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J Nicolet

Publications and source records attributed to J Nicolet.

At least 109 records · Page 6Linked to original sources
PubMed1994

RTX toxin genotypes and phenotypes in Actinobacillus pleuropneumoniae field strains.

Actinobacillus pleuropneumoniae serotype reference strains and 204 A. pleuropneumoniae field strains representing all 12 serotypes and both biovars 1 and 2, obtained from laboratories from various countries worldwide, were analyzed for the presence of the toxin genes apxIC, apxIA, apxIB, apxID, apxIIC, apxIIA, apxIIIC, apxIIIA, apxIIIB, and apxIIID by DNA-DNA hybridization with specific gene probes. Expression of the toxins ApxI, ApxII, and ApxIII was assessed by immunoblot analysis with monoclonal antibodies. The results show that the patterns of apx genes and those of the expressed Apx toxins in biovar 1 field strains are the same as those of the genes and toxins of corresponding serotype reference strain. We found only three strains which had certain apx genes missing compared with the genes in their serotype reference strains. Analysis of the expression of the three toxins showed that nearly all strains expressed their apx genes and produced the same Apx toxins as their serotype reference strain. We found only one strain that did not produce ApxI, although it contained the apxICABD genes, and one strain which did not express ApxII but which contained apxIICA. Several field strains which initially showed that their serotype did not correspond to the apx gene profile of the reference strain and which had an unexpected virulence for the given serotype revealed that their initial serotyping was erroneous. We show that the apx gene profiles are inherent to a given serotype. The method cannot differentiate between all 12 serotypes. However, it allowed us to distinguish five groups of toxin gene patterns which showed pathological, toxicological, and epidemiological significance. None of the biovar 2 strains contained apxIII genes. The apxI and apxII genes in the biovar 2 strains, however, were the same as those found in the serotype reference strains of biovar 1.

Actinobacillus pleuropneumoniae↗
PubMed1994

[Evaluation of two ELISA techniques for the diagnosis of bovine paratuberculosis].

A sensitivity of 50% and a specificity of 98% were obtained in the evaluation of a serological method (commercial absorbed ELISA, Commonwealth Serum Laboratories, Parkville, Australia) for the diagnosis of paratuberculosis. The population used in the study consisted of 20 infected, suspect and non-infected herds from the region of the Plateau de Diesse. Another evaluated non-absorbed ELISA test had a sensitivity of 30% and a specificity of 91%.

Animals↗
PubMed1994

[Infection with Mycoplasma mycoides ssp. mycoides LC (large colony type) in bezoar goat kids (Capra aegagrus cretica) in the Bern (Switzerland) Zoo].

Mycoplasma mycoides ssp. mycoides LC (large colony type) (MML) was isolated from three 2 to 6 weeks old wild goat kids (Capra aegagrus cretica) dead of septicemia in a Swiss zoo. Necropsy revealed peritonitis, pneumonia and enteritis. MML was isolated out of the ear canal of most of the healthy animals in the flock. The high density of the animals, the presence of concomitant diseases and the carriage among healthy animals seem to have been important predisposing factors for the MML-infection.

Animals↗
PubMed1993

[How can compliance be ameliorated in diabetic patients?].

The compliance of diabetic patients is very poor. In addition to the knowledge of the various stages of acceptance of the disease as described by A. Lacroix in this journal, it is necessary to learn more about the patient's personality. In this article, four different personalities are proposed using the test "Persona" (Polymanagement SA, Geneva) in order to have the correct choice of therapy, corresponding to the personality. We hope that in the long term, by using this test, therapeutic compliance for the diabetic patients will be improved.

Diabetes Mellitus↗
PubMed1993

Analysis of hemolysin operons in Actinobacillus pleuropneumoniae.

