chloramphenicol, oxytetracycline, streptomycin, nalidixic acid and sulphadimethoxine) on clinically isolated strains ofPseudomonas aeruginosa, Proteus mirabilis andEscherichia coli were investigated. The antibacterial activity was assessed from the minimal inhibitory concentration for the antibiotics alone or in combination with EDTA-tromethamine. EDTA-tromethamine potentiated the antibacterial activity of ampicillin, chloramphenicol, oxytetracycline and streptomycin up to four-fold. There were no significant or consistent synergistic effects with nalidixic acid or sulphadimethoxine.Abbreviations cfu colony-forming units - EDTA ethylenediaminetetraacetic acid - MIC minimal inhibitory concentration - tromethamine tris(hydroxymethyl)aminomethane Part of this paper was communicated at the XLV Congress of the Italian Society of Veterinary Sciences, Palermo, 25–28 September 1991  相似文献   

4.
Combinations of EDTA-tromethamine and 7 antimicrobial agents (chloramphenicol, nalidixic acid, oxytetracycline, penicillin, polymyxin-B, streptomycin, and a triple sulfonamide preparation) were tested for synergistic activities against Staphylococcus aureus, Corynebacterium renal, Listeria monocytogenes, Erysipelothrix rhusiopathiae, and a beta-hemolytic streptococci. Two in vitro tests were used--minimal inhibitory concentrations of the drugs and a 2-dimensional Microtiter checkerboard technique. A slight synergistic action was seen when L monocytogenes was exposed to combinations of penicillin-EDTA or streptomycin-EDTA.  相似文献   

5.
Thein vitro synergistic effects of combinations of EDTA-tromethamine and five antimicrobial agents (ampicillin, cephalexin, oxytetracycline, streptomycin and sulphadimethoxine) on three clinically isolated Gram-positive bacteria (Staphylococcus aureus, Staphylococcus hominis andStreptococcus faecium) were investigated. The bacteria had been isolated from three cases of canine otitis resistant to -lactam antibiotic therapy. The antimicrobial activity was evaluated by measuring the minimal inhibitory concentration for the antibiotics alone or in combination with EDTA-tromethamine. EDTA-tromethamine potentiated the activity of cefalexin againstS. aureus andS. hominis, of oxytetracycline againstS. aureus andS. faecium and of streptomycin againstS. faecium. No significant effects were noted on the activity of oxytetracycline againstS. hominis. The remaining combinations gave a slight synergistic effect. As previously shown for Gram-negative resistant bacteria, these data suggest that the association of EDTA-tromethamine and appropriate antibiotic therapy may be useful to overcome persistent infections of soft tissues in domestic animals.Abbreviations cfu colony forming units - EDTA ethylenediaminetetraacetic acid - MIC minimal inhibitory concentration - tromethamine tris(hydroxymethyl)- aminomethane Part of this paper was communicated at the XLVI Congress of the Italian Society of Veterinary Sciences, Venice, 30 September – 3 October 1992  相似文献   

6.
Possible synergistic effects of the combination of EDTA-tromethamine (EDTA-Tris) and three antimicrobial agents (cephaloridine, kanendomycin and enrofloxacin) against resistant Gram-positive and Gram-negative bacteria are reported. Bacteria were isolated from eight cases of chronic otitis externa, five cases of chronic dermatitis and four cases of recurrent cystitis in dogs which had previously been treated with one of the three antibiotics without success. Animals exposed to EDTA-tromethamine plus the antibiotic recovered completely within 10 days, and were controlled clinically and bacteriologically for 180 days. Local irrigation with EDTA-tromethamine solution was well tolerated and no side effects were recorded.  相似文献   

7.
The concentration of EDTA-Tris (3.22 mM EDTA and 0.05 M Tris) used as a lavage to treat otitis externa, cystitis or other persistent infections in dogs and cats, was found to prevent the growth of Pseudomonas aeruginosa, Staphylococcus aureus and beta streptococci when present in growth media. Pseudomonas aeruginosa was rapidly lysed in this solution. Escherichia coli and Proteus vulgaris grew in the presence of EDTA-Tris, but to a lesser extent than the controls without these compounds. Minimal inhibitory concentrations (MIC) for 8 antimicrobial agents with and without EDTA-Tris were determined for E. coli and P. vulgaris. A potentiation effect on E. coli (greater than 50% decrease MIC) was observed when EDTA-Tris was combined with penicillin, oxytetracycline or chloramphenicol. A similar effect was observed with P. vulgaris when combinations of EDTA-Tris plus gentamicin, oxytetracycline, polymyxin-B or triple sulfa were used. The results of this study indicate that EDTA-Tris appears to have merit in selected cases of otitis externa, cystitis or other persistent infections where lavage might be used.  相似文献   

