Evaluation of the ability of colistin,amoxicillin (components of Potencil®), and fluoroquinolones to attenuate bacterial endotoxin‐ and Shiga exotoxin‐mediated cytotoxicity—In vitro studies

Escherichia coli is one of the major pathogens in humans and animals causing localized and systemic infections, which often lead to acute inflammation, watery diarrhea, and hemorrhagic colitis. Bacterial lipopolysaccharide (LPS) and Shiga exotoxins (Stx) are mostly responsible for such clinical signs. Therefore, highly effective treatment of E. coli infections should include both eradication of bacteria and neutralization of their toxins. Here, for the first time, we compared the in vitro ability of common antibiotics to decrease LPS‐ and Stx‐mediated cytotoxicity: colistin, amoxicillin (used separately or combined), enrofloxacin, and its metabolite ciprofloxacin. Three experimental scenarios were realized as follows: (a) the direct effect of antibiotics on endotoxin, (b) the effect of antibiotic treatment on LPS‐mediated cytotoxicity in an experiment mimicking “natural infection,” (c) the effect of antibiotics to decrease Stx2e‐mediated cytotoxicity. Two cell lines, A549 and Vero cells, were used to perform cytotoxic assays with the methyl tetrazolium (MTT) and lactate dehydrogenase leakage (LDH) methods, respectively. Colistin and amoxicillin, especially used in combination, were able to attenuate LPS toxic effect, which was reflected by increase in A549 cell viability. In comparison with other antibiotics, the combination of colistin and amoxicillin exhibited the highest boster or additive effect in protecting cells against LPS‐ and Stx2e‐induced toxicity. In summary, in comparison with fluoroquinolones, the combination of colistin and amoxicillin at concentrations similar to those achieved in plasma of treated animals exhibited the highest ability to attenuate LPS‐ and Stx2e‐mediated cytotoxicity.     

阿莫西林和硫酸粘菌素对猪鸡大肠杆菌和沙门氏菌的体外联合抗菌作用

探讨了阿莫西林与硫酸粘菌素对猪鸡的大肠杆菌和沙门氏菌的联合抗菌效果。采用微量稀释法分别测定阿莫西林与硫酸粘菌素单药对大肠杆菌和沙门氏菌的最低抑菌浓度（MIC）,采用棋盘稀释法测定阿莫西林与硫酸粘菌素联用对大肠杆菌和沙门氏菌的MIC并计算联合指数（FIC）。试验结果显示,对14株试验菌株体外联合抗菌呈协同与相加作用的占78.6%,呈无关作用的占21.4%,无拮抗作用,表明阿莫西林和硫酸粘菌素可联合应用于治疗猪鸡大肠杆菌和沙门氏菌感染。     

牛奶中阿莫西林残留的检测及其消除规律的研究

选用2组健康正常泌乳奶牛注射阿莫西林,剂量分别为1 mL/20 kg体重(正常剂量组)和2 mL/20 kg体重(加倍剂量组),连续用药5 d后开始取奶样检测其中的阿莫西林残留量.休药0 h,正常剂量组奶样中阿莫西林残留量为9.0μg/kg,加倍剂量组奶样中阿莫西林残留量为16.9μg/kg.随着休药时间的延长,奶样中阿莫西林残留量迅速降低.     

Use of Camelina sativa in the Diets of Young Turkeys

Camelina sativa is one of various oilseed crops being studied for its potential value in biofuel production. The resultant by-product of oil extraction, camelina meal (CM), could be marketable as a livestock feed. Our study evaluated the potential use of CM as a feed ingredient in turkey poult starter diets. This was a pilot study to determine whether further work investigating inclusion of CM as a potential feed ingredient in turkey diets might be of value if a least-cost formulation warranted its integration. Results indicate that CM may be a potentially useful minor ingredient in turkey diets if economically feasible, but caution should be exercised in using CM above 5% of finished feed in a poult starter diet. In an appended test, similar weight gain and feed conversion were attained with a diet containing camelina oil as a replacement for vegetable oil compared with the control diet.     

Depletion of colistin in eggs following medication of laying hens

The depletion of colistin in eggs was determined separately for the albumen, the yolk and the whole egg after oral and intramuscular administrations of colistin sulphate. Residues were assayed by an agar plate diffusion method with Bordetella bronchoseptica ATCC 4617 as test organism. Colistin residues were not detected after drug administration by the oral route, but could be detected in the yolk until eight days after intramuscular injection. The total amount excreted represented 0.9% of the dose applied.     

