3-氟-5-硝基苯甲氰的合成

以4-氟苯胺为原料,经N-乙酰化、硝化合成2-硝基-4-氟乙酰苯胺,所得产物经酸性水解脱乙酰基得4-氟-2-硝基苯胺,然后经溴化、重氮化、脱重氮基得1-溴-3-氟-5-硝基苯,最后经氰化合成了目标产物3-氟-5-硝基苯甲氰.产物用1HNMR进行表征.     

传统发酵食品中乳酸菌的安全性评估

本文以传统发酵食品中分离的38株乳酸菌(lactic acid bacteria,LAB)为研究对象,利用溶血试验、明胶液化试验和吲哚试验测试受试菌株相关产毒代谢产物,采用K-B纸片法检测菌株对25种抗生素的耐药表型,运用聚合酶链式反应检测菌株携带的耐药基因。结果表明:38株乳酸菌的溶血试验、明胶液化试验和吲哚试验均为阴性,说明菌株在生长代谢过程中不产生相关毒力物质;38株菌对头孢曲松、头孢噻肟、四环素、多西环素、氯霉素、克林霉素和红霉素表现敏感;对其余18种抗生素呈不同程度耐受,其中对磺胺异噁唑耐药率最高(52.63%),其次是卡那霉素(34.21%)、万古霉素(31.58%)、阿米卡星(26.32%)、链霉素(15.79%)、利福平(2.63%);耐药谱分析受试大部分乳酸菌存在多重耐药现象;PCR共检测出3种耐药基因,分别是氯霉素耐药基因cat A(2.63%)、万古霉素耐药基因van A(5.26%)、利福平耐药基因rpo B(42.11%)。结果表明从传统发酵食品中分离的38株乳酸菌不存在相关产毒代谢产物安全隐患,但对部分抗生素呈现出不同程度耐受,并且利福平耐药基因rpo B的检出率较高。本研究为传统发酵食品中乳酸菌安全评价体系的完善提供理论参考。     

土壤无机矿物对抗生素的吸附机理研究进展

抗生素作为一类离子型有机污染物被大量引入环境,对动物及人类的潜在危害已经不可忽视。吸附/解吸则主要控制着抗生素的环境迁移、转化与归宿,土壤有机质与无机矿物对抗生素具有同等强吸附能力,本文侧重介绍土壤无机矿物对抗生素的吸附机理,从无机矿物表面特性(如S—OH)和结构组成(如2∶1型、1∶1型),以及抗生素母体携带官能团的量和种类(如—OH、—CHO、—COOH)等方面来阐述无机矿物对抗生素的吸附机理,认为离子交换与亲水作用对无机矿物吸附抗生素起主导作用。还讨论了环境中pH值、离子强度和溶解有机质对无机矿物吸附抗生素的影响。并比较研究者在观点上异同点,对将来研究方向提几点建议。     

金黄色葡萄球菌耐药性与生物被膜能力的鉴定

本文选择常见的典型食源性微生物金黄色葡萄球菌,从食品微生物安全角度出发,对127株葡萄球菌的菌株特性、耐药性与生物被膜生长能力进行研究,包括菌株生化鉴定;PCR扩增葡萄球菌特异16S rRNA与金葡菌特异femA基因,通过对耐药基因mecA和orfX检测确定菌株的耐药特性;最后,运用结晶紫染色法进行生物被膜能力检测。127株菌株包括119株金葡菌(均携带16S rRNA与femA)与8株凝固酶阴性葡萄球菌8株(仅携带16S rRNA)。119株金葡菌中,107株携带mecA基因与orfX基因,为耐甲氧西林金葡球菌(MRSA);8株凝固酶阴性葡萄球菌中,均携带mecA基因。所有菌株均能生成生物被膜,其中能形成强、中等与弱粘附生物被膜能力菌株分别有5(3.9%)、47(37.0%)和75(59.1%)株。金葡菌中耐药性与生物被膜较为普遍,由于食源性微生物形成生物被膜后,具有逃逸常规消毒和杀菌手段的能力,成为食品安全中的潜在隐患。     

