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F Portaels

Publications and source records attributed to F Portaels.

At least 109 records · Page 6Linked to original sources
PubMed1995

[Mycobacterium ulcerans cutaneous infections: Buruli ulcers].

Mycobacterium ulcerans skin infection or Buruli ulcers are common in children in many rural tropical areas. The usual clinical appearance is a deep, rapidly developing chronic ulcer associated with necrosis of subcutaneous fat. Patients are usually seen at an advanced stage. Bacteriologic identification is not always possible because the pathogen, Mycobacterium ulcerans, is an atypical mycobacteria that is difficult to isolate and grows slowly in culture. Medium although of little assistance in tropical regions, the histological features are highly characteristic and can allow diagnosis in areas in which the disease is rare and unsuspected. The pathogenic effects of Mycobacterium ulcerans are due to the production of a necrotizing exotoxin with an immunosuppressive action. Treatment using antituberculosis and antileprosy drugs has been disappointing. Surgery is usually required and causes extensive sequels in many cases, the best technique being an excision/graft procedure. Many epidemiologic characteristics of Buruli ulcers which are andemic in regions with and aquatic ecosystem are still unclear including the mode of infection, transmission and reservoir. Recent outbreaks, particularly in west Africa, may be related to changes in the natural environment.

Adolescent↗
PubMed1994

Fast atom bombardment mass spectrometry of mycobacterial phenolic glycolipids.

Fast atom bombardment mass spectra were successfully recorded for intact glycosylphenolphthiocerol dimycocerosates (phenolic glycolipids, PGLs) from Mycobacterium kansasii, M. leprae, M. tuberculosis, M. marinum, M. bovis and M. haemophilum. Characteristic fragment ions from the loss of the oligosaccharide moiety and one of the long-chain multimethyl-branched mycocerosic acids were observed in most cases. A tandem mass spectrometric experiment was carried out on the PGL from M. tuberculosis, revealing the type of mycocerosic acids esterified to individual homologues. Mass spectra of homologues separated by reversed-phase high-performance liquid chromatography gave information on the substitution pattern in certain cases. The potential of matrix-assisted laser desorption ionization spectroscopy was demonstrated by a successful analysis of the PGL from M. tuberculosis.

Benzyl Alcohols↗
PubMed1994

Restriction fragment length polymorphism analysis of drug resistant Mycobacterium tuberculosis strains isolated in Belgium.

The recently identified insertion element IS6110 is present in most strains of the Mycobacterium tuberculosis complex. Restriction fragment length polymorphism (RFLP) based on IS6110 generates strain specific fingerprints and allows typing of M. tuberculosis strains. We present here the results of a RFLP study on 12 multi drug and 10 single drug resistant, recent isolates of M. tuberculosis received from different clinical microbiology laboratories in Belgian hospitals. All isolates originating from different patients yielded distinct RFLP patterns possessing 2 to 13 copies of IS6110. There was no correlation between the number or location of IS6110 copies and the drug resistance patterns. These results illustrate the existence of a broad polymorphism among Belgian isolates. Though this preliminary study did not reveal an outbreak or a micro-epidemic, we consider that the establishment of a DNA fingerprint bank in Belgium will be extremely helpful for tracing recent sources of infection, for the control of a possible spread of multidrug resistant organisms, and for the surveillance of tuberculosis in general.

DNA Fingerprinting↗
PubMed1994

Characterization of the virulence of Mycobacterium avium complex (MAC) isolates in mice.

The virulence of different isolates of MAC was studied in naturally susceptible BALB/c mice. In preliminary experiments, MAC bacteria forming smooth transparent colonies on solid media (SmT variants) were found to be virulent for BALB/c mice, causing progressive infection; smooth opaque (SmOp) were generally avirulent, being slowly eliminated from the infected organs; and rough (Rg) variants were either avirulent or as virulent as SmT variants. We chose to compare the virulence of different isolates of MAC of different origins, studying only the SmT morphotype. Strains of MAC isolated from naturally infected animals were those that most consistently caused progressive infections. AIDS patients-derived isolates were of intermediate virulence or devoid of virulence in mice. The environmental strains were eliminated from mice or did not proliferate. Strains of MAC isolated from individuals who were not infected by HIV varied in virulence from completely avirulent to highly virulent. There was no close correlation between virulence and restriction fragment length polymorphism (RFLP) type, although all highly virulent strains were of the A/I type. There was also no correlation between virulence analysed in vivo and the ability to grow in cultured macrophages.

Animals↗
PubMed1994

Characterization of rifampin-resistance in pathogenic mycobacteria.