高效液相色谱荧光法检测鸡组织中阿莫西林残留

建立了高效液相色谱荧光法检测鸡组织中阿莫西林（ AMO ）的残留量。鸡组织样品经磷酸二氢钠溶液提取,乙腈去蛋白,正己烷去脂肪,饱和二氯甲烷萃取,上清液经水杨醛在酸性条件下沸水浴衍生化。以0．01 mol／L 的磷酸二氢钾溶液和乙腈溶液为流动相,梯度洗脱,流速为1 mL／min,高效液相色谱荧光检测,激发波长为358 nm,发射波长为440 nm。阿莫西林在25～1000μg／kg质量浓度范围内,线性关系良好。当阿莫西林添加水平为13～125μg／kg时,鸡组织中AMO的平均回收率在72．82％～88．82％,相对标准偏差在6．21％～9．63％;检测限、定量限分别为5μg／kg（S／N≥3）、13μg／kg（S／N≥10）。该方法操作简便,可适用于鸡组织中阿莫西林的提取和检测,且准确度和精密度均符合残留分析的要求。     

A modified method for the detection of antibiotic residues in slaughter animals.

Biological methods in current use for the detection of antibiotic residues in slaughter animals are reviewed. A modified method is suggested in which the conditions for the control have been standardized. By the use of a semi-defined medium, the batch-to-batch variations are minimized. In order to facilitate the detection of sulfonamides the medium is supplemented with trimethoprim. The standardized conditions included the use of a sporulating organism, Bacillus subtilis, an inoculum size of 0.5 × 10⁵ spores per ml medium, and 5 ml medium of pH 6.0 per plate. A preincubation-diffusion time of 1 h in room temperature is recommended before incubation.The modified method was compared with the currently prescribed Swedish method. The new method was easier to perform and showed a more uniform sensitivity to most of the antibiotics used.     

硫酸粘杆菌素的急性毒性及对小鼠骨髓细胞的微核效应

为评价国产硫酸粘杆菌素的安全性 ,进行了改良寇氏法测定LD50 小鼠骨髓细胞的微核试验。结果显示 ,国产硫酸粘杆菌素的LD50 为 71 1 45mg/kg ,属于低毒类化合物 ;小鼠骨髓微核试验结果为阴性 ,表明其不具致突变作用     

Pharmacokinetics of a novel amoxicillin/colistin suspension after intramuscular administration in pigs

He, J., Tang, S., Li, L., Zhang, C., Li, X., Xia, X., Xiao, X. Pharmacokinetics of a novel amoxicillin/colistin suspension after intramuscular administration in pigs. J. vet. Pharmacol. Therap. 34 , 42–50. An amoxicillin (AMO) or colistin (COS) oil suspension was developed and corresponding pharmacokinetics studies were conducted in pigs after i.m. injection. The combination product is a white‐ to cream‐colored oil suspension which is easy to be re‐dispersed. Settling volume ratio, syringeability and flowability of the product is well consistent with the technical standards set by the Ministry of Agriculture of People’s Republic of China. Two studies were conducted to investigate the pharmacokinetics of the combination product in swine. First, the pharmacokinetics of the combination product was compared with those of the same products merely removing either AMO or COS. No significant change in the major pharmacokinetic parameters (C_max, T_max, MRT, t_1/2λ, AUC and AUMC) was observed when either component was removed from the combination product, indicating that AMO and COS do not interfere with each other in their absorption and distribution in the tissue when used as a combination. Second, the pharmacokinetics of the combination product was compared with that of their respective single products. It was found that the apparent elimination half‐lives (t_1/2λ) of AMO and COS in combination product were 6.38 and 8.09 h, which were 2.40 and 2.38 times longer than the single products, respectively. Thus, the novel AMO/COS suspension extended significantly the half‐life of both drugs to maintain a longer drug residence time in pigs when compared to their single products.     

Determination of milk/plasma ratio and milk and plasma pharmacokinetics of amoxicillin after intramuscular administration in lactating cows

This study was conducted to determine the passage ratio of amoxicillin into milk and its pharmacokinetics in milk and plasma after intramuscular administration. Five healthy dairy cows (Holstein, weighing 450–500 kg, aged 2–4 years) were used in this study. They received single intramuscular amoxicillin at a dose of 14 mg/kg body weight. Blood and milk samples were collected prior to drug administration (0); after 15, 30, 45, 60, and 90 min; and 2, 3, 4, 6, 8, 10, and 12 hr after administration. The plasma and milk concentrations of amoxicillin were determined using high‐performance liquid chromatography with ultraviolet detection. The passage ratio of amoxicillin into milk and plasma was determined using both AUC‐based calculation and milk and plasma concentrations at sampling times; it was calculated 0.46 and 0.52, respectively. The terminal half‐life and mean residence time of amoxicillin were 6.05 and 8.60 hr in plasma and 2.62 and 5.35 hr in milk, respectively. The C_max2 levels of amoxicillin in plasma and milk were measured as 1,096 and 457 ng/ml, respectively. It was observed that amoxicillin exhibited a secondary peak in plasma and milk. This study was the first to report on the passage ratio of amoxicillin into milk in lactating cows.     

