猪源沙门氏菌毒力基因检测及脉冲场凝胶电泳分型研究

为了解上海及周边地区猪源沙门氏菌的血清型分布、毒力基因及分子分型情况,我们对21株临床分离到的猪源沙门氏菌用沙门氏菌属诊断血清鉴定血清型;采用多重聚合酶链式反应,检测17个主要的毒力基因;应用脉冲场凝胶电泳(PFGE)技术进行分子分型,探寻21株沙门氏菌之间的亲缘关系。结果显示,21株沙门氏菌中,19株血清型为7∶c∶5,1株为4∶i∶2,1株未鉴定出;21株沙门氏菌的17个毒力基因中检出16个,菌株之间无差别;经PFGE后,每个菌株产生13~18条电泳条带,用Bionumerics软件进行聚类分析表明,21株猪源沙门菌相似度在77%~100%,可分为2种不同的基因型,其中A型有19株、B型2株,亲缘关系较近。本次实验分离的沙门氏菌血清型以7∶c∶5为主,含有16个主要的毒力基因,A型为优势基因型。     

猪源肠球菌林克酰胺、截短侧耳素及链阳菌素A类耐药基因lsa(E)的检测及传播方式

为研究lsa(E)在猪源肠球菌中的流行情况及传播方式,本研究从广西某猪场分离的56株肠球菌中检测到15株携带多重耐药外排泵基因lsa(E)的肠球菌,利用脉冲场凝胶电泳(PFGE)对lsa(E)基因阳性的肠球菌进行亲缘关系分析,并对不同克隆型的菌株进行耐药表型和相关耐药基因型检测,通过Southem杂交定位lsa(E)基因在不同菌株中的位置.PFGE结果显示15株lsa(E)基因阳性的肠球菌共有7种不同的PFGE谱型,表明携带lsa(E)基因的肠球菌在同一猪场存在垂直传播的现象.药物敏感性试验结果显示,7株分离株除对红霉素、四环素、庆大霉素和环丙沙星100％耐药外,对利奈唑胺、氟苯尼考、利福平和左氧氟沙星也具有较高的耐药率,分别为57.1％、85.7％、71.4％和85.7％.耐药基因erm(B),aac(6')-Ⅰe-aph(2")-Ⅰa和aph(3")-Ⅲa的检出率分别为:100％、85.7％和72.4％;Southern杂交结果显示,lsa(E)基因在6株菌中定位于质粒22 kb～54 kb,而在1株菌中定位于染色体.本研究为临床制定合理措施控制lsa(E)快速传播提供依据.     

屠宰场猪链球菌分离菌株分型及其致病性和耐药性分析

为了解吉林省猪链球菌的流行情况,从屠宰场采集的猪咽拭子和鼻拭子样品中分离鉴定猪链球菌,并进行菌株血清型、基因型和毒力表型的鉴定,以及致病性和耐药性的分析。结果表明,从100份样品中共分离鉴定猪链球菌104株,其中29株鉴定为血清2型、9型和1型等几种常见的致病性血清型,其他75株不属于常见的致病性血清型。血清2型的菌株中,2株经鉴定为ST1基因型和mrp+epf+sly+毒力型,并经动物试验鉴定为强毒菌株;其他菌株均为ST28基因型和mrp+epf-sly-毒力型,具有中等毒力。血清9型的菌株,均为mrp-epf-sly-毒力型,动物试验鉴定均为强毒菌株。根据Kirby-Bauer纸片扩散法的药敏试验结果,98%的猪链球菌分离株对四环素耐药;对大环内酯类、克林霉素和链霉素的耐药率都在50%以上;对β-内酰胺类、氯霉素和喹诺酮类抗生素的耐药率小于20%。总体分析,从屠宰场分离的猪链球菌强毒菌株所占的比例并不高,但是菌株多重耐药的情况非常严重。     