Among the twelve different serotypes of Actinobacillus pleuropneumoniae, the causative agent of swine pleuropneumonia, a strongly active hemolysin I (HlyI) is produced by serotypes which are particularly virulent, and less active hemolysin II (HlyII) is produced by all serotypes except type 10. In the serotypes 1, 5a, 5b, 9, 10 and 11, which produce HlyI, the hemolysin (hly) operon consists of a structural hlyIA gene, encoding pre-HlyI, an activator gene, hlyIC, necessary for the activation of pre-Hly to active Hly, and two genes, hlyIB and hlyID, involved in Hly secretion. These genes are clustered in the order, hlyICABD. This is characteristic to RTX toxin (repeats in the structural toxin) operons. The HlyII operons in all serotypes producing HlyII consist only of the pre-HlyII-encoding gene, appA, and its activator gene, appC. The serotypes, which produce HlyII, but not HlyI, contain a truncated HlyI operon, with the promoter, hlyIB and hlyID, and a small segment of the C terminus of hlyIA. This partial HlyI operon might have been formed by deletion of hlyIC and most of hlyIA. In serotype 3, which produces HlyII, but no HlyI, and which releases only minute amounts of this Hly into the growth medium, none of the hlyI genes and consequently no Hly secretion genes were found. The above results postulate that HlyII is secreted via the products of hlyIB and hlyID, and explain the low amount of HlyII secreted by serotype 3. Cloning and analysis of the structural genes encoding pre-HlyI and pre-HlyII among the different serotypes revealed differences in the hlyIA genes which are highly similar in the serologically related serotypes 1, 9 and 11, and differ from the serotypes, 5a, 5b and 10. The hlyIIA genes, in contrast, seem to be conserved in all serotypes.

Actinobacillus pleuropneumoniae↗
PubMed1993

A case of laboratory acquired infection with Escherichia coli O157:H7.

A case of laboratory-acquired infection with Escherichia coli O157:H7 is presented. Evidence of the identity of the infecting strain was provided by toxin type and plasmid profiles. Because no obvious technical errors in laboratory practices could be demonstrated we conclude that the infecting dose for E. coli O157:H7 may be small. The clinical course was uncomplicated; during reconvalescence, the patient's serum recognized a unique 87 kDa band on immunoblots of the infecting strain.

Antibodies, Bacterial↗
PubMed1993

DNA sequence determination and biochemical analysis of the immunogenic protein P36, the lactate dehydrogenase (LDH) of Mycoplasma hyopneumoniae.

The DNA sequence of the gene encoding the early and specific immunogenic protein P36 of Mycoplasma hyopneumoniae has been determined. Comparison of the DNA sequence and the deduced amino acid sequence of P36 with known genes and proteins in data banks indicated that P36 is a L-lactate dehydrogenase (LDH) (EC 1.1.1.27). Biochemical analysis of protein P36 expressed from the cloned gene in Escherichia coli confirmed that P36 has L-lactate dehydrogenase activity. Protein P36 of M. hyopneumoniae therefore is termed LDH and its gene ldh. M. hyopneumoniae LDH was shown to contain the typical domains of LDH of other bacterial species. Immunologically however, we have shown that polyclonal antibodies against M. hyopneumoniae LDH do not cross-react with related LDH and show high specificity for M. hyopneumoniae. The ldh gene is preceded by several typical -10 sequences found in promoters of prokaryotes, but lacks the -35 sequence. Sequences rich in A+T, however, precede the -10 boxes, suggesting that factors involved in transcription initiation and their regulation may be different in M. hyopneumoniae compared to other bacterial species, but the putative ribosome binding site seems to be conserved.

Amino Acid Sequence↗
PubMed1993

Intestinal carriage of Clostridium difficile in neonate dogs.

A total of 70 puppies and their dams, distributed in 14 litters, were submitted to weekly fecal examinations for C. difficile during the first 10 weeks after birth. During the study, 94.3% of the puppies and 42.9% of the dams harboured C. difficile at least once in their feces. We calculated that 58% of the puppies carried toxigenic C. difficile at least once during the survey. In the puppies, C. difficile carriage rates ranging from 3.1% to 67.1% were observed at different moments of the observation period. In comparison, C. difficile carriage rate was 1.4% in a control group of healthy dogs more than 3 months old. Discrepancies in the toxigenic phenotype of the C. difficile strains isolated in the same litter showed that the neonate dogs were transiently infected with different strains, and that the dam is often not the source of infection with C. difficile. We could not demonstrate any pathogenicity of C. difficile for neonate dogs.

Animals↗
PubMed1993

Three supplementary diagnostic tests for Campylobacter species and related organisms.

