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F Portaels

Publications and source records attributed to F Portaels.

At least 127 records · Page 7Linked to original sources
PubMed1991

Pulmonary disease caused by Mycobacterium malmoense. Comments on the possible origin of infection and methods for laboratory diagnosis.

Mycobacterium malmoense was isolated from sputum and gastric lavage from a 68-year-old man with gastric adenocarcinoma. The patient meets the criteria for diagnosis of pulmonary mycobacteriosis. The cultural, physiological and biochemical properties of the isolates were compared with other slowly growing mycobacterial species. Fatty and mycolic acid analyses revealed the presence of 2-methyleicosanoic and 2,4,6-trimethyltetracosanoic acids and alpha-, alpha'-and ketomycolates, all regarded as typical for M. malmoense. The possible origin of M. malmoense infections and methods for laboratory diagnosis are discussed. This is the first case of documented infection due to this organism in Belgium.

Adenocarcinoma↗
PubMed1991

IS901, a new member of a widespread class of atypical insertion sequences, is associated with pathogenicity in Mycobacterium avium.

An insertion sequence (IS901), found in pathogenic strains of Mycobacterium avium, but absent in M. avium complex isolates from patients with acquired immune deficiency syndrome (AIDS), has been isolated and sequenced. This insertion element has a nucleotide sequence of 1472 bp, with one open reading frame (ORF1), which codes for a protein of 401 amino acids. The amino acid sequence, terminal ends and target site of IS901 are similar to those of IS900, present in Mycobacterium paratuberculosis. However, the DNA sequences of these two IS elements exhibit only 60% homology, compared to a DNA homology of 98% between their respective hosts. IS901, like IS900, appears to belong to a family of related insertion elements present in actinomycetes and other bacteria. M. avium strains containing IS901 were found to be more virulent in mice than closely related strains lacking IS901. IS901 may be a useful tool for the study of the genetics of virulence in the M. avium complex and for obtaining stable integration of foreign genes into mycobacteria.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Specific identification of Mycobacterium leprae by the polymerase chain reaction.

Oligonucleotide primers have been used to amplify DNA regions of the M. leprae genome by the polymerase chain reaction. A first set of primers, PLp1 and PLp2, identifies a specific 386 bp DNA fragment located in the gene coding for the 65 kDa antigen of M. leprae. A second pair of primers, targetted to the same gene, leads to the amplification of a 154 bp DNA piece conserved in mycobacteria. Primers PLp1 and PLp2 discriminate the pathogenic species from other mycobacteria, detect down to 40 bacilli, and constitute potentially useful tools for the identification of M. leprae in clinical specimens.

Animals↗
PubMed1990

Geographically distinct isolates of Mycobacterium leprae exhibit no genotypic diversity by restriction fragment-length polymorphism analysis.

Differentiation of microorganisms for taxonomic purposes is based primarily on phenotypic characteristics, which are the direct or cumulative result of gene expression. Since expression of phenotypic characteristics usually relies on in vitro growth of a microorganism, non-cultivable organisms, such as Mycobacterium leprae, present major problems for the identification of potential variants based on phenotypic similarities or differences between individual isolates. We have employed the use of restriction fragment-length polymorphism (RFLP) analysis of chromosomal DNA of M. leprae isolates, including human isolates from geographically distinct regions of the world and isolates from a Sooty Mangabey monkey and an armadillo, to assess the relatedness among these isolates. Restriction endonuclease (EcoRI, BstEII, PstI, and PvuI) digests of chromosomal DNA were analysed using DNA probes encoding all or part of the 12 kD, 18 kD, 28 kD, 65 kD and 70 kD proteins of M. leprae as well as a probe containing an M. leprae-specific sequence repeated up to 20 times in the M. leprae chromosome. Comparison of the resulting autoradiographs showed that the RFLP patterns were all identical, indicating that these isolates contained no polymorphism with respect to the restriction endonuclease sites analysed. In addition, RFLP patterns of two separate human M. leprae isolates remained unchanged after three cycles of experimental infection in the armadillo model. These results indicated that the M. leprae isolates tested in this study were indistinguishable at the genotypic level, strongly suggesting homogeneity among members of this species.

Animals↗
PubMed1990

Isolation of mycobacteria from stools and intestinal biopsies from HIV seropositive and HIV seronegative patients with and without diarrhea in Kinshasa, Zaïre. Preliminary results.