The emergence of rifampin-resistant strains of pathogenic mycobacteria has threatened the usefulness of this drug in treating mycobacterial diseases. Critical to the treatment of individuals infected with resistant strains is the rapid identification of these strains directly from clinical specimens. It has been shown that resistance to rifampin in Mycobacterium tuberculosis and Mycobacterium leprae apparently involves mutations in the rpoB gene encoding the beta-subunit of the RNA polymerases of these species. DNA sequences were obtained from a 305-bp fragment of the rpoB gene from 110 rifampin-resistant and 10 rifampin-susceptible strains of M. tuberculosis from diverse geographical regions throughout the world. In 102 of 110 rifampin-resistant strains 16 mutations affecting 13 amino acids were observed. No mutations were observed in rifampin-susceptible strains. No association was found between particular mutations in the rpoB gene and drug susceptibility patterns of multidrug-resistant M. tuberculosis strains. Drug-resistant M. tuberculosis strains from the same outbreak and exhibiting the same IS6110 DNA fingerprint and drug susceptibility pattern contained the same mutation in the rpoB gene. However, mutations are not correlated with IS6110 profiling outside of epidemics. The evolution of rifampin resistance as a consequence of mutations in the rpoB gene was documented in a patient who developed rifampin resistance during the course of treatment. Rifampin-resistant strains of M. leprae, Mycobacterium avium, and Mycobacterium africanum contained mutations in the rpoB gene similar to that documented for M. tuberculosis. This information served as the basis for developing a rapid DNA diagnostic assay (PCR-heteroduplex formation) for the detection of rifampin susceptibility of M. tuberculosis.

Amino Acid Sequence↗
PubMed1994

Systematic study of the 3-hydroxy fatty acid composition of mycobacteria.

Twenty-seven strains belonging to 12 Mycobacterium species were studied for 3-hydroxy fatty acid composition. Mycobacterial cells were subjected to both mild and strong acid methanolysis, after which the liberated hydroxy fatty acids were purified and analyzed by gas chromatography-mass spectrometry as methyl ester trimethylsilyl ether derivatives. Altogether, 21 3-hydroxy fatty acids containing 14 to 28 carbon atoms were detected; 10 were straight chain, 6 were 2-methyl branched chain, and 5 were 2,4,6-trimethyl branched chain. The mycobacterial strains were classified in groups according to 3-hydroxy fatty acid patterns.

Esterification↗
PubMed1994

DNA fingerprint analysis of drug resistant Mycobacterium tuberculosis strains isolated in the Czech Republic.

DNA fingerprints were established in 12 drug resistant and 12 susceptible M. tuberculosis strains collected from patients residing in Prague, Czech Republic. The Restriction Fragment Length Polymorphism (RFLP) technique was based on the detection of the insertion sequence IS6110 in PvuII digested chromosomal DNA. All investigated strains possessed at least 5 copies of IS6110 ranging from 5 to 15 copies in the drug resistant isolates and 5 to 11 copies in susceptible isolates. Three multidrug resistant strains displayed identical fingerprints (5 bands), and two strains resistant to pyrazinamid had the same banding pattern (12 bands). The remaining isolates differed either in number or location of the IS6110 copies. Thorough epidemiological analysis did not furnish proof of direct contact among these patients.

Antitubercular Agents↗
PubMed1993

Spectrum of immunodeficiency in HIV-1-infected patients with pulmonary tuberculosis in Zaire.

Tuberculosis (TB) is the most common opportunistic infection in African patients who die from AIDS, yet the stage of immunodeficiency at which TB develops is uncertain. We studied the immune status of HIV-infected outpatients with pulmonary TB in relation to their clinical presentation in a cross-sectional study of 216 HIV-seropositive and 146 HIV-seronegative ambulatory incident cases of smear-positive and culture-positive pulmonary TB in Kinshasa, Zaire. HIV-seropositive and seronegative patients had median CD4 lymphocyte counts of 316.5/microL and 830.5/microL, respectively. Of the HIV-seropositive patients, 32.9% had less than 200 CD4 lymphocytes/microL, 37% between 200 and 499, and 30.1% 500 or more. Clinical AIDS, as defined by the WHO clinical case-definition or a modified version, was of similar limited use as a predictor of immunodeficiency. Among HIV-seropositive patients, oral candidosis, lymphopenia, a negative tuberculin purified protein derivative test, and cutaneous anergy were strongly associated with CD4 counts of less than 200/microL, and seemed to be better markers of immune dysfunction. We conclude that pulmonary TB develops across a broad spectrum of HIV-induced immunodeficiency and that a diagnosis of pulmonary TB is of limited use as a marker of stage of HIV disease in African HIV-infected outpatients.

AIDS-Related Opportunistic Infections↗
PubMed1993

Long-term follow-up of pulmonary disease caused by Mycobacterium avium in a previously healthy patient.

