Escherichia coli O29:H21 is a human enterotoxigenic serotype that produces heat-stable (ST-I) enterotoxin, adheres diffusely to HeLa cells, and presents colonization factor antigen IV (CFA/IV) composed of CS5CS6 surface antigens. In one strain studied the genes for diffuse adherence and CFA/IV (CS5CS6) production were found to be present in the same plasmid encoding ST-I. The virulence plasmid (Ent) presented two unrelated basic replicons homologous to repFIC and repW. Gene(s) encoding diffuse adherence did not share homology with the probe for F1845 fimbrial adhesin which is responsible for this phenotype in other E. coli strains. Ent plasmids containing genes for diffuse adherence have not been described previously.

Acridine Orange↗

PubMed1995

Blood-retina barrier in acute retinal branch vein occlusion.

BACKGROUND: Extensive clinical studies on retinal branch vein occlusion have not yet been able to clarify its pathogenesis. A study designed to look at the associated blood-retina barrier changes may contribute to a better understanding of the different forms of evolution of this pathology. METHODS: A prospective study was done in seven patients with recent large temporal branch vein occlusion. Vitreous fluorophotometry, fluorescein angiography and retinal colour photography were performed within the 1st week after the onset of symptoms, 1 week later, and at 12 and 24 weeks. RESULTS: A more marked blood-retina barrier breakdown was found at 1, 2, 12 and 24 weeks in the eyes that later developed extensive capillary nonperfusion. CONCLUSIONS: Our results suggest that the breakdown of the blood-retina barrier may play an important role in the subsequent development of retinal nonperfusion in eyes with large branch vein occlusion. We postulate that the eyes that will present later extensive capillary nonperfusion develop, from the initial stages of the disease, a progressive "ischaemic capillaropathy" characterized by blood-retina barrier breakdown. Retinal pigment epithelium degeneration and arterial lumen narrowing, secondary to the vein obstruction, may help to increase and perpetuate the blood-retina barrier breakdown during the first 6 months after the occlusion.

Acute Disease↗

PubMed1995

[Analysis of the junctional rhythm characteristics in patients with nodal reentry tachycardia treated with slow pathway radiofrequency ablation].

PURPOSE: To study the quantitative and qualitative aspects of junctional rhythm (JR) during radiofrequency (RF) catheter ablation of slow pathway in atrioventricular nodal reentrant tachycardia. METHODS: Twenty five patients, 5 males, ages ranging from 15 to 76 years, with recurrent atrioventricular nodal reentrant tachycardia, underwent to RF catheter ablation of slow pathway. During RF applications (40V, duration 60s) electrocardiographic was continuously recorded. The recordings were posteriorly used to study the presence and characteristics of JR (number of episodes, frequency and time of onset) at the effective and ineffective RF sessions. All variables were expressed as median and mean +/- SD. Univariate analysis of the effects of each variable on success or failure of ablation were performed using x2 test. A p value < 0.05 was considered significant. RESULTS: One hundred forty nine RF sessions were performed, 25 effective and 124 ineffective (mean per patient 6, range 1 to 22). JR was present in 18 of 25 effective and 44 of 124 ineffective sessions (p < 0.05). Mean time of appearance was 12s, occurring later this time in 9 of 18 effective and in 10 of 44 ineffective sessions (p < 0.05). Mean number of episodes was 3, occurring higher number in 7 of 18 effective and in 4 of 44 ineffective sessions (p < 0.05). Median of frequency of JR was 100bpm; 11 of 18 effective and 15 of 44 ineffective sessions presented higher frequencies (p < 0.05). CONCLUSION: JR during slow pathway ablation is a sensitive marker of ablation success. JR predictor of success has higher number of episodes, higher frequency and later time of appearance than that one of ineffective sessions.

Adolescent↗

PubMed1992

Inhibition of enteropathogenic Escherichia coli adherence to HeLa cells by immune rabbit sera.

