An epidemic of bloody diarrhea: Escherichia coli O157 emerging in Cameroon?

Between November 1997 and April 20, 1998, bloody diarrhea sickened 298 persons in Cameroon. Laboratory investigation of the epidemic (case-fatality rate, 16.4%) documented amoebiasis in one of three patients and three types of pathogens: multidrug-resistant Shigella dysenteriae type 1, S. boydii, and enterohemorrhagic Escherichia coli. We report the first isolation of E. coli O157:H7 in Cameroon and the second series of cases in the Central African region.     

Sorbitol-fermenting, β-glucuronidase-positive, Shiga toxin-negative Escherichia coli O157:H7 in free-ranging red deer in South-Central Spain

We investigated the prevalence of Escherichia coli O157:H7 in free-ranging red deer in south-central Spain, to assess their potential as reservoir hosts of sorbitol-fermenting (SF) E. coli O157:H7 strains, which are emerging causes of hemolytic uremic syndrome in Europe. Fecal samples from 264 hunter-harvested Iberian red deer (Cervus elaphus) were collected in 25 different game estates and examined for E. coli O157:H7 by culture and PCR. E. coli O157:H7 was detected and isolated in 4 of the 25 game estates sampled (16%) and the isolates obtained (four in total) were further phenogenotypically characterized. One of them was biochemically typical of E. coli O157:H7, that is, neither fermented sorbitol nor exhibited β-glucuronidase (GUD) activity, and carried genes encoding Shiga toxins (Stx) 1 and 2, the intimin subtype γ1, the enterohemorrhagic E. coli (EHEC)-hemolysin, and the ter gene cluster. The rest of the isolates (three of four) fermented sorbitol, exhibited GUD activity after 18-24?h incubation, and carried genes encoding the intimin subtype γ1 and the EHEC-hemolysin, although no Stx-encoding genes were detected. All these atypical isolates carried the sfp gene cluster, lacked the ter gene cluster, and were unable to grow on cefixime tellurite sorbitol MacConkey agar, which are typical features of SF E. coli O157:H7 strains isolated from patients. In total, SF, GUD-positive, Stx-negative E. coli O157:H7 strains were isolated in 3 of the 25 game estates sampled (12%), with an overall sample-level prevalence of 1.1% (3/264). Our findings indicate that free-ranging red deer may be one of the possible reservoir hosts of Stx-negative derivatives of SF E. coli O157:H7.     

Prevalence, Phenotypes and Virulence Factors Characteristics of Escherichia coli O157 strains in Yuxi City

Objectives To determine and analyze the carrier rate and characteristics of Escherichia coli O157 in milk cattle, pigs, chickens and patients who suffered from diarrhea; and provide scientific information for the prevention and treatment of infections of E. coli： O157 as well as establishing the check techniques O157. Methods Surveillance spots were set up at one biggest milk cattle feedlot, one pigs slaughterhouse, two chickens markets and the laboratory department of Yuxi municipal hospital in Yuxi city, to collect feces of cattle, pigs, chickens, patients with diarrhea, the numbers of specimen were 70, 250, 350 and 400 respectively, to isolate and culture for E. coli O157 with immunomagnetic separation and immunochromatography technology were carried out. The purified strains were cultured and examined by 3 differential media as well as France biomerieux AMS VITEK32GNI ＋ s or identification system for Enterobacteriaceae API 20E strips, serological tests, polymerase chain reactions （PCR）, phage type. Results 11 strains of E.coli O157 were separated from 70 cattle feces, 250 pigs＇ feces and 400 patients＇ feces. Obtained 4 strains of E. coli O157 ： H7, 6 strains E. coli O157： Hund and 1 patient with diarrhea were 1.4 %, 2.0%, 0 and 1.2% respectively. The authors understood the morphologies, biochemistries, serologies, virulence factors, phage types, tellurite resistance of 11 strains of E. coli O157. Conclusions Multiple strains of E. coli O157 exist in a single crowd or a single flock of animals and a single animal or patient shed two strains or more simultaneously. The phenotypes and virulence factors characteristics of E. coli O157 strains exist difference to a certain extent. Genetic finger- printing techniques can define and identify further the differences among the strains.     

Geographic Divergence of Bovine and Human Shiga Toxin–Producing Escherichia coli O157:H7 Genotypes,New Zealand

Shiga toxin-producing Escherichia coli (STEC) O157:H7 is a zoonoticpathogen of public health concern worldwide. To compare the local and large-scalegeographic distributions of genotypes of STEC O157:H7 isolates obtained from variousbovine and human sources during 2008–2011, we used pulsed-field gelelectrophoresis and Shiga toxin–encoding bacteriophage insertion (SBI) typing.Using multivariate methods, we compared isolates from the North and South Islands ofNew Zealand with isolates from Australia and the United States. The STEC O157:H7population structure differed substantially between the 2 islands and showed evidenceof finer scale spatial structuring, which is consistent with highly localizedtransmission rather than disseminated foodborne outbreaks. The distribution of SBItypes differed markedly among isolates from New Zealand, Australia, and the UnitedStates. Our findings also provide evidence for the historic introduction into NewZealand of a subset of globally circulating STEC O157:H7 strains that have continuedto evolve and be transmitted locally between cattle and humans.     

