scholarly journals Identification of Enterohemorrhagic Escherichia coli O26:H− Genes Required for Intestinal Colonization in Calves

2005 ◽  
Vol 73 (3) ◽  
pp. 1735-1743 ◽  
Author(s):  
Pauline M. van Diemen ◽  
Francis Dziva ◽  
Mark P. Stevens ◽  
Timothy S. Wallis
Keyword(s):  
Escherichia Coli ◽  
Public Health Problem ◽  
The United States ◽  
Human Infection ◽  
Enterohemorrhagic Escherichia Coli ◽  
Secreted Proteins ◽  
Type I ◽  
Intestinal Colonization ◽  
Important Public Health Problem ◽  
Type Iii

ABSTRACT Enterohemorrhagic Escherichia coli (EHEC) infections in humans are an important public health problem and are commonly acquired via contact with ruminant feces. The serogroups that are predominantly associated with human infection in the United States and Europe are O157 and O26. Serotypes O157:H7 and O26:H− differ in their virulence and tissue tropism in calves and therefore may colonize calves by distinct mechanisms. The mechanisms underlying EHEC intestinal colonization and pathogenesis are poorly understood. Signature-tagged mutagenesis was used to identify 59 genes of EHEC O26:H− that are required for the intestinal colonization of calves. Our results indicate important roles for locus of enterocyte effacement (LEE)-encoded type III secreted proteins in intestinal colonization. In addition, colonization is facilitated by cytotoxins, putative type III secreted proteins unlinked to the LEE, a putative fimbrial operon, and numerous genes involved in central metabolism and transport and genes of unknown function. Our data also imply that the elaboration of type I fimbriae by EHEC O26:H− is disadvantageous for persistence within the bovine intestines. These observations have important implications for the design of vaccines to control these important zoonotic pathogens.

scholarly journals Two Enteropathogenic Escherichia coli Type III Secreted Proteins, EspA and EspB, Are Virulence Factors

1998 ◽  
Vol 188 (10) ◽  
pp. 1907-1916 ◽  
Author(s):  
Akio Abe ◽  
Ursula Heczko ◽  
Richard G. Hegele ◽  
B. Brett Finlay
Keyword(s):  
Escherichia Coli ◽  
Virulence Factors ◽  
Enterohemorrhagic Escherichia Coli ◽  
Laser Scanning Microscopy ◽  
Secreted Proteins ◽  
Confocal Laser ◽  
Infection Model ◽  
Enteropathogenic Escherichia Coli ◽  
Type Iii

Enteropathogenic Escherichia coli (EPEC) belongs to a family of related bacterial pathogens, including enterohemorrhagic Escherichia coli (EHEC) O157:H7 and other human and animal diarrheagenic pathogens that form attaching and effacing (A/E) lesions on host epithelial surfaces. Bacterial secreted Esp proteins and a type III secretion system are conserved among these pathogens and trigger host cell signal transduction pathways and cytoskeletal rearrangements, and mediate intimate bacterial adherence to epithelial cell surfaces in vitro. However, their role in pathogenesis is still unclear. To investigate the role of Esp proteins in disease, mutations in espA and espB were constructed in rabbit EPEC serotype O103 and infection characteristics were compared to that of the wild-type strain using histology, scanning and transmission electron microscopy, and confocal laser scanning microscopy in a weaned rabbit infection model. The virulence of EspA and EspB mutant strains was severely attenuated. Additionally, neither mutant strain formed A/E lesions, nor did either one cause cytoskeletal actin rearrangements beneath the attached bacteria in the rabbit intestine. Collectively, this study shows for the first time that the type III secreted proteins EspA and EspB are needed to form A/E lesions in vivo and are indeed virulence factors. It also confirms the role of A/E lesions in disease processes.

scholarly journals The gut at war: the consequences of enteropathogenic Escherichia coli infection as a factor of diarrhea and malnutrition

2000 ◽  
Vol 118 (1) ◽  
pp. 21-29 ◽  
Author(s):  
Ulysses Fagundes-Neto ◽  
Isabel Cristina Affonso Scaletsky
Keyword(s):  
Escherichia Coli ◽  
Diarrheal Disease ◽  
Driving Forces ◽  
Public Health Problem ◽  
Clinical Aspects ◽  
Small Intestinal Mucosa ◽  
Enteropathogenic Escherichia Coli ◽  
Important Public Health Problem ◽  
The Impact