We analyzed 307 recent clinical isolates and reference strains of Campylobacter spp., Helicobacter spp., and Arcobacter spp. for arylsulfatase and pyrazinamidase activities and susceptibility to polymyxin B. All isolates studied were identified by DNA dot hybridization prior to testing. Campylobacter concisus, C. sputorum, and Helicobacter fennelliae were positive for arylsulfatase. C. jejuni, C. coli, C. lari, C. upsaliensis, and C. concisus were positive for pyrazinamidase. Only Helicobacter spp. were resistant to polymyxin B. C. fetus subsp. fetus, C. hyointestinalis, C. mucosalis, and Arcobacter spp. were negative in all three tests. The tests were simple to perform and read, and with the exception of C. sputorum biovars, all isolates within a species gave consistently positive or negative results in all the assays. These three phenotypic tests may help refine current methods for phenotypic identification of Campylobacter spp. and related organisms in a reference laboratory setting.

Amidohydrolases↗
PubMed1993

Novel Campylobacter-like organism resembling Helicobacter fennelliae isolated from a boy with gastroenteritis and from dogs.

We isolated a Campylobacter-like organism resembling Helicobacter fennelliae from a 5 1/2-year-old boy with gastroenteritis. Similar strains had been found previously in fecal specimens from healthy and diarrheic dogs. These isolates could be differentiated from H. fennelliae by a lack of catalase and arylsulfatase activities. This group of organisms seems to be homogeneous by a nonradioactive dot blot DNA hybridization assay.

Animals↗
PubMed1992

Serotype specificity of immunological assays for the capsular polymer of Actinobacillus pleuropneumoniae serotypes 1 and 9.

The cross-reactivity of the purified polysaccharides of Actinobacillus pleuropneumoniae serotypes 1 and 9 were examined using a variety of highly sensitive assays, such as radioimmunoassay, latex agglutination, enzyme-linked immunosorbent assay (ELISA), and immunoblotting. In addition, conventional immunodiffusion was included for comparison. Latex agglutination, utilizing affinity-purified IgG to capsule, was also used to serotype whole cells. Agglutination or precipitation tests (radioimmunoassay, latex agglutination, and immunodiffusion) indicated no cross-reactivity between the capsules of serotypes 1 and 9, and no cross-reactivity between whole cells by latex agglutination. Assays that required binding of the capsule to a solid support (ELISA and immunoblotting) did demonstrate cross-reactions between serotypes 1 and 9 capsules, although reactions with the heterologous serotype were weaker than with the homologous serotype. The cross-reactivity could not be attributed solely to nonspecific factors because similar cross-reactivity did not occur with serotype 5 or 7 capsules by any assay. Reactivity of antisera with homologous or heterologous capsule was reduced, but not completely eliminated, by adsorption with washed, live bacteria of the heterologous serotype. Thus, the assay, as well as the antigen or specificity of the antibody reagent used, may influence the results of A. pleuropneumoniae serotyping or serological tests.

Actinobacillus pleuropneumoniae↗
PubMed1992

Immunological and pathological reactions in piglets experimentally infected with Mycoplasma hyopneumoniae and/or Mycoplasma flocculare.

The aim of this work was to examine in vivo whether infection with Mycoplasma hyopneumoniae (M. hyop) and/or Mycoplasma flocculare (M. floc) would interact and influence the severity of enzootic pneumonia in piglets. Specific pathogen-free, hysterectomy-derived piglets were allocated to six groups and experimentally inoculated with M. hyop. and/or M. floc at the age of 2 or 8 weeks. Clinical symptoms, frequency of coughing and temperature measurement were noted daily. Lung lesions were recorded by post-mortem examination and histological observations. The cross-inoculation with both mycoplasmas did not influence the clinical or the pathological picture of the disease. Evolution of specific and crossreacting antibodies was analyzed by ELISA and immunoblotting. Animals inoculated with M. floc did not develop any lesions but showed a weak antibody response 6-8 weeks post-infection (p.i.). No cross-reacting antibodies against M. hyop proteins were detected. In animals inoculated with M. hyop, the first antibody response was detectable 4-5 weeks p.i. and was stronger in piglets infected at the age of 2 weeks than at the age of 8 weeks. Three cross-reacting antibodies against M. floc proteins with molecular weights of 110, 47 and 33 kDa were detected by antibodies to M. hyop. Experimental infections with both mycoplasmas did not show differences in the pattern of species-specific proteins.

Animals↗
PubMed1992

Q fever endocarditis: diagnostic approaches and monitoring of therapeutic effects.