Phylogenetic Analysis of Enterohemorrhagic Escherichia coli O157, Germany, 1987�C2008

Multilocus variable number tandem repeat analysis (MLVA) is a subtyping technique for characterizing human pathogenic bacteria such as enterohemorrhagic Escherichia coli (EHEC) O157. We determined the phylogeny of 202 epidemiologically unrelated EHEC O157:H7/H^– clinical isolates through 8 MLVA loci obtained in Germany during 1987–2008. Biodiversity in the loci ranged from 0.66 to 0.90. Four of 8 loci showed null alleles and a frequency <44.1%. These loci were distributed among 48.5% of all strains. Overall, 141 MLVA profiles were identified. Phylogenetic analysis assigned 67.3% of the strains to 19 MLVA clusters. Specific MLVA profiles with an evolutionary persistence were identified, particularly within sorbitol-fermenting EHEC O157:H^–.These pathogens belonged to the same MLVA cluster. Our findings indicate successful persistence of this clone.     

Foodborne general outbreaks of Shiga toxin-producing Escherichia coli O157 in England and Wales 1992-2002: where are the risks?

Between 1 January 1992 and 31 December 2002, Shiga toxin-producing Escherichia coli O157 (STEC O157) accounted for 44 of the 1645 foodborne general outbreaks of infectious intestinal disease reported to the Health Protection Agency Communicable Disease Surveillance Centre. These outbreaks, although rare, were characterized by severe infection, with 169 hospital admissions and five deaths reported. STEC O157 outbreaks were compared with other pathogens to identify factors associated with this pathogen. Single risk variable analysis and logistic regression were employed. Two distinct aetiologies were identified. Foodborne outbreaks of STEC O157 infection in England and Wales were independently associated with farms, which related to milk and milk products, and with red meats/meat products, which highlighted butchers' shops as a cause for concern. The introduction and adherence to effective control measures, based on the principles of hazard analysis, provide the best means of minimizing the risk of foodborne infection with this pathogen.     

商丘市E.coli.O157:H7动物带菌的监测与鉴定

目的　了解商丘市家畜、家禽E .coli.O15 7:H7带菌情况 ,并进行生物学特性研究。方法　在发生病人的村庄和周围村庄、波尔山羊养殖场每月进行集中采样。每只羊采集 5克最新鲜的粪便直接接种MEC培养基中送检。结果　从 2 0 4 3份标本中检出 0 15 7:H714 6珠 ,具有Stx2毒素基因的 6 8珠。疫区家畜、家禽携带 0 15 7:H7大肠杆菌高达 2 3%。结论　此次对疫区家畜、家禽标本中所分离到的E .coli.0 15 7:H7大肠杆菌 ,通过血清学、生化学、毒力基因等鉴定试验 ,其生物学性状多样化 ,菌株产毒基因表现不一。不同种类的家畜、家禽中所分离的产毒菌株比例差别显著 ,尤其是羊类分离率最高。     

河南豫东地区产志贺样毒素E.coli O157:H7感染病例的流行病学调查研究

[目的]探讨河南省局部地区腹泻病人感染及携带大肠杆菌O157：H7的情况，观察带菌时间及预后。[方法]采用流行病学监测方法发现病人，通过病人粪便mEC肉汤增菌14h、胶体金免疫卡筛选、免疫磁珠法集菌、CHROMAGAR—O157：H7显色培养基分离、rfbO157、rfbO111、hlyA、stx1、stx2、eaeA引物PCR扩增方法进行毒力因子测定等方法，观察、研究感染病人的发病和预后。[结果]从1303份腹泻病人中共分离出的38株O157：H7菌株，检出率2．9％，PCR rfbO157扩增均为阳性。其中2株具有stx2、hlyA和eaeA毒力基因，36株为O157：H7不产毒株。[结论]我省首次从病人中分离出O157：H7产毒株，病人发病后可于第3～8d内检出病原体。     

Changes in prevalence of ovine paratuberculosis following vaccination with Gudair®: Results of a longitudinal study conducted over a decade

Since its registration in 2002, Gudair® vaccine has become the key tool for managing paratuberculosis in sheep in Australia. This study was conducted to evaluate its effectiveness in reducing paratuberculosis prevalence in 12 flocks over more than one decade. Flocks with variable initial prevalence (5, 4 and 3 with low, medium, and high prevalence, respectively) were enrolled in the study in 2003–04. Six biennial faecal samplings were conducted in these flocks over a 10 year period. At each sampling, faeces from four age groups (3, 4, 5 and 6 year-old sheep) were collected from each flock. The aim was to select 7 or 14 pools of faeces constituted with pellets from 50 or 25 sheep from each age group, respectively, but the numbers and sizes of pools did vary due to logistical issues. Samples were cultured using pooled faecal culture approach and sheep level paratuberculosis prevalence was estimated. Changes in probability of a pool being positive and in paratuberculosis prevalence over time were evaluated by fitting generalised-linear and linear mixed models. The proportion of positive faecal pools significantly declined over time from 50.3% at the first sampling in 2003–04 to only 3.1% at the last sampling in 2013–14, suggestive of a 30-fold reduction in the odds of a pooled faecal sample to be positive (p < 0.001). Similarly, the average animal level prevalence in flocks dropped from 7.64% at the first sampling to 0.12% at the last sampling. However, faecal shedding persisted and was still present in 3 of the 8 flocks (37.5%) that remained in the study at the last sampling conducted in 2013–14. This is the longest study ever conducted to evaluate paratuberculosis vaccine effectiveness. The results will enable sheep producers to make informed decisions on managing paratuberculosis, and in evaluating the risks of purchasing and trading vaccinated sheep.     