Diarrheal disease is still the most prevalent and important public health problem in developing countries, despite advances in knowledge, understanding, and management that have occurred over recent years. Diarrhea is the leading cause of death in children under 5 years of age. The impact of diarrheal diseases is more severe in the earliest periods of life, when taking into account both the numbers of episodes per year and hospital admission rates. This narrative review focuses on one of the major driving forces that attack the host, namely the enteropathogenic Escherichia coli (EPEC) and the consequences that generate malnutrition in an early phase of life. EPEC serotypes form dense microcolonies on the surface of tissue-culture cells in a pattern known as localized adherence (LA). When EPEC strains adhere to epithelial cells in vitro or in vivo they cause characteristic changes known as Attaching and Effacement (A/E) lesions. Surface abnormalities of the small intestinal mucosa shown by scanning electron microscopy in infants with persistent diarrhea, although non-specific, are intense enough to justify the severity of the clinical aspects displayed in a very young phase in life. Decrease in number and height of microvilli, blunting of borders of enterocytes, loss of the glycocalyx, shortening of villi and presence of a mucus pseudomembrane coating the mucosal surface were the abnormalities observed in the majority of patients. These ultrastructural derangements may be due to an association of the enteric enteropathogenic agent that triggers the diarrheic process and the onset of food intolerance responsible for perpetuation of diarrhea. An aggressive therapeutic approach based on appropriate nutritional support, especially the utilization of human milk and/or lactose-free protein hydrolyzate-based formulas and the adequate correction of the fecal losses, is required to allow complete recovery from the damage caused by this devastating enteropathogenic agent.

scholarly journals EspZ of Enteropathogenic and Enterohemorrhagic Escherichia coli Regulates Type III Secretion System Protein Translocation

mBio ◽  
2012 ◽  
Vol 3 (5) ◽  
Author(s):  
Cedric N. Berger ◽  
Valerie F. Crepin ◽  
Kobi Baruch ◽  
Aurelie Mousnier ◽  
Ilan Rosenshine ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Type Iii Secretion ◽  
Protein Translocation ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Enterohemorrhagic Escherichia Coli ◽  
Host Cells ◽  
Dependent Manner ◽  
Content Type ◽  
Type Iii

ABSTRACTTranslocation of effector proteins via a type III secretion system (T3SS) is a widespread infection strategy among Gram-negative bacterial pathogens. Each pathogen translocates a particular set of effectors that subvert cell signaling in a way that suits its particular infection cycle. However, as effector unbalance might lead to cytotoxicity, the pathogens must employ mechanisms that regulate the intracellular effector concentration. We present evidence that the effector EspZ controls T3SS effector translocation from enteropathogenic (EPEC) and enterohemorrhagic (EHEC)Escherichia coli. Consistently, an EPECespZmutant is highly cytotoxic. Following ectopic expression, we found that EspZ inhibited the formation of actin pedestals as it blocked the translocation of Tir, as well as other effectors, including Map and EspF. Moreover, during infection EspZ inhibited effector translocation following superinfection. Importantly, while EspZ of EHEC O157:H7 had a universal “translocation stop” activity, EspZ of EPEC inhibited effector translocation from typical EPEC strains but not from EHEC O157:H7 or its progenitor, atypical EPEC O55:H7. We found that the N and C termini of EspZ, which contains two transmembrane domains, face the cytosolic leaflet of the plasma membrane at the site of bacterial attachment, while the extracellular loop of EspZ is responsible for its strain-specific activity. These results show that EPEC and EHEC acquired a sophisticated mechanism to regulate the effector translocation.IMPORTANCEEnteropathogenicEscherichia coli(EPEC) and enterohemorrhagicE. coli(EHEC) are important diarrheal pathogens responsible for significant morbidity and mortality in developing countries and the developed world, respectively. The virulence strategy of EPEC and EHEC revolves around a conserved type III secretion system (T3SS), which translocates bacterial proteins known as effectors directly into host cells. Previous studies have shown that when cells are infected in two waves with EPEC, the first wave inhibits effector translocation by the second wave in a T3SS-dependent manner, although the factor involved was not known. Importantly, we identified EspZ as the effector responsible for blocking protein translocation following a secondary EPEC infection. Interestingly, we found that while EspZ of EHEC can block protein translocation from both EPEC and EHEC strains, EPEC EspZ cannot block translocation from EHEC. These studies show that EPEC and EHEC employ a novel infection strategy to regulate T3SS translocation.

