舒巴坦对氟喹诺酮类药物体外抗菌活性的影响试验

随着抗生素的广泛应用,细菌的耐药菌株显著增加,成为预防和控制临床细菌感染性疾病的主要障碍。产超广谱β-内酰胺酶（Extended Spectrum β-lactamases,ESBLs）是细菌对β-内酰胺类抗生素耐药最重要的机制,它能水解氧氨基头孢菌素和氨曲南,但也能被β-内酰胺酶抑制剂所抑制。ESBLs产生的细菌,不仅对β-内酰胺环类抗生素耐药,     

绵羊源大肠杆菌的分离以及对β-内酰胺类药物的耐药性分析

为了调查石河子地区绵羊肠道正常菌群大肠杆菌对β-内酰胺类抗生素耐药表型和耐药基因的携带情况,本研究采用常规细菌分离方法结合16S rRNA检测方法分离鉴定绵羊源羊肠道正常大肠杆菌,利用K-B纸片扩散法和PCR分析分离株对β-内酰胺类5种临床常用抗菌药的耐药表型及SHV、CTX-M-1、CTX-M-2、CTX-M-9、T...     

主动外排系统介导的大肠杆菌多重耐药性的确证

为检测和证实主动外排系统(外输泵)在细菌多重耐药机制中的作用，用四环素和水扬酸钠对大肠杆菌质控株进行了体外人工诱导，筛选出多重耐药株，再用能量抑制剂CCCP(Carbongl cyanide m-chloropheyhydrazone)时耐药株和质控株进行了环丙沙星摄取抑制试验。结果：在耐药株，其菌体内环丙沙星稳态浓度明显低于质控株；多重耐药株在有CCCP存在时，菌体内环丙沙星的浓度随时间的延长而递增，而无CCCP的抑制时，菌体内环丙沙星的浓度递增缓慢；在质控株，不论有无CCCP存在，菌体内环丙沙星的浓度都随时间的延长而呈递增趋势，且保持较耐药株明显高的水平。结论：体外诱导多重耐药大肠杆菌多重耐药性的产生，可能主要依赖于菌体外输泵的激活。     

48株大肠杆菌超广谱β-内酰胺酶基因型检测

为了解重庆地区部分鸭场大肠杆菌中超广谱β-内酰胺酶(ESBLs)基因分布情况及抗生素的应用对鸭场环境菌的影响。本试验采用PCR技术,对48株大肠杆菌(包括20株病料分离株和28株鸭场土壤分离株)的ESBLs基因TEM、SHV、CTX-M进行检测。结果表明,TEM、SHV、CTX-M型基因在病料分离株中的检出率分别为100%、30%、25%,鸭场土壤中的检出率分别为57.1%、21.4%、28.6%。不同来源的菌株均能检测出耐药基因,且部分细菌携带两种以上耐药基因;病料分离株和鸭场土壤分离株中携带的ESBLs基因均以TEM型为主。     

新疆石河子市牛源大肠杆菌分离鉴定及对β-内酰胺类药物的耐药性分析

为调查石河子市牛源大肠杆菌对β-内酰胺类药物的耐药表型和耐药基因携带情况,采集健康牛群粪便,采用常规细菌分离鉴定方法并结合16S rRNA PCR检测方法进行分离鉴定;参考Clermont方法对分离菌株进行系统分子分群,采用PCR方法检测分离菌株的β-内酰胺类耐药基因blaCTX-M、blaOXA、blaSHV和blaTEM携带情况,通过K-B纸片法测定分离菌株耐药表型。结果显示：分离鉴定出100株牛肠道大肠杆菌分属于A、B1、C和F群;分离株对头孢唑林和阿莫西林的耐药率在50%以上,对氨苄西林、头孢氨苄与头孢吡肟的耐药率均在5%以下,所有分离株对头孢吡肟敏感;5株分离菌株检测到blaSHV基因片段,1株检测到blaCTX-M基因片段,所有菌株均未检测到blaOXA和blaTEM基因片段。结果表明,石河子市牛源正常大肠杆菌已少部分携带耐药基因,且对部分β-内酰胺类药物产生了耐药性。结果提示,应加快减抗政策的实施。     

不同动物源大肠杆菌对13种抗菌药物的敏感性试验

近年来由于抗菌药物在养殖业和宠物行业的不合理使用,使得大肠杆菌在生产中较多地发生多重耐药现象,由此引起的相关疾病也较难防治,给养殖业造成极大的损失。研究通过对不同动物源性大肠杆菌进行13种抗菌药物的敏感试验,以期对其耐药性进行初步总结,为抗菌药物在不同动物的合理应用提供参考和指导。     

