Antimicrobial ratings: the importance of importance

Debate about antimicrobial resistance (AMR) in animals and the impact on humans is often inappropriately focussed on the crude amount of antimicrobials used in animals without deference to issues of ‘intensity of use’, ‘quality of use’ and especially the class of agents being administered. In the latter case, tools for helping to manage how the use of specific antimicrobial agents impact on the risk and consequences of antimicrobial resistance in humans have been available for almost two decades. These consist of antimicrobial ratings systems, which formally define the importance of each individual agent in human health by assigning them to a position on a graduated scale of ‘importance’ comprising up to four categories of risk. Until recently, these published ratings have only had a modest impact on antimicrobial stewardship at the frontline of medical and veterinary practice, although they will undoubtedly have a substantial influence into the future. This article considers the evolution of the available ‘antimicrobial ratings systems’ applicable to Australian and international settings and their pivotal future‐role in the educating of animal managers, policy makers and prescribers. Faithful application of these rating systems at all levels of decision making to do with antimicrobial use is now seen as central to the protection of animals, humans and economies from the scourge of AMR.     

中国鲎(Tachypleus tridentatus)基因工程抗菌肽的制备及其抗菌活性

从中国鲎血细胞RT-PCR扩增抗菌肽tachyplesins基因,经改造构建原核和真核表达载体pET-KRN、pPIC9-KRY,并分别在大肠杆菌DE3和毕赤酵母GSll5中诱导表达.用Tris-Tricine SDS-PAGE检测并进一步电洗脱纯化表达产物,经体外生物活性测定表明,表达产物KRN对大肠杆菌、金黄色葡萄球菌、枯草杆菌、伤寒沙门菌的抑菌环为25、22、25、16mm;MIC值为3.57、7.14、3.57、14.28mg/L.表达产物KRY对大肠杆菌、金黄色葡萄球菌、枯草杆菌、伤寒沙门菌和李氏杆菌的抑菌环为26、22、25、18、16mm;MIC值为1.57、3.14、1.57、6.28、6.28mg/L,对水霉的抑菌效果尤其显著,抑菌环达35mm.     

抗菌脂肽Surfactin的抗菌活性及应用

Surfactin是枯草芽孢杆菌属不同菌株代谢产生的一种抗菌脂肽,不仅能抑制多种革兰氏阳性菌、革兰氏阴性菌和真菌等病原菌,而且还具有抗病毒、抗支原体、抗原虫等活性,是潜在的抗生素理想替代品之一。本文对抗菌脂肽Surfactin的结构、理化性质、抗菌机制及应用研究进展进行了综述,为Surfactin的进一步研究和应用提供参考。     

2019年我国兽用抗菌药物使用情况分析研究

对2019年国内兽用抗菌药物销量数据进行了统计分析,按照兽用抗菌药销售量等同于使用量的评价指标,结果发现,国内兽药使用总量为37159.12吨;其中,使用量最大的是四环素类,占比36.56%;促生长用抗菌药的用量为14871.05吨,占比48.12%;每吨动物产品兽用抗菌药使用量为160 g。与2018年相比,兽用抗菌药物使用量略有上升,每吨动物产品使用的抗菌药物量也同比增加,这提示我国兽用抗菌药物使用管理不能放松,减抗政策需继续实施,久久为功。     

国外禽用抗菌药的耐药性监测与控制

介绍了以美国、加拿大、丹麦和日本为代表的一些发达国家对禽类病原菌的耐药性监测情况,分析了禽类病原菌耐药性成因,提出了禽用抗菌药耐药性控制策略,为禽类健康养殖和人类公共卫生健康提供参考。     

Antimicrobial stewardship in the dairy industry: responding to the threat of antimicrobial resistance

Dairy Australia is the national service body for the Australian dairy industry. Its role is to help farmers adapt to a changing operating environment and achieve a profitable, sustainable dairy industry. Although the use of antibiotics in Australian agriculture is relatively low in global terms, Dairy Australia recognises important drivers for continuous improvement in antimicrobial stewardship (AMS). Dairy Australia’s first strategic priority is to support profitable farms. This priority has driven the development of a range of on‐farm change management programs in the animal health and welfare fields to optimise the unit cost of production and dairy cattle welfare. Dairy Australia’s third strategic priority is to further develop a ‘trusted dairy industry’. Previous and current work under these two strategies position the dairy industry favourably with respect to confronting the challenge of antimicrobial resistance (AMR) and supporting sound AMS with the guiding principle of ‘as little as possible, as much as necessary’. However, given an incomplete but ongoing threat of AMR, more work is needed. Supported by Dairy Australia, the dairy industry has developed an antimicrobial use strategy aligning with the Australian Animal Sector National AMR Plan 2018.     

