鸭源多重耐药鼠鼻罗氏菌的分离鉴定、耐药性及耐药基因检测

鼠鼻罗氏菌是一种常见的条件性致病菌。2020年我国东北地区某农场的鸭出现流黏性鼻液、咳嗽、呼吸急促等散发性呼吸系统症状以及进食量减少、精神低沉等症状。为了确定发病原因,提出针对性的预防和治疗方案,无菌采集发病鸭鼻拭子进行细菌分离培养。分离菌株经培养特性鉴定、染色镜检、生化试验、16S rDNA序列分析,确定为鼠鼻罗氏菌。动物致病性试验结果显示,分离菌株对鸭具有一定的致病性。分离菌株药物敏感性测定结果显示,其对卡那霉素、庆大霉素、链霉素、红霉素、氟苯尼考、头孢氨苄、恩诺沙星耐药,对多西环素敏感。β-内酰胺类耐药基因(TEM、OXA-23)检测结果均为阴性。结果表明,引发疫情的病原为鸭源鼠鼻罗氏菌,其对多种药物耐药。本研究首次在东北地区禽体内分离出致病性鼠鼻罗氏菌,对多重耐药鼠鼻罗氏菌病的预防和控制具有一定指导意义。     

A型产气荚膜梭菌感染绿壳蛋鸭的病理发生学研究

为了探究A型产气荚膜梭菌感染鸭后的病理变化情况。选取37日龄健康绿壳蛋鸭灌喂A型产气荚膜梭菌进行人工感染,观察不同时间的临床症状和病理变化。结果:感染72 h后病鸭开始出现腹泻症状,随着时间的增加,临床症状表现越来越明显。96 h后出现褐色粪便,剖检可见部分组织间有纤维素性渗出液。120 h后剖检可见部分组织有出血点。144 h后鸭出现死亡,剖检可见以十二指肠、空肠、回肠的出血点及坏死最为严重,该时期的病理切片观察结果主要为:十二指肠肠腔充满变性、脱落、坏死的上皮细胞,肠绒毛发生崩解脱落并有血细胞和少量炎性细胞浸润,间杂大量淋巴细胞;回肠绒毛总体结构较为完整,部分肠绒毛发生断裂,并伴有充血现象;空肠肠腔充满变性、脱落、坏死的上皮细胞,肠绒毛发生崩解脱落,并有血细胞和少量炎性细胞浸润,肌纤维间隙较大、断裂、密度明显减小。     

湖北荆州地区鸭大肠杆菌分离鉴定及生物学特性

从荆州地区鸭场的145份病料中分离到68株鸭大肠杆菌,并通过菌体形态、菌落形态、革兰氏染色特性、生化特性、血清型等一系列的鉴定,确认为鸭大肠杆菌。药敏试验证明各菌株的耐药谱不同。动物致病性试验表明该菌对小白鼠有较强的致病性,可引起小白鼠死亡。各菌株感染雏鸭,均能复制典型的临床症状。     

鸭疫里氏杆菌的分离鉴定

从死亡及濒死期雏鸭的肝、脾、肺和腹水等病料中分离到8株细菌,经培养特性、形态特征观察和生化试验等,鉴定为鸭疫里氏杆菌（Riemerella anatipestifer）。用分离株人工感染7日龄健康雏鸭,复制出与自然发病雏鸭相同的病例。药敏试验表明,该菌株对氟苯尼考、丁胺卡那霉素、林町霉素高度敏感,对卡那霉素、恩诺沙星等11种药物均有不同程度的耐药性。     

人工感染鸭疫里氏杆菌雏鸭的病理学变化

用鸭疫里氏杆菌(Riemerella anatipestifer)人工感染7日龄雏鸭，对其进行了临床症状、病理剖检和病理组织学观察。试验结果表明，人工感染鸭疫里氏杆菌24h后，感染鸭开始出现死亡，且在48h内全部死亡。剖检可见典型的纤维素性心包炎、肝周炎、气囊炎。病理组织学检查表明，在感染鸭的心、肝、脾、肺组织出现纤维素性炎症，脑和肾组织分别出现脑膜炎和坏死性肾炎等变化。     

猪链球菌2型昆明鼠动物病理模型的建立

为研究猪链球菌2型的病原特性、致病机理及对其疫苗与救治药物效果评价提供平台,选用20~25 g健康昆明鼠,以猪链球菌2型山东株为病原,以腹腔注射为感染途径,对猪链球菌2型昆明鼠病理模型进行了探讨(试验随机分为5组,每组10只)。结果表明,感染鼠能表现出典型的临床症状及病理变化,具有较好的重复性,且临床症状及病理变化与本动物猪类似。剖检后从脑、肺,以及胸腔、腹腔和心包积液中都可以分离出猪链球菌2型,分离菌株生物学特性与攻毒菌株一致。按Reed-Munch法计算此菌株对昆明鼠的半数致死量为7×108cfu。感染后2周的血清平均抗体水平为1∶64。这说明昆明鼠能够很好地用作猪链球菌2型的动物病理模型。     

