Enterotoxigenic Escherichia coli

The enterotoxigenic Escherichia coli are a pervasive cause of serious diarrheal illness in developing countries. Presently, there is no vaccine to prevent these infections, and many features of the basic pathogenesis of these organisms remain poorly understood. Until very recently most pathogenesis studies had focused almost exclusively on a small subset of known “classical” virulence genes, namely fimbrial colonization factors and the heat-labile (LT) and heat stable (ST) enterotoxins. However, recent investigations of pathogen-host interactions reveal a surprisingly complex and intricately orchestrated engagement involving the interplay of classical and “novel” virulence genes, as well as participation of genes highly conserved in the E. coli species. These studies may inform further rational approaches to vaccine development for these important pathogens.     

Enterotoxigenic Escherichia coli isolated from food.

Approximately 8% of 240 isolates of Escherichia coli obtained from food of animal origin in the United States were found to be enterotoxigenic, as determined in adrenal cells, rabbit ileal loops, and assays in infant mice. These organisms were of diverse serotypes that are not included among the so-called enteropathogenic serotypes and would not have been identified by usual laboratory methods. These enterotoxigenic E. coli are of potential importance to public health.     

Enteroaggregative escherichia coli virulence factors in traveler's diarrhea strains

Enteroaggregative Escherichia coli (EAEC) is associated with diarrhea in Spanish travelers to developing countries. In this study, the polymerase chain reaction was used to test EAEC isolates for genes encoding putative virulence factors, including EAEC adhesins, the plasmid-encoded toxin (Pet), a heat-stable enterotoxin (EAST), and Shigella enterotoxins 1 and 2 (ShET1 and ShET2). Findings included a low prevalence of genes for Pet (4.3%), ShET2 (4.3%), and the adherence factor AAF/II (8.7%). The overlapping genes encoding the ShET1 and the Pic mucinase were present in most EAEC strains tested (56.5%); however, some strains that carried this locus did not produce both proteins, as determined by Western immunoblot. Surprisingly, ShET1 and ShET2 genes were also found in other E. coli pathotypes, as was the EAST toxin locus. These findings underscore the heterogeneity of EAEC strains and suggest that the ShET1 may be an important virulence factor in traveler's diarrhea.     

A case of bilateral escherichia coli endogenous endophthalmitis

The first reported case of bilateral endogenous endophthalmitis is presented and discussed with reference to pertinent literature. Diagnostic and therapeutic recommendations for suspected gramnegative endophthalmitis are presented and include: immediate paracentesis of the eye for gram stain and culture, systemic therapy with an antibiotic such as gentamicin and either subconjunctival, subtenon or intraocular injection of antibiotics. Despite these measures vision may be lost and, as in this case, enucleation necessary.     

The acquisition of escherichia coli by new-born babies

Summary In discussing the background of these studies the importance of faecal carriage of Gram negative organisms by hospital patients is stressed. In many instances it was shown that transmission is by an oral route. This discussion leads on to an assessment of the dose required forEscherichia coli to implant in the bowel. The difficulties of studying the spread ofE. coli within a faecal specimen are discussed. A number of papers are quoted which show that E. coli are present in the vagina of women and that the acquisition of theseE. coli by babies is related to the length of time that the birth takes, and that there is a relationship between theE. coli found in the faeces of the mothers, the mucus swallowed by the babies at birth and subsequently in the faeces of the babies. Most of the earlier studies quoted deal predominantly with enteropathogenic serotypes, but it was later shown that other serotypes can be similarly acquired by the babies. Although this appears to be the general method by which babies acquire their faecalE. coli, it is well established that they can also be obtained from the environment, hence ward outbreaks of infantile gastroenteritis. Studies on normally delivered babies show that generally two thirds obtain their faecalE. coli from their mothers while the rest appear to pick up environmental strains. Very detailed biochemical and serological studies need to be performed to assess this. Caesarian section babies are generally not likely to become colonized by their mothers' faecalE. coli and studies are described which show that the babies faeces or rectal swabs are usually the first areas colonized and that theE. coli are spread from there. Extensive environmental studies suggest that contaminated hands and uniforms of the nursing staff may be the main vector for transmittingE. coli. There is a wide variety ofE. coli serotypes present in a maternity ward at any time and these are related to the presence of the babies excreting them. A variation in the ability of strains to spread was noted.