FDA在保证食品安全中的作用和跟踪、解决近期菠菜中大肠杆菌E.coli O157:H7爆发的措施

美国食品药物管理局食品安全和应用营养中心主任、博士罗伯特E.布莱克先生在美国参议院卫生、教育、劳工、退休基金委员会上的演讲。译者注:近期,美国多个州爆发大肠杆菌E.coliO157:H7,此次爆发影响广泛,引起美国公众的广泛关注。而此间美国食品药物管理局(FDA)作为全美食品安全质量主管机构,联合联邦政府其它部门、     

Immunogenicity of a novel Stx2B–Stx1B fusion protein in a mice model of Enterohemorrhagic Escherichia coli O157:H7 infection

Shiga toxin type 1 and 2 produced by Enterohemorrhagic Escherichia coli (EHEC) O157:H7 are responsible for hemolytic uremic syndrome, a life-threatening sequela. We constructed a novel fusion protein carrying both of the immunogenic B subunits derived from the two toxins, designated Stx2B–Stx1B (2S for short), expressed in the E. coli BL21 and harvested the purified protein by a simple anion-exchange chromatography method. The fusion protein induced high level humoral IgG in mice, subclass analysis showed IgG1 dominate the IgG increase trend, which indicated that a partial to Th2 response contributed to this humoral reactivity. High level neutralizing antibodies elicited by this fusion protein inhibited cytotoxicity of toxins and protected mice from lethal dose challenge of lysed EHEC O157:H7.     

The risk of non-specific hospitalised infections following MMR vaccination given with and without inactivated vaccines in the second year of life. Comparative self–controlled case-series study in England

Observational cohort studies in high-income settings have suggested that vaccination order may affect children’s subsequent risk of a heterologous infection, with live vaccines reducing and inactivated vaccines (given on their own or with a live vaccine), increasing the risk. We used the self-controlled case-series method, which automatically controls for the individual level confounding to which such cohort studies are prone, to test this hypothesis. We compared the relative incidence (RI) of infections post-vaccination in two calendar periods in England; in Period 1 (September 2002–August 2006) live measles, mumps, rubella (MMR) vaccine was given on its own and in Period 2 (September 2006–April 2010) inactivated vaccines (7-valent pneumococcal conjugate vaccine (PCV7) and sometimes the combined Haemophilus influenzae type b/meningococcal group C vaccine (Hib-MenC)) were given concomitantly with MMR. Admissions for an infection of the upper or lower respiratory tract, gastrointestinal system or other site in children aged 11–23 months were selected from the Hospital Episode Statistics database in England and linked to child health immunisation histories. The analysis included a total of 24,144 infections in 21,067 children in Period 1 and 36,880 in 31,616 children in Period 2. The RI of admission for any infection in Period 1 was 1.00 (95% confidence interval 0.95–1.06) compared with 0.95 (95% confidence interval 0.90–1.00) in Period 2. Comparing the two periods showed no evidence of a difference in the relative incidence estimates with a ratio of RI of 0.94 (95% confidence interval 0.87–1.02), RIs within 90 days of vaccination were 0.94 (0.91–0.97) in Period 1 and 0.94 (0.91–0.97) in Period 2, consistent with a temporary healthy vaccinee effect. In conclusion, we found no evidence to support the hypothesis that there is a reduction in heterologous infections after MMR on its own or an increase after MMR given concomitantly with an inactivated vaccine.     

Investigation of serum bactericidal activity in childhood and adolescence 3–6 years after vaccination with a single dose of serogroup C meningococcal conjugate vaccine

Serogroup C meningococcal conjugate vaccines were introduced in Greece in 2001, and although no cases of serogroup C meningococcal disease were recorded in 2004, a steady increase was observed since 2005. In this study, serum bactericidal activity was assessed in sera of 269 vaccinated children at a mean time of about 5 years after vaccination. Non-protective antibody titers were observed in most children vaccinated at age <6 years (85.9%), followed by those between 6 and 10 years (62.2%). This percentage was considerably lower in adolescents vaccinated at an age >10 years (37.8%) (p < 0.01). Geometric mean concentrations of serum IgG antibodies against serogroup C showed a similar variation. The results indicate that serum bactericidal antibody titers significantly correlate with age of vaccination; most children do not have protective antibody titers few years after immunization in infancy and childhood whereas most adolescents maintain sustained protection.