8.
采用2倍稀释法测定了恩诺沙星及其他8种抗菌药对鸡毒支原体BG44T株的最小抑菌浓度（MIC）,再以棋盘法测定恩诺沙星分别与其他8种抗菌药不同联合对鸡毒支原体BG44T株的敏感性。结果显示：恩诺沙星、替米考星、泰乐菌素、吉他霉素、林可霉素、沃尼妙林、泰妙菌素、氯霉素及氟苯尼考对鸡毒支原体BG44T株的MIC分别为0．063、0．004、0．016、0．063、16、〈0．004、0．008、8、8μg／mL。在8种不同联合用药对鸡毒支原体BG44T株的药敏试验中,恩诺沙星＋替米考星、恩诺沙星＋泰乐菌素、恩诺沙星＋吉他霉素、恩诺沙星＋林可霉素、恩诺沙星＋沃尼妙林、恩诺沙星＋泰妙菌素联合表现出相加作用,恩诺沙星＋氯霉素、恩诺沙星＋氟苯尼考表现出拮抗作用。  相似文献   

9.
Combinations of EDTA-Tris and two aminoglycoside antibiotics (amikacin and neomycin) were tested for synergistic activities against the microorganisms associated with otitis externa in dogs and for the solutions' stability over time. Synergistic activity was observed when EDTA-Tris plus amikacin and EDTA-Tris plus neomycin were tested againstStaphylococcus intermedius, Proteus mirabilis, Pseudomonas aeruginosa, andEscherichia coli, but not againstCandida albicans. Stability studies over a 3-month period indicated that the test solutions were stable at room temperature and that their antimicrobial activity was maintained.Abbreviations CFU colony-forming units - EDTA (ethylenedinitrilo)tetraacetic acid, disodium salt - FIC fractional inhibitory concentration - MBC minimal bactericidal concentration - MIC minimal inhibitory concentration - Tris tris(hydroxymethyl)aminomethane  相似文献   

10.
The effects of combining erythromycin (Ery) with oxytetracycline (Oxy) or spectinomycin (Sp) on Pasteurella haemolytica were evaluated in vitro using the chessboard (checkerboard) technique. These combinations were selected because all are drugs widely used in bovine respiratory disease treatment, and they represent possible sequential or complementary mechanisms of action. Using the recommended breakpoints of greater than 4 micrograms/ml for Ery, 16 micrograms/ml for Oxy, and 32 micrograms/ml for Sp, of the 33 P. haemolytica isolates, 32 were resistant to Oxy, 27 to Sp, and 14 to Ery. Based on the fractional inhibitory concentration index, Ery and Oxy in combination were synergistic or additive against 32 of 33 isolates. The combination of Ery and Sp was synergistic or additive against 27 of 33 isolates. No instances of antagonism were seen. When the effects were considered within the context of therapeutically achievable serum/tissue concentrations, the effects of Ery and Oxy in combination were only marginal. Thus, against P. haemolytica isolates, Ery and Sp appeared to represent an effective antimicrobial combination, whereas Ery and Oxy were only of marginal efficacy as a combination.  相似文献   

11.
抗菌药物联合应用对霉形体的药效学研究   总被引：4，自引：0，他引：4  
本研究采用试管肉汤稀释法和棋盘法测定了１７种抗菌药物单独或几种药联合对鸡败血霉形体Ｓ＿６株（ＭＧＳ＿６）的最低抑菌和最低杀菌浓度．结果表明，ＭＧＳ＿６对北里霉素、四环素、红霉素、氟哌酸等高度敏感；四环素类与ＴＭＰ联合呈现协同作用。对实验性感染ＭＧＳ＿６的病鸡进行联合用药治疗试验，初步筛选出几个有良好治疗作用的联合用药配方。本研究是对联合应用抗菌药物治疗实验性鸡败血霉形体病进行的初步探讨，对防治本病具有一定的理论与实践意义。  相似文献   

12.
The pharmacodynamic properties of a new veterinary fluoroquinolone antimicrobial agent, ibafloxacin, were evaluated. Minimal inhibitory concentrations (MIC), time-kill kinetics, postantibiotic effect (PAE) and postantibiotic subminimal inhibitory concentration effects (PA-SME) were determined against pathogenic canine Gram-negative and Gram-positive bacterial isolates from dermal, respiratory and urinary tract infections. The synergistic interactions between ibafloxacin and its main metabolite, 8-hydroxy-ibafloxacin were investigated. Finally, the efficacy of ibafloxacin was tested in in vivo canine infection models. Ibafloxacin had good activity against Pasteurella spp., Escherichia coli, Klebsiella spp., Proteus spp. and Staphylococcus spp. (MIC90=0.5 microg/mL), moderate activity against Bordetella bronchiseptica, Enterobacter spp. and Enterococcus spp. (MIC50=4 microg/mL) and low activity against Pseudomonas spp. and Streptococcus spp. The time-killing analysis confirmed that ibafloxacin was bactericidal with a broad spectrum of activity. The PAE and PA-SME were between 0.7-2.13 and 1-11.5 h, respectively. Finally, studies in dog models of wound infection and cystitis confirmed the efficacy of once daily oral ibafloxacin at a dosage of 15 mg/kg. Additional studies are needed to better define the importance of AUC/MIC (AUIC) and Cmax/MIC ratios on the outcome of fluoroquinolone therapy in dogs.  相似文献   