宁夏地区牛源肠球菌分离鉴定及耐药性与毒力基因检测

为了了解宁夏地区牛源肠球菌的耐药性及耐药基因和毒力基因的携带情况,本试验使用显色培养基及PCR法对肠球菌进行分类鉴定;采用药敏纸片琼脂扩散法(K-B法)测定肠球菌对16种抗菌药物的敏感性;最后采用PCR方法对9种相关耐药基因与7种肠球菌毒力基因进行检测并测序。结果显示,在分离鉴定出的255株肠球菌中,屎肠球菌有78株(30.59%),粪肠球菌有53株(21.96%)。药敏试验结果显示,分离菌对磺胺异恶唑和杆菌肽耐药率达到了100%;其次是苯唑西林(92.16%)、红霉素(65.88%)、四环素(65.49%)和青霉素(56.86%)。分离菌对万古霉素和利奈唑胺高度敏感,敏感率分别为92.54%与95.29%。耐药基因检测结果显示,氨基糖苷类耐药基因aph(3)′-Ⅲ的检出率最高,为100%;其次是红霉素类耐药基因ermB,为46.27%;未检出耐万古霉素耐药基因VanA、VanB、VanC。已检测的毒力基因明胶酶gelE的携带率最高,为37.60%;其次为心内膜炎抗原efaA,为36.10%。结果表明,宁夏地区牛源肠球菌的多重耐药现象比较严重,应当加以重视。     

宠物犬及犬粮源沙门氏菌的耐药性分析及PFGE分型

为了解宠物犬和犬粮源沙门氏菌的耐药表型特征与耐药基因分布,以及不同分离菌株之间的同源性,本研究采用K-B法测定27株分离菌的药物敏感性、PCR检测耐药基因、脉冲场凝胶电泳(PFGE)进行基因分型。结果显示,27株沙门氏菌分离株对氨苄西林、阿莫西林/克拉维酸、链霉素、复方新诺明、强力霉素耐药率在29.63%~22.22%,33.33%分离菌对3种及3种以上抗生素耐药,其中阿莫西林/克拉维酸-氨苄西林-复方新诺明-强力霉素所占比率最大,为66.67%(6/9);74.07%分离菌至少含有1种耐药基因,以str A-B、bla PSE、tet B、sul1检出率最高,分别为40.7%、37.0%、29.6%、25.9%,四环素类、氯霉素类、磺胺类、β-内酰胺类耐药基因与耐药表型符合率较高,分别为100%、100%、87.5%、72.7%;27株分离菌形成12种PFGE基因型,优势型别为pt1和pt7型。本研究结果表明宠物犬和犬粮源沙门氏菌呈现多重耐药,耐药表型与其相对应的耐药基因间存在密切的相关性;PFGE基因型呈多态性,而其与血清型之间不呈相关性,但与多重耐药菌株(耐8)间存在一定程度的关联性。     

山东地区零售鸡肉中沙门菌耐药基因东地区零售鸡肉中沙门菌耐药基因、毒力基因及PFGE分型研究

为了解山东地区零售鸡肉中沙门菌耐药和毒力基因的携带状况以及PFGE分子分型情况,采用PCR方法对分离的25株沙门菌携带的耐药基因和毒力基因进行检测,并运用XbaⅠ酶进行酶切并完成PFGE分析,利用BioNumerics软件对分离菌株的指纹图谱进行聚类分析。结果显示,分离菌株携带耐药基因的携带情况与耐药表型的符合率为95%,其中88%的分离菌株携带酰胺醇类耐药基因(catⅠ)和β-内酰胺类耐药基因(blatem-1/blapsE-1/blaCMY-1/blaoxA-1);所有分离菌株均携带fimAstn、IacP、prgK四种毒力基因,其次是spvr、spva、spvc,携带率均为64%;25株沙门菌共分为10个群,包括16个不同的带型,菌株相似度为60%~100%。     

牛呼吸道疾病克雷伯菌毒力及耐药性分析

为分析牛呼吸道疾病克雷伯菌的毒力性及其耐药性,采集患呼吸道疾病牛样品,对克雷伯菌进行分离鉴定,并对其血清型、毒力性、耐药性及其可移动元件的水平传播情况进行检测。结果显示,分离得到10株致病性克雷伯菌。在这些菌株中,检测出3种血清型,K2为优势血清型。分离菌对氨苄西林及阿莫西林的耐药率高达100.0%(10/10),其中8株为多重耐药菌。ureA毒力基因、gyrA与acc(3)-IIa耐药基因的检出率高达100.0%(10/10)。可移动元件中IS26的检出率高达80.0%(8/10)。可移动遗传元件不仅促进了细菌之间耐药基因的传播,还有可能与耐药基因有协同作用,增强细菌的耐药性。这为治疗由克雷伯菌导致的牛呼吸道疾病提供了依据。     