To determine the role of mycobacteria as etiologic agent in HIV related enteritis in Africa, the following study was performed in 1986, in the department of Internal Medicine in Mama Yemo Hospital in Kinshasa, Zaire. Stool and intestinal biopsies were obtained from HIV seropositive and HIV seronegative patients with and without diarrhea. Patients with known Mycobacterium tuberculosis infection were not enrolled. Acid fast bacilli were found in fecal smears of 6 (10%) of 59 HIV seropositive patients and in none of 41 HIV seronegative patients (p = 0.04). Isolation rates of mycobacteria were slightly lower in HIV seropositive patients than in HIV seronegative patients (25% vs 44%, p = 0.08) and significantly lower in patients with diarrhea than in patients without diarrhea (15% vs 44%, p = 0.02). Mycobacterium avium-intracellulare was the species most frequently isolated from stools, in 12% of the HIV seropositive and in 22% of the HIV seronegative patients. Mycobacteria were not isolated from any of the intestinal biopsies obtained in 17 HIV seropositive patients with persistent diarrhea and any of these biopsies showed histological evidence of a mycobacterial infection. This study suggests that mycobacteria do not seem to play a major role in causing diarrhea in HIV seropositive patients.

Adult↗
PubMed1989

DNA probes demonstrate a single highly conserved strain of Mycobacterium avium infecting AIDS patients.

Strains of the Mycobacterium avium intracellulare complex (MAIC) have become important colonisers of patients with acquired immunodeficiency syndrome (AIDS). Restriction fragment length polymorphisms were used to study the DNA from 88 MAIC isolates, including 51 derived from 47 AIDS patients. MAIC isolates from 33 of 45 AIDS patients were identical at the molecular level and distinct from the mycobacteria isolated from the stools of healthy subjects. The study also showed that serotyping correlates poorly with the genetic identity of these organisms. Mycobacterium paratuberculosis, which has been implicated in Crohn's disease, was not identified in any of the cultures studied.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Two-dimensional gas chromatography with electron capture detection for the sensitive determination of specific mycobacterial lipid constituents.

A method was developed for determining two characteristic mycobacterial lipid constituents, tuberculostearic acid (as its pentafluorobenzyl ester) and 2-eicosanol (as its pentafluorobenzoyl ester), by using gas chromatography with electron capture detection. A microprocessor-controlled column-switching system (two-dimensional gas chromatography) facilitated sample preparation and increased specificity. The usefulness of the technique was illustrated by its ability to reveal picogram amounts of tuberculostearate in a suspension of Mycobacterium leprae isolated from a naturally infected armadillo. Two-dimensional gas chromatography with electron capture detection may in some instances provide a convenient alternative to gas chromatography-mass spectrometry for use in demonstrating the presence of mycobacteria in a complex environment.

Animals↗
PubMed1989

New data on the ultrastructure of the membrane of Mycobacterium leprae.

In previous reports on the ultrastructure of Mycobacterium leprae, we described the occurrence of symmetric membranes in normal-looking bacilli from fresh or frozen samples primarily fixed with aldehydes. In those reports we admitted that such a symmetric profile, which is not found in the other normal mycobacteria, would not represent the structure of the normal membrane of the leprosy bacillus. We, therefore, re-analyzed the ultrastructure of the membrane of M. leprae. In the present work the micromorphology of the M. leprae membrane was studied by transmission electronmicroscopy after the fixation of fresh samples by OsO4 plus calcium followed by glutaraldehyde plus formaldehyde and calcium followed by uranyl acetate. The study of samples from two patients with lepromatous (LL) leprosy, three armadillos with natural leprosy, and one nude mouse with experimental leprosy showed that normal-looking bacilli present in lead-stained sections had asymmetric membranes with a thickness of 6.49 +/- 0.36 nm. These membranes showed periodic acid-Schiff (PAS)-positive components exclusively located in the outer half of the bilayer. We demonstrated that the symmetric profile of the M. leprae membrane described in our previous reports corresponds, as admitted in those reports, to an abnormal membrane structure. Such an abnormality was now found to result from the use of primary fixation with aldehydes or of samples stored frozen before fixation. These results indicate that, although ultrastructurally similar to that of the other mycobacteria, the membrane of M. leprae has a peculiar sensitivity to fixation by aldehydes. Such a characteristic, which was not found in M. lepraemurium, M. aurum, M. avium, and M. tuberculosis H37Ra, must reflect a unique membrane molecular structure, which is presently unknown.

Animals↗
PubMed1988

Selective isolation of mycobacteria from soil: a statistical analysis approach.

