Serotypes and colonization factors of enterotoxigenic Escherichia coli isolated in various countries

One hundred and six enterotoxigenic E. coli (ETEC) isolated from many geographical areas were serotyped and investigated for the presence of colonization factor antigens CFA/I and CFA/II, the expression of mannose-resistant haemagglutination (MRHA) and the levels of surface hydrophobicity. CFA/I was found in 6 (17%) of 36 LT⁺STa⁺ strains and in 15 (54%) of 28 STa⁺ strains; CFA/II was found in 16 (44%) of 36 LT⁺STa⁺ strains. None of 42 LT⁺ strains showed CFA/I or CFA/II. CFA/I was found in ETEC of serotypes O63:K?:H?, O78:K80, O128:K67 and O153:K?:H45, whereas CFA/II was found in serotypes O6:H?, O6:K15:H16 and 06:K?:H40. Of the 69 CFA/I^? CFA/II^? ETEC strains, 9 (13%) showed MRHA with some of the seven erythrocyte species used and 21 (30%) were hydrophobic. Among the 21 hydrophobic strains CFA-negative we have detected: (i) 6 LT⁺ strains of serogroup O25 negative for MRHA, (ii) 5 strains O159 (4 LT⁺ and 1 LT⁺ STa⁺) also negative for MRHA, and (iii) 3 STa⁺ strains of serotype O27:K?:H7 that haemagglutinated calf and sheep erythrocytes when grown on Minca-Is. The 106 ETEC strains belonged to 20 different 0 serogroups. However, 77 (73%) were of one of nine serogroups (O6, O8, O25, O27, O78, O148, O153, O159 and O167). E. coli strains belonging to O6 and O153 groups predominated among ETEC isolated in Spain, O159 strains in the Central African Republic, O25 and O148 strains in Japan, and O15 and O78 strains in India.     

Epidemiology and properties of heat-stable enterotoxin-producing Escherichia coli serotype O169:H41.

Enterotoxigenic Escherichia coli (ETEC) serotype O169:H41 organisms have become the most prevalent ETEC in Japan since the first outbreak in 1991. It was assumed that the outbreaks were due to clonal spread of this new ETEC serotype. The relationship of 32 strains isolated from 6 outbreaks were examined for biotype, antibiotic susceptibility, enterotoxigenicity, protein banding pattern, lipopolysaccharide banding pattern, plasmid analysis, and ribotyping. Further, the strains were examined by haemagglutination, surface hydrophobicity, and the ability to adhere to HEp-2 cells. The present study suggests that the outbreaks were caused by multiple clones of STp-producing O169:H41 since they showed differences in ribotype and outer membrane protein banding patterns. The strains did not agglutinate human or bovine red blood cells in a mannose-resistant manner. They adhered to HEp-2 cells in a manner resembling enteroaggregative E. coli. Five strains were examined by dot-blot tests for the colonization factor antigens CFA/I, CS1, CS2, CS3, CS4, CS5, CS6, CS7, PCFO159, PCFO166 and CFA/III. Although four strains expressed CS6, no structure for CS6 was identified. A strain that the anti-CS6 MAbs did not react with could adhere to HEp-2 cells in mannose resistant manner; thus, it is unlikely that CS6 play an important role in the adhesion to the cells. Electron microscopy studies of the O169:H41 strains suggested that curly fimbriae, a possible new colonization factor, may be playing an important role in the adhesion of the bacteria to HEp-2 cells. In conclusion, outbreaks due to ETEC O169:H41 were caused by multiple clones, and the strains should be examined in detail for a possible new colonization factor.     

