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J De Rycke

Publications and source records attributed to J De Rycke.

At least 37 records · Page 2Linked to original sources
PubMed1991

Characteristics of alpha-hemolytic strains of Escherichia coli isolated from dogs with gastroenteritis.

Twenty-four hemolysin producing (Hly+) strains of Escherichia coli isolated from dogs with gastroenteritis were investigated for their virulence markers and their phenotypic properties. The strains were distributed over eleven known E. coli O-serogroups and most of them were heterogeneous for their phenotypes. All strains were found to produce alpha-hemolysin which was detected by Southern hybridization and colony immunoblotting using a specific gene probe and a monoclonal antibody. Eight strains were carrying plasmids encoding alpha-hemolysin sequences (hly-plasmids) and 16 strains carried chromosomal hly-determinants. Twelve of the strains showed enterotoxic activities which were tested for in different assays. Among these, three O42:H37 and two O70:H-strains carrying hly-plasmids were found to harbour other plasmids encoding the heat-stable enterotoxin STA1. The other seven strains showing enterotoxicity in the ileal loop or the suckling mouse assay were negative for STA1, STA2, or LT. None of the 24 strains were positive for invasiveness or for production of Vero (Shiga-like) toxins. The production of alpha-hemolysin was closely associated with the production of cytotoxic necrotizing factor (CNF), which was detected in 17 of 24 strains. Of these, 16 elaborated CNF1 and one strain produced an unknown CNF type. Surprisingly, all strains carrying ST-plasmids and six of eight strains carrying hly-plasmids were negative for CNF. Thus, in canine E. coli strains CNF production seems to be closely associated with production of chromosomally encoded alpha-hemolysin whereas hly-plasmids are more often associated with ST-producing, CNF negative isolates.

Animals↗
PubMed1991

Pathogenicity of Listeria monocytogenes isolates in immunocompromised mice in relation to listeriolysin production.

The virulence of 74 Listeria monocytogenes isolates from clinical cases and food products and of 11 isolates of other Listeria species was tested in mice immunocompromised with carrageenan. Isolates of species other than L. monocytogenes were not lethal to such mice. All 29 clinical isolates of L. monocytogenes (serotypes 1/2a, 1/2b, 4b) and 33 of 42 isolates of various serotypes isolated mainly from dairy products killed all test mice (100% lethality) at an inoculum of 10(4) cfu/mouse. All lethal strains of L. monocytogenes were haemolytic and possessed the 58-Kda band specific for listeriolysin O as demonstrated by SDS-PAGE immunoblotting. The nine avirulent strains of L. monocytogenes had detectable haemolytic activity, but in six of them this activity was significantly weaker than in virulent strains and the 58-Kda band was not detected. The other three avirulent strains were highly haemolytic and possessed the 58-Kda band, which suggests that other factor(s) could be involved in the virulence of L. monocytogenes.

Animals↗
PubMed1991

[Coliform bacilli which produce cytotoxins: importance in veterinary medicine and public health].

This article reviews published data (October 1st, 1990) on 4 types of cytotoxins produced by animal and human pathogenic strains of E coli, ie, verotoxins, also named Shiga-like toxins, cytotoxic necrotizing factors, haemolysin, and cytolethal distending toxin. The biological and molecular properties are described for each type of cytotoxin, the association of producing strains with animal pathology, and the role of domestic animals as reservoirs of strains pathogenic for man.

Animals↗
PubMed1990

A single protein of 110 kDa is associated with the multinucleating and necrotizing activity coded by the Vir plasmid of Escherichia coli.

A lethal and necrotic factor which causes cell multinucleation in HeLa cell cultures has previously been shown to be coded by the Vir plasmid of Escherichia coli. Using an absorbed rabbit antiserum which neutralized the Vir toxic properties, we have compared the SDS-PAGE immunoblots from laboratory and field strains which either produce or do not produce Vir toxicity. A single band of 110 kDa was found to be specifically associated with vir toxicity in E. coli strains. This antiserum also recognized the 115 kDa protein band which was previously identified as the cytotoxic necretozing factor (CNF) of certain E. coli strains. These results suggest that the toxin coded by the Vir plasmid is a protein of 110 kDa distinct from, but immunologically related to CNF.