某规模化种鸡场沙门菌流行病学调查和耐药性分析

试验旨在调查国内某规模化种鸡场沙门菌流行状况,为种鸡场沙门菌净化提供基础资料。1 744份样品被采集进行沙门菌分离、血清型鉴定、耐药性分析及脉冲场凝胶电泳(PFGE)方法亚分型。结果显示:168株沙门菌被分离鉴定,分离率为9.63%,其中肠炎沙门菌有157株,为优势血清型(93.45%);抗生素耐药性试验表明,多重耐药现象较为严重,耐药种类在三种以上的肠炎沙门菌株有130株(77.38%);随机选取28株肠炎沙门菌进行PFGE亚分型显示,这些菌株属于同一个聚类簇,表明它们可能来自于同一克隆株。     

山东省肉鸡屠宰生产链中沙门菌耐药性分析及毒力基因检测

通过调查山东省不同市肉鸡屠宰生产链中沙门菌分离株血清型、耐药性及毒力相关基因,为肉鸡的健康安全生产提供数据支撑。对前期获得的233株沙门菌通过血清型快速分型试剂盒鉴定其血清型,采用最小抑菌浓度(MIC)进行13种抗菌药物的药敏试验;应用PCR技术检测位于菌株毒力岛(SPI)和毒力质粒(spv)上共15种毒力基因的携带情况。结果显示,233株沙门菌共分属25种不同的血清型,其中肠炎沙门菌、印第安纳沙门菌、汤普逊沙门菌和德尔卑沙门菌为优势血清型。233株肉鸡屠宰生产链中沙门茵对庆大霉素的耐药率最高(100%);对多西环素、氨苄西林、大观霉素、四环素、氟苯尼考和磺胺异恶唑耐药率分别为84.94%、75.73%、67.78%、56%、52%和50%。72%的菌株表现为多重耐药(≥3),产生了57种耐药谱型。沙门菌的毒力岛基因sptP、sseL、mgtC、siiE、sopB的携带率是100%,毒力基因spvA、spvB、spvC、spvD、spvR、iacP、avrA、prgK、fima和stn的检出率分别是60%、34%、49%、51%、63%、99%、38%、99%、99%和99%。结果表明,在4种优势血清型中并非均出现高耐药性,出现高耐药性的血清型主要以汤普逊沙门菌为主,汤普逊沙门菌相对于其他血清型毒力基因的携带率较高,沙门菌耐药性和毒力基因的携带间并没有明显的关联性。     

超市零售鸡肉粪肠球菌耐药性及毒力因子流行分布特征

于2020年从惠州、肇庆、郑州、天津4个城市的超市采集零售鸡肉样品96份,进行粪肠球菌的分离鉴定;采用琼脂二倍稀释法测定肠球菌的最小抑菌浓度(MIC);PCR方法检测肠球菌的耐药基因和毒力基因。结果显示,共分离到41株粪肠球菌(郑州10株,肇庆14株,惠州10株,天津7株),没有分离到屎肠球菌;所有菌株对氨苄西林、万古霉素、利奈唑胺敏感,对四环素、多西环素的耐药率均达到75%以上,对利福平、氯霉素、氟苯尼考、HLSR的耐药率为20%～40%。天津分离株的耐药率最低,惠州地区分离株耐药率最高。在郑州的分离株中检测到1株替加环素耐药菌株。惠州的分离株所携带的耐药基因种类、检出率大多高于其他地区。耐药基因tetL最为流行,检出率高于50%。其次是ermB,检出率为48.78%。17株粪肠球菌检测出optrA基因,检出率为41.46%。已检测的毒力基因中efaA的携带率最高,为95.12%(39/41)。其他依次为gelE 73.17%(30/41)、agg 58.54%(24/41)、asal 36.59%(15/41)、ace 34.15%(14/41)、cylA 9.76%(4/41)。...     