A 64-year-old white male with cavitary lung disease is presented. Mycobacterium avium was isolated from sputa and gastric lavage and the American Thoracic Society criteria for nontuberculous mycobacterial disease were met. Seven years follow-up and treatment regimens are discussed. This case illustrates that medical treatment of M. avium pulmonary disease can be disappointing and requires regular clinical, radiological, microbiological and haematological reassessment to evaluate efficacy and toxicity of therapy. Despite in vitro resistance to the standard antimycobacterial agents, prolonged treatment regimens can be successful and are the therapy of choice. Another drug combination, based on in vitro susceptibility patterns, has to be started for patients who fail to respond or who relapse. Lifelong treatment may be necessary to keep the patient stable and to prevent further destruction of lung parenchyma.

Anti-Bacterial Agents↗
PubMed1993

Biochemical properties and fatty acid composition of Mycobacterium haemophilum: study of 16 isolates from Australian patients.

The biochemical properties and fatty acid compositions of 16 strains of Mycobacterium haemophilum from Australian patients were studied. The strains proved to be indistinguishable from each other but could readily be differentiated from other slowly growing mycobacteria with similar cultural features. Mycolic acid analyses revealed the presence of alpha-, methoxy-, and ketomycolates. The fatty acid composition supports the validity of the fact that M. haemophilum is a distinct species. The fatty acid composition was consistent among the 16 strains, but it was unusual in that there was some resemblance to the fatty acid composition of M. leprae. The wide range of pHs (5.4 to 7.4) that supported growth of M. haemophilum on artificial medium is in keeping with suggestions that M. haemophilum exists in an environmental habitat.

Australia↗
PubMed1993

Identification of Mycobacterium species by using amplified ribosomal DNA restriction analysis.

A rapid procedure for the identification of cultured Mycobacterium isolates, based on the combination of enzymatic amplification and restriction analysis, is described. The 16S rRNA genes (rDNA) of 99 strains belonging to 18 different species of the genus Mycobacterium were enzymatically amplified. Amplified rDNA restriction analysis with the enzymes CfoI, MboI, and RsaI was carried out. The combination of the amplified rDNA restriction analysis patterns obtained after restriction with CfoI and MboI enabled differentiation between Mycobacterium asiaticum (number of strains = 4), M. avium (n = 22), M. chelonae (n = 5), M. flavescens (n = 1), M. fortuitum (n = 6), M. gordonae (n = 6), M. intracellulare (n = 13), M. marinum (n = 7), M. nonchromogenicum (n = 1), M. simiae (n = 5), M. terrae (n = 5), the M. tuberculosis complex (n = 11), and 2 of 4 strains of M. xenopi. Further restriction with RsaI was necessary to differentiate between the species M. kansasii (n = 5), M. scrofulaceum (n = 4), and the 2 other M. xenopi strains. The M. avium-M. intracellulare complex was characterized by a specific MboI pattern, and M. avium and M. intracellulare strains could further be differentiated by restriction with CfoI. The whole procedure, including sample preparation prior to the polymerase chain reaction, can be carried out within 8 h, starting from a pure culture.

Base Sequence↗
PubMed1993

Rapid, early and specific diagnosis of tuberculosis and other mycobacterial diseases in Burundi.

The potential usefulness of ELISA based serological tests to assist in rapid, early and specific diagnosis of tuberculosis was investigated. The materials were selected, based on published data and on our preliminary findings. Initially screening tests were performed using crude antigens such as Purified Protein Derivate (PPD) and a BCG-filtrate. Unfortunately, the results with these antigens were not promising. The specificity of both antigens using sera from 94 healthy controls was 64%. As a consequence of these findings, the crude antigens were excluded from further tests, and the study was continued with purified antigens. The work focused on 2 purified proteins: Antigen 60 (A60), a lipopolysaccharide-protein complex, and P32, a stress protein produced in zinc deprived cultures, identified as Antigen 85 A in the BCG reference system, both isolated from Mycobacterium bovis BCG. The commercial A60 based ELISA and our own P32 based ELISA were used to test a total of 300 sera from HIV positive, negative and unscreened individuals, mainly originating from Burundi. These sera were collected from clinical established cases of pulmonary TB, extrapulmonary TB, and patients with non-tuberculous tropical diseases such as salmonellosis, trypanosomiasis, malaria, etc. and healthy individuals. The A60 based ELISA had a sensitivity of 76.8% for the proven cases of active pulmonary tuberculosis and 61.9% for the extrapulmonary tuberculosis cases. No difference was shown between HIV positive and HIV negative patients. Specificity reached 95.2% for healthy individuals, but dropped to 68.1% when persons with active non-tuberculous tropical diseases were included. Eighty-six percent of the pulmonary cases and 87.7% of the extrapulmonary cases were detected by the ELISA-P32. These findings suggest that this test might be useful as a confirmatory test for the diagnosis of extrapulmonary tuberculosis. Again no difference was noticed between HIV negative and positive patients. The main contraindication for the use of the ELISA-P32 for the diagnosis of tuberculosis is its low specificity: 70.2% with sera from healthy controls and 22.2% for hospitalised patients and persons with non-tuberculous tropical diseases. In a small recent prospective study 4 out of 10 HIV+ persons with no evidence for TB yielded a positive result for the ELISA-P32. Two of them developed pulmonary tuberculosis within 6 months, whereas 2 P32-positives and 6 P32-negatives remained up to now without any manifestations of tuberculosis. The difference was not significant, but the number of cases was limited.(ABSTRACT TRUNCATED AT 400 WORDS)

Antigens, Bacterial↗
PubMed1992

Proposed minimal standards for the genus Mycobacterium and for description of new slowly growing Mycobacterium species.