Outbreaks of cholera-like diarrhoea caused by enterotoxigenic Escherichia coli in the Brazilian Amazon Rainforest

The relationship between enteropathogens and severe diarrhoea in the Brazilian Amazon is poorly understood. In 1998, outbreaks of acute diarrhoea clinically diagnosed as cholera occurred in two small villages localized far from the main cholera route in the Brazilian rainforest. PCR was performed on some enteropathogens and heat-labile (LT) and/or heat-stable (STh) toxin genes, the virulence determinants of enterotoxigenic Escherichia coli (ETEC), were detected. Further characterization of ETEC isolates revealed the presence of two clones, one from each outbreak. One presenting serotype O167:H5 harboured LT-I and STh toxin genes and expressed the CS5CS6 colonization factor. The other, a non-typeable serotype, was positive for the LT-I gene and expressed the CS7 colonization factor. The current study demonstrates the importance of molecular diagnosis in regions such as the Amazon basin, where the enormous distances and local support conditions make standard laboratory diagnosis difficult. Here we also show that the mis-identified cholera cases were in fact associated with ETEC strains. This is the first report of ETEC, molecularly characterized as the aetiological agent of severe diarrhoea in children and adults in the Brazilian Amazon Rainforest.     

Isolation of enterotoxigenic Escherichia coli from British troops in Saudi Arabia.

Specimens from 181 patients with diarrhoea were examined by a Military General Hospital in a 3-month period during deployment of troops to Saudi Arabia in 1990/1. DNA probes for heat labile (LT) and heat stable (ST) enterotoxin genes identified enterotoxigenic Escherichia coli (ETEC) in 47 of the specimens (26%) and 49 ETEC strains were isolated. The majority (55%) belonged to a novel ETEC serotype having the O-antigen 159 and a flagellar antigen designated as a provisional new type. They produced ST and the coli surface associated antigen (CS)6. Strains of serotype O6:H16 represented 22% of the ETEC examined. They produced ST, LT and CS3 together with either CS1 or CS2. The remaining ETEC belonged to seven O:H serotypes. Overall, ST was the only enterotoxin gene identified in 73% of the ETEC and 67% of the strains expressed CS6 in the absence of other colonization antigens. Resistance to three or more antibiotics was observed in 53% of the ETEC, including most of the O159 strains.     

Enterotoxigenic Escherichia coli associated diarrhoea among infants aged less than six months in Calcutta, India

The role of enterotoxigenic Escherichia coli (ETEC) as etiologic agents of diarrhoea in infants aged less than six months was assessed in a hospital based study in Calcutta, India. Of the 218 cases examined, ETEC strains were isolated from 26 (11.9%) cases. Among these, in 17 cases ETEC was the sole infecting pathogen (p = 0.0085). Of the 26 isolates (each isolate representing a case), 24 were distributed among seven different O:K:H serotypes and two different colonization factor antigens (CFAs) I and II. Two of the remaining isolation were untypable, non-haemagglutinating, and were nonhydrophobic as measured by the salt aggregation test (SAT). Of the 26 ETEC strains detected, 15 (57.7%) produced heat-labile toxin (LT) only, 8 (30.8%) liberated heat-stable toxin (ST) only, and the remaining 3 (11.5%) produced both LT and ST. No ETEC strain was isolated from the 102 age-matched controls included in this study. All the ETEC isolates were multiple drug resistant. The study showed that the diarrhoea due to ETEC was of brief duration, mostly within the range of 3 to 7 days.     

上海地区首次发现和阿奇霉素耐药高度相关的肠产毒性大肠埃希菌O∶6血清群的流行克隆

目的 基于监测网络对肠产毒性大肠埃希菌（ETEC）成年人腹泻病例开展分子特征研究,探索流行病学对实验室技术和数据需求的实践模式。方法 以ETEC腹泻流行季节的成年人病例为对象进行流行病学设计和抽样,鉴定肠毒素型、血清群、耐药表型、定殖因子及分子型,通过多维度与多变量数据展示获得ETEC多个动态表型特征。结果 2016-2018年监测网络符合条件的ETEC病例84株。优势血清/毒素型依次为O：6（STh）、O：25（LT）、O：159（STh）、O：153（STh）,O：6（STh+CS21）取代O：25和O：159成为2018年的流行克隆,2017年的6例O：153（STh+CFA/I+CS8+PT34）为输入型暴发案例;成年人ETEC耐药率超过30%有磺胺异恶唑、萘啶酸、氨苄青霉素和阿奇霉素,多重耐药菌（MDR）达58.3%,血清/毒素型别提示弱毒株易形成MDR;分子分型证实O：6血清群优势克隆（PT20~24）的遗传相似度超过O：25和O：159,且与阿奇霉素最低抑菌浓度（MIC）和耐药基因mphA间存在高度相关性（87.5%,28/32）,O：6（STh+CS21+mphA）耐药克隆始于2016年。结论 上海地区ETEC成年人腹泻病例新的流行克隆为O：6（STh+CS21+mphA）,首次观察到阿奇霉素耐药基因mphA和ETEC某个血清群存在关联。基于流行病学构建的多维度和多变量分析技术,有助揭示ETEC潜在传播规律,达到精准监测和预警暴发目的。     