Educational interventions to address misconceptions about antibiotic residues in milk can alter consumer perceptions and may affect purchasing habits

The industrialization of the agri-food industry and resultant decrease in the number of people employed on farms has contributed to a knowledge gap among consumers about food production processes. A commonly reported concern of dairy consumers is the use of antibiotics in dairy animals, even though these drugs are an important tool for promoting animal health and welfare and food safety. The extent to which consumers are aware of antibiotic residue avoidance practices in dairy production is unknown, and it is unclear whether acquisition of such knowledge could affect purchasing behavior and perceptions of dairy farming. The objectives of this study were to assess consumers' perceptions about the quality and production of dairy products in the United States and determine whether educational materials on processes that limit the occurrence of antibiotic residues in milk can change consumers' perceptions of dairy products and purchasing behaviors. We surveyed 804 consumers and assigned them to 1 of 3 interventions: (1) a control arm (reading the content of the Dairy page of the USDA's myplate.gov website); (2) an educational brochure on the processes that prevent antibiotic residues in milk; and (3) a video on the same processes. We found that a majority (86.1%) of participants believe that the quality of dairy products in the United States is high, although many had concerns about the treatment of dairy animals and chemicals (pesticides, antibiotics, hormones) in dairy products. Compared with the control intervention, the brochure was associated with a significant decrease in the level of concern consumers had about chemicals in their milk [−0.20 points on a Likert scale, 95% confidence interval (CI), −0.32 to −0.08] and a significantly increased comfort in purchasing conventional dairy products (odds ratio 2.43, 95% CI, 1.62 to 3.66). The video was associated with even stronger effects: a 0.29-unit decrease in the level of concern about chemicals in milk (95% CI, −0.42 to −0.016) and 2.94 times greater odds of purchasing conventional dairy products (95%, CI 1.92 to 4.49). Although consumer food decision making is complex and driven by multiple factors, it appears that education about the processes that promote food safety can reassure consumers about their concerns and potentially affect purchasing habits.     

芽孢杆菌的产酶特性及其对抗生素的耐受性

以4株枯草芽孢杆菌（Bacillus subtilis）和2株地衣芽孢杆菌（Bacillus licheniformis）为研究对象,通过测定其成胞率、中性蛋白酶活性及对24种抗生素的耐受性,从中筛选优良芽孢杆菌。结果表明,从6株芽孢杆菌中筛选得到3株成胞率和产中性蛋白酶均较好的芽孢杆菌,分别为枯草芽孢杆菌BLCC1-0552、BLCC1-0615和地衣芽孢杆菌BLCC1-0441,液体发酵24 h后,成胞率较高,均达到98%;中性蛋白酶活性分别为90.58 U/mL、100.32 U/mL和24.72 U/mL。其中,枯草芽孢杆菌BLCC1-0615固体发酵玉米-豆粕型常规饲料产中性蛋白酶活力最高,发酵48 h时达到2 154.49 U/g。3株芽孢杆菌对抗生素的耐受性不一致,其中枯草芽孢杆菌BLCC1-0615对24种抗生素中的17种表现敏感,敏感率最高为70.83%。因此,确定优良菌株为枯草芽孢杆菌BLCC1-0615,其成胞率、产中性蛋白酶能力好及对抗生素耐受性较低,具有作为饲料添加剂应用于畜禽饲料中的潜力。     

Intramammary administration of platelet concentrate as an unconventional therapy in bovine mastitis: First clinical application