We have studied the effect of immune rabbit sera on the localized (LA) and diffuse (DA) adherence to HeLa cells of 10 enteropathogenic Escherichia coli (EPEC) strains belonging to serogroups O55, O86, O111, O119, and O142. Anti-La1 serum, obtained by rabbit immunization with an E. coli strain harboring a cloned DNA fragment from an EPEC LA plasmid, strongly inhibited the adherence of all serogroups but one (O142). Similar results were obtained with anti-LA2 serum, which is anti-O111 serum absorbed with a non-adherent O111:H- EPEC strain. In contrast, non-absorbed anti-O55 and anti-O111 sera showed an inhibitory effect mainly on the adherence of homologous strains. Except for one experiment diffuse adherence was not inhibited by any antiserum used. The inhibitory effect of immune sera on localized adherence does not seem to be correlated with plasmid curing since adherence plasmid pMS49 proved to be stable after treatment with anti-O55 and anti-O111 sera. The cross-inhibition of adherence by anti-LA sera suggests that localized adherence-related adhesins of the O55, O86, O111, and O119 strains share similar antigens.

Animals↗

PubMed1989

Virulence factors and biochemical characteristics of serotypes of Escherichia coli serogroup O29.

Escherichia coli strains belonging to serogroup O29 were studied. Invasiveness was the most common virulence factor described in this serogroup, but a few papers also reported production of heat-stable (ST) enterotoxin. In the present study invasive ability was found in O29:H- strains, whereas production of ST-I enterotoxin was observed only in serotype O29:H21 strains, showing that virulence was a characteristic of specific serotypes or bioserotypes within the O29 serogroup. Different serotypes were found among strains that were neither invasive nor toxigenic. Invasive strains were biochemically less active than the toxigenic ones and presented the invasiveness plasmid (pINV) of about 120 to 140 megadaltons, whereas hybridization tests showed that ST-I production was related to a plasmid of about 90 megadaltons. A diffuse adherence pattern to HeLa cells was observed in all ST-I isolates, but the role of this adherence in the pathogenicity of these strains was not determined. Thus, a unique biochemical pattern and plasmid profile may be useful characteristics to distinguish between pathogenic (toxigenic or invasive) and nonpathogenic O29 strains.

Antigens, Bacterial↗

PubMed1988

A basic replicon of virulence-associated plasmids of Shigella spp. and enteroinvasive Escherichia coli is homologous with a basic replicon in plasmids of IncF groups.

Shigella species and enteroinvasive Escherichia coli strains carry a large (120- to 140-megadalton) plasmid called pINV, which contains genes essential for the invasiveness of these pathogens. Hybridization with specific probes derived from the RepFIC and RepFIB replicons of the IncF1 Ent plasmid P307 showed that pINVs present in 35 clinical isolates are homologous with RepFIC but not RepFIB, regardless of the serogroup of the Shigella or E. coli strain. RepFIC of P307, in turn, is very similar to RepFIIA replicons of IncFII R plasmids. These and other related replicons constitute the RepFIIA family. With one pINV, pWR110, a plasmid of Shigella flexneri 5, we demonstrated the existence of a functional replicon, RepINV, with a restriction map similar to that of RepFIIA of plasmid R1. We isolated the putative inc RNA coding region of RepINV, which is a major determinant of incompatibility. The nucleotide sequence of the RepINV-inc RNA-coding region was determined and compared with the corresponding sequences of RepFIC and RepFIIA. The differences were small, but apparently were sufficient to affect the target specificity of the inc RNAs, thus rendering the replicons compatible with each other. We conclude that pINVs present in Shigella spp. and enteroinvasive E. coli constitute a homogeneous group, containing one basic replicon that belongs to the RepFIIA family of replicons.

Base Sequence↗

PubMed1985

Detection of genes for heat-stable enterotoxin I in Escherichia coli strains isolated in Brazil.