Bacterial Proteins↗
PubMed1990

Detection of cytotoxic necrotising factor (CNF) in extracts of Escherichia coli strains by enzyme-linked immunosorbent assay.

An enzyme-linked immunosorbent assay (ELISA) consisting of a double sandwich technique with rabbit and sheep antibodies, was developed for the detection of cytotoxic necrotising factor (CNF) in extracts of Escherichia coli strains. The assay was evaluated by comparison with the results obtained with an assay based on toxicity for HeLa cell cultures. In a study of extracts of 27 CNF+ and 45 CNF- strains obtained by ultrasonic disintegration, no false positive and only three false negative results were recorded; the latter were obtained with strains that produced less CNF than any of the others examined. Frozen-thawed extracts contained about four times more CNF cytotoxic activity than extracts prepared ultrasonically; the testing of 54 CNF+ and 68 CNF- frozen-thawed extracts resulted in no false positive and only one false negative response. Whichever type of extract was used, no significant cross-reaction was observed with heat-labile (LT) or heat stable (ST) enterotoxin, verotoxin (VT1, VT2), haemolysin, or Vir cytotoxin.

Animals↗
PubMed1990

Evidence for two types of cytotoxic necrotizing factor in human and animal clinical isolates of Escherichia coli.

We have characterized the in vitro and in vivo toxic properties of cell sonic extracts from 22 animal and human clinical isolates of Escherichia coli that caused both necrosis in the rabbit skin and multinucleation in tissue cultures, two toxic properties previously reported as being specific for E. coli cytotoxic necrotizing factor (CNF). Two distinct toxic phenotypes were observed. Type 1, which was displayed by originally described CNF strains, was characterized by extensive multinucleation and rounding of cells in HeLa cell culture assays, moderate necrosis in the rabbit skin test, and absence of necrosis in the mouse footpad test. Type 2, which has recently been shown to be associated with E. coli Vir plasmid, was characterized by moderate multinucleation, by polymorphism and elongation of HeLa cells, and by an intense necrotic response in both the rabbit skin test and the mouse footpad test. The distinction between the two cytotoxins accounting for these effects (CNF 1 and CNF 2), together with their partial relatedness, was confirmed by seroneutralization studies of both cytopathic effects and necrosis in the rabbit skin test. In addition, type 2 extracts were more lethal in the mouse intraperitoneal test and induced a moderate, although not totally repetitive, fluid accumulation in the ileal loop test. The original toxic properties of these recently recognized categories of E. coli strains, together with their association with enteritis and septicemia, suggest that these strains may play a significant role in pathology.

Animals↗
PubMed1990

Facetectomy of the patella in patellofemoral osteoarthritis.

Patellofemoral osteoarthritis is a common disease which may occur alone or in association with tibiofemoral gonarthrosis. In cases of isolated symptomatic patello-femoral osteoarthritis with typical lateral malalignment and formation of osteophytes at the lateral border of the patello-femoral joint we perform a lateral facetectomy of the patella and associated lateral retinaculum release. The results of a prospective study of 20 cases with a mean follow-up of 2 years are presented. A good-to-moderate result was obtained in 90%. The average age was 60 years. We had 2 failures with a subjective rating of poor. The principal reason was tibiofemoral gonarthrosis too far advanced at the time of the operation, which then progressed in the postoperative course. On the other hand this technique results in marked improvement for many cases and carries only a small risk. Further reconstructive surgery of the knee is not excluded. Because of the minor surgery and quick recovery, this operation presents a valid alternative to more involved operations such as patellectomy, Bandi or Maquet reconstructive procedures, or a patellofemoral prosthesis.

Adult↗
PubMed1990

Toxic effects for lambs of cytotoxic necrotising factor from Escherichia coli.

