生鲜乳金黄色葡萄球菌污染来源调查及其耐药性

为考察贵阳市生鲜乳中金黄色葡萄球菌污染环节及其对药物的敏感性,采集贵阳市周边5个大型奶牛场及一个牛奶加工厂的乳区棉签拭子75份和各生产环节奶样310份,按国家标准(GB 4789.10—2010)分离鉴定金黄色葡萄球菌,并测定其对9种常用抗菌药物的敏感性。结果表明:生鲜乳中金黄色葡萄球菌污染主要来源于牛乳头内;传统的"弃前三把奶"工艺对降低生鲜乳中金黄色葡萄球菌污染的作用不明显;规范的乳区消毒可以有效地降低乳头外环境金黄色葡萄球菌对生鲜乳安全的影响;所调查奶牛场的金黄色葡萄球菌对磺胺类、β-内酰胺类和四环素类药物的耐药水平较高。     

Effects of sex ratio, stocking density and age of hybrid tilapia on seed production in concrete tanks in Saudi Arabia

The influence of sex ratio, stocking density and age of hybrid tilapia (Oreochromis niloticus X O. aureus) brood fish on seed production in concrete tanks were evaluated in 1992 and 1993. A sex ratio of 1:2 and 1:3 (male: female) and a density of 2 fish m-2 gave the best result with respect to number of seed female-1 day-1 and number of seed kg-1-1 female day-1. Maximum seed production female-1 day-1 was recorded for 3-year-old females and the minimum for 1-year-olds, but in terms of seed kg-1 female day-1 and seed m-2 day-1, 1-year-olds produced the maximum number of seed followed by 2-, 3- and 4-year-old females. Seasonal pattern in seed production was apparently influenced by season and temperature. From the first harvest on 21 April 1993 the production increased gradually, reaching a peak during the third harvest and a second peak during the sixth harvest. Thereafter seed production gradually decreased, reaching a minimum during the tenth harvest on 27 October 1993. No seed were found during the last harvest of 18 November 1993. Maximum production coincided with the highest water temperature of around 28°C.     

Effects of dietary carbohydrate level on growth and body composition of juvenile tilapia, Oreochromis niloticus×O. aureus

A growth trial was conducted to feed juvenile tilapia (initial weight, 9.1±0.1 g), Oreochromis niloticus×O. aureus, isonitrogenous diets for 8 weeks. Six diets were formulated containing 29% crude protein from casein and gelatin, 10% crude fat from soybean oil and refined soybean lecithin and varying levels of corn starch ranging from 6% to 46% at increments of 8%, with corresponding energy to protein (E/P) ratios of 35.6, 37.9, 40.2, 42.5, 44.8 and 47.1 kJ g^?1. Weight gain (WG), specific growth rate, feed efficiency ratio and protein efficiency ratio were significantly higher in fish fed diets with starch ≥22% (or E/P ratio ≥40.2 kJ g^?1) than in fish fed diets with 6% or 14% starch (or E/P ratio of 35.6 or 37.9 kJ g^?1). No further improvement was measured when dietary starch content increased beyond 22%. Body protein retention showed the same general pattern as WG, and was highest in fish fed the 22% starch diet. Body composition was significantly affected by dietary starch level. Fish fed diets with starch ≥30% had significantly higher lipid content than fish fed diets with 6% or 14% starch. Ash content was negatively correlated with starch inclusion level, but moisture and protein contents did not show discernible trends among treatments. Results indicate that hybrid tilapia can utilize 46% dietary starch without growth retardation, while 22% starch in feed for juvenile tilapia containing 29% protein and 10% lipid, or an E/P ratio of 37.9 kJ g^?1 is optimal.     

金黄色葡萄球菌快速检测方法的研究进展

金黄色葡萄球菌是引起人类细菌性食物中毒及奶牛乳房炎的重要细菌之一,在自然界中广泛分布。本文将重点介绍金黄色葡萄球菌的几种快速检测方法。     

Observations on the reproductive performance of three mouth-brooding tilapia species in low-salinity underground water

The reproductive performance and seed production of three mouth‐brooding tilapia species, Oreochromis spilurus (Günther), Oreochromis aureus (Steindachner) and Taiwanese red tilapia hybrid, were compared in low‐salinity underground water (3–5 g L^?1) to select species with the highest reproductive rate. Two‐year‐old males and females having average body weights of 454 and 259 g, respectively, were stocked in 2‐m³ fibreglass breeding tanks (two tanks per species) at 1:3 male to female sex ratio and at average density of three fish m^?2. Seeds (unhatched eggs; yolk‐sac fry and the swim‐up fry) were collected weekly for 112 days. The results showed O. spilurus to have significantly higher (P<0.05) mean spawning parameters expressed as total seed tank^?1 (84 154), seed kg female^?1 day^?1 (284), seed m^?2 day^?1 (190.3) and seed female^?1 day^?1 (76.3), than O. aureus and red tilapia. Monthly seed production in O. spilurus and red tilapia gradually increased from May, peaked in July and declined in August, while in O. aureus, it continued to decrease from May to August. In this study, the observed production levels of seed in O. spilurus were among the highest levels reported for tilapia; therefore, O. spilurus could be selected as a potential candidate for mass seed production in commercial tilapia hatcheries.     