Ⅰ型鸭肝炎病毒基因C型株的分离与鉴定

在湖北某养殖场的雏鸭群中,出现以角弓反张和肝脏树枝状出血为特征的传染性疾病,根据临床病症初步判断疑似鸭肝炎病毒感染。使用本实验室建立的RT-PCR方法对鸭胚分离毒株进行鉴定,扩增出与预期大小相符的929bp的目的片段。该片段序列与GenBank上公布的Ⅰ型鸭肝炎病毒基因C型株序列同源性达98%,由此可以确定该雏鸭群感染了新型Ⅰ型鸭肝炎病毒。雏鸭回归试验结果表明,尿囊液接种非免疫7日龄雏鸭,48h后试验组出现症状,60h出现雏鸭死亡,出现角弓反张等症状,病理剖检及组织病理学切片都能观察到特征性病理变化,对照组不出现任何临床症状及病理变化。     

鸭疫里氏杆菌的分离鉴定及药敏试验分析

从广东、福建不同地区临床疑似鸭疫里氏杆茵感染病死鸭中分离到12株鸭疫里氏杆菌,通过细菌形态、培养特怔、生化试验,鉴定为鸭疫里氏杆菌。采用微量液体二倍稀释法,测定了14种常用抗菌药物对12株鸭疫里氏杆菌的抗菌活性,结果表明,有2个菌株均对14种药物高度敏感,其MIC值均≤1μg/mL,其它菌株MIC值差异较大,所有抗菌药对Y4菌株的最小抑菌浓度较高,其MIC值均≥32μg/mL。     

雏鸭胰脏组织损伤在新型鸭肝炎病毒感染过程中的变化特点

对新型鸭肝炎病毒人工感染9日龄樱桃谷雏鸭的胰脏损伤特点进行了研究。对感染雏鸭在接毒后12、24、48、72、96、168h以及14d时胰脏病理组织学变化的观察结果表明：感染雏鸭的胰脏组织在接毒后24h出现胰腺细胞的局灶性坏死及嗜酸性小体，且在接毒后48h分布广泛而严重；接毒后72～168h期间，胰脏组织中出现炎性细胞浸润并且逐渐增多，而胰腺的局灶性坏死及嗜酸性小体逐渐减少；接毒后14d，仅见到组织炎性细胞的浸润。应用透射电镜对接毒后48h胰脏的超微结构观察结果显示，胰腺细胞发生坏死．同时出现凋亡细胞的形态特征。本试验结果表明，在新型鸭肝炎病毒感染雏鸭时，胰脏的局灶性坏死是典型病理变化之一，胰腺细胞在发生坏死的同时，可能也发生凋亡，二者同时出现在同一胰脏组织内。     

1株鸭源巴氏杆菌强毒株的分离鉴定

对江西省某养鸭场送检的病死鸭进行病理剖检、细菌分离,经生化鉴定确定病原为多杀性巴氏杆菌。该分离菌株对头孢氨苄、头孢曲松、头孢唑啉、甲氧嘧啶、复方新诺明和氯霉素高度敏感;对大观霉素、卡那霉素等中度敏感;对头孢噻肟、四环素、林可霉素和诺氟沙星低度敏感;对阿莫西林、青霉素、氨苄西林和头孢吡肟不敏感。将分离菌株人工感染鸡、鸭、兔和小白鼠,感染后24 h内死亡率为100%,死亡动物均分离到与原分离菌株形态特征、培养特性一致的细菌,结果表明该分离菌株为多杀性巴氏杆菌强毒株。     

Phase I evaluation of CCNU (lomustine) in tumor-bearing cats

1-(2-Chloroethyl)3-cyclohexyl-1-nitrosourea (CCNU) is an alkylating agent in the nitrosourea subclass. A prospective evaluation of CCNU was done to determine the maximally tolerated dosage of CCNU in tumor-bearing cats. Response data were obtained when available. Twenty-five cats were treated with CCNU at a dosage of 50-60 mg/m3 body surface area. Complete hematologic data were available for 13 cats. Neutropenia was the acute dose-limiting toxicity. The median neutrophil count at the nadir was 1,000 cells/microL (mean, 2,433 cells/microL; range, 0-9,694 cells/microL). The time of neutrophil nadir was variable, occurring 7-28 days after treatment, and counts sometimes did not return to normal for up to 14 days after the nadir. Based on these findings, a 6-week dosing interval and weekly hematologic monitoring after the 1st treatment with CCNU are recommended. The nadir of the platelet count may occur 14-21 days after treatment. The median platelet count at the nadir was 43,500 cells/microL. No gastrointestinal, renal, or hepatic toxicities were observed after a single CCNU treatment, and additional studies to evaluate the potential for cumulative toxicity should be performed. Five cats with lymphoma and 1 cat with mast cell tumor had measurable responses to CCNU. Phase II studies to evaluate antitumor activity should be completed with a dosing regimen of 50-60 mg/m3 every 6 weeks.     