---

Die Neugeborenenbesiedlung mit Escherichia coli

Zusammenfassung Die Bedeutung der Ausscheidung von gramnegativen Keimen durch Krankenhauspatienten zeichnet sich auf dem Hintergrund der Diskussion ab. In vielen Beispielen wurde gezeigt, daß es zu einer oralen Aufnahme kam. Die Diskussion geht darauf hinaus, die für das Angehen im Rektum erforderliche Bakterienmenge zu erfassen. Die methodischen Schwierigkeiten, um dieE.-coli-Menge im Stuhl zu beurteilen, werden erwähnt. Eine Anzahl von Arbeiten werden zitiert, bei denen demonstriert wurde, daßE. coli in der Vagina von Frauen vorhanden sind, und daß die Aufnahme vonE. coli durch Neugeborene mit der Dauer der Geburt in Relation steht. Es werden die gleichen Coli-Typen zuerst im mütterlichen Stuhl, dann im Vaginalschleim und, nachdem dieser von den Säuglingen bei der Geburt geschluckt wurde, bis zum Stuhl der Säuglinge verfolgt. Die Mehrzahl der älteren zitierten Arbeiten befassen sich mit enteropathogenen Serotypen, aber es wurde in neueren Publikationen gezeigt, daß andere Serotypen von den Neugeborenen in ähnlicher Weise erworben werden können. Obgleich dies der normale Weg der Besiedlung von Säuglingen zu sein scheint, ist es klar, daß sie auch durch die Umgebung erworben werden können, wie bei Kleinraumepidemien von infantiler Gastroenteritis nachgewiesen wurde. Säuglinge mit einem normalen Geburtsablauf zeigen, daß sie ca. zwei Drittel ihrer Stuhl-Coli-Flora von der Mutter erhalten, der Rest hingegen nimmt die Stämme von der Umgebung auf. Sorgfältige biochemische und serologische Untersuchungen sind nötig, um dies festzustellen. Bei Säuglingen, die durch eine Sectio entbunden werden, ist es unwahrscheinlich, daß sie durch die mütterlichen fäkalen Coli-Typen besiedelt werden. Bei diesen Kindern zeigten Untersuchungen, daß sie zuerst anal besiedelt werden, undE. coli sich von dort aus weiterverbreitet. Ausgiebige Umgebungsuntersuchungen lassen vermuten, daß kontaminierte Hände und Bekleidung des Pflegepersonals der Hauptüberträger vonE. coli sind. In der Entbindungsstation ist eine große Zahl verschiedener Coli-Typen zu jeder Zeit nachweisbar, und sie stehen zu den im gleichen Zeitraum ausgeschiedenen Bakterien in enger Beziehung. Unterschiedliche Ausbreitungstendenzen konnten bei den verschiedenen Stämmen beobachtet werden.

     

Enterotoxigenic Escherichia coli and diarrheal disease in Mexican children.

Enterotoxigenic strains of Escherichia coli were isolated from eight (16%) of 50 Mexican children admitted to the hospital with diarrhea and from one of 50 children hospitalized for nonenteric disorders. All of the toxigenic strains tested elaborated a heat-labile enterotoxin, and in seven of nine patients no E. coli capable of concomitant production of heat-stable enterotoxin were found. None of the strains of E. coli with classical enteropathogenic serotypes isolated from nine patients with diarrhea produced either heat-labile or heat-stable enterotoxin. Although the results of this study strongly suggest that enterotoxigenic strains of E. coli are probably responsible for a significant number of cases of diarrhea in an indigenous Mexican pediatric population, further proof will require demonstration of in vivo production of enterotoxin and/or antitoxin.     

婴幼儿大肠埃希菌性肺炎177例临床分析

目的分析婴幼儿大肠埃希菌性肺炎患儿的临床特征及药敏情况,指导临床肺炎诊治。方法回顾性分析177例住院婴幼儿大肠埃希菌性肺炎患儿的临床表现、X线表现、细菌耐药情况及治疗预后。结果患儿的临床表现主要的症状为咳嗽、咳痰、发热,容易出现呼吸困难。 X线主要表现为片状影或间质渗出。大肠埃希菌多数菌株对泰能、美平、头孢他定、丁胺卡那霉素、左氧氟沙星、哌拉西林/他唑巴坦、头孢哌酮/舒巴坦敏感性高,对大多数β内酰胺类抗生素普遍耐药。产超广谱β内酰胺酶（ ESBLs ）菌33例,阳性率为18.6％。痰液培养细菌阳性转阴比较慢,治疗主要以经验疗法和药敏试验结果结合,病程迁延,预后尚好。结论婴幼儿大肠埃希菌肺炎是儿科常见病,临床诊治相对容易。但大肠埃希菌抗菌药物的耐药率高,需引起重视。     

Virulence properties of escherichia coli strains in patients with chronic pyelonephritis

Summary In 50Escherichia coli strains obtained from the bladder puncture urine of patients with chronic pyelonephritis, determinations of virulence properties were performed. All of theE. coli strains isolated from 26 acute episodes of pyelonephritis were found in the smooth form. 30% possessed K 1 antigen, 77% showed the ability to form hemolysin and 30% produced colicin V (aerobactin). Fimbriae (detected by mannose-resistant hemagglutination) were registered in 81%, and plasmids ranging between 50 and 70 Md were demonstrated in 70% of the bacteria. In contrast to this, only 70% of theE. coli strains isolated from 24 patients at an inactive stage of pyelonephritis were found in the smooth form; 10% of these encoded K 1 antigen, 20% hemolysin and 10% colicin V. Plasmids in the range 50 to 70 Md could be found in 30%. On the basis of multivariate analysis of variance and discriminant analysis, it was confirmed that uropathogenic strains possess several virulence properties, mannose-resistant hemagglutination being of particular importance.