大肠杆菌对抗菌药物耐药机制的研究进展

大肠杆菌对抗菌药物的耐药性日益严重,尤其在我国情况更为突出。本文就大肠杆菌对常见抗菌药物的耐药机制方面进行了概述,以期为进一步研究家禽大肠杆菌病的综合防治提供依据。     

大肠杆菌acrA基因的克隆、表达、抗体制备及不同耐药水平大肠杆菌AcrA表达水平的检测

检测不同耐药水平大肠杆菌AcrA表达水平，探讨耐药水平与AcrA蛋白表达水平之间的关系。对acrA基因进行克隆、表达、制备抗AcrA抗体，Western blot方法比较同耐药水平大肠杆菌AcrA表达水平。结果表明，多重耐药株SEMR的AcrA表达明显高于单药耐药株SEICI和SEICH以及质控株ATCC25922。因此SEMR多重耐药性的产生与AcrA的高效表达直接有关。     

宠物犬源大肠杆菌氟苯尼考耐药基因floR的检测及药物敏感性分析

floR是氟苯尼考特异性耐药基因之一,当前宠物犬源大肠杆菌氟苯尼考耐药基因floR的研究报道很少,故本试验利用PCR方法对宠物犬源大肠杆菌氟苯尼考耐药基因floR进行检测,并采用微量肉汤稀释法测定宠物犬源大肠杆菌对10种抗菌药物的最小抑菌浓度(MIC)。结果显示,20株宠物犬源大肠杆菌中floR耐药基因的阳性菌株数为9株,阳性检出率为45%;对氟苯尼考的耐药率为65%,并呈现3~7重的多重耐药性。结果表明,随着氟苯尼考在兽医临床的广泛应用,其耐药率越来越高,需不断加强对氟苯尼考等抗菌药物的耐药性监控。     

外排泵抑制剂小肽1号对抗菌药抗菌活性的影响

为了观察外排泵抑制剂小肽1号对抗菌药抗菌活性的影响,本试验采用标准微量稀释法,测定了6类8种抗菌药单用和与小肽1号联用对12株临床分离鸡大肠杆菌的MIC值。结果表明,12株鸡大肠杆菌中有9株为产超广谱酶的多重耐药菌株,小肽1号（1∶2）使恩诺沙星等8种药物的抗菌活性多数增强2倍,使氟苯尼考对A8、A15的抗菌活性增强了4倍,小肽1号（1∶2或1∶4）使恩诺沙星、甲替沙星、环丙沙星的抗菌活性增强2倍,使左旋氧氟沙星对A13的抗菌活性增强4倍。以上结果表明,细菌外排泵抑制剂-小肽1号对大多数药物的抗菌活性有一定的增强作用,产酶多重耐药的鸡大肠杆菌至少同时存在产ESBLs、外排泵两种耐药机制。     

食品动物源大肠杆菌多重耐药性监测

为掌握畜禽源大肠杆菌的耐药情况,了解其对各种抗菌药物的敏感程度,自广东地区临床分离鉴定出294株食品动物源大肠杆菌,采用琼脂稀释法测定294株大肠杆菌对14种抗菌药物的敏感性。结果显示,食品动物源大肠杆菌对各抗菌药的敏感性不同,且多重耐药现象较严重;受试大肠杆菌对四环素和复方新诺明的耐药率较高,均达到80%以上;对第3代头孢菌素类耐药率相对较低。     

鸭大肠杆菌制苗用基础种子的建立及高密度发酵培养试验研究

从定型的优势血清型菌株中选择了2株,制备了基础种子,并对基础种子第1代、第10代和第13代的传代细菌的培养特性、免疫原性以及毒力进行了测定。结果证明,鸭大肠杆菌GX-5株和GX-21株的基础种子传至13代,其培养特性、免疫原性和毒力均不发生变化,表明这两个分离株是良好的疫苗生产菌株,为建立种子批提供了依据。本试验还进行了鸭大肠杆菌高密度发酵试验,获得了鸭大肠杆菌在马丁肉汤培养基中的最佳发酵条件,即发酵温度37.5 ℃,pH 7.4,初糖浓度10 g/L,补糖量为10 g/L,接种量为4%,通气量为1 L/L·min,搅拌转速为200 r/min,培养12 h后得到的发酵菌液浓度最高,D_{600 nm}值达到30.32。本研究为鸭大肠杆菌抗原的规模化生产奠定了基础,也为新疫苗的研制和开发提供了基础材料。     