Heat-stable enterotoxin I (STI) can be assayed in intestinal loops of pigs and rabbits and in the gut of infant mice. To produce a simpler and more discriminating assay procedure, we used three gene probes corresponding to three forms of STI called STIa, STIb, and STIc. We tested 159 Brazilian isolates, of which 40 were positive in the infant mouse assay. The STIb and STIc probes are similar (93% DNA homology) and are both different from the STIa probe (70% DNA homology). Of 33 strains that were still active for STI 3 years after their isolation, 25 reacted with both the STIb and STIc probes, 4 reacted with the STIc probe only, and 7 reacted strongly with the STIa probe and weakly or not at all with the other probes. Two strains reacted with all three probes. Further analysis showed that each of these two strains contains a small plasmid that reacts with the STIa probe and a large plasmid that reacts with the STIc probe in one strain and weakly with both the STIa and STIc probes in the other strain. It was also shown that the STIa probe reacts with the cloning vehicle pACYC184 used for the cloning of STIc. We conclude that the gene probes used can identify most STI-producing strains and that in cases of positive responses with several probes careful scrutiny is necessary for analysis.

Bacterial Toxins↗

PubMed1982

Correlation of invasiveness with plasmid in enteroinvasive strains of Escherichia coli.

Explore the source record for details and available documents.

Escherichia coli↗

PubMed1980

Spinal cord lesions due to water sports and occupations: our experience in 20 years.

The authors reviewed 162 clinical cases selected from several cases and referring to paraplegic patients, who have been treated in a polyvalent rehabilitation centre during approximately 20 years. The cases studied focused on those of vertebromedullar traumatisms due to water sports, work and road accidents, since in the authors' opinion the inclusion of the latter is of particular interest to the global comparative analysis.

Accidents, Traffic↗

PubMed1980

Biochemical and cultural characteristics of invasive Escherichia coli.

The biochemical characteristics of 97 invasive Escherichia coli strains of different O serogroups were studied. Considered as a group, the behavior of the strains was quite variable. However, none of them decarboxylated lysine and all but seven strains, belonging to the O124 serogroup, were nonmotile. The growth of 25 strains obtained on MacConkey, salmonella-shigella, xylose-lysine-desoxycholate, and Hektoen enteric agars was compared. MacConkey and Hektoen enteric agars yielded the highest average growth for these strains, whereas salmonella-shigella agar had the lowest average counts.

Amino Acids↗

PubMedDate not supplied

Can bacterial translocation be a beneficial event?

Infection is a major concern in intestinal transplant recipients. Bacterial migration to extraintestinal sites is a central component of the gut hypothesis of sepsis. However, some studies have cited the beneficial effects of bacterial translocation (BT) on the host acquired immune system. We evaluated the role of previous BT on a subsequent BT challenge, examined the BT index in organs as well as changes in white blood cell (WBC) count in mesenteric lymph and blood for correlation with outcomes. Wistar rats (n = 60) were divided into a BT group (n = 20), which underwent inoculation of 10 mL of 10(10) CFU/mL Escherichia coli R-6 confined to the small intestine as opposed to a BT1-14 group (n = 20), which underwent the BT procedure on days 1 and 14 or a S1-BT14 group (n = 20) that received 10 mL of saline on day 1 and the BT procedure on day 14. Half of the animals were killed 2 hours following the BT procedure. Samples from different compartments were collected for culture. Mesenteric lymph and peripheral blood were examined for WBC counts. The other half of the hosts was subjected to outcome evaluation concerning weight gain and mortality. Animals undergoing double BT showed a significantly lower index of bacterial recovery (liver, spleen, and blood) compared with those having a single BT (P < .05). The WBC count of mesenteric lymph cells after double BT was similar to naïve animals, but significantly lower than the single BT group (P < .05). The outcome was unchanged among double BT versus other groups. A previous BT challenge was efficient to generate a host-defense mechanism against a second BT episode induced by intestinal overgrowth with the same bacterial strain.

Animals↗