广东省2013年副溶血弧菌暴发与散发菌株的病原学特征

目的 了解2013年广东省副溶血弧菌暴发与散发分离株的血清型别、抗菌药物耐药性、毒力基因携带情况以及分子分型特征.方法 对36株暴发分离株和43株散发分离株进行血清分型、药敏试验以及耐热直接溶血毒素基因(tdh)、耐热相关溶血毒素基因(trh)、GS-PCR和orf8基因的PCR检测,并进行脉冲场凝胶电泳(PFGE)分型.结果 36株暴发分离株全部为O3:K6血清型,43株散发分离株的优势血清型为O3:K6型(23株,53.49%).药敏检测结果显示,对氨苄西林(96.20%)和头孢噻吩(40.50%)的耐药率较高;对复方新诺明和氯霉素则高度敏感,敏感性均为100%.多重耐药分析显示,83.33%(30/36)的暴发分离株同时耐受≥3种抗菌药,37.21%(16/43)的散发分离株同时耐受≥3种抗菌药物.毒力基因PCR检测显示,36株暴发分离株均为tdh⁺tdh^-型菌株.86.05%(37/43)的散发分离株为tdh⁺tdh^-型菌株,11.63%(5/43)为tdh^-tdh⁺型菌株,仅1株为tdh⁺tdh⁺型菌株.暴发分离株全部携带GS-PCR和/或orf8基因,51.16%(22/43)的散发分离株携带GS-PCR和/或orf8基因.PFGE显示,79株副溶血弧菌经NotⅠ酶切后的PFGE图谱可分为3个聚类,32种PFGE型别,相似值为59.8%～100.0%.暴发菌株聚集在同一个聚类中,散发菌株散布在各个聚类中.结论 2013年广东省副溶血弧菌优势血清型为O3:K6型,菌株对多数抗菌药物仍然比较敏感,但存在多重耐药现象,多数菌株携带tdh基因,大部分O3:K6型菌株携带GS-PCR和/或orf8基因;PFGE结果提示广东省副溶血弧菌存在遗传多样性.     

热敏感肠毒素基因探针的制备及其特性的研究

LT基因探针是新近发展起来检测ETEC-LT⁺菌的一个快速诊断方法。本文较详细地介绍了它的制作方法并对其特性作了进一步地探讨。结果表明LT探针的特异性较强、敏感性较高,可测定7个菌/ml菌悬液和35个菌/ml粪便悬液(直接在硝酸纤维素滤膜上点样,用DNA-DNA原位杂交法检测)。基因探针法操作比常规的粪便培养分离鉴定简单、经济,有效期可达45~60天,一次能检测大量标本,这些特点使它适用于现场的大量标本检测和流行病学调查,因此将为深入研究ETEC的流行病学提供一个有用的工具。     

Over-expression of major colonization factors of enterotoxigenic Escherichia coli, alone or together,on non-toxigenic E. coli bacteria