In accordance with Recommendation 30b of the International Code of Nomenclature of Bacteria, which calls for the development of recommended minimal standards for describing new species, we propose minimal standards for describing the genus Mycobacterium and new slowly growing species of this genus. The minimal standards for assignment of a strain to the genus Mycobacterium include acid-alcohol fastness, a DNA G+C content in the range from 61 to 71 mol%, and mycolic acid detection with characterization of C22 to C26 pyrolysis esters. The recommended minimal standards for describing a new slowly growing Mycobacterium species are based on the results of phenotypic and genomic studies and include the results of the following conventional tests: growth at 25, 30, 33, 37, 42, and 45 degrees C; pigmentation; resistance to isoniazid, thiophene-2-carboxylic acid hydrazide, hydroxylamine, p-nitrobenzoic acid, sodium chloride, thiacetazone, picrate, and oleate; catalase activity; Tween hydrolysis; urease activity; niacin detection; and nitrate reductase, acid phosphatase, arylsulfatase, pyrazinamidase, and alpha-esterase activities. In addition, a mycolic acid profile should be determined, and DNA-DNA hybridization experiments in which the difference between the denaturation temperature of the homologous reaction and the denaturation temperature of the heterologous reaction is determined should be performed. This proposal has been endorsed by the members of the Subcommittee for Taxonomy of the Mycobacteria of the International Committee on Systematic Bacteriology.

Base Composition↗
PubMed1992

Biologically distinct subtypes of Mycobacterium avium differ in possession of insertion sequence IS901.

Mycobacterium avium causes disease, principally tuberculosis in immunocompromised individuals. It is the most frequent cause of disseminated infections in AIDS patients in the West. The pathogen is also associated with disease in animals, chiefly birds and livestock, and may be isolated from environmental samples such as soil and water. Analysis of strains of M. avium isolated from clinical, veterinary, and environmental sources for the presence of the mycobacterial insertion sequences IS900 and IS901 demonstrates the specific association of IS901 to animal pathogenic M. avium strains. In contrast, most clinical M. avium strains and all AIDS-derived strains examined so far lacked IS901. Significant differences in the plasmid contents and serotypes of strains with and without IS901 were also found. We therefore suggest that the presence of IS901 divides M. avium into two clearly distinct subtypes with differing host range, virulence, plasmid possession, and serotyping antigens. By using DNA sequence data from IS901 and M. avium DNA, a set of polymerase chain reactions were developed for the specific detection and differentiation of these subtypes.

Animals↗
PubMed1991

Structural elucidation and antigenicity of a novel phenolic glycolipid antigen from Mycobacterium haemophilum.

The structure of a novel antigenic glycolipid that distinguishes the opportunistic pathogen Mycobacterium haemophilum from all other mycobacteria was established by a series of degradation reactions leading to products that were analyzed by gas/liquid chromatography-mass spectrometry. The complete structure of the oligosaccharide unit was determined as 2,3-di-O-CH3-alpha-L-Rhap(1----2)3-O-CH3-alpha-L-Rhap(1----4 )-2,3-di-O-CH3-alpha-L-Rhap(1----. The lipid portion of the phenolic glycolipid was composed of two component phenolphthiocerols differing by two methylene groups, as determined by analysis of their per-O-trideuteriomethylated derivatives. The diol unit of the phenolphthiocerols has a threo relative configuration. The absolute stereochemistry of the asymmetric centers of the phenolphthiocerols is uncertain, but the centers are probably 3R, 4S, 9R, and 11R as found for phthiocerol A from Mycobacterium tuberculosis. The hydroxyl functions of the branched glycolic chain are esterified to a complex mixture of multi-methyl branched mycocerosic acids, C27, C30, C32, C34, and C37 with molecular weights (as methyl esters) of 424, 466, 494, 522, and 564, respectively. The stereochemistry of the methyl branches of the mycocerosates have R absolute configuration. The glycolipid is highly antigenic and appears to be specific for M. haemophilum. There are intriguing similarities between the product from M. haemophilum and the well-known phenolic glycolipid I of Mycobacterium leprae, a matter that is discussed.

Animals↗