scholarly journals Dynamics of the Type III Secretion System Activity of Enteropathogenic Escherichia coli

mBio ◽  
2013 ◽  
Vol 4 (4) ◽  
Author(s):  
Erez Mills ◽  
Kobi Baruch ◽  
Gili Aviv ◽  
Mor Nitzan ◽  
Ilan Rosenshine
Keyword(s):  
Escherichia Coli ◽  
Type Iii Secretion ◽  
Public Health Problem ◽  
Effector Proteins ◽  
Host Cells ◽  
Global Public Health ◽  
Secretion Systems ◽  
Comprehensive Description ◽  
Content Type ◽  
Type Iii

ABSTRACT Type III secretion systems (TTSSs) are employed by pathogens to translocate host cells with effector proteins, which are crucial for virulence. The dynamics of effector translocation, behavior of the translocating bacteria, translocation temporal order, and relative amounts of each of the translocated effectors are all poorly characterized. To address these issues, we developed a microscopy-based assay that tracks effector translocation. We used this assay alongside a previously described real-time population-based translocation assay, focusing mainly on enteropathogenic Escherichia coli (EPEC) and partly comparing it to Salmonella. We found that the two pathogens exhibit different translocation behaviors: in EPEC, a subpopulation that formed microcolonies carried out most of the translocation activity, while Salmonella executed protein translocation as planktonic bacteria. We also noted variability in host cell susceptibility, with some cells highly resistant to translocation. We next extended the study to determine the translocation dynamics of twenty EPEC effectors and found that all exhibited distinct levels of translocation efficiency. Further, we mapped the global effects of key TTSS-related components on TTSS activity. Our results provide a comprehensive description of the dynamics of the TTSS activity of EPEC and new insights into the mechanisms that control the dynamics. IMPORTANCE EPEC and the closely related enterohemorrhagic Escherichia coli (EHEC) represent a global public health problem. New strategies to combat EPEC and EHEC infections are needed, and development of such strategies requires better understanding of their virulence machinery. The TTSS is a critical virulence mechanism employed by these pathogens, and by others, including Salmonella. In this study, we aimed at elucidating new aspects of TTSS function. The results obtained provide a comprehensive description of the dynamics of TTSS activity of EPEC and new insights into the mechanisms that control these changes. This knowledge sets the stage for further analysis of the system and may accelerate the development of new ways to treat EPEC and EHEC infections. Further, the newly described microscopy-based assay can be readily adapted to study the dynamics of TTSS activity in other pathogens.

scholarly journals ClpXP Protease Controls Expression of the Type III Protein Secretion System through Regulation of RpoS and GrlR Levels in Enterohemorrhagic Escherichia coli

2005 ◽  
Vol 187 (12) ◽  
pp. 4086-4094 ◽  
Author(s):  
Sunao Iyoda ◽  
Haruo Watanabe
Keyword(s):  
Escherichia Coli ◽  
Protein Secretion ◽  
Deletion Mutant ◽  
Regulatory Gene ◽  
Secretion System ◽  
Enterohemorrhagic Escherichia Coli ◽  
Multicopy Plasmid ◽  
Type Iii ◽  
Protein Secretion System ◽  
Type Iii Protein Secretion

ABSTRACT Expression of the type III protein secretion system (TTSS), encoded in the locus of enterocyte effacement (LEE) of enterohemorrhagic Escherichia coli (EHEC), has been shown to be controlled by various regulators. In a search for additional regulatory genes, we identified a DNA fragment containing clpX and clpP that has a positive regulatory effect on LEE expression in EHEC O157. The expression of LEE-encoded Esp proteins was significantly reduced in a clpXP deletion mutant. Deletion of grlR, a negative regulatory gene within LEE, markedly increased LEE expression even in the clpXP mutant. To verify the regulatory mechanism of GrlR expression, a chromosomal epitope-tagged allele of grlR (grlR-FLAG) was constructed. GrlR-FLAG expression was increased significantly in the clpXP deletion mutant, suggesting that the GrlR level is under the control of ClpXP, and this regulation is critical for the ClpXP-dependent expression of LEE in EHEC. Deletion of rpoS, the gene encoding a stationary-phase-inducing sigma factor that is a substrate for ClpXP protease, partially restored LEE expression in the clpXP mutant. A multicopy plasmid carrying rpoS strongly repressed expression of Esp proteins, suggesting that positive regulation by ClpXP is partially mediated through a negative effect of RpoS on LEE expression. We also found that rpoS deletion induces transcription of pchA, which encodes one of the positive regulators for LEE expression in EHEC. These results suggest that ClpXP controls expression of LEE through the regulation of RpoS and GrlR levels in EHEC.

scholarly journals Analysis of the Clonal Relationship of Serotype O26:H11 Enterohemorrhagic Escherichia coli Isolates from Cattle