Enterotoxigenic Escherichia coli (ETEC) is an important cause of diarrheal disease and deaths among children in developing countries and the major cause of traveller's diarrhea. Since surface protein colonization factors (CFs) of ETEC are important for pathogenicity and immune protection is mainly mediated by locally produced IgA antibodies in the gut, much effort has focused on the development of an oral CF-based vaccine. We have recently described the development of recombinant strains over-expressing CFA/I; the most prevalent CF among human clinical ETEC isolates. Here, non-toxigenic recombinant E. coli strains over-expressing Coli surface antigen 2 (CS2), CS4, CS5, and CS6, either alone, or each in combination with CFA/I were constructed by cloning the genes required for expression and assembly of each CF into expression vectors harboring a strong promoter. Immunological assays showed that recombinant strains expressing single CFs produced those in significantly larger amounts than did corresponding naturally high producing reference strains. Recombinant strains co-expressing CFA/I together with another CF also expressed significantly larger amounts of both CFs compared with the corresponding references strains. Further, when tested in mice, oral immunization with formalin-killed recombinant bacteria co-expressing one such double-expression CF pair, CFA/I + CS2, induced specific serum IgG + IgM and fecal IgA antibody responses against both CFs exceeding the responses induced by immunizations with natural reference strains expressing CFA/I and CS2, respectively. We conclude that the described type of recombinant bacteria over-expressing major CFs of ETEC, alone or in combination, may be useful as candidate strains for use in an oral whole-cell CF-ETEC vaccine.     

Enterotoxin-producing Escherichia coli O169:H41, United States

From 1996 to 2003, 16 outbreaks of enterotoxigenic Escherichia coli (ETEC) infections in the United States and on cruise ships were confirmed. E. coli serotype O169:H41 was identified in 10 outbreaks and was the only serotype in 6. This serotype was identified in 1 of 21 confirmed ETEC outbreaks before 1996.     

Serotypes of CNF1-producingEscherichia coli strains that cause extraintestinal infections in humans

The O:K:H serotypes of 137 necrotoxigenicEscherichia coli (NTEC) producing the cytotoxic necrotizing factor type 1 (CNF1) isolated from human extraintestinal infection were determined. Although NTEC producing CNF1 belonged to 58 different serotypes, only 10 of them accounted for 54% of strains. The most common serotypes, in order of frequency, were: O4:K?:H5, O6:K13:H1, O83:K1:H31, O75:K95:H5, O2:K1:H6, O2:K7:H-, O75:K1:H7, O2:K?:H1, O4:K12:H1 and O22:K13:H1. CNF1 strains of serotypes O2:K7:H- and O4:K12:H1 express P-fimbriae, whereas CNF1 strains of serotypes O2:K?:H1, O2:K1:H6 and O75:K95:H5 possess the adhesin responsible for MRHA type III. Among CNF1 strains of serotype O4:K?:H5 there exist some that express P-fimbriae and others that possess MRHA type III. Lastly, the majority of CNF1 strains of serotypes O6:K13:H1, O22:K13:H1, O75:K1:H7 and O83:K1:H31 do not express P-fimbriae nor the adhesin responsible to MRHA type III. Our results show that extraintestinal infections are caused by a limited number of virulent clones, as suggested by the theory of special pathogenicity.     

A systematic review of ETEC epidemiology focusing on colonization factor and toxin expression

Introduction

Vaccine development for enterotoxigenic Escherichia coli (ETEC) is dependent on in-depth understanding of toxin and colonization factor (CF) distribution. We sought to describe ETEC epidemiology across regions and populations, focusing on CF and toxin prevalence.

Methods

We conducted a systematic review of the published literature, including studies reporting data on ETEC CF and toxin distributions among those with ETEC infection. Point estimates and confidence intervals were calculated using random effects models.

Results

Data on 17,205 ETEC isolates were abstracted from 136 included studies. Approximately half of the studies (49%) involved endemic populations, and an additional 17% involved only travel populations. Globally, 60% of isolates expressed LT either alone (27%) or in combination with ST (33%). CFA/I-expressing strains were common in all regions (17%), as were ETEC expressing CFA/II (9%) and IV (18%). Marked variation in toxins and CFs across regions and populations was observed.

Discussion/conclusions

These results demonstrate the relative importance of specific CFs in achieving target product profiles for a future ETEC vaccine. However, heterogeneity across time, population, and region, confounded by variability in CF and toxin detection methodologies, obfuscates rational estimates for valency requirements.     

