Stable Silver Nanoparticles Synthesis by Citrus Sinensis(Orange) and Assessing Activity Against Food Poisoning Microbes

Silver nanoparticles are considerecl as good antimicrobial agent. AgNPs were synthesized by mixing silver nitrate solution with citrus sinesb extract for 2 h at 37 and analyzed by UV-visible spectra, SEM, XRD, and FTIR. AgNPs were tested against B. subtilis, Shigello, S. oureus, ond E. coli. Minimum inhibitory concentration of AgNPs was 20 I^g/mL for B. subtilis and Shigello and 30 I^g/mL for S. oureus and E. coll. Antibiofilm activity （80% to 90%） was observed at 25 IJg/mL. AgNPs were stable for five months with sustained an＇timicrobial activity. Biosynthesized AgNPs can bE： used to inhibit food poisoning microbial growth.

Etiological Analysis of a Food Poisoning Caused by Staphylococcus Aureus

Objective To analyze the etiology of food poisoning,provide data support for food poisoning treatment,and protect people’s health.Methods RT-PCR was used to screen suspicious food and vomit.An enzyme-linked immunofluorescence assay(ELFA)was used to detect Staphylococcus aureus enterotoxin.RT-PCR was used to detect enterotoxin genotypes.An automatic drug sensitivity reading system was used for drug resistance analysis and mass spectrometry identification.Results Staphylococcus aureus were isolated from 5 leftovers and 2 vomitus samples.The enterotoxin types of 7 strains were sed and seen;the drug sensitivity test showed that 7 strains were resistant to penicillin,and 6 strains were inducible clindamycin resistant.Conclusion This is a food poisoning event caused by Staphylococcus aureus,which produces sed and sees enterotoxins.The isolated strains have different degrees of drug resistance.

Seafood Cited As Biggest Cause of Food Poisoning

选注者言:读了这篇文章,也许我们对“生猛海鲜”这四个字会产生别样的理解。海鲜之害人,可谓“生猛”也！美国是一个环境保护较好,医疗水平较高的国度,然而,下面这个事实确实让读者乍舌: The group noted that most people who become ill from food poisoning or whodie are not affected in outbreaks but in single-case incdents. It said 75 million casesof food poisoning occur in the United States each year and 5,000 people die from it.本文的另一个新信息是:蛋品也是一个不可忽视的“病源”！

Transfer of Paralytic Shellfish Toxins via Marine Food Chains:A Simulated Experiment

Objective To study the transfer of paralytic shellfish toxins （PST） using four simulated marine food chains： dinoflagellate Alexandrium tamarense→Artemia Artemia salina→Mysid shrimp Neomysis awatschensis; A. tamarense→N. awatschensis; A. tamarense→A, salina→Perch Lateolabrax japonicus; and A. tamarense→L, japonicus. Methods The ingestion of A. tamarense, a producer of PST, by L. japonicus, N. awatschensis, and A. salina was first confirmed by microscopic observation of A. tamarense cells in the intestine samples of the three different organisms, and by the analysis of Chl.a levels in the samples. Toxin accumulation in L. japonicus and N. awatschensis directly from the feeding on A. tamarense or indirectly through the vector of A. salina was then studied, The toxicity of samples was measured using the AOAC mouse bioassay method, and the toxin content and profile of A. tamarense were analyzed by the HPLC method. Results Both A. salina and N. awatschensis could ingest A. tamarense cells. However, the ingestion capability of A. salina exceeded that of N. awatschensis. After the exposure to the culture of A. tamarense （2 000 cells·mL^-1） for 70 minutes, the content of Chl.a in A. salina and N. awatschensis reached 0.87 and 0.024 μg.mg^-1, respectively. Besides, A. tamarense cells existed in the intestines of L. japonicus, N. awatschensis and A. salina by microscopic observation. Therefore, the three organisms could ingest A. tamarense cells directly. A. salina could accumulate high content of PST, and the toxicity of A. salina in samples collected on days 1, 4, and 5 of the experiment was 2.18, 2.6, and 2.1 MU.g^-1, respectively. All extracts from the samples could lead to death of tested mice within 7 minutes, and the toxin content in anemia sample collected on the 1st day was estimated to be 1.65×10 ^5 μg STX equal/individual. Toxin accumulation in L japonicus and N. awatschensis directly from the feeding on A. tamarense or indirectly from the vector ofA. salina was also studied. The mice injected with extracts from L japonicus and N. awatschensis samples that accumulated PST either directly or indirectly showed PST intoxication symptoms, indicating that low levels of PST existed in these samples. Conclusion Paralytic shellfish toxins can be transferred to L. japonicus, N. awatschensis, and A. salina from A. tamarense directly or indirectly via the food chains.