The lethal effect, clinical signs and lesions caused by the intravenous inoculation into six lambs (seven to 10 days old) of a partly purified preparation of cytotoxic necrotising factor (CNF) from Escherichia coli, strain BM2-1, were investigated. Two control preparations were also tested in two lambs each: (i) the same as above but heated for one hour at 60 degrees C, a treatment which inactivates CNF and preserves residual endotoxic activity; and (ii) purified material from a CNF-defective mutant of BM2-1. Whereas none of the lambs in either of the control groups died or showed significant clinical signs or lesions, all the lambs inoculated with partly purified CNF developed severe clinical signs starting six hours after inoculation which consisted mainly of neurological signs and mucoid diarrhoea. The most striking lesions were oedema and haemorrhages in the central nervous system, and foci of coagulation necrosis in the myocardium. Mucus hypersecretion in the gastrointestinal tract was not associated with cellular inflammation.

Animals↗
PubMed1989

Cytotoxic effect of multinucleation in HeLa cell cultures associated with the presence of Vir plasmid in Escherichia coli strains.

Escherichia coli strain S5 possesses a virulent plasmid termed Vir, which codes for a lethal toxin and a surface antigen. This strain and two trans-conjugant strains, which have received the Vir plasmid from S5, produced a specific and thermolabile cytopathic effect of multinucleation in an HeLa cell cultures assay, whereas isogenic Vir- strains did not. Moreover sonicates of two epidemiologically unrelated Vir+ strains, exerted the same type of cytotoxicity. This effect, together with lethality for chicken, was specifically neutralized by a rabbit antiserum prepared against Vir+ sonicates. The Vir cytopathic effect appeared morphologically distinct from the one caused by the cytotoxic necrotizing factor of E. coli, which was partially related immunologically. We therefore propose to call this type of toxin 'Vir cytotoxin'.

Antigens, Surface↗
PubMed1989

Immunochemical identification and biological characterization of cytotoxic necrotizing factor from Escherichia coli.

The aim of this study was to identify Escherichia coli cytotoxic necrotizing factor (CNF) by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis and to investigate the possible dissociation of CNF from hemolysin (Hly), which is often produced by CNF-producing strains. CNF was purified from cell lysates of a CNF-producing strain by using ammonium sulfate precipitation, ion-exchange chromatography, gel filtration, and preparative nondenaturing PAGE. All eluates from successive longitudinal slices of a preparative polyacrylamide gel were tested for cytoxicity and analyzed by SDS-PAGE; CNF activity was quantitatively correlated with a protein of 115 kilodaltons (kDa). This procedure increased both cytotoxicity and lethal activity (about 300-fold). We then compared SDS-PAGE protein patterns of enriched lysates from eight field and mutant E. coli strains producing both CNF and Hly, Hly alone, or neither; the 115-kDa band was present solely in CNF-producing strains, irrespective of Hly production. A neutralizing antiserum was produced against unpurified CNF from strain BM2-1 and then extensively adsorbed with cells and extracts of a CNF-defective mutant from BM2-1. The adsorbed antiserum possessed antitoxin activity and neutralized both lethal and necrotic effects of cell lysates from all the CNF-producing strains tested. In an immunoblot of enriched extract from BM2-1, the adsorbed antiserum recognized, besides the 115-kDa protein, another protein of 59 kDa, which was present in the CNF-defective mutant from BM2-1 and was not associated with cytotoxicity. We can conclude from these findings that CNF is a protein of 115 kDa associated with both cytotoxicity and in vivo toxicity, distinct from Hly, and present in all presumed CNF-producing strains tested.

Animals↗
PubMed1989

An in vivo assay for the detection of cytotoxic strains of Escherichia coli.

We have examined the local and systemic responses produced in mice by the inoculation of the footpad with cell-free sonicates from cytotoxic and non-cytotoxic strains of Escherichia coli. The cytotoxic strains, previously characterized in HeLa cell culture assay, produced one of the following cytotoxins: (1) cytotoxic necrotizing factor (CNF; 5 strains); (2) a cytotoxin that induced polynucleation of cells but was serologically distinct from CNF (4 strains); (3) Shiga-like toxin (3 strains). Whereas extracts from non-cytotoxic strains induced only a slight and transitory local edema, those from cytotoxic strains produced a marked local inflammatory response. This response, specific for the type of cytotoxin, was measured by increase in footpad thickness, persistence of inflammation and occurrence of necrosis of the leg extremity. Type 1 and 2 extracts produced persistent inflammatory lesions with, in the case of type 2 extracts only, necrosis of the leg extremity. Conversely, type 3 activity was characterized by a transient local infiltration with no apparent residual lesions. The mouse footpad test therefore provides an in vivo assay for the differential diagnosis of cytotoxic strains of E. coli.