高效液相色谱荧光检测法同时检测鸡血浆中阿莫西林和氨苄西林残留

建立高效液相色谱荧光法同时检测鸡血浆中阿莫西林和氨苄西林的残留量。鸡血浆经乙腈提取,饱和二氯甲烷萃取,酸性条件下水杨醛沸水浴衍生化后,以0.01mol/L的磷酸二氢钾溶液（A）和乙腈溶液（B）为流动相,梯度洗脱,流速为1.0mL/min,荧光检测激发波长为354nm,发射波长为445nm。阿莫西林和氨苄西林线性范围均为5.0~5 000.0μg/L,线性关系良好（r=0.999 9,0.999 6）。当阿莫西林和氨苄西林添加水平均为5.0~125.0mg/L时,鸡血浆样品平均回收率均高于74.72%,相对标准偏差（RSD）均低于8.65%,日内相对标准偏差分别低于4.99%和10.60%,日间相对标准偏差分别低于7.98%和11.29%。测定鸡血浆样品中AMO的检测限（LODs）为2.0μg/L（S/N=3）、定量限（LOQs）为5.0μg/L（S/N=10）,AMP的检测限为1.0μg/L（S/N=3）、定量限为2.5μg/L（S/N=10）。该方法操作简便、快速,且结果精确、灵敏、可靠,可适用于鸡血浆中阿莫西林、氨苄西林同时提取和检测。     

黏杆菌素神经毒性的研究进展

系统回顾了黏菌素神经毒性的发生情况、主要症状、作用机制、神经毒性反应的危险因素以及神经毒性的预防与治疗,为期为神经毒性研究以及临床用药提供参考资料。     

An improved microbiological procedure for detection of streptomycin residues in milk and animal tissues.

A method is described which allows detection of 0.025 µg streptomycin sulfate per ml. This represents an improvement of sensitivity by 8 times when compared with the currently used method. By adding penicillin to the assay medium in subinhibitory concentrations, a synergistic effect of streptomycin and penicillin is exerted towards the test organism, Bacillus subtilis, resulting in an increased sensitivity to streptomycin.     

离子交换层析法提取黏杆菌素的研究

本文采用D152型弱酸性阳离子交换树脂对多黏类芽孢杆菌(Paenibacillus polymyxa)发酵液中黏杆菌类(Colistin)的提取条件进行了研究。通过静态与动态吸附相结合的方法，确定了影响提取效果的三个重要参数即洗脱液Hcl浓度、上样液浓度和洗脱液流速。结果表明，当上样液浓度为20000IU／ml，1mol／L HCl以2.0ml／min的流速洗脱时可获得最好的提取效果，收率达到52．8％。     

1日龄火鸡新城疫免疫后外周血液的免疫学变化

应用ＮＤ来活苗与弱毒苗联合及单独弱毒苗对１日龄火鸡进行早期免疫，于第６０日进行ＮＤ强毒攻击。分别在第７、１４、２１、３５和日龄检测外周血液的免疫学变化。结果表明，１日龄火鸡疫苗接种后其外周血液中Ｔ细胞、Ｂ淋巴细胞和淋巴细胞数量、血清ＩｇＧ，ＩｇＭ，ＩｇＡ含量及ＨＩ抗体滴度均明显升高，可获得良好的免疫保护效应，其中活苗与死苗联合免疫组优于单独活苗免疫组。     

Depletion of florfenicol in lactating dairy cows after intramammary and subcutaneous administration