猪源粪肠球菌的基因型及耐药性分析

为了解上海地区规模化猪场中粪肠球菌的耐药性和基因型,2013年3月-2014年5月从上海地区10个规模化养猪场收集到分离鉴定的粪肠球菌133株,采用微量肉汤稀释法对12种抗菌药物进行药敏试验,采用PCR技术分别检测分离株中β-内酰胺类抗生素耐药相关基因(TEM)、氨基糖苷类抗生素耐药相关基因[aac(6’)/aph(2")和aph(3’)-Ⅲ和ant(6)-Ⅰ]、四环素耐药相关基因(tetM)、红霉素耐药相关基因(ermB和mefA)和万古霉素耐药相关基因(vanA和vanB)。结果显示,在133株粪肠球菌中,耐药基因ermB、tetM、TEM、ant(6)-Ⅰ、aac(6’)/aph2"、aph(3’)-Ⅲ、vanA的检出率分别为:95.5%(127/133)、91.0%(121/133)、63.2%(84/133)、45.9%(61/133)、42.1%(56/133)、24.1%(32/133)、3.0%(4/133);未检出mefA和vanB基因的菌株。分离菌株对12种抗菌药物的耐药性较为严重,且以6~9耐为主要耐药株,占81.2%。试验表明,上海地区猪源粪肠球菌多重耐药现象严重,携带抗菌药物相关耐药基因是导致分离株耐药的主要原因。     

抗菌肽的研究进展

抗菌肽,又称为肽抗生素,是多种生物体经外界环境诱导由特定基因编码、核糖体合成并由一些腺体分泌的参与到生物体固有免疫反应的小分子多肽。经试验证实,其除了具有广谱高效的抗菌活性之外,对于部分真菌、原虫、病毒及癌细胞等也具备强有力的杀伤作用,甚至某些抗菌肽对HIV-1病毒的增殖也具有抑制作用。论述了抗菌肽的研究现状,并对其应用及现存问题进行了深入的探讨。     

Antimicrobial Susceptibility of Escherichia coli Isolated from Iranian Broiler Chicken Flocks, 2005–2006

Escherichia coli is a major pathogen of worldwide importance in commercially produced poultry, contributing significantly to economic losses in chickens and turkeys. One hundred thirty-five cases in broilers were examined and cultured for isolation and antimicrobial sensitivity evaluation of E. coli between January 2005 and December 2006. In 103 cases (76.3%) E. coli were isolated and in 32 cases (23.7%) no E. coli growth was observed. Multiple resistances were seen in all isolates. All isolates were uniformly resistant to Tiamuline, Tylosin, and Bacitracin. We observed low levels of resistance to Gentamicin (12%), Kanamycin (0%), and Florfenicol (39%). Percentages of resistance to Tiamuline, Bacitracin, Tylosin, Colistin, and Erythromycin (≥99%); Tetracycline (96%); Oxytetracycline (93%); Flomequine (87%); Neomycine (87%); Lincospectin (79%); Difloxacin (78%); Enrofloxacin (76%); Cotrimoxazole (72%); Chloramphenicol (52%); and Ampicillin (49%) were determined. Our data show high levels of multiresistance among Iranian E. coli isolates. It seems that the pattern of antibiotic resistance of bacteria that are clinically important for the poultry industry should be monitored.     

Antimicrobial susceptibility of bacteria isolated from neonatal foal samples submitted to a New Zealand veterinary pathology laboratory (2004 to 2013)

AIMS: To describe antimicrobial susceptibility, and identify antimicrobial resistance (AMR), in bacteria isolated from New Zealand foals.

METHODS: A database search was performed of submissions to a veterinary pathology laboratory between April 2004 and December 2013 for bacterial culture of samples from foals <3 weeks of age. Culture and susceptibility results were compiled with demographic information. Susceptibility results were as defined for the Kirby-Bauer disk diffusion susceptibility test based on Clinical Laboratory Standards Institute guidelines. Multi-drug resistance (MDR) was defined as non-susceptibility to ≥3 of a panel of antimicrobials (ceftiofur, enrofloxaxin, gentamicin, penicillin, tetracycline, trimethoprim-sulfonamide); penicillin susceptibility was not included for Gram-negative isolates.

