Adsorption and antibacterial effect of copper-exchanged montmorillonite on Escherichia coli K88

Calcium montmorillonite (Ca-MMT), sodium montmorillonite (Na-MMT) and acid-activated montmorillonite (AAM), and their Cu²⁺-exchanged montmorillonites (Cu-MMT), Cu*Ca-MMT, Cu*Na-MMT and Cu*AAM, were used to study the antibacterial activity on Escherichia coli K₈₈. AAM, Na-MMT and Ca-MMT showed some ability to reduce bacterial plate counts by 37.4%, 13.4% and 14.2%, respectively. Exchanging the montmorillonite with Cu²⁺ enhanced the antibacterial activity. The Cu*AAM, Cu*Na-MMT and Cu*Ca-MMT reduced the bacterial plate counts by 98.6%, 97.5% and 95.6%. Attempts were made to study the desorption of Cu²⁺ by washing with sterile physiological saline solution for 24 h. The washing solutions did not show a significant reduction of the bacterial counts, while the washed Cu-MMT retained their full antibacterial activity. Results from time-depending studies showed that the reduction of the bacterial counts by Cu-MMT increased during 24 h. The ranking of antibacterial activity of the three Cu-MMT was as Cu*AAM > Cu*Na-MMT > Cu*Ca-MMT. E. coli thrived optimally in a pH range from 5 to 7. Beyond this range, the bacterial counts decreased as the pH reduced the viability of the bacteria. The ranking of antibacterial activity of Cu-MMT was not affected by pH. The mechanism by which bacterial counts are reduced may involve the enhanced affinity of Cu-MMT for E. coli K₈₈ and the antibacterial activity of Cu²⁺.     

2019年江苏省部分地区儿童腹泻沙门氏菌的感染率及耐药状况研究

目的 了解江苏省部分地区2019年5岁以下食源性腹泻儿童中沙门氏菌感染的流行病学特征、血清分布及耐药性。方法 从江苏省各设区市哨点医院肠道门诊采集食源性腹泻患儿粪便标本,按照江苏省食源性疾病监测方案进行细菌的分离与鉴定、血清分型,用微量肉汤稀释法进行药敏试验。结果共收集3582份腹泻儿童粪便,沙门氏菌的检出率为2.9％,1～2岁患儿居多。全年均有检出,夏季高发。共有24种血清型的沙门氏菌,优势血清型为鼠伤寒沙门氏菌和肠炎沙门氏菌,分别占41.9％和18.1％。耐药检测结果显示,沙门氏菌对红霉素的耐药率最高,达96.1%。其次为氨苄西林、氨苄西林/ 舒巴坦、萘啶酸和四环素,分别为67.5%、56.6%、53.5%和51.3%;对甲氧苄氨嘧啶/磺胺甲噁唑、氯霉素和环丙沙星呈现中度耐药,耐药率分别为33.3％,31.6％和26.8％;对一、二、三代头孢类抗生素的耐药率有显著性差异。对阿奇霉素和亚胺培南的耐药率较低,为7.5％和2.6％。多重耐药率达72.4％。结论 江苏省部分地区腹泻儿童沙门氏菌感染以1～2岁高发,男孩多于女孩。主要血清型是鼠伤寒沙门氏菌和肠炎沙门氏菌,多重耐药现象严重,在临床用药时应选择较为敏感的药物。     

Rapid detection of oilfish and escolar in fish steaks: A tool to prevent keriorrhea episodes

The outbreak of keriorrhea caused by the wax ester-rich oilfish and escolar has become a frequent and worldwide concern. To help prevent such episodes, rapid detection of these fishes in the supply chain of the seafood industry and by food and health inspection agencies is essential. Through a combination of DNA, GC–MS and TLC analyses with reference to authentic samples, fish steaks of oilfish and escolar mislabeled as other species could be accurately identified. The TLC method developed is inexpensive and provides a reliable and importantly rapid identification within 30 min.     