Pharmacokinetics and bioavailability of carbetocin after intravenous and intramuscular administration in cows and gilts

The pharmacokinetics of carbetocin, which is used to control postpartum hemorrhage after giving birth, was studied in cows and gilts after a single intravenous (IV) or intramuscular (IM) injection. Blood samples from animals were assessed by oxytocin radioimmunoassay, and then the pharmacokinetic parameters were calculated using a noncompartmental model. For gilts, there was no significant difference between half-life (T_1/2λZ), mean residue time (MRT), and maximum concentration (C_max) between IM and IV administration. Conversely, the time to reach the C_max (T_max) and MRT were higher following administration of 350 μg/animal in cows via the IM administration compared with IV. The longest T_1/2λZ was 0.85 hr, indicating carbetocin was absorbed and eliminated rapidly in both animal species after administration. The T_max was similar between cows and gilts following IM administration. Moreover, the C_max after IM injection was about half that of IV administration in both animals. The bioavailability was more than 80% in cows, suggesting administration via the IM route is efficient. This is in agreement with the longer T_1/2λZ in cows after IM administration. However, the IV route is recommended for gilts due to a lower bioavailability (35%) and shorter T_1/2λZ after IM administration compared with IV.     

中国伞形科当归属及相关类群毛状体和果实结构的系统学价值

深入研究了当归属及其相关7属,古当归属,高山芹属,柳叶芹属,独活属,欧当归属,山芹属及前胡属毛状体和果实结构。结果显示毛状体及果实结构(如:毛状体细胞,翅,油管,维管束,中果皮,内果皮,结合面及结晶)可以用于区分当归属及其相关类群。滇南当归及隆萼当归应从当归属移入独活属,其余当归属物种分为结合面宽及结合面窄两组,前者与前胡属较为相似,但与独活属差别较大,后者与古当归属,高山芹属,柳叶芹属,欧当归属有相似之处。支持分子系统学揭示的当归属不是个自然类群,当归属与前胡属共同位于当归分支,而独活属位于独活分支。山芹属果实结构与其他属不同,翅的中果皮无细胞,且伴生油管位于维管束内侧,为分子系统学显示此属与高山芹属,柳叶芹属,及欧当归属亲缘关系较远提供了形态学依据。     

Genetic and phenotypic parameters and annual trends for growth and fertility traits of Charolais and Hereford beef cattle breeds in Kenya

This study estimated genetic and phenotypic parameters and annual trends for growth and fertility traits of Charolais and Hereford cattle in Kenya. Traits considered were birth weight (BW, kg), pre-weaning average daily gain (ADG, kg/day) and weaning weight (WW, kg); calving interval (CI, days) and age at first calving (AFC, days). Direct heritability estimates for growth traits were 0.36 and 0.21; 0.25 and 0.10; 0.23 and 0.13 for BW, ADG and WW in Charolais and Hereford, respectively. Maternal heritability estimates were 0.11 and 0.01; 0.18 and 0.00; 0.17 and 0.17 for BW, ADG and WW in Charolais and Hereford, respectively. Direct-maternal genetic correlations ranged between −0.46 and 1.00; −0.51 and −1.00; −0.47 and −0.39 for BW, ADG and WW in Charolais and Hereford, respectively. Genetic correlations ranged from −0.99 to unity and −1.00 to unity for growth and fertility traits respectively. Prospects for improvement of growth and fertility traits exist.     

Genetic diversity and antimicrobial resistance of Campylobacter and Salmonella strains isolated from decoys and raptors

Infections caused by thermotolerant Campylobacter spp. and Salmonella spp. are the leading causes of human gastroenteritis worldwide. Wild birds can act as reservoirs of both pathogens. A survey was carried out to determine the prevalence, genetic diversity and antimicrobial resistance of thermotolerant Campylobacter and Salmonella in waterfowl used as decoys and wild raptors in Andalusia (Southern Spain). The overall prevalence detected for Campylobacter was 5.9% (18/306; CI_95%: 3.25–8.52) in decoys and 2.3% (9/387; CI_95%: 0.82–3.83) in wild raptors. Isolates were identified as C. jejuni, C. coli and C. lari in both bird groups. Salmonella was isolated in 3.3% (10/306; CI_95%: 2.3–4.3) and 4.6% (18/394; CI_95%: 3.5–5.6) of the decoys and raptors, respectively. Salmonella Enteritidis and Typhimurium were the most frequently identified serovars, although Salmonella serovars Anatum, Bredeney, London and Mikawasima were also isolated. Pulsed-field gel electrophoresis analysis of isolates showed higher genetic diversity within Campylobacter species compared to Salmonella serovars. Campylobacter isolates showed resistance to gentamicin, ciprofloxacin and tetracycline, while resistance to erythromycin and tetracycline was found in Salmonella isolates. The results indicate that both decoys and raptors can act as natural carriers of Campylobacter and Salmonella in Spain, which may have important implications for public and animal health.     