RESULTS: Submissions from 102 foals were examined, and 127 bacterial isolates were cultured from 64 (63%) foals. Of the 127 isolates, 32 (25%) were Streptococcus spp., 30 (24%) were Staphylococcus spp., 12 (10%) were Enterococcus spp. and 26 (21%) were Escherichia coli. Of 83 Gram-positive isolates, 57 (69%) were susceptible to penicillin. Over all isolates, 92/126 (73%) were susceptible to gentamicin and 117/126 (93%) to enrofloxacin; 62/82 (76%) of Gram-positive, and 22/42 (52%) of Gram-negative bacteria were susceptible to ceftiofur; 53/81 (65%) of Gram-positive, and 23/44 (52%) of Gram-negative bacteria were susceptible to tetracycline; 59/82 (72%) of Gram-positive, and 23/44 (43%) of Gram-negative bacteria were susceptible to trimethoprim-sulfonamide. Of 126 isolates, 33 (26%) had MDR; >1 isolate with MDR was cultured from 24/64 (38%) foals, and ≥2 isolates with MDR were recovered from 8/64 (13%) foals.

CONCLUSIONS: Multi-drug resistance, including resistance to commonly used antimicrobials, was found in bacterial isolates from foals in New Zealand.

CLINICAL RELEVANCE: The results of this study are of concern from a treatment perspective as they indicate a potential for antimicrobial treatment failure. For future surveillance of AMR and the creation of national guidelines, it is important to record more data on samples submitted for bacterial culture.     

大黄酸对伪中间葡萄球菌的抗菌活性及作用机制

伪中间葡萄球菌（Staphylococcus pseudintermedius）是犬脓皮病主要致病菌,具有多重耐药性,严重威胁犬及人类健康。本研究从脓皮病患犬中分离20株伪中间葡萄球菌,并揭示大黄酸对伪中间葡萄球菌的抗菌活性及抗菌机理。通过测定最小抑菌浓度、最低杀菌浓度、抑菌曲线和黏附抑制试验分析了大黄酸对伪中间葡萄球菌的抑菌活性;检测大黄酸对伪中间葡萄球菌细胞膜完整性、通透性,细胞活性氧（ROS）水平等,结合电镜观察细菌细胞形态和超微结构,从而探究大黄酸的抑菌机理。结果表明,大黄酸对伪中间葡萄球菌的最小抑菌浓度为12.5 μg·mL^-1,亚抑菌浓度能够显著抑制伪中间葡萄球菌生长和黏附;经大黄酸处理后,伪中间葡萄球菌细胞膜通透性改变,胞外β-半乳糖苷酶活性增加（P<0.05）;ROS测定结果显示,大黄酸处理后细菌细胞ROS水平增高3.9倍（1×MIC）和6.4倍（2×MIC）;大黄酸处理后,电镜观察伪中间葡萄球菌表面存在大量分泌物、皱缩,胞壁破裂、电子密度降低、内容物泄漏等。综上,大黄酸可通过改变细菌细胞膜通透性、破坏膜完整性,诱导细菌细胞产生大量ROS等作用机制达到抗菌目的。     

18种抗菌药物对绵羊肺炎支原体和丝状支原体分离株的抗菌活性

应用微量法测定了18种常用抗菌药物对绵羊肺炎支原体分离株HD1-goat和丝状支原体分离株XT1-goat的抗菌活性.结果表明,喹诺酮类药物及盐酸多西环素、酒石酸泰乐菌素对两个分离株均有很高的抗菌活性;硫氰酸红霉素对分离株HD1-goat无抑制生长作用,但对分离株XT1-goat有很高的抑制和杀灭活性;氨基糖苷类药物和...     

世界动物卫生组织和食品法典委员会两种风险分析系统及其专业术语的比较

比较了世界动物卫生组织（OIE）法典中使用的Covello—Merkhofer系统和由美国国家科学院（USNAS）设计的Codex Alimentarius食品法典采用的风险分析系统及其专用术语的不同。     

抗菌脂肽对肉鸡抗氧化能力及血清生化指标的影响

为研究不同水平抗菌脂肽对肉鸡抗氧化能力及血清生化指标的影响,将1日龄健康AA肉鸡600只,随机分为5组:对照组(不含抗菌脂肽及抗生素)、抗生素对照组及在基础日粮中分别添加4 000、8 000和12 000 U/kg抗菌脂肽组,试验期为42 d。结果发现:4 000 U/kg抗菌脂肽能显著提高血清T-AOC及肝脏SOD水平,8 000 U/kg抗菌脂肽能显著提高血清SOD水平,同时能显著降低肝脏MDA水平。4 000 U/kg抗菌脂肽能显著提高血清TP及GLOB水平,而12 000 U/kg抗菌脂肽能提高血清GOT及GPT水平,但差异不显著。抗菌脂肽对血清UN及TC含量无明显影响。结果表明适宜的抗菌脂肽添加量(4 000 U/kg)能提高肉鸡抗氧化机能,且能促进蛋白质的代谢。     