Animals↗
PubMed1987

Cytotoxins in non-enterotoxigenic strains of Escherichia coli isolated from feces of diarrheic calves.

We have examined the cytotoxic responses produced in HeLa and Vero cell cultures by sonicates from 15 non-enterotoxigenic (STa-, LT-) strains of E. coli, highly lethal for mice parenterally LD50 less than 3 X 10(7) CFU), which had been isolated from feces of diarrheic calves. Three types of cytotoxic responses were observed. Type 1 (five strains) consisted of enlargement, rounding and polynucleation of HeLa cells, an effect previously reported with cytotoxic necrotizing factor (CNF) in E. coli from infant and piglet enteritis. Type 2 toxicity (three strains and the control Vir strain S5) was also characterized by enlargement and polynucleation of HeLa cells, but in contrast to Type 2 effect, cells were elongated. Sonicates from the latter strains were lethal for chickens, producing the lesions previously described with Vir strains. Type 3 toxicity (two strains and the control VT strain H19), produced an extensive destruction of both Vero and HeLa cell cultures. Cytotoxic effects were completely abolished upon heating for 1 h at 60 degrees C for Type 1 and 2 extracts and at 80 degrees C for Type 3 extracts. Seroneutralization assays showed that cytotoxins of the same type were closely related antigenically. In addition, a slight cross-neutralization was observed between Type 1 (CNF) and Type 2 (Vir) toxins.

Animals↗
PubMed1986

Prevalence of various enteropathogens in the feces of diarrheic and healthy calves.

The presence of various enteropathogens was examined in the feces of homebred dairy calves reared in a restricted geographical area of France (North West of County of Indre-et-Loire) during winter 1983-1984. Two distinct surveys were carried on: a case-control study including 32 diarrheic calves and 21 healthy calves bred in 53 different farms; and a separate study on nine diarrheic calves in another farm. The following infectious agents were looked for, by specific methods of detection: Escherichia coli K99 and E. coli lethal for mice, Salmonella species, Yersinia enterocolitica, Campylobacter jejuni, enterotoxigenic Clostridium perfringens, Chlamydia psittaci, rotaviruses, coronaviruses, Cryptosporidium. In the case-control survey, no enterotoxigenic E. coli (K99+) was detected in either group of calves. Four agents were more often detected in diarrheic calves than in healthy calves, i.e. rotavirus (12/32 vs 1/21), lethal E. coli (6/32 vs 1/21), Cryptosporidium (2/32 vs 0/21) and Salmonella typhimurium (1/32 vs 0/21). One at least of these four agents was present in 16 diarrheic calves (50%) vs only 2 healthy calves (10%) (P less than 0.01). On the other hand, the occurrence of Campylobacter jejuni and of C. perfringens, enterotoxin was similar in both groups of calves, accounting respectively for about 20% and 10% of total calves. Moreover, coronavirus-like particles were significatively associated with healthy calves (7/32 vs 11/21; P less than 0.05). In the other study, all the main categories of enteropathogens were detected throughout the period of observation in the same farm with the exception of enterotoxigenic E. coli. But each calf taken individually was rarely shedding more than two agents at a time. In addition, specific antibodies against C. perfringens enterotoxin, as tested in an ELISA test, were present in the serum of all the calves examined in both surveys. This study confirms the primary role of rotavirus and Cryptosporidium as agents of diarrhea in calves under three weeks. It also suggests the possible participation of E. coli strains that are lethal for mice and underlines the potential hazard for human health of bovine reservoirs of Campylobacter jejuni and enterotoxigenic C. perfringens.

Animals↗
PubMed1984

[Role of nonenterotoxigenic Escherichia coli strains (K99-,ST-) in the neonatal pathology of the calf].