乳制品中金黄色葡萄球菌PCR快速检测方法的建立

为快速检测乳制品中的金黄色葡萄球菌,本研究将纳米氢氧化钛和纳米氢氧化锆固定在滤纸片上以去除PCR反应抑制因子,并以Nuc为靶基因,建立一种无需样品前增菌的PCR快速检测方法,同时确定该方法的特异性、灵敏度和实用性,并评估该方法所用试剂在冷冻保存条件下的稳定性与实用性。结果表明,该PCR快速检测方法在检测97株目标菌及83株非目标菌后未出现假阳性或假阴性结果;该方法无需增菌处理,可在4 h内完成检测,检测限为10¹ CFU·25 g^-1或10¹ CFU·25 mL^-1;该方法与传统检测方法在实际乳制品样品中金黄色葡萄球菌的检出率及活菌检测率均一致(符合率100%);此外,该检测方法所用试剂在-20℃冷冻条件下可稳定保存至少12个月。综上所述,本研究建立的PCR快速检测方法特异性强、灵敏度高,且实用性良好,能有效去除样品基质中的PCR反应抑制因子,为乳制品中金黄色葡萄球菌的快速检测提供了参考依据。     

高温逆境对黄金葛叶片中渗透调节物质积累的影响

以3~5个叶片的黄金葛扦插苗为试材,采用单因素随机区组设计,设4个温度处理,3次重复,测定不同温度、不同时间处理下黄金葛叶片内渗透调节物质含量的变化。结果表明,在同一时间高温胁迫下,随温度的不断升高,黄金葛叶片的可溶性蛋白含量整体呈下降趋势,可溶性糖含量呈上升趋势;同一温度处理下,在35℃,不同时间处理可溶性蛋白含量和可溶性糖含量变化不大,在45℃处理40 h,可溶性蛋白含量比胁迫初期降低了35.02%,而可溶性糖含量比胁迫初期增加了97.06%。     

成纤维上皮细胞炎症反应模型的建立

利用培养金黄色葡萄球菌培养基过滤液建立成纤维上皮细胞炎症反应模型，用于观察和研究炎症反应过程中细胞形态的变化。将培养金黄色葡萄球菌培养基除菌过滤冻干，用细胞培养基稀释，按照一定蛋白含量加到上皮细胞的培养基中，制作细胞炎症反应模型。结果显示，成纤维上皮细胞发生炎症反应，高浓度细菌滤过液的细胞形态发生变化，细胞边缘模糊不清，细胞出现空泡，随着培养时间的延长低浓度的大量大型细胞开始增加；在添加金黄色葡萄球菌培养基滤过液培养24h后利用^3H—TdR方法测定细胞增殖率，细胞增殖差异是显著的。结果表明，建立细胞炎症反应模型是可行的，并为以后炎症反应机理研究和抗炎性反应药物研究奠定了基础。     

Comparison of three commercial rapid agglutination test kits for identification of coagulase positive staphylococci from foods and animals.

Three rapid agglutination assays for the identification of Staphylococcus aureus Monostaph (Bionor A/S, Skien, Norway), Staphyslide-Test (BioMerieux, Lyon, France) and Staph-Rapid-Test (Roche, Basel, Switzerland), were compared. A total of 104 Gram-positive, catalase positive cocci were tested: Nineteen Staphylococcus reference strains comprising 15 spp. (4 strains were coagulase positive), and 7 Micrococcus reference strains comprising 4 spp.; 22 food isolates comprising 13 S. aureus, 8 coagulase positive Staphylococcus spp., and 1 Micrococcus sp.; 56 animal isolates comprising 11 S. aureus, 9 S. hyicus subsp. hyicus, 2 S. intermedius, 15 coagulase positive and 19 coagulase negative Staphylococcus spp. Totally 54 strains were coagulase positive. Considering agglutination of a coagulase positive strain as a correct identification, Monostaph, Staph-Rapid-Test, and Staphyslide-Test correctly identified 52 (96.3%), 47 (87.0%) and 48 (89.0%) of the coagulase positive staphylococci, respectively. Monostaph, Staph-Rapid-Test and Staphyslide-Test showed 1 (2.0%), 4 (8.0%) and 4 (8.0%) false positive reactions respectively. Monostaph, Staph-Rapid-Test and Staphyslide-Test gave 0 (0.0%), 6 (5.8%) and 7 (6.7%) non-interpretable reactions, respectively. Monostaph may be a good alternative to the tube-coagulase test for rapid and reliable identification of coagulase positive staphylococci from both food and veterinary sources. However, false negative reactions may occur with coagulase positive strains of S. hyicus subsp. hyicus and S. intermedius.     

Field trial of a staphylococcal mastitis vaccine in dairy herds: clinical, subclinical and microbiological assessments

Objective To assess the efficacy of a new staphylococcal mastitis vaccine under commercial dairying conditions.
Design A field trial involving 1819 cows and heifers conducted on seven dairy herds in Victoria. The trial was done 'blind'; approximately half the animals were vaccinated and the remainder were untreated controls.
Procedure The vaccine was given twice during the last 10 weeks of pregnancy. Effects of vaccination were assessed, during the ensuing lactation, on the basis of clinical and sub-clinical mastitis and microbiological investigations of the milk.
Results A total of 273 cases of clinical mastitis were recorded. Staphylococcus aureus was isolated from 112 of these, 45 cases in vaccinates and 67 cases in controls; the difference was not statistically significant. One herd was notable in having a high incidence of clinical staphylococcal mastitis. This herd accounted for 15.8% of the animals in the field trial but 54.5% of cases of clinical staphylococcal mastitis. For this herd, vaccinated animals had significantly lower incidence of clinical staphylococcal mastitis and prevalence of subclinical mastitis, relative to controls. An unexpected feature of the trial as a whole was the low incidence of clinical mastitis from which S aureus was isolated in pure culture (26.3% of cases) and the high incidence of clinical Streptococcus uberis mastitis (22.7% of cases).
Conclusions The trial showed that the vaccine was efficacious in reducing the incidence of clinical mastitis and prevalence of subclinical mastitis in a herd that had a serious staphylococcal mastitis problem.