In Vitro Evaluation of Dietary Fiber Anti-Infectious Properties against Food-Borne Enterotoxigenic Escherichia coli

Dietary fibers have well-known beneficial effects on human health, but their anti-infectious properties against human enteric pathogens have been poorly investigated. Enterotoxigenic Escherichia coli (ETEC) is the main agent of travelers’ diarrhea, against which targeted preventive strategies are currently lacking. ETEC pathogenesis relies on multiple virulence factors allowing interactions with the intestinal mucosal layer and toxins triggering the onset of diarrheal symptoms. Here, we used complementary in vitro assays to study the antagonistic properties of eight fiber-containing products from cereals, legumes or microbes against the prototypical human ETEC strain {"type":"entrez-nucleotide","attrs":{"text":"H10407","term_id":"875229","term_text":"H10407"}}H10407. Inhibitory effects of these products on the pathogen were tested through growth, toxin production and mucus/cell adhesion inhibition assays. None of the tested compounds inhibited ETEC strain {"type":"entrez-nucleotide","attrs":{"text":"H10407","term_id":"875229","term_text":"H10407"}}H10407 growth, while lentil extract was able to decrease heat labile toxin (LT) concentration in culture media. Lentil extract and specific yeast cell walls also interfered with ETEC strain {"type":"entrez-nucleotide","attrs":{"text":"H10407","term_id":"875229","term_text":"H10407"}}H10407 adhesion to mucin beads and human intestinal cells. These results constitute a first step in the use of dietary fibers as a nutritional strategy to prevent ETEC infection. Further work will be dedicated to the study of fiber/ETEC interactions within a complex gut microbial background.     

Virulence genotypes and serotypes of verotoxigenic Escherichia coli isolated from cattle and foods in Argentina

Virulence factors of Verotoxin-producing Escherichia coli(VTEC) strains isolated from hamburgers and ground beef were studied in Argentina by PCR. Their virulence profiles were correlated with those corresponding to strains isolated from calves and adult cattle. Most virulent profiles (VTs⁺ eae ⁺Mp⁺) were present in E. colifrom healthy and diarrheic calves corresponding to O5:H-, O5:H27, O20:H?, O26:H11, O38:H?, O103:H-, O103:H2, O111:H-, O118:H16, O165:H-serotypes. The presence of the eaegene was significantly more frequent among VTEC strains isolated from calves (20/26; 76%) than from adult cattle (1/39; 2.5%) (p< 0.005). VT2⁺ eae ^? E. coliwas prevalent in foods and adult cattle at slaughterhouse. The prevalence of the eaegene was similar between VTEC strains isolated from meat (0/21) and adult cattle (1/39; 2.5%) which constitutes the main population processed at slaughterhouses in Argentina. Serotyping showed that VTEC strains were distributed among 31 serotypes, some of which (O20:H19, O91:H21, O113:H21, O116:H21, O117:H7, O171:H2, OX3:H21) were shared between bovine and food strains. These O serogroups have been isolated from cases of haemorrhagic colitis (HC) and haemolytic-uraemic syndrome (HUS) in humans in several continental European countries. This study confirms the role of cattle as a reservoir of many VTEC serotypes other than O157:H7 and represents a base for future diagnostic, prevention and control strategies of EHEC in this country. In addition, this study affirms the advantages of PCR-based screening of E. coliisolates given the finding of so many verotoxin-producing strains.     

Surveys of human enterotoxigenic Escherichia coli from three different geographical areas for possible colonization factors.

Enterotoxigenic Escherichia coli (ETEC) from Burma, central Africa (Rwanda and Zaire) and Peru, were screened by enzyme-linked immunoassays for the colonization factor antigens (CFAs) and putative colonization factors (PCFs): CFA/I, CFA/II, which consists of three coli surface-associated (CS) antigens, CS1, CS2 and CS3, CFA/III, CFA/IV (CS4, CS5, CS6), CS7, PCFO9, PCFO159. H4, PCFO166, and CS17. The highest proportion of ETEC with identifiable colonization factors (71%) were found in the strains from Burma, which were mainly positive for CFA/I (38%), but strains producing CFA/II (4%), CFA/IV (11%), CS7 (10%), CS17 (4%), PCFO159, H4 (2%) and PCFO166 (2%) were also found. Sixty-nine percent of the ETEC from central Africa were positive for known colonization factors. While CFA/I positive strains were important (12%), a higher number of ETEC producing CFA/IV (33%) and CS17 (24%) were found. Fifty-two percent of the Peruvian strains produced identifiable colonization factors. The largest group of strains produced antigens of the CFA/IV complex (17%), while ETEC producing CFA/II (6%), CFA/III and CS6 (2%), CS7 (6%), PCFO9 (6%), PCFO166 (8%) and CS17 (7%) were also found. These surveys show that there is a considerable variation in the proportions and types of colonization factor found in different geographical areas. From 29 to 48% of the ETEC did not possess an identifiable colonization factor. These were particularly of the LT only producing type. These results have important implications for vaccine formulation.     