重庆地区5岁以内儿童腹泻病毒病原及流行病学特点

目的了解重庆地区5岁以内儿童腹泻病毒病原及流行病学特点。方法收集重庆医科大学附属儿童医院2010年8～11月就诊的5岁以内腹泻患儿的粪便标本共500份,采用胶体金法检测A组轮状病毒(Rotavirus,RV),RT-PCR法检测B、C组RV、诺如病毒(Norovirus,NV)GⅠ和GⅡ、肠道腺病毒(Adenovirus,ADV)、札如病毒(Sapovirus,SLV)和星状病毒(Astrovirus,ASV),取NV和SLV阳性PCR产物测序,并对病毒基因进行分型。采用MEGA 5.05软件构建进化树,Kimura’s two-parameter法计算遗传距离,邻接法(Neighbor-joining)boot-strap重复检验1 000次。结果 500份标本中,检测到A组RV阳性标本134份,阳性率为26.8%;NV GⅡ型阳性标本132份,阳性率为26.4%;ADV阳性标本31份,阳性率为6.2%;SLV阳性标本9份,阳性率为1.8%;ASV阳性标本1份,阳性率为0.2%;未检测到B、C组RV和NV GⅠ型。随机选择22份NV阳性标本进行测序及基因分型,其中GⅡ/4占绝对优势,其次为GⅡ/6、GⅡ/2、GⅡ/3和GⅡ/7。SLV可分为4个基因亚型,其中GⅠ/1为优势株,其次为GⅠ/2、GⅡ/1和GⅠV 1。结论重庆地区5岁以下儿童腹泻以病毒感染为主,RV是主要的病原体,其次为NV、ADV、SLV和ASV。     

Molecular characteristics of Escherichia coli serogroup O78 strains isolated from diarrheal cases in bovines urge further investigations on their zoonotic potential

We investigated the virulence properties and clonal relationship of 21 Escherichia coli strains of serogroup O78 isolated from diarrhoeic cattle and calves. Isolates were screened for 18 genes representing virulence features of different Escherichia coli pathotypes. None of the strains harboured enterotoxin-genes estIa/Ib, eltIa/Ib, or Shiga toxin (stx) genes, genes involved in adhesion (eae, f5, f41) hemolysin gene hlyA or invasion gene ipaC. With a high prevalence we detected enterotoxin astA (61.9%), genes involved in iron acquisition, like fyuA, irp (each 57.1%) and iucD (81.0%), and the operon sequence of Colicin V plasmids (38.1%). Some strains possessed toxin genes cdt-IIIB and cnf1/2 (both 14.3%), the invasion gene tia (23.8%), and the serine protease encoding gene espP (23.8%). Moreover, we could show that E. coli O78 strains under investigation were able to adhere to and invade MDBK-cells with varying efficiencies. The results indicate that the closely related O78 strains, constituting two major PFGE-clusters, harbor various virulence features for bovine intestinal disease but cannot be grouped into one of the common E. coli intestinal pathogenic or other pathotypes according to their virulence gene pattern. Nevertheless, the ability to adhere, invade or harbor toxin genes lets us suggest that O78 strains isolated from diarrheal cases in bovines urges further investigations on the zoonotic potential of these strains.     

Waterborne transmission of protozoan parasites: review of worldwide outbreaks - an update 2004-2010

The present update gives a comprehensive review of worldwide waterborne parasitic protozoan outbreaks that occurred and were published globally between January 2004 and December 2010. At least one hundred and ninety-nine outbreaks of human diseases due to the waterborne transmission of parasitic protozoa occurred and were reported during the time period from 2004 to 2010. 46.7% of the documented outbreaks occurred on the Australian continent, 30.6% in North America and 16.5% in Europe. Cryptosporidium spp. was the etiological agent in 60.3% (120) of the outbreaks, Giardia lamblia in 35.2% (70) and other protozoa in 4.5% (9). Four outbreaks (2%) were caused by Toxoplasma gondii, three (1.5%) by Cyclospora cayetanensis. In two outbreaks (1%) Acanthamoeba spp. was identified as the causative agent. In one outbreak, G. lamblia (in 17.6% of stool samples) and Cryptosporidium parvum (in 2.7% of stool samples) as well as Entamoeba histolytica (in 9.4% of stool samples) and Blastocystis hominis (in 8.1% of stool samples) were detected. In those countries that are likely affected most a lack of surveillance systems is noticeable. However, countries that established surveillance systems did not establish an international standardization of reporting systems.     