Intake, live animal scores/measurements and carcass composition and value of late-maturing beef and dairy breeds

The objectives of this study were to compare the progeny of 1) late-maturing beef with dairy breeds and 2) Charolais (CH), Limousin (LM), Simmental (SM) and Belgian Blue (BB) sires bred to beef suckler dams, for feed intake, blood hormones and metabolites, live animal measurements, carcass traits and carcass value in bull and steer production systems. The bull system included 50 late-maturing beef breeds and 22 Holsteins (HO) slaughtered at approximately 15 months of age, whereas the steer system consisted of 56 late-maturing beef breeds and 23 British Friesians (FR) slaughtered at approximately 24 months of age. Beef breeds were suckled until approximately 8 months of age, while dairy breeds were artificially reared until weaning at approximately 3 months of age. All animals were finished on an ad libitum concentrate diet. Mean live weight, live weight gain, carcass gain and feed efficiency were greater (P < 0.05) in beef than dairy breeds in both systems during the finishing period when offered concentrates. Although there was no difference in feed intake between beef and dairy breeds, intake expressed relative to live weight was lower (P < 0.001) in beef breeds in both systems. At 10 months of age and pre-slaughter, beef breeds had higher (P < 0.001) muscularity scores and greater scanned muscle depth (P < 0.001) than their dairy contemporaries. Carcass weight, kill-out proportion, carcass conformation score, meat proportion and value were greater (P < 0.001) and carcass fat and bone proportions were lower (P < 0.05) in beef than dairy breeds in both systems. Insulin concentrations were lower (P < 0.001) in beef than dairy breeds, whereas there was no difference in blood metabolites or IGF-1 concentrations. Feed intake expressed relative to live weight or feed efficiency did not differ between CH, LM, SM or BB sired progeny. Muscularity scores were greater (P < 0.05) in BB than SM, whereas skeletal scores were lower (P < 0.05) in LM than SM. Limousin had lower (P < 0.05) carcass gain per day of age than CH and SM, whereas SM had a lower (P < 0.05) carcass conformation score than BB and CH and a higher (P < 0.05) carcass fat score than CH. Simmental had a lower (P < 0.05) carcass meat proportion and a higher (P < 0.05) carcass fat proportion than CH, LM and BB, which were similar (P > 0.05). The improvement obtained for beef over dairy breeds in live weight gain was 12%, while the improvements in carcass gain and meat produced was 24% and 33%, respectively. This demonstrates that the importance of carcass data contributing to breed comparison studies cannot be over-emphasised.     

Babesiosis in dogs and cats--expanding parasitological and clinical spectra

Canine babesiosis caused by different Babesia species is a protozoal tick-borne disease with worldwide distribution and global significance. Historically, Babesia infection in dogs was identified based on the morphologic appearance of the parasite in the erythrocyte. All large forms of Babesia were designated Babesia canis, whereas all small forms of Babesia were considered to be Babesia gibsoni. However, the development of molecular methods has demonstrated that other Babesia species such as Babesia conradae, Babesia microti like piroplasm, Theileria spp. and a yet unnamed large form Babesia spp. infect dogs and cause distinct diseases. Babesia rossi, B. canis and Babesia vogeli previously considered as subspecies are identical morphologically but differ in the severity of clinical manifestations which they induce, their tick vectors, genetic characteristics, and geographic distributions, and are therefore currently considered separate species. The geographic distribution of the causative agent and thus the occurrence of babesiosis are largely dependent on the habitat of relevant tick vector species, with the exception of B. gibsoni where evidence for dog to dog transmission indicates that infection can be transmitted among fighting dog breeds independently of the limitations of vector tick infestation. Knowledge of the prevalence and clinicopathological aspects of Babesia species infecting dogs around the world is of epidemiologic and medical interest. Babesiosis in domestic cats is less common and has mostly been reported from South Africa where infection is mainly due to Babesia felis, a small Babesia that causes anemia and icterus. In addition, Babesia cati was reported from India and sporadic cases of B. canis infection in domestic cats have been reported in Europe, B. canis presentii in Israel and B. vogeli in Thailand. Babesiosis caused by large Babesia spp. is commonly treated with imidocarb dipropionate with good clinical response while small Babesia spp. are more resistant to anti-babesial therapy. Clinical and parasitological cure are often not achieved in the treatment of small Babesia species infections and clinical relapses are frequent. The spectrum of Babesia pathogens that infect dogs and cats is gradually being elucidated with the aid of molecular techniques and meticulous clinical investigation. Accurate detection and species recognition are important for the selection of the correct therapy and prediction of the course of disease.     