13.
The minimal inhibitory concentrations of penicillin G, ampicillin, gentamicin, erythromycin and rifampicin were determined for nine strains of Corynebacterium equi. The effect of combinations of any two of these antibiotics on the killing of these strains was determined at antibiotic concentrations achievable in horses using recommended drug dosages (ampicillin 4.0 μg/ml, gentamicin 1.0 μg/ml and erythromycin 0.25 μg/ml). Penicillin G was used at 4.0 μg/ml and rifampicin at 0.063 μg/ml. The combinations of gentamicin with erythromycin or rifampicin gave antagonistic effects on killing compared to either drug alone. Combinations of erythromycin with rifampicin or penicillin showed synergistic effects, as did penicillin-gentamicin. All other combinations, and a triple combination of penicillin-rifampicin-erythromycin, showed additive effects only.  相似文献   

14.
Penetration of penicillin G, dihydrostreptomycin, oxytetracycline, and chloramphenicol into interstitial fluid of calves was estimated using subcutaneously implanted, multiple perforated spherical polypropylene capsules as a model. Antibiotic concentrations were determined in simultaneously withdrawn serum and capsular fluid (CF) samples at intervals after single and multiple intramuscular injections of antibiotics at recommended dose schedules. Peak concentrations of penicillin G in CF were 57% of those in serum, and the drug was eliminated from CF at a slower rate than from serum. Dihydrostreptomycin diffused into CF to a limited degree and was eliminated from CF much more slowly than from serum leading to gradual drug accumulation in CF upon repeated dosing. Multiple injections of oxytetracycline resulted in CF drug levels comparable with those in serum. Concentrations of chloramphenicol in CF were generally similar to free (non-protein bound) serum drug levels. CF concentrations of penicillin G were within the range of the minimal inhibitory concentrations of the drug for pathogenic gram positive micro-organisms and CF levels of dihydrostreptomycin, oxytetracycline, and chloramphenicol were apparently sufficient to inhibit the majority of gram negative pathogens involved in bovine injections. Advantages and limitations of the tissue cage model are briefly discussed.  相似文献   

15.
The present study investigated the in vitro inhibitory activity of terbinafine, itraconazole, caspofungin, fluvastatin and ibuprofen against 15 isolates of Pythium insidiosum in double and triple combinations and determined in vivo correlations using rabbits with experimental pythiosis. The minimal inhibitory concentration (MIC) was determined in accordance with the Clinical and Laboratory Standards Institute M 38-A2 protocol (2008), and the in vitro interactions were evaluated using a checkerboard microdilution method. For the in vivo study, 20 rabbits inoculated with P. insidiosum zoospores were divided into four groups: group 1 was treated with terbinafine and itraconazole; group 2 was treated with terbinafine, itraconazole and fluvastatin; group 3 was treated with terbinafine and caspofungin; and group 4 was the control group. Combinations of terbinafine with caspofungin or ibuprofen were synergistic for 47% of the isolates, and antagonism was not observed in any of the double combinations. The triple combinations were mostly indifferent, but synergism and antagonism were also observed. In the in vivo study, the histological aspect of the lesions was similar among the groups, but group 2 showed the lowest amount of hyphae and differed significantly from the other groups.  相似文献   

16.
In vitro simulations of the gastric and small intestinal fermentation with varying doses of carvacrol, thymol, eugenol and trans-cinnamaldehyde and binary combinations thereof were carried out to calculate dose–response equations for the antimicrobial effect against the main pig gut flora components. Interaction effects were evaluated following the isobole method. In gastric simulations eugenol and trans-cinnamaldehyde showed clearly less inhibitory activity towards lactobacilli than carvacrol and thymol, which could also be observed in the small intestinal simulations. The minimum concentration for carvacrol, thymol, eugenol and trans-cinnamaldehyde in small intestinal simulations to reduce the number of total anaerobic bacteria compared to control with a probability of 99.7% was 255, 258, 223 and 56 mg/l respectively. This strong activity of trans-cinnamaldehyde was due to its effect against coliform bacteria; a dose of 104 mg/l gave a reduction of 1 log CFU/ml vs. 371, 400 and 565 mg/l for carvacrol, thymol and eugenol respectively. Few combinations demonstrated synergism; most mixtures showed zero interaction or antagonism. Only carvacrol + thymol was slightly synergistic.  相似文献   