Bovine udder infections induce a variety of changes in gene expression of different growth factors that may suggest their possible role in glandular tissue protection or repair processes. Growth factors and also chemokines and cytokines may act synergistically to increase the infiltration of neutrophils and macrophages to promote angiogenesis, fibroplasia, matrix deposition, and, ultimately, re-epithelialization. Considering the vast applications, typically in human medicine, of platelet concentrate (PC) and its ease of preparation, the aim of our study was to evaluate an alternative therapy to stimulate the regeneration of glandular tissue, administering a concentration in excess of the growth factors contained in the PC. In each one of the 3 farms examined in the trial, PC was prepared from donor cows in good health, free from infections, and with no records of medications administered during the previous 2 mo. The platelet produced in one farm was used only for treating the cows of the same farm in a heterologous way. A total of 229 mastitic quarters were divided in 3 groups: antibiotic group (treated with intramammary antibiotic), antibiotic and PC group (treated intramammarily with antibiotics in association with PC), and PC group (treated with intramammary PC alone). The diagnosis of mastitis was based on somatic cell count and bacteriological evaluation of the milk from the affected quarter. Platelet concentrate, alone or in association with antibiotic, was used for 3 consecutive days as an unconventional therapy in bovine acute and chronic mastitis. Our data show that the associated action of antibiotic and PC performed significantly better than the antibiotic alone, either for the recovery of the affected mammary quarters or for somatic cell count reduction. In the same way, the association antibiotic plus PC showed significantly fewer relapses compared with the antibiotic alone, either for acute or chronic mastitis. The treatment with only PC did not show statistically significant differences compared with both antibiotic alone or associated treatment for acute mastitis, and it was better than the use of only antibiotic for chronic mastitis. Our results show that PC alone may be useful for a quick resolution of the inflammatory response, playing a role in limiting the tissue damage to the mammary gland parenchyma and reducing the recurrence rates.     

The nosocomial transmission rate of animal-associated ST398 meticillin-resistant Staphylococcus aureus

The global epidemiology of meticillin-resistant Staphylococcus aureus (MRSA) is characterized by different clonal lineages with different epidemiological behaviour. There are pandemic hospital clones (hospital-associated (HA-)MRSA), clones mainly causing community-acquired infections (community-associated (CA-)MRSA, mainly USA300) and an animal-associated clone (ST398) emerging in European and American livestock with subsequent spread to humans. Nosocomial transmission capacities (R_A) of these different MRSA types have never been quantified. Using two large datasets from MRSA outbreaks in Dutch hospitals (dataset 1, the UMC Utrecht for 144 months; dataset 2, 51 hospitals for six months) and a recently developed mathematical model, we determined the genotype-specific R_A for ST398 and non-ST398 isolates (categorized as HA-MRSA), using observational data, the detection rate of MRSA carriage and the discharge rate from hospital as the input. After detection of 42 MRSA index cases in dataset 1 (all non-ST398 MRSA) 5076 people were screened, yielding 30 secondary cases. In dataset 2, 75 index cases (51 non-ST398 MRSA and 24 ST398) resulted in 7892 screened individuals and 56 and three secondary cases for non-ST398 MRSA and ST398, respectively. The ratio between discharge and the detection rate was 2.7. R_A values (95% confidence interval (CI)) were 0.68 (0.47–0.95) for non-ST398 MRSA in dataset 1, 0.93 (0.71–1.21) for non-ST398 MRSA in dataset 2 and 0.16 (0.04–0.40) for ST398. The R_A ratio between non-ST398 MRSA and ST398 was 5.90 (95% CI 2.24–23.81). ST398 is 5.9 times less transmissible than non-ST398 MRSA in Dutch hospitals, which may allow less stringent transmission-control measures for ST398 MRSA.     

LC-MS法测定动物源性食品中抗生素残留的不确定度评定

液相色谱-质谱联用法测定动物源性食品中抗生素类化合物的不确定度来源,主要有样品处理过程引入的不确定度、标准曲线拟合引入的不确定度、重复性测量引入的不确定度等.本文对各不确定度量进行了评定,计算了合成不确定度和扩展不确定度.     

PH计法检测牛奶中的抗生素

抗生素能抑制乳酸菌的繁殖,将接种了乳酸菌的牛奶,在适宜的条件下短时间培养,根据牛奶中pH值的变化情况,就可检测出牛奶中是否含有抗生素。该方法具有检测用时间短,检测所需费用低的特点。