We compared four decontamination methods for the isolation of mycobacteria from soil specimens. Different media were used: Löwenstein-Jensen, Ogawa and various modified Ogawa media. Statistical analysis demonstrated that the best results (low contamination and high positivity rates) were obtained when the specimens were incubated in trypticase soy broth, treated with solutions containing malachite green and cycloheximide, then decontaminated with sodium hydroxide and inoculated onto Ogawa media. The lowest contamination rates were obtained with Ogawa medium containing 500 micrograms cycloheximide ml-1. The use of these techniques is proposed for the isolation of mycobacteria from heavily contaminated clinical specimens as well as from soil.

Culture Media↗
PubMed1988

Fatty and mycolic acids of Mycobacterium malmoense.

The fatty acids and mycolic acids of 16 clinical isolates of Mycobacterium malmoense were studied by gas chromatography and thin-layer chromatography. All strains contained 2-methyleicosanoic and 2,4,6-trimethyltetracosanoic acids and alpha-, alpha'-, and keto-mycolic acids. The reported findings suggest that lipid analysis is a very useful approach in the species identification of M. malmoense.

Chromatography, Gas↗
PubMed1988

Effects of freezing and thawing on the viability and the ultrastructure of in vivo grown mycobacteria.

The influence of different frequencies of freezing-thawing cycles on the viability of in vivo grown mycobacteria was investigated. Pieces of armadillo tissues naturally or experimentally infected with Mycobacterium leprae were analyzed. The viability of M. leprae was determined by mouse foot pad titration. The viability of cultivable mycobacteria, sometimes present in armadillo tissues, was determined by culture. Electron-microscopic studies were performed on fresh or frozen-thawed armadillo tissues with natural leprosy and on livers of C57BL/6 mice experimentally infected with M. avium or M. lepraemurium. We found that the percentage of viable M. leprae bacilli is identical for naturally infected and experimentally infected tissues, frozen and thawed once. When the tissues were subjected to a second freezing-thawing cycle, a considerable loss of viability was observed (65%-97%). A third freezing-thawing cycle was lethal for most of the M. leprae cells, and after four freezing-thawing cycles no viable bacilli were found. The cultivable mycobacteria present in some armadillo tissues were found to be more resistant than M. leprae to freezing-thawing since these mycobacteria could still be cultivated after four freezing-thawing cycles. The results of the electron-microscopy study support the conclusion that M. leprae is more sensitive to freezing-thawing than the cultivable mycobacteria and show that the cytoplasmic membrane appears to be the target for the lethal action of freezing-thawing on mycobacterial cells. These results emphasize the importance of avoiding repeated thawing and refreezing of M. leprae-infected tissues when viable M. leprae cells need to be studied.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Biochemical characteristics and fatty acid compositions of some armadillo-derived mycobacteria and their relation to Mycobacterium gordonae.

The long-chain components of 75 strains of mycobacteria, cultivated from Mycobacterium leprae-infected or non-infected armadillos, and of eight clinical and 15 environmental isolates of M. gordonae, were compared. Four major groups could be distinguished based on the presence of 10-methyloctadecanoic (tuberculostearic) and 2-methyl 3-hydroxyeicosanoic acids and secondary alcohols (2-octadecanol and 2-eicosanol). Some heterogeneity was found in strains assigned to M. gordonae: the characteristic absence of tuberculostearic acid and secondary alcohols and the presence of the branched C14 and the hydroxylated C20 acids were seen in only 34 of the 49 strains studied. Three strains were identified as M. malmoense, one as M. kansasii, ten as belonging to the M. avium-M. intracellulare-M. scrofulaceum complex and eight as belonging to new groups of armadillo-derived mycobacteria (ADM 1, ADM 2 and ADM 3) by conventional bacteriological tests and fatty acid compositions, though M. malmoense was heterogeneous in its fatty acids composition. Four strains, identified as M. avium by conventional tests, differed from this species by their fatty acid compositions. Thirteen strains showed some similarity to M. simiae and ten strains differed from all other known mycobacteria.

Animals↗
PubMed1987

Skin granulomas due to Mycobacterium gordonae.

A 38-year-old woman presented with small, ulcerated, red or bluish nodules on the right hand, clinically resembling mycobacterial granulomas; these appeared a few months after a bite by a rat, while the patient was collecting frogs in a pond in the Belgian Ardennes. The histopathologic picture was compatible with a diagnosis of mycobacterial infection and rare acid-fast bacilli could be found. Repeated bacteriologic investigations were performed and these led to the identification of a strain displaying characteristics of Mycobacterium gordonae. The skin condition responded well to rifampicin (300 mg/day) within 6 months.

Adult↗