Prevalence of gastric lesions in racing Alaskan sled dogs

Human and equine athletes are reported to have a high prevalence of gastric disease, and anecdotal evidence suggests a similar phenomenon applies to racing sled dogs. To investigate the prevalence of gastric disease in racing sled dogs, we conducted 2 gastroscopy studies on dogs competing in the annual Iditarod Sled Dog Race. A pilot study of dogs that were either dropped from the 2000 Iditarod Sled Dog Race because of illness or that finished the race indicated that, approximately 5 days after competing, 10 of 28 dogs (35%) had endoscopic evidence of gastric ulceration, erosion, or hemorrhage. The next year, an endoscopic study of 73 dogs participating in the 2001 Iditarod race was performed in order to evaluate a larger population of dogs. Data from 70 of these dogs could be used; 34 (48.5%) had ulceration, erosion, gastric hemorrhage, or some combination of these findings. When this group of 70 dogs was compared retrospectively to a control group of 87 dogs presented to the Texas A&M University (TAMU) Veterinary Medical Teaching Hospital, the Iditarod sled dogs had a significantly higher prevalence (P = .049) of gastric lesions. These findings suggest that, similar to athletes of other species, elite canine athletes have an increased prevalence of gastric disease compared to the canine population at large.     

Furosemide continuous rate infusion in the horse: evaluation of enhanced efficacy and reduced side effects

Continuous rate infusion (CRI) of furosemide in humans is considered superior to intermittent administration (IA). This study examined whether furosemide CRI, compared with IA, would increase diuretic efficacy with decreased fluid and electrolyte fluctuations and activation of the renin-angiotensin-aldosterone system (RAAS) in the horse. Five mares were used in a crossover-design study. During a 24-hour period, each horse received a total of 3 mg/kg furosemide by either CRI (0.12 mg/kg/h preceded by a loading dose of 0.12 mg/kg IV) or IA (1 mg/kg IV q8h). There was not a statistically significant difference in urine volume over 24 hours between methods; however, urine volume was significantly greater after CRI compared with IA during the first 8 hours ([median 25th percentile, 75th percentile]: 9.6 L [8.9, 14.4] for CRI versus 5.9 L [5.3, 6.0] for IA). CRI produced a more uniform urine flow, decreased fluctuations in plasma volume, and suppressed renal concentrating ability throughout the infusion period. Potassium, Ca, and Cl excretion was greater during CRI than IA (1,133 mmol [1.110, 1,229] versus 764 mmol [709, 904], 102.7 mmol [96.0, 117.2] versus 73.3 mmol [65.0, 73.5], and 1,776 mmol [1,657, 2.378] versus 1,596 mmol [1,457, 1,767], respectively). Elimination half-lives of furosemide were 1.35 and 0.47 hours for CRI and IA, respectively. The area under the excretion rate curve was 1,285.7 and 184.2 mL x mg/mL for CRI and IA, respectively. Furosemide CRI (0.12 mg/kg/h) for 8 hours, preceded by a loading dose (0.12 mg/kg), is recommended when profound diuresis is needed acutely in horses.     

The Epidemiology of Gastrointestinal Nematodes of Dairy Cattle in Central Kenya

The epidemiology of H. placei and of other gastrointestinal nematodes in yearling dairy cattle was examined on two farms in Kiambu District, central Kenya during each of 13 one-month periods from April 1993 to April 1994. On each farm, 32 newly weaned dairy calves were given a single dose of albendazole and then placed on experimental pastures. Twelve of the animals were designated for bi-monthly slaughter (n = 2) and analysis of worm population characteristics and 20 were designated for blood and faecal collection and for weighing. Two parasite-free tracer calves were grazed alongside the weaner calves each month throughout the study period and were also slaughtered for analysis of worm populations. Faecal egg counts, haematological and serum pepsinogen determinations, herbage larval counts, and animal live weight changes were recorded monthly. The study revealed that Haemonchus placei, Trichostrongylus axei, Cooperia spp. and Oesophagostomum radiatum were responsible for parasitic gastroenteritis and that H. placei was the predominant nematode present in the young cattle on both farms. Faecal egg counts from resident cattle and necropsy worm counts revealed that pasture larval levels were directly related to the amount of rainfall. The total worm burdens in the animals were highest during the rainy season (March–June and October–December) and lowest during the dry seasons (July–September and January–February). The very low recovery of immature larvae of H. placei from the tracer calves indicated that arrested development is not a feature of the life cycle of this parasite in central Kenya. The maintenance of the parasite population depended on continuous cycling of infection between the host and the pasture. The agroclimatic conditions of the study area were such that, in general, favourable weather conditions for the development and survival of the free-living stages of gastrointestinal nematodes existed all year round.     