Eighteen Holstein dairy cows ranging in body weight from 500–700 kg and with an average milk yield of 37 ± 6 kg/day were used to investigate the depletion of florfenicol (FFL) in milk and plasma of dairy cows. Three groups of six were administered FFL: Group A, intramammary (IMM) infusion of ~2.5 mg FFL/kg BW at three consecutive milking intervals (total amount of ~7.5 mg/kg BW); Group B, one IMM infusion (20 mg/kg BW) into one quarter and Group C, one subcutaneous (SC) treatment (40 mg/kg BW). IMM infusions were into the right front quarter. Cows were milked daily at 06:00 and 18:00 h. The highest concentrations (C_max) and time to C_max (T_max) were: 1.6 ± 2.2 μg·FFL/mL milk at 22 h (Group A), 5.5 ± 3.6 μg·FFL/mL milk at 12 h (Group B), and 1.7 ± 0.4 μg·FFL/mL milk at 12 h (Group C). The half‐lives (t_1/2) were ~19, 5.5, and 60 h, for Groups A, B, and C, respectively. FFL was below the limit of detection (LOD) by 60 h in three Group B cows, but above the LOD at 72, 84, and 120 h in three cows. FFL was above the LOD in milk from Group C's cows for 432–588 h. Plasma values followed the same trends as milk. The results demonstrate that IMM‐infused FFL is bioavailable and below the LOD within 72–120 h. The concentration of FFL was detectable in both plasma and milk over the course of 2–3 weeks after SC administration. The absence of residue depletion data presents problems in determining safe levels of FFL residues in milk and edible tissues. The data presented here must not be construed as approval for extra‐label use in food animals.     

Pharmacokinetic profiles of amoxicillin trihydrate in freshwater crocodiles (Crocodylus siamensis) after intramuscular administration at two doses

The aim of the present study was to elucidate the pharmacokinetic profiles of amoxicillin trihydrate (AMX) in Siamese freshwater crocodiles (Crocodylus siamensis). Crocodiles were administered a single intramuscular injection of AMX, at a dose of either 5 or 10 mg/kg body weight (b.w.). Blood samples were collected at preassigned times up to 120 hr. The plasma concentrations of AMX were measured using a validated liquid chromatography tandem-mass spectrometry method. AMX plasma concentrations were quantifiable for up to 72 hr (5 mg/kg b.w.) and 96 hr (10 mg/kg b.w.). The elimination half-life (t_1/2λz) of AMX following dosing at 5 mg/kg b.w. (8.72 ± 0.61 hr) was almost identical to that following administration at 10 mg/kg b.w (8.98 ± 1.13 hr). The maximum concentration and area under the curve from zero to the last values of AMX increased in a dose-dependent fashion. The average binding percentage of AMX to plasma protein was 21.24%. Based on the pharmacokinetic data, susceptibility break point, and the surrogate PK-PD index (T > MIC, 0.25 μg/ml), intramuscular administration of AMX at dose of 5 mg/kg b.w. every 4 days might be appropriate for the treatment of susceptible bacterial infections in freshwater crocodiles.     

Efficacy of Spray-Dried Bovine Serum on Health and Performance of Turkeys Challenged with Pasteurella multocida

Improvements in survival and performance during enteric challenges have been reported when plasma proteins have been consumed. However, the effect of plasma proteins during respiratory challenge has not been studied. The current study used 80 Nicholas turkey poults allotted to a 2 × 2 factorial arrangement. Treatments consisted of challenge or no challenge and Innavax (INX)-treated water or untreated water. Tap water was mixed daily with 0 or 1.30, 0.65, 0.325, and 1.30% (wt/wt) INX on d 0 to 7, 8 to 14, 15 to 21, and 22 to 49, respectively. Spray-dried bovine serum was mixed with other ingredients (lactose, citric acid, lecithin, propylene glycol, and mineral oil) used as processing and mixing aids to produce INX. Poults were challenged on d 35 by swabbing the tonsils with Pasteurella multocida Type III. Consumption of INX during the first week improved performance in poults; whereas from d 8 to 35 performance was not affected by water treatment. After the challenge (d 35), INX did improve average daily gain (ADG) and feed efficiency. Innavax improved survival (d 35 to 49) of challenged poults (94.1% survival) compared with challenged poults consuming untreated water (63.2% survival). These data suggest that addition of INX to drinking water systems will increase performance of poults the first week after placement. Furthermore, addition of INX to drinking water reduced mortality in turkeys exposed to Pasteurella multocida in the present study.     

不同日龄火鸡胸腺组织形态结构的研究

为了探索火鸡胸腺随日龄变化的规律,协助做好火鸡的免疫与疾病研究,分别取28,58和88日龄火鸡的胸腺,采用石蜡组织制片,H-E染色,在显微镜下进行对比观察,比较不同日龄火鸡胸腺的组织形态结构。结果表明,火鸡胸腺由表面的被膜和中央的实质构成,被膜伸入实质将其分成许多大小不等的胸腺小叶,每一个小叶又由外周的皮质和中央的髓质组成。且随着火鸡日龄的不断增加,胸腺小叶的面积逐渐增大,数量逐渐增多,皮质部和髓质部的面积也同时增大,皮质内胸腺细胞和巨噬细胞及髓质内胸腺小体和髓质上皮细胞的数量逐渐增多。