Enterotoxigenic strains of Escherichia coli have been extensively studied over the last ten years, especially in the calf. On the other hand, septicemic strains have received much less attention during the same period, in spite of a lack of information about their pathogenicity in the calf and about the attributes of their virulence. Virulence of septicemic E. coli includes invasion from the portal entry into the blood, multiplication in blood and organs, resistance to phagocytosis and lethal action of serum, and production of lesions by toxins. Most information obtained recently concerns the last phases of microbial pathogenicity, i.e. multiplication and production of lesions. Antigens K are considered to be mainly responsible for the resistance to phagocytosis. Antigens O would play the major role, qualitatively and quantitatively, in the resistance to bactericidal effect of serum. The ability to grow in iron-deficient medium would constitute a decisive advantage. This ability is attributed to proteins of the outer membrane, some of them being coded by plasmids. Endotoxin is the basic toxic principle that accounts for the production of lesions in the host. It is generally admitted that its toxic effect is due to the lipid A portion of LPS. The biochemical composition of lipid A being very homogeneous in Enterobacteriaceae, its pathological effect is considered to be directly related to the concentration in serum, i.e. without specific endotoxic activity exerted by some serotypes. Numerous clinical and experimental arguments suggest the occurrence of an enterotoxemic form of colibacillosis in calves. Enterotoxemic colibacillosis would result from the strictly intestinal multiplication of some strains of E. coli and the systemic diffusion of corresponding endotoxins. Such a syndrome has been well-documented in piglets, namely oedema disease. Oedema disease is attributed to a limited number of serotypes. Experimental reproduction has led to the evidence that two toxic principles are needed to fully produce the disease: the endotoxin and a neurotoxin, called EDP. These results, together with observations on humans and other animal species, raise two major questions: 1) what are the circumstances that favour the passage of endotoxins through intestinal epithelium ? 2) could a specific endotoxic activity be attributed to some serotypes of E. coli?

Animals↗
PubMed1982

[Frequency of enteropathogenic K99+ ST+ Escherichia coli and rotaviruses in neonatal diarrhea of calves. Survey of a veterinarian's clientele in Sarthe].

A clinical and microbiological study was carried out on 21 diarrhoeic calves less than 20 days old, belonging to 20 different farms in the French department of Sarthe. Each diarrhoeic calf was compared with a clinically healthy calf of the same age, from the same farm. Two visits were made : one during the acute phase of diarrhoea, the other 10 to 15 days later. Of the 21 diarrhoeic calves, nine died. On the first visit, rotavirus was found in faeces of 11 diarrhoeic calves and E. coli K99+ ST+ in faeces of three diarrhoeic calves, in two cases together with rotavirus. At the same time, rotavirus was found in the faeces of five control calves whereas E. coli K99+ ST+ was not present. On the second visit, rotavirus was detected in the faeces of one of the 12 surviving diarrhoeic calves and in the faeces of two control calves. No E. coli K99+ and ST+ was found in any of the two groups. Short duration antibiotic treatment (sulfonamide + colistin) carried out on the first visit did not result in increased resistance of E. coli to the ten antibiotics tested. On the contrary, cases of resistance to certain of these antibiotics were more frequent during the acute phase of illness (and before any treatment) than 10 to 15 days later. This fact was explained by the presence, in at least five cases, of multiresistant E. coli strains which disappeared with recovery.

Animals↗
PubMed1982

[Demonstration of strains of Escherichia coli with septicemic characteristics in the feces of calves with mucoid enteritis].

During a field study on neonatal diarrhea of calves, we examined the bacteremic ability of 78 strains of Escherichia coli isolated from diarrheic and non-diarrheic newborn calves. The following tests were performed: growth in newborn calf serum, mortality in adult mice inoculated intraperitoneally with about 5 X 10(7) bacteria, mortality and effect on weight gain in baby mice inoculated by oral route with about 10(8) bacteria. In addition, we tested their ability to adhere in vitro to intestinal villi of newborn lamb. Among the 78 isolates, 58% were able to grow in newborn calf serum and 22% were non-adherent to lamb intestinal villi. Fifteen isolates were pathogenic for adult mice, 12 of them originating from calves with a syndrome that we called "mucoid enteritis" and which consisted of the following signs: very abundant feces, bright and viscous, containing mucus, and physical prostration. From the 15 strains displaying a lethal effect on adult mice, 12 were adherent and 7 provoked at least 20% mortality in baby mice. Our observations suggest that bacteriemic E. coli with adhesive properties could be responsible for mucoid enteritis in calves.

Animals↗