60株大肠杆菌的分离与致病性鉴定

大肠杆菌(Escherichia coli,E.coli)是鸡肠道常在菌,部分菌株具有致病性。鸡大肠杆菌病就是由大肠杆菌中的某些致病性菌株引起的鸡感染性疾病。致病性大肠杆菌均携带毒力岛基因ChuA。为鉴定分离自临床病例的鸡大肠杆菌的致病性,本试验采用PCR法检测ChuA基因进行分子生物学鉴定,60株大肠杆菌中有31株属于致病性大肠杆菌,总阳性率为51.67%。     

肉鹅大肠杆菌病的病原分离与鉴定

本试验旨在研究肉鹅大肠杆菌的生化特性、药敏情况、血清型和致病性。2010年12月江苏省某肉鹅场鹅群出现呼吸困难,死亡增多现象,对病死鹅剖检发现以气囊炎和肺部坏死为主,无菌采集病料分离到一株细菌,经分离培养、染色镜检、生化特性鉴定,确定为大肠杆菌,微量凝集试验表明其血清型为O₂。经过肺结节压片镜检,没有发现霉菌的菌丝;检测健康鹅和患病鹅各10只的鹅新城疫抗体,发现其抗体滴度比较高且整齐度较好,两者之间的抗体无明显差异。对分离菌株进行药敏试验,结果表明对氟苯尼考等7种药物敏感,对先锋Ⅴ等16种药物已产生了耐药性。将分离到的菌株接种21日龄雏鹅进行动物回归试验,引起80%死亡率,说明该分离菌株对雏鹅具有较强的致病性。     

广东地区猪源大肠杆菌耐药性及其系统发育群的研究简

为分析广东地区猪源大肠杆菌耐药性及其系统进化背景,试验于2011年从患病猪分离出264株大肠杆菌,包括粪便源131株和肝源133株,采用琼脂稀释法测定18种抗菌药物的敏感性,多重PCR法确定系统进化关系,并对不同来源菌株的耐药性和系统进化背景进行分析比较。结果发现,大肠杆菌多重耐药现象严重,共存在128种耐药谱型。分离菌株对氨苄西林、复方新诺明、萘啶酸和四环素高度耐药,对黏菌素、头孢他啶和阿米卡星较敏感。种群进化分析结果表明,分离菌株主要分布在共生型的A组和B1组（91.66%）,且不同来源菌株的种群进化分布差异不显著(P＞0.05)。结合药敏试验结果发现,不同进化组别的分离菌株对特定抗菌药物的耐药性存在显著差异（P＜0.05）。通过对大肠杆菌耐药性及其系统发育群进行综合分析,为兽医临床用药提供依据。     

Naturally acquired attaching and effacing Escherichia coli in sheep

In a series of experiments involving the inoculation of sheep with Escherichia coli O157:H7, and subsequent detailed histopathological examination of the intestinal mucosa, attaching-effacing (AE) lesions formed by elements of the natural flora were observed in 18% of animals. These incidental AE lesions typically were small and sparse, and were not associated with clinical disease. It was possible to identify further some of the lesional bacteria, revealing that E. coli O115 had formed lesions in one of the seven affected animals, and similarly E. coli O26 had formed some of the lesions in another. As AE strains, source flocks, housing and feed sources were diverse, a common source of lesion-forming bacteria appears to be unlikely. It is postulated that subclinical AE lesions are a mechanism of persistence of AE bacteria in sheep.     

辽西地区鸡大肠杆菌分离鉴定、药敏及IHA诊断液制备

本试验从辽西地区部分养鸡场采集具有典型临诊特征的鸡大肠杆菌病的病、死鸡病料,进行细菌分离培养和鉴定,分离到89株鸡大肠杆菌。通过血清型鉴定,鉴定出血清型的82株,血清型9种,分别为O₁、O₂、O₈、O₁₅、O₁₈、O₃₅、O₇₈、O₁₁₄、O₁₄₁,其中O₁₈、O₃₅型鸡大肠杆菌为辽西地区优势流行血清型。将分离纯化的O₃₅型鸡大肠杆菌超声裂解后,加入致敏双醛化处理过的红细胞,制备O₃₅型鸡大肠杆菌间接血凝诊断液,验证其特异性、敏感性和稳定性,完成诊断液的标准化。同时采用Kirby-Bauer纸片法,选择12种标准药敏片对此89株分离菌株进行药敏试验。结果表明,间接血凝诊断液特异性和敏感性好,质量稳定。而药敏试验结果显示,各地区均有耐药菌株的出现,仅对氟苯尼考、头孢噻呋、左旋氧氟沙星、盐酸沙拉沙星这4种药物敏感性较高。     

traT and CNF2 genes of Escherichia coli isolated from milk of healthy cows and sheep