Seedling Defoliation and Drought Stress: Variation in Intensity and Frequency Affect Performance and Survival

Our ability to restore rangelands is limited, and it is unknown if seedling herbivory on its own, or in interaction with other stressors, is a major contributor to restoration failure. To address this, we conducted two experiments: a No Defoliation (ND) experiment (n = 48), in which seedlings from three perennial grasses (crested wheatgrass [Agropyron cristatum {(L.} Gaertn.], bluebunch wheatgrass [Psuedoroegnaria spicata {Pursh} Á. Love], Sandberg bluegrass [Poa secunda J Presl]) were subjected to wet and dry water regimes for 4 mo, and a concurrent Defoliation (D) experiment (n = 95), in which seedlings were factorially assigned to two defoliation treatments—frequency (LOW, HIGH) and intensity (30% vegetation removal, 70% vegetation removal). Indicators of seedling performance were aboveground and belowground biomass (AGB and BGB), root:shoot ratio, tillering, and mortality. The effect size statistic, Hedge’s g, allowed for comparisons between performance measures. Water stress induced reductions in most performance measures: BGB (g = ND: –1.3; D: –1.6), root:shoot ratio (g = ND: n.s.; D: –0.2), and tillering (g = ND: –1.7; D: –1.2), though not significantly for all species. For ABG, water stress interacted with defoliation, reducing performance less at an intensity of 70% (g = –2.0) as opposed to 30% (g = –3.0), but not always significantly in the former. Water stress also caused less reduction in AGB when no defoliation occurred (ND: –0.8; g = D: –2.5). Intensity and frequency of defoliation interacted; seedlings were generally resistant to reductions in performance except at high frequency, 70% defoliation. Agropyron cristatum and P. spicata displayed similar sensitivity to treatments, mostly in terms of changes in AGB and BGB, while P. secunda also experienced increased mortality and reduced tillering. If these differences in sensitivity result in differential survival, herbivory could impact species postrestoration population demographics.     

Zoonotic diseases of fish and their prevention and control

Fish and aquatic-derived zoonotic diseases have caused considerable problems in the aquaculture industry and fishery worldwide. In particular, zoonotic diseases can pose widespread threats to humans. With the world’s growing population and potential global trade of aquaculture and fish, the risk of environmental contamination and development of fish and aquatic-derived zoonoses in humans are increasing. The important causes of zoonoses include bacteria, parasites, viruses, and fungi. The zoonotic bacterial agents are divided into two main groups: Gram-positive (Mycobacteriaceae, Streptococcaceae, Erysipelothricaceae families) and Gram-negative (Aeromonadaceae, Vibrionaceae, Pseudomondaceae, Enterobacteriaceae, and Hafniaceae families). The premier parasitic agents include cestodes (tapeworm; e.g. Diphyllobothrium spp.), trematodes (fluke; e.g. Opisthorchis spp.), and nematodes (round worm; e.g. Anisakis spp.). In addition, protozoan organisms such as Cryptosporidium spp. are also considered fish-derived zoonotic pathogens. Two groups of fish-associated fungi causing basidiobolomycosis and sporotrichosis also pose a zoonotic risk for humans. The majority of the fish-derived zoonotic diseases are transmitted to humans mainly via the consumption of improperly cooked or raw fish or fish products. Therefore, the incidence of zoonotic diseases can be reduced by properly processing fish and fish products, e.g. by thermal (heat/freezing) treatment. The prevalence of zoonotic agents in fishes varies seasonally and should be regularly monitored to evaluate the prevalence of pathogens in both wild and cultured fish populations. This review focuses on the fish zoonotic agents/diseases and their control and prevention.