鼠伤寒沙门氏菌所致暴发性食物中毒的病原学研究

武汉市某单位因食用奶油糕点引起暴发性食物中毒,患者年龄为2.5～63岁,从患者肛门拭子中,分离出鼠伤寒沙门氏菌。取材78份,其中22例为阳性,分离率为28.2％,对阳性患者进行病原的追踪观察,发现成人病后带菌时间较长,而幼儿病后带菌时间较短,故成人病后的带菌现象是一个值得重视的问题。

Update on molecular diversity and multipathogenicity of staphylococcal superantigen toxins

Staphylococcal superantigen(SAg)toxins are the most notable virulence factors associated with Staphylococcus aureus,which is a pathogen associated with serious community and hospital acquired infections in humans and various diseases in animals.Recently,SAg toxins have become a superfamily with 29 types,including staphylococcal enterotoxins(SEs)with emetic activity,SE-like toxins(SEIs)that do not induce emesis in primate models or have yet not been tested,and toxic shock syndrome toxin-1(TSST-1).SEs and SEIs can be subdivided into classical types(SEA to SEE)and novel types(SEG to SEIY,SE01,SE02,SEI26 and SEI27).The genes of SAg toxins are located in diverse accessory genetic elements and share certain structural and biological properties.SAg toxins are heat-stable proteins that exhibit pyrogenicity,superantigenicity and capacity to induce lethal hypersensitivity to endotoxin in humans and animals.They have multiple pathogenicities that can interfere with normal immune function of host,increase the chances of survival and transmission of pathogenic baaeria in host,consequently contribute to the occurrence and development of various infeaions,persistent infeaions or food poisoning.This review focuses on the following aspeas of SAg toxins:(1)superfamily members of classic and novelty discovered staphylococcal SAgs;⑵diversity of gene locations and molecular structural characteristics;(3)biological characteristics and activities;(4)multi-pathogenicity of SAgs in animal and human diseases,including bovine mastitis,swine sepsis,abscesses and skin edema in pig,arthritis and septicemia in poultry,and nosocomial infections and food-borne diseases in humans.

Comparative study of chemistry compositions and antimicrobial potentials of essential oils and oleoresins from dried and fresh Mentha longifolia L.

Objective:To investigate the chemical compositions and antimicrobial potentials of the essential oils and oleoresins obtained from fresh and dried Mentha longifolia L.Methods:Gas chromatography and gas chromatography-mass spectrometer techniques were used to determine the profiling of the essential oils and oleoresins.In order to determine the antimicrobial efficacy of the volatile oil and oleoresins,the pathogenic fungus Aspergillus niger(1884),Aspergillus flavus(2479),Fusarium monoliforme(1893),Fusarium graminearum(2088)and Penicillium viridicatum(2007)were undertaken whereas four pathogenic bacteria Bacillus subtilis(1790),Staphylococcus aureus(3103)(Gram-positive),Escherichia coli(1672),Pseudomonas aeruginosa(1942)(Gram-negative)were selected for the present study.Food poisoned,inverted Petri plate,agar well diffusion and disk diffusion methods were employed for investigating antimicrobial potentials.Results:Piperitenone oxide,an oxygenated monoterpene,dominated the chemical compositions of essential oils and oleoresins whose compositions varied from 23.5%-87.8%.Both essential oils showed good antifungal activities against Aspergillus and Fusarium species.The antibacterial investigations revealed that Gram-positive bacteria were more sensitive to the essential oils.Conclusions:Drying the fresh herbal materials influences the chemical contents and the biological activities of the essential oils and oleoresins.Such results indicate that essential oils of Mentha longifolia L.can be possible candidates for further investigations to isolate and characterize their active principles as possible new natural preservatives.