The objectives of the present study were to isolate Escherichia coli from milk of apparently healthy cows and sheep and to investigate the presence of traT and cytotoxic necrotising factor-2 (CNF2) virulence genes by multiplex polymerase chain reaction (PCR). Milk samples collected from a total of 1028 apparently healthy ruminants (737 cows and 291 sheep) in eastern Turkey were streaked onto 5% sheep-blood agar. E. coli was isolated and identified by biochemical tests in 5.9% (61/1028) of milk samples. Correct amplification with the molecular length of 232 bp was obtained from all E. coli isolates by the species-specific PCR. The isolation rates of the agent were calculated to be 7.6% (56/737) in cows and 1.7% (5/291) in sheep. The difference between these proportions was statistically significant (p < 0.001). Multiplex PCR showed that traT and CNF2 genes were present in 62.3% and 6.6% of all isolates, respectively. Both genes were present in 16.4% of the isolates, with only 14.7% having neither gene.     

Detection of Escherichia coli O157 and Escherichia coli O157:H7 by the immunomagnetic separation technique and stx1 and stx2 genes by multiplex PCR in slaughtered cattle in Samsun Province, Turkey

This study was conducted to investigate the presence of Escherichia (E.) coli O157 and E. coli O157:H7 and stx1 and stx2 genes on cattle carcasses and in rectal samples collected from Samsun Province of Turkey. A total of 200 samples collected from cattle carcasses and the rectal contents of 100 slaughtered cattle from two commercial abattoirs were tested using the immunomagnetic separation technique and multiplex PCR methods. E. coli O157 and E. coli O157:H7 were detected in 52 of the 200 samples (26%) tested. Of the positive samples, 49 were E. coli O157 and three were E. coli O157:H7. The E. coli O157 strain was isolated from 24 carcasses and 25 rectal samples, while E. coli O157:H7 was isolated from two carcasses and one rectal sample. Of the 49 samples positive for E. coli O157, 32 were from the rectal and carcass samples of the same animal, while two E. coli O157:H7 isolates were obtained from rectal swabs and carcasses of the same animal. The stx1 and stx2 genes were both detected in 35 E. coli O157 isolates and one E. coli O157:H7 isolate, but the stx2 gene was only detected alone in two E. coli O157 isolates. Overall, 16 carcasses tested positive for E. coli O157 and one carcass tested positive for E. coli O157:H7 based on both carcass and rectal samples. Overall, the results of this study indicate that cattle carcasses pose a potential risk to human health due to contamination by E. coli O157 and E. coli O157:H7 in the feces.     

An investigation of factors associated with the prevalence of verocytotoxin producing Escherichia coli O157 shedding in Scottish beef cattle

The prevalence of verocytotoxin-producing Escherichia coli (VTEC) O157 in 12-30-month-old beef finishing cattle in Scotland was determined using 1g faeces samples enriched in buffered peptone water, followed by immunomagnetic separation (IMS) and isolation on sorbitol MacConkey agar with cefixime and tellurite supplement (CT-SMAC). A validated questionnaire was used to collect information that could be associated with the samples. Generalised Linear Models and Generalised Linear Mixed Models were used to identify factors associated with shedding both between and within groups. A total of 14,856 samples were collected from 952 farms, of which 1231 were positive for VTEC O157. Prevalence levels were calculated with 95% confidence intervals as follows: 7.9% (6.5%, 9.6%) of animals sampled were estimated to be shedding VTEC O157, while 22.8% (19.6%, 26.3%) of farms were estimated as having at least one animal shedding in the group sampled. The median percentage of animals shedding in positive groups was 25% (20%, 32%). An increased probability of a group containing a shedding animal was associated with larger numbers of finishing cattle, the presence of pigs on the farm, or the farm being classed as a dairy unit stocking beef animals. Farms that spread slurry on grazing land were more likely to have shedding animals, while those that spread manure were at lower risk. Groups with older animals were less likely to be identified as positive. There was no significant regional difference in group shedding probabilities, but the proportion of positive groups dropped over two successive years of the study. Higher mean levels of shedding in positive groups were associated with animals being housed rather than at pasture, and this effect was stronger in groups which had recently had a change in housing or diet. Farms with animals at pasture had lower mean prevalence where water was supplied from a natural source, as had farms with higher numbers of finishing cattle. There remained unexplained variability in mean prevalence levels on positive farms in different areas of Scotland.