2009 ◽  
Vol 75 (21) ◽  
pp. 6947-6953 ◽  
Author(s):  
Lutz Geue ◽  
Sabrina Klare ◽  
Christina Schnick ◽  
Birgit Mintel ◽  
Katharina Meyer ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Cluster Analysis ◽  
Human Infection ◽  
Enterohemorrhagic Escherichia Coli ◽  
Clonal Relationship ◽  
Space And Time ◽  
Virulence Markers ◽  
Relationship Of ◽  
Cattle Farms

ABSTRACT Twelve cluster groups of Escherichia coli O26 isolates found in three cattle farms were monitored in space and time. Cluster analysis suggests that only some O26:H11 strains had the potential for long-term persistence in hosts and farms. As judged by their virulence markers, bovine enterohemorrhagic O26:H11 isolates may represent a considerable risk for human infection.

scholarly journals The first isolation of Panton-Valentine leukocidin (PVL) positive community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) in Russia

2007 ◽  
Vol 12 (11) ◽  
Author(s):  
T Baranovich ◽  
V Potapov ◽  
T Yamamoto
Keyword(s):  
Public Health ◽  
Staphylococcus Aureus ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Public Health Problem ◽  
The United States ◽  
Important Public Health Problem ◽  
Methicillin Resistant ◽  
Important Public Health ◽  
Panton Valentine Leukocidin ◽  
Valentine Leukocidin

Since the first report of pediatric deaths in 1997-1999 in the United States, community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) has become an increasingly important public health problem worldwide.

scholarly journals Shiga toxin-producing Escherichia coli (STEC) food-borne outbreaks

2017 ◽  
Vol 63 (1) ◽  
pp. 45 ◽  
Author(s):  
A. PEXARA (Α. ΠΕΞΑΡΑ) ◽  
A. S. ANGELIDIS (Α. Σ. ΑΓΓΕΛΙΔΗΣ) ◽  
A. GOVARIS (Α. ΓΚΟΒΑΡΗΣ)
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Intestinal Flora ◽  
Food Poisoning ◽  
Significant Risk ◽  
Public Health Problem ◽  
Human Infection ◽  
Food Sources ◽  
E Coli ◽  
Food Borne

Escherichia coli (E. coli) are Gram negativo, non-sporulating bacteria, which belong to the normal intestinal flora of humans and animals. Shiga toxin-producing E. coli (STFC) arc a group of if. coli that is defined by the capacity to produce toxins called Shiga toxins (Stx). hollowing ingestion of STEC, the significant risk of two serious and potentially life-threatening complications of infection, hemorrhagic colitis and hemolytic uremic syndrome (HUS), makes STHC food poisoning a serious public health problem. Besides Stx, human pathogenic STFC harbor additional virulence factors that are important for their pathogenicity. Although human infection may also be acquired by direct transmission from person to person or by direct contact of humans with animal carriers, the majority of STFC infections are food-borne in origin.The gastrointestinal tract of healthy ruminants seems to be the foremost important reservoir for STFC and ingestion of undercooked beef one of the most likely routes of transmission to humans, Other important food sources include faecally contaminated vegetables and drinking water, The serogroup classification of STHC is based on the somatic (O) and flagellar (H) antigens, and, to date, more than 200 STFC serogroups have been identified, Human STFC infections are, however, associated with a minor subset of 0;H serotypes. Of these, the 0157:H7 or the 0157 :H- serogroups (STFC 0157) are the ones most frequently reported to be associated with food-borne outbreaks. However other non-0157 STFC serogroups such as E. coli 026, 0103, O l l i , 012I, 045 and 0145 have caused several outbreaks in recent years.Two outbreaks of gastroenteritis caused by E. coli 0157:117 were first reported in the US, following the consumption of undercooked hamburgers, in 1982. Since then several outbreaks were reported worldwide. A major E. coli 0157:117 outbreak occurred in Japan and contaminated radish sprouts was identified as the vehicle of infection. More than 6,000 school children were affected, 101 people were hospitalized with lILS and 12 deaths were recorded. The recent outbreak of STFC 0104:114 infection and HUS reported in Germany in the spring of 2011 was one of the largest outbreaks worldwide. As of 27 July, 3 126 cases of STFC infections, 773 cases of HUS including 46 deaths linked to the outbreak in Germany and occurring in the Furopean Union (FU) (including Norway), Outside the FU 8 cases of STFC and 5 cases of HUS, including 1 death have been reported in the USA, Canada and Switzerland, all with recent travel history to Germany.The present review on major STliC food-borne outbreaks recorded worldwide highlights the need for eontrol measures in order to prevent or at least minimize the occurrence of similar events in the future.

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