17.
Minimum inhibitory concentrations (MIC) and minimum mycoplasmacidal concentrations (MMC) of the antimicrobials danofloxacin, florfenicol, oxytetracycline, spectinomycin and tilmicosin were determined in vitro for 20 isolates of Mycoplasma mycoides subspecies mycoides small colony type (MmmSC), the causative agent of contagious bovine pleuropneumonia (CBPP). The majority of strains were most susceptible to tilmicosin, followed by danofloxacin, oxytetracycline, florfenicol and spectinomycin with MIC50 values of 0.015, 0.25, 0.5, 1 and 8 microg/ml, and MMC50 values of 0.06, 0.5, 8, 8 and 16 microg/ml, respectively. However, tilmicosin had poor mycoplasmacidal activity against two recent strains from Portugal. There was no evidence of resistance to danofloxacin in any of the strains.  相似文献   

18.
Eight isolates of Brucella abortus were obtained from cows before and after they were treated with oxytetracycline and streptomycin. The susceptibility to these antibiotics was determined by broth-dilution minimal inhibitory and minimal lethal concentrations. Differences were not found in the minimal lethal concentrations of oxytetracycline or streptomycin in isolates obtained from cows before and after they were treated. This indicates that treatment failures in the cows were not the result of development of resistance to the antibiotics by B abortus.  相似文献   

19.
The effects of continuous oxytetracycline administration on the development of parasitaemia of Babesia divergens during both natural and artificial infections were studied. During natural exposure on grazing heavily infested with Ixodes ricinus, seven out of 42 cattle with no previous exposure to tick-borne diseases were injected every four days with a long acting preparation of oxytetracycline at a dose rate of 20 mg/kg. During the six week grazing period 21 untreated cattle developed a patent parasitaemia of B divergens and all became seropositive by the fluorescent antibody test. In contrast, no parasites were observed in treated cattle and antibody titres remained low. Artificial infections were studied with different dose levels of oxytetracycline and their effects on antibody stimulation noted. First, four groups of cows were infected with 10(8) erythrocytes infected with B divergens, three groups being injected every four days with the long acting oxytetracycline formulation at dose levels of 20, 10 and 5 mg/kg, respectively. The highest level completely inhibited parasite replication and antibody formation; the same was observed in one animal dosed at 10 mg/kg but the remainder, plus those treated at 5 mg/kg, developed both low parasitaemia and high antibody titres. The untreated cows developed severe babesiosis. A further untreated control group was added and three weeks after cessation of oxytetracycline treatment all were infected with 10(9) erythrocytes infected with a homologous isolate of B divergens. The controls, plus those in which the previous infection had been completely inhibited, developed severe clinical babesiosis but the remainder were refractory to parasite development.  相似文献   

20.
【目的】 探讨常见兽药恩诺沙星(ENR)、喹烯酮(QCT)、土霉素(OTC)和硫酸多黏菌素B(PMB)对细胞的单一及联合毒性效应。【方法】 以L02、AML12、Marc145、HEK293T、TM3和SK-N-SH细胞为模型, 通过结晶紫染色获得不同浓度下4种药物对6种细胞的相对抑制率, 进行浓度-效应方程拟合, 并分别计算药物在不同生长抑制率下的效应浓度(ECF, 其中F=10、20、25、33、50)。按EC50∶EC50、EC33∶EC33∶EC33、EC25∶EC25∶EC25∶EC25的比例分别进行二元、三元、四元药物等毒性比混合, 以1/2为稀释因子进行浓度梯度处理, 计算抑制率并拟合实际作用曲线, 采用浓度加和模型(CA)和独立作用模型(IA)法评价不同药物之间的联合效应。【结果】 4种药物对6类细胞的生长抑制均存在剂量-效应关系, 无论在哪种细胞中, QCT的毒性最强, PMB毒性最小。4种抗菌药两两组合出现协同的概率较高, 尤其是与OTC的组合, OTC+QCT在6种细胞中均有明显的协同抑制。TM3细胞中易出现相加而对肝细胞和肾细胞协同的可能性更大, 对不同的细胞同一组合的效应变化可能不同。在三元和四元组合中, 相加效应出现的概率上升且变化更为复杂, 易随浓度的变化出现多段效应。【结论】 常见兽药对肝脏、肾脏、神经及生殖细胞具有一定毒性, 且这些药物的联合毒性效应不是简单的相加, 组分、浓度等会影响联合效应, 在应用时要注意配伍禁忌。  相似文献   

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