Study on the Anti-Escherichia coli Activity and Mechanism of Water Extract of Radix isatidis Powder

In order to explore the antibacterial activity and mechanism of the Radix isatidis powder water extract,the effects of the Radix isatidis powder water extract on the morphology and structure of Escherichia coli (E.coli) were tested by scanning electron microscopy and transmission electron microscopy.The effects of the Radix isatidis powder water extract on the conductivity and total leakage rate of E.coli and the content of alkaline phosphatase in the culture medium of the content of protein,DNA and RNA were stained by DAPI to detect the effect of the Radix isatidis powder water extract on the nucleic acid of E.coli,and the effect of the Radix isatidis powder water extract on the metabolism of E.coli in vivo,in vitro,ALT,AST,pyruvic acid and ATP.The results showed that after the Radix isatidis powder water extract acted on E.coli for 10 h,it was observed by SEM that the bacteria appeared to overflow and shrink,the length of the bacteria became shorter obviously,many residues were formed due to breakage,some of them were sunken in the middle and deformed.Under TEM,it was observed that the boundary of the cell wall of E.coli was unclear,the wall membrane was zigzag,deformed and some of the bacteria were broken.The protein content outside the cell was significantly different from that in the blank control group from 8 h (P<0.01), and that in the cell from 4 h (P<0.01). DNA content had no significant difference with blank control group before 12 h (P>0.05), but had significant difference with blank control group from 16 h (P<0.01); RNA content began to decrease at 8 h, and was significantly different from blank control group at 12 h (P<0.05), and was extremely significant from 16 h (P<0.01). There was no significant difference between ALT and AST (P>0.05). The pyruvate content in culture medium and bacteria was higher than that in blank control group, and the difference was very significant from 4 h (P<0.01). The ATP content in the culture medium was significantly different from that in the blank control group (P<0.01), and the ATP content in the cell was significantly different from that in the blank control group from 4 h (P<0.01).In conclusion,the Radix isatidis powder water extract could inhibit the synthesis and metabolism of bacterial genetic material and the content of pyruvate and ATP by destroying the integrity of cell wall and cell membrane.     

板蓝根微粉水提物抗大肠杆菌活性及其机制的探究

为了探究板蓝根微粉水提物的抗菌活性及其抗菌机制，试验通过扫描电镜、透射电镜检测板蓝根微粉水提物对大肠杆菌形态和结构影响；酶标仪测定板蓝根微粉对大肠杆菌电导率、胞内物质总漏出率影响；测定大肠杆菌培养液中碱性磷酸酶含量以及大肠杆菌菌体内、外蛋白质含量；通过DAPI染色DNA、RNA，检测板蓝根微粉水提物对大肠杆菌核酸的影响；检测板蓝根微粉水提物对大肠杆菌菌体内、外谷丙转氨酶（ALT）、谷草转氨酶（AST）、丙酮酸以及三磷酸腺苷（ATP）等菌体内代谢的影响。结果显示，板蓝根微粉水提物作用大肠杆菌10 h后，扫描电镜检测可见菌体出现溢缩，菌体长度明显变短，断裂形成许多残体，有的中间凹陷，发生变形；透射电镜下可观察大肠杆菌的胞壁界限模糊不清，壁膜呈现锯齿状，弯弯曲曲，变形，有的菌体破碎。总漏出率、电导率以及碱性磷酸酶含量测定结果显示，板蓝根微粉水提物各组D_{600 nm}均高于空白对照组，且呈剂量依赖性。菌体外蛋白质含量从8 h开始与空白对照组差异极显著（P<0.01）；菌体内蛋白质含量从4 h开始与空白对照组差异极显著（P<0.01）。DNA含量在12 h前与空白对照组无显著差异（P>0.05），从16 h开始与空白对照组差异极显著（P<0.01）；RNA含量在8 h开始降低，在12 h时与空白对照组差异显著（P<0.05），从16 h开始差异极显著（P<0.01）。ALT和AST浓度测定无显著性差异（P>0.05）。培养液和菌体内的丙酮酸含量均高于空白对照组，且从4 h开始与空白对照组差异极显著（P<0.01）。培养液中的ATP含量与空白对照组差异极显著（P<0.01）；菌体内ATP含量从4 h开始与空白对照组差异极显著（P<0.01）。综上，板蓝根微粉水提物可以通过破坏细胞壁、细胞膜的完整性，抑制细菌遗传物质合成和代谢，影响丙酮酸和ATP含量从而实现抗大肠杆菌作用。