The scope of current diagnostic methods for Q fever endocarditis includes serology, direct demonstration of Coxiella burnetii in the resected heart valve tissue, and animal inoculation studies. Illustrated by a clinical case report, the different methods are presented and discussed. Serology represents the primary method, using the techniques of complement fixation, indirect immunofluorescence, and enzyme-linked immunosorbent assay (ELISA). The latter two techniques allow the detection of immunoglobulins G, M, and A to the phase I and II antigens of C. burnetii. After cardiac surgery, we visualized C. burnetii on smears and specifically stained it on histologic sections of the resected heart valve by light and electron microscopic immunohistochemistry. In addition, seroconversion in animals after inoculation with valve specimens confirmed the presence of C. burnetii in the heart valve. The antibody titers determined by ELISA correlated well with the patient's clinical course during the treatment period. Therefore it is suggested that its usefulness for monitoring the efficacy of antimicrobial agents in patients with Q fever endocarditis should be further evaluated.

Endocarditis, Bacterial↗
PubMed1992

Occurrence and phenotypic properties of verotoxin producing Escherichia coli in sporadic cases of gastroenteritis.

Five verotoxin producing Escherichia coli strains were detected in 405 patients with infectious gastroenteritis and 3 such strains were detected in 11 patients with the hemolytic uremic syndrome in Switzerland. Production of verotoxin 2 was associated with the latter three strains. Four strains reacted with the probe for the virulence plasmid of Escherichia coli O157:H7, and six reacted with a recently described probe for the eae gene of enteropathogenic Escherichia coli. None of the strains was of serotype O157:H7. The methods available at present for detecting toxins or toxin genes will reliably detect all such verotoxin producing strains.

Adult↗
PubMed1992

Chromosomal heterogeneity of various Mycoplasma hyopneumoniae field strains.

Restriction enzyme digestion and field inversion gel electrophoresis were used to analyze the chromosomes of strains of Mycoplasma hyopneumoniae and the related organism Mycoplasma flocculare. The chromosome size for the M. hyopneumoniae type strain was calculated from individual fragments to be 1,011.3 +/- 32.9 kbp. The chromosomes of M. hyopneumoniae field strains were approximately the same size. The restriction patterns obtained for the chromosomes of phenotypically similar M. hyopneumoniae strains were quite different. Therefore, the species M. hyopneumoniae seems to be very heterogeneous. A field inversion gel electrophoresis analysis of the entire chromosomes allowed us to distinguish M. hyopneumoniae strains easily and hence to characterize further the species M. hyopneumoniae. The chromosome size for M. flocculare was calculated to be 988.3 +/- 39.5 kbp. Restriction enzyme XhoI, which statistically should cut the M. hyopneumoniae chromosome frequently, did not cut the DNA of any of the M. hyopneumoniae strains but did digest M. flocculare DNA, indicating that there is a site-specific modification at CTCGAG which probably belongs to a restriction modification system in M. hyopneumoniae and is absent in M. flocculare.

Animals↗
PubMed1992

Comparison of Campylobacter carriage rates in diarrheic and healthy pet animals.

To explore the clinical significance of campylobacter infections for dogs and cats we compared intestinal carriage rates for Campylobacter sp. between animals with gastroenteritis and healthy controls. We cultured fecal specimens of 405 diarrheic dogs and 203 cats as well as 71 asymptomatic dogs and 35 cats using a selective medium in addition to filtration on a non-selective blood agar plate. We identified 224 campylobacter isolates using conventional phenotypic tests and DNA hybridization. There were 112 isolates, of C. upsaliensis, 43 C. jejuni and 69 other Campylobacter sp. For cats, there was no association between campylobacter carriage and disease, irrespective of the animals age. For dogs older than 12 months there was also no difference in campylobacter carriage rates between diarrheic and healthy animals. However, in younger dogs 44% of animals with diarrhea shed campylobacters in their feces, more than twice the rate in asymptomatic controls (21%), a significant difference. C. jejuni and C. upsaliensis contributed equally to this association between diarrhea and campylobacter prevalence. The parallel use of two culture methods enabled us to show that the recovery of Campylobacter sp. by filtration may be less than optimal and that filtering is probably unsuitable as a reference method for culturing C. upsaliensis. Finally we found that almost half of the campylobacter isolates from cats belong to a phenotypically homogeneous group of strains closely resembling C. upsaliensis but hybridizing only weakly with C. upsaliensis DNA.

Animals↗