Diversity of Ectoparasites in Sheep Flocks in Sa~o Paulo,Brazil

The occurrence of ectoparasites in sheep flocks is frequently reported but seldom quantified. Sheep production used to be a predominantly family activity in the state of Sa~o Paulo (Brazil), but it began to become a commercial activity in the past decade. Thus, information about the ectoparasites existing in sheep flocks has become necessary. The present data were obtained by means of questionnaires sent to all sheep breeders belonging to the `Associaça~o Paulista de Criadores de Ovinos' (ASPACO; Sa~o Paulo State Association of Sheep Breeders). Response reliability was tested by means of random visits paid to 10.6% of the respondents. Most of the properties (89.5%) reported the presence of one or more ectoparasites. Screw-worm (Cochliomyia hominivorax) was the most frequent ectoparasite (72.5%), followed by bot fly larvae (Dermatobia hominis, 45.0%), ticks (Amblyomma cajennense) and Boophilus microplus, 31.3%) and finally lice (Damalinia ovis, 13.8%). Combined infestations also occurred, the most common one being screw-worm with bot fly larvae (36.0%) followed by bot fly larvae with ticks (13.9%), screw-worm with ticks (9.3%), bot fly larvae with lice (6.9%), and ticks with lice (5.0%). The most common triple combination was screw-worm, bot fly larvae and ticks (12.8%). Breeds raised for meat or wool were attacked by bot fly larvae and ticks more often than other breeds. Lice were only absent from animals of indigenous breeds. The relationships among these ectoparasites are discussed in terms of sheep breeds, flock size, seasonality and the ectoparasitic combinations on the host.     

Evaluation of biohydrogenation rate of canola vs. soya bean seeds as unsaturated fatty acids sources for ruminants in situ

An experiment was conducted to study disappearance of C14 to C18 fatty acids, lag times and biohydrogenation (BH) rates of C18 fatty acids of ground soya bean and canola seeds in situ. Three ruminally fistulated Dallagh sheep were used to determine ruminal BH of unsaturated fatty acids (UFAs). Differences in the disappearance of fatty acids through the bags and lag times were observed between the oilseeds. We saw that the longer the incubation time of the oilseeds in the rumen, the lower the content of C18:2 and C18:3. Significantly higher lag times for both C18:2 and C18:3 were observed in ground canola compared to ground soya bean. BH rates of C18:2 and C18:3 fatty acids in soya bean were three times higher than those of canola. These results suggest that the fatty acid profile of fat source can affect the BH of UFAs by rumen micro‐organisms. So that UFAs of canola had higher ability to escape from ruminal BH. It seems that fatty acid profile of ruminant products is more affected by canola seed compared to soya bean seed.     

Serum biochemical values and mineral element contents of tissues in yaks

Serum biochemical values and the wet weight to dry weight ratios of tissues were determined in yaks in Shandan county of Gansu province. The liver, kidney, heart and muscle contents of seven elements in yaks were also analysed. Most serum biochemical values were similar to those of cattle, camels and sheep, but the calcium concentration was considerably above the normal range for other ruminants. The liver contained the highest concentrations of copper, manganese and cobalt and the kidney of selenium, iron and calcium.Abbreviations Alb albumin - ALT alanine aminotransferase - AST aspartate aminotransferase - BUN blood urea nitrogen - Chol cholesterol - Glob globulin - -GT -glutamyl transpeptidase - IP inorganic phosphorus - TP total protein     

Avian brood parasitism — a growing research area in behavioral ecology (part Ⅱ)

正We are pleased to publish the second special issue on avian brood parasitism and to be responsible guest editors for the two special issues of Chinese Birds (Vol. 3, No. 4, 2012 and Vol. 4, No. 1, 2013), entitled "Avian Brood Parasitism - A Growing Research Area in Behavioral Ecology". The first issue was published in December 2012. The goal of the two special issues is to publish accumulated knowledge and some of the recent developments in     

Internal Parasites and Haematological Values in Cattle Slaughtered in Buea Subdivision of Cameroon

Tropical Animal Health and Production -