2018—2020年北京市海淀区腹泻患者弯曲菌流行特征及PFGE分型研究

目的 分析和掌握2018-2020年北京市海淀区腹泻患者中弯曲菌流行特征和脉冲场凝胶电泳（PFGE）分型情况。方法 对2018-2020年在3家哨点医院就诊的756例腹泻患者便标本进行弯曲菌的分离和鉴定,对其中25株弯曲菌菌株进行PFGE分型试验。结果 弯曲菌总体检出率为4.37%(33/756),空肠弯曲菌和结肠弯曲菌检出率分别为3.04%(23/756)和1.32%(10/756);不同性别、年龄和职业之间的弯曲菌检出率比较,差异均无统计学意义（P>0.05）;48.48%(16/33)的弯曲菌感染患者出现了发热,弯曲菌患者大便性状以水样便为主。弯曲菌检出主要集中在5～7月,除不明食品外,可疑暴露食品占比最高的为肉与肉制品。17株空肠弯曲菌聚类分析得到16种带型,8株结肠弯曲菌聚类分析得到7种带型。结论 海淀区弯曲菌污染状况不容乐观,本研究填补了北京市海淀区腹泻患者弯曲菌感染状况数据的空白,为海淀区食源性疾病的预防和控制提供了参考依据。     

Infection risk assessment of diarrhea-related pathogens in a tropical canal network

A quantitative microbial risk assessment (QMRA) of Cryptosporidium, Giardia and diarrhegenic Escherichia coli (DEC) infection was performed using Monte Carlo simulations to estimate the human health risks associated with the use of canal water for recreational purposes, unrestricted and restricted irrigation in a tropical peri-urban area. Three canals receiving municipal, agricultural, and, predominantly, industrial wastewater were investigated. Identification of pathogenic protozoans revealed the major presence of Cryptosporidium hominis and both assemblages A and B of Giardia lamblia. The highest individual infection risk estimate was found to be for Giardia in an exposure scenario involving the accidental ingestion of water when swimming during the rainy season, particularly in the most polluted section, downstream of a large wholesale market. The estimated annual risks of diarrheal disease due to infection by the protozoan parasites were up to 120-fold greater than the reported disease incidence in the vicinity of the studied district and the entire Thailand, suggesting a significant host resistance to disease beyond our model's assumptions. In contrast, annual disease risk estimates for DEC were in agreement with actual cases of diarrhea in the study area.     

Modeling the impact of climate variability on diarrhea-associated diseases in Taiwan (1996-2007)

Diarrhea is an important public health problem in Taiwan. Climatic changes and an increase in extreme weather events (extreme heat, drought or rainfalls) have been strongly linked to the incidence of diarrhea-associated disease.This study investigated and quantified the relationship between climate variations and diarrhea-associated morbidity in subtropical Taiwan. Specifically, this study analyzed the local climatic variables and the number of diarrhea-associated infection cases from 1996 to 2007. This study applied a climate variation-guided Poisson regression model to predict the dynamics of diarrhea-associated morbidity. The proposed model allows for climate factors (relative humidity, maximum temperature and the numbers of extreme rainfall), autoregression, long-term trends and seasonality, and a lag-time effect. Results indicated that the maximum temperature and extreme rainfall days were strongly related to diarrhea-associated morbidity. The impact of maximum temperature on diarrhea-associated morbidity appeared primarily among children (0-14 years) and older adults (40-64 years), and had less of an effect on adults (15-39 years). Otherwise, relative humidity and extreme rainfall days significantly contributed to the diarrhea-associated morbidity in adult. This suggested that children and older adults were the most susceptible to diarrhea-associated morbidity caused by climatic variation. Because climatic variation contributed to diarrhea morbidity in Taiwan, it is necessary to develop an early warning system based on the climatic variation information for disease control management.     

人产肠毒素大肠杆菌基因工程疫苗的研究进展

产肠毒素大肠杆菌(ETEC)是引起腹泻的主要致病菌之一,在世界范围内,每年可导致数亿人发生腹泻,尤其是发展中国家的婴幼儿和儿童。目前,世界各国通过构建新型的ETEC基因工程疫苗预防ETEC引起的腹泻。将ETEC的肠毒素基因和菌毛蛋白基因转化至无毒的受体菌中,构建出基因工程疫苗,免疫人体后可有效预防ETEC引起的腹泻。本文就ETEC的致病机理及国内外ETEC基因工程疫苗的最新研究进展作一综述。