---

Virulenzeigenschaften bei Escherichia coli-Stämmen von Patienten mit chronischer Pyelonephritis

Zusammenfassung Bei 50Escherichia coli-Stämmen, die aus dem Blasenpunktionsurin von Patienten mit chronischer Pyelonephritis gewonnen wurden, erfolgten Bestimmungen ihrer Virulenzeigenschaften. In den 26 Fällen mit einer akuten Erkrankung fanden sich ausschließlich S-Formen der Bakterien, K 1 Antigen wurde in 30% nachgewiesen, 77% verfügten über die Fähigkeit zur Hämolysinbildung und 30% über die zur Colicin V (Aerobactin)-Produktion. In 70% fanden sich Plasmidspezies der Größe zwischen 50 und 70 Md. Demgegenüber wurden bei den 24 Patienten mit einem inaktiven Stadium der Pyelonephritis nur in 70% derE. coli-Stämme S-Formen gefunden. Bei ihnen konnten in 10% K 1 Antigen, in 20% Hämolysin und in 10% Colicin V bestimmt werden. Plasmide zwischen 50 und 70 Md. lagen in 30% der Bakterienstämme vor. Nach der multivariaten Varianz- und Diskriminanzanalyse bestätigt sich, daß uropathogene Bakterienstämme über mehrere Virulenzeigenschaften verfügen müssen, dabei kommt der Fähigkeit zur mannoseresistenten Hämagglutination eine besondere Bedeutung zu.

     

In vitro cartilage degradation by escherichia coli and staphylococcus aureus

Effects of Escherichia coli and Staphylococcus aureus on cartilage and chondrocytes in culture are reported. Under these conditions, bacterial effects on cartilage degradation and cell viability are measured in the absence of inflammation. E coli causes a 28% loss and S aureus an 83% loss of cartilage glycosaminoglycan within 48 hours. Collagen content is unchanged. Both bacterial species induce chondrocyte death in explants and in monolayers within 48 hours. Bacterial effects on glycosaminoglycans and cell viability do not result from depletion of nutrients from the culture medium. Serum in the culture media inhibits the bacterial effects on cartilage degradation but does not prevent cell death.     

Enterotoxigenic Escherichia coli isolated from patients at a hospital in Dacca.

Enterotoxigenic strains of Escherichia coli, a significant cause of acute, watery, cholera-like diarrhea, were isolated from 23 of 65 patients with diarrhea in whom no other enteric pathogens were found during one week (November 1974) at the Cholera Research Hospital, Dacca, Bangladesh. Diarrhea associated with enterotoxigenic strains of E. coli occurred primarily in adults but affected persons of all age groups and could not be distinguished from cholera or from other cholera-like diarrhea on clinical grounds. Routine bacteriologic methods were inadequate for identification of enterotoxigenic E. coli as the etiologic agent of the diarrhea. The enterotoxigenic E. coli, producing heat-stable and/or heat-labile enterotoxin, were detected by use of assays in the Y1 adrenal cell, the Chinese hamster ovary cell, the rabbit ileal loop, and the infant mouse. The two tissue culture assays yielded comparable results in tests with 640 (193 positive, 447 negative) of 643 isolates of E. coli. The results of this study support the idea that enterotoxigenic E. coli play a significant role as pathogens in the etiology of acute watery diarrhea.     

重组人IL-21融合蛋白在大肠杆菌中的可溶性形式表达、纯化及体外对T细胞增殖的影响

目的 为重组人白细胞介素-21(rhIL-21) 的生物学活性和功能研究奠定基础.方法 构建重组表达质粒pGEX4T-2/IL-21,通过降低培养温度等优化条件于大肠杆菌中表达出可溶性形式的rhIL-21融合蛋白,纯化后以不同质量浓度作用于T细胞,观察其对T细胞增殖的影响.结果 大肠杆菌表达出可溶性形式的rhIL-21融合蛋白,纯化纯度达95%;纯化后的rhIL-21蛋白作用后T细胞增殖增加,且随rhIL-21蛋白质量浓度的增加,T细胞增殖率升高.结论 大肠杆菌中获得rhIL-21的可溶性表达形式,纯化后的蛋白对T细胞增殖有促进作用;此为rhIL-21的生物活性及功能研究奠定了基础.     

Involvement of escherichia coli dnaZ gene product in DNA elongation in vitro.

E. coli dnaZ gene product is required for conversion of phiX174, fd, and ST-1 single-stranded phage DNAs to duplex DNAs in vitro. This protein has been purified about 5000-fold. It functions in the elongation of RNA- or DNA-primed single-stranded DNA that is catalyzed by DNA polymerase III(DNA nucleotidyltransferase; deoxynucleosidetriphosphate: DNA deoxynucleotidyltransferase; EC 2.7.7.7) in conjunctions with two other E. coli protein preparations referred to as DNA elongation factors I and III. It also functions in similar reactions catalyzed by DNA polymerase II in combination with E. coli DNA binding protein and DNA elongation factors I and III.