Vaccination with EtpA glycoprotein or flagellin protects against colonization with enterotoxigenic Escherichia coli in a murine model

Enterotoxigenic Escherichia coli (ETEC) remain a leading cause diarrheal illness, prompting a search for vaccine targets that led to the recent discovery of EtpA, a secreted adhesin of ETEC that acts by bridging flagella and host cells. In a murine model, immunization with recombinant EtpA glycoprotein inhibited colonization by two EtpA-producing human ETEC strains, H10407 and E24377A. In addition, vaccination with recombinant flagellin (serotype H11) generated antibodies that specifically recognized the tips of flagella from E24377A expressing a heterologous flagellar serotype (H28) and afforded significant protection against colonization. EtpA and/or flagellin could be valuable subunit antigens in the formulation of a broadly protective ETEC vaccine.     

Prevalence and characteristics of human and bovine verotoxigenic Escherichia coli strains isolated in Galicia (north-western Spain)

An epidemiological study was carried out to determine the incidence and the serotypes of verotoxigenic Escherichia coli (VTEC) that cause infections in Galicia (north-western Spain). Although, VTEC strains were isolated from 55 (14%) of the 387 calves sampled and the majority of bovine VTEC strains belonged to serotypes (026:H11 or H–, 091:H21, 0103:H2, 0105:H18, 0111:H–, 0113:H21, 0126:H–, 0128:H– and 0157:H7 or H–) previously associated with human haemorrhagic colitis (HC) and haemolytic uraemic syndrome (HUS) in other countries, VTEC are not a common cause of human infections in Spain. Thus, VTEC (026:H11 and 086:H10) were isolated from only 3 (0.6%) of the 482 children with diarrhoea investigated. We examined the 69 (3 humans and 66 bovines) VTEC strains that were initially isolated as E. coli producing a toxin cytotoxic to Vero and HeLa cells by polymerase chain reaction (PCR) using specific primers for VT1, VT2 and eae genes. PCR showed that 38 (55%) of VTEC strains carried VT1 genes, 18 (26%) possessed VT2 genes, and 10 (14%) carried both VT1 and VT2 genes. Three (one human and two bovine) strains which were formerly VTEC had lost the ability to produce verotoxins upon subculture and became negative for VT 1 and VT2 by PCR. In total 35 (51%) of 69 VTEC strains, including the two human VT1⁺ strains of serotype 026:H11, were positive for eae sequences when tested by PCR. Presence of the eae gene was significantly more frequent (100%; 21/21) among VTEC strains with serotypes (026:H11, 0111:H–, 0157:H–and 0157:H7) considered as enterohaemorrhagic E. coli (EHEC) than among VTEC strains with non-EHEC serotypes (29%; 14/48) (p < 0.001). Results obtained in this study indicate that cattle may be an important source of VTEC involved in human disease. However, severe clinical syndromes caused by VTEC, such as HC and HUS, are uncommon in Spain, in comparison with North America and the UK. In any case, VTEC disease can appear on the scene very suddenly, as occurred in the UK and North America in the 1980s.     

上海市2012－2013年4种致泻性大肠埃希菌监测

目的 基于临床医院开展4种致泻性大肠埃希菌(DEC)人群监测,探讨公共卫生实验室对临床实验室需求的直接技术指导的实践模式。方法 设立哨点医院,以标准化方法筛选和鉴定DEC菌型;构建DEC流行特征基线;对疑似暴发病例开展基于实验室和流行病学调查。结果 2012－2013年选择上海地区4家哨点医院检测7 204份腹泻标本确认的712例DEC感染病例,阳性率为9.9%。其中肠致病性大肠埃希菌(EPEC)感染351例;肠产毒性大肠埃希菌(ETEC)感染292例;肠侵袭性大肠埃希菌(EIEC)感染32例;产志贺样毒素大肠埃希菌(STEC/EHEC)感染6例;DEC混合感染31例。EPEC感染以1～5岁儿童最多见,菌型均为aEPEC;ETEC流行峰值在8月,阳性率>20%,感染病例2012年聚集于1～28日龄和2013年的20～60岁人群(P< 0.05),菌型以耐热肠毒素(ST)型最多(59.6%),其次为不耐热肠毒素(LT)型(27.8%)和ST/LT型(12.6%);2013年儿童感染EIEC病例明显增加(P< 0.01);未监测到EHEC O157 : H7,但确认2例EHEC O26 : H11(eae-hlyA-stx1a)儿童病例;调查确认2012年上海地区15例新生儿ETEC聚集性感染病例与四川省自贡市新生儿病例属于同一克隆(STh-CS21-CFA/I-ClyA-EatA-ST2332- SHNL0005)。结论 上海地区DEC型谱特征已发生改变,ETEC对新生儿院内感染和食源性感染性腹泻构成潜在暴发风险,需加强实验室主动监测。     

Aetiology of Diarrhoea and Virulence Properties of Diarrhoeagenic Escherichia coli among Patients and Healthy Subjects in Southeast Nigeria

Diarrhoeal diseases are one of the most important causes of illness and death all over the world. In Nigeria, the aetiology of diarrhoeagenic bacteria and the virulence of various Escherichia coli pathotypes have not been well-studied because most currently-published data were from the southwestern axis of the country. In total, 520 stool samples were collected from infants, young children, and other age-groups with acute diarrhoeal diseases in Enugu and Onitsha, southeastern Nigeria. Stool samples were collected from 250 apparently-healthy individuals, with similar age distribution and locality, who were considered control subjects. The stool samples were screened for diarrhea-causing bacterial agents. E. coli strains were isolated from both the groups and were examined by polymerase chain reaction (PCR) for 16 virulence genes. Of the 520 stool samples in the diarrhoea group, 119 (44.74%) were E. coli. Fifty (49.02%) were enteropathogenic E. coli (EPEC), 22 (21.57%) were enterotoxigenic E. coli (ETEC) while 7.84% was enteroaggregative E. coli (EAEC). Sex had no effect on the distribution of diarrhoeagenic bacteria, except for EIEC. The E. coli strains isolated from the diarrhoea and healthy asymptomatic age-matched control groups examined by PCR for 16 virulence genes indicate that the detection of EAEC, ETEC, EPEC, and EIEC was significantly associated with diarrhoea (p=0.0002). The study confirmed that several bacterial pathogens, such as E. coli, play an important role in the aetiology of acute diarrhoea in southeastern Nigeria. A routine surveillance, especially for diarrhoeagenic E. coli, would be useful in identifying outbreaks and help identify the potential reservoirs and transmission routes.Key words: Diarrhoea, Escherichia coli, Virulence, Nigeria     

Outbreaks of enterotoxigenic Escherichia coli infection in American adults: a clinical and epidemiologic profile.

Because enterotoxigenic Escherichia coli (ETEC) is not identified by routine stool culture methods, ETEC outbreaks may go unrecognized, and opportunities for treatment and prevention may be missed. To improve recognition of adult ETEC outbreaks, we compared them with reported outbreaks of viral gastroenteritis. During 1975-95, we identified 14 ETEC outbreaks in the United States and 7 on cruise ships, caused by 17 different serotypes and affecting 5683 persons. Median symptom prevalences were: diarrhoea 99%, abdominal cramps 82%, nausea 49%, fever 22%, vomiting 14%. The median incubation period was 42 h, and for 8 of 10 outbreaks, the mean or median duration of illness was > 72 h (range 24-264). For 17 (81%) ETEC outbreaks, but for only 2 (8%) viral outbreaks, the prevalence of diarrhoea was > or = 2.5 times the prevalence of vomiting. ETEC outbreaks may be differentiated from viral gastroenteritis outbreaks by a diarrhoea-to-vomiting prevalence ratio of > or = 2.5 and a longer duration of illness.