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Françoise Portaels

Publications and source records attributed to Françoise Portaels.

At least 37 records · Page 2Linked to original sources
PubMed2005

Mycobacterium ulcerans disease.

Mycobacterium ulcerans disease (Buruli ulcer) is an important health problem in several west African countries. It is prevalent in scattered foci around the world, predominantly in riverine areas with a humid, hot climate. We review the epidemiology, bacteriology, transmission, immunology, pathology, diagnosis and treatment of infections. M. ulcerans is an ubiquitous micro-organism and is harboured by fish, snails, and water insects. The mode of transmission is unknown. Lesions are most common on exposed parts of the body, particularly on the limbs. Spontaneous healing may occur. Many patients in endemic areas present late with advanced, severe lesions. BCG vaccination yields a limited, relatively short-lived, immune protection. Recommended treatment consists of surgical debridement, followed by skin grafting if necessary. Many patients have functional limitations after healing. Better understanding of disease transmission and pathogenesis is needed for improved control and prevention of Buruli ulcer.

Africa, Western↗
PubMed2005

Comparative evaluation of the nitrate reduction assay, the MTT test, and the resazurin microtitre assay for drug susceptibility testing of clinical isolates of Mycobacterium tuberculosis.

OBJECTIVES: To evaluate the performance of three rapid low-cost methods for the detection of resistance to first-line drugs in Mycobacterium tuberculosis. METHODS: One hundred M. tuberculosis clinical isolates were tested by the nitrate reductase assay (NRA), the MTT test and the resazurin microtitre assay (REMA), and the results compared with those obtained with the gold standard proportion method (PM) on Lowenstein Jensen medium. RESULTS: The results using the three methods showed a good sensitivity and specificity between 94% and 100% for the detection of rifampicin and isoniazid resistance. Specificity for ethambutol and streptomycin using MTT and resazurin was low (58-89%). In contrast, NRA showed a good agreement for all first-line drugs tested. CONCLUSIONS: This study shows a high level of agreement of these three low-cost methods compared with the PM for rapid detection of rifampicin and isoniazid resistance. However, more standardization is needed for ethambutol and streptomycin using the MTT test and resazurin microtitre assay. The nitrate reductase assay might represent an inexpensive procedure for rapid detection of resistance to first-line drugs in low-resource countries.

Antitubercular Agents↗
PubMed2005

Mycobacteria in drinking water distribution systems: ecology and significance for human health.

In contrast to the notorious pathogens Mycobacterium tuberculosis and M. leprae, the majority of the mycobacterial species described to date are generally not considered as obligate human pathogens. The natural reservoirs of these non-primary pathogenic mycobacteria include aquatic and terrestrial environments. Under certain circumstances, e.g., skin lesions, pulmonary or immune dysfunctions and chronic diseases, these environmental mycobacteria (EM) may cause disease. EM such as M. avium, M. kansasii, and M. xenopi have frequently been isolated from drinking water and hospital water distribution systems. Biofilm formation, amoeba-associated lifestyle, and resistance to chlorine have been recognized as important factors that contribute to the survival, colonization and persistence of EM in water distribution systems. Although the presence of EM in tap water has been linked to nosocomial infections and pseudo-infections, it remains unclear if these EM provide a health risk for immunocompromised people, in particular AIDS patients. In this regard, control strategies based on maintenance of an effective disinfectant residual and low concentration of nutrients have been proposed to keep EM numbers to a minimum in water distribution systems.

Amoeba↗
PubMed2005

Multicenter evaluation of the nitrate reductase assay for drug resistance detection of Mycobacterium tuberculosis.

The performance of the nitrate reductase assay was evaluated in a multicenter laboratory study to detect resistance of Mycobacterium tuberculosis to the first-line anti-tuberculosis drugs rifampicin, isoniazid, ethambutol and streptomycin using a set of coded isolates. Compared with the gold standard proportion method on Löwenstein-Jensen medium, the assay was highly accurate in detecting resistance to rifampicin, isoniazid and ethambutol with an accuracy of 98%, 96.6% and 97.9%, respectively. For streptomycin, discrepant results were obtained with an overall accuracy of 85.3%. The assay proved easy to be implemented in countries with limited laboratory facilities.

Antitubercular Agents↗
PubMed2005

Infection with Mycobacterium ulcerans induces persistent inflammatory responses in mice.

Buruli ulcer (BU) is a devastating, necrotizing, tropical skin disease caused by infections with Mycobacterium ulcerans. In contrast to other mycobacterioses, BU has been associated with minimal or absent inflammation. However, here we show that in the mouse M. ulcerans induces persistent inflammatory responses with virulence-dependent patterns. Mycolactone-positive, cytotoxic strains are virulent for mice and multiply progressively, inducing both early and persistent acute inflammatory responses. The cytotoxicity of these strains leads to progressive destruction of the inflammatory infiltrates by postapoptotic secondary necrosis, generating necrotic acellular areas with extracellular bacilli released by the lysis of infected phagocytes. The necrotic areas, always surrounded by acute inflammatory infiltrates, expand through the progressive invasion of healthy tissues around the initial necrotic lesions by bacteria and by newly recruited acute inflammatory cells. Our observations show that the lack of inflammatory infiltrates in the extensive areas of necrosis seen in advanced infections results from the destruction of continuously produced inflammatory infiltrates and not from M. ulcerans-induced local or systemic immunosuppression. Whether this is the mechanism behind the predominance of minimal or absent inflammatory responses in BU biopsies remains to be elucidated.

Animals↗
PubMed2005

Genotyping Mycobacterium ulcerans and Mycobacterium marinum by using mycobacterial interspersed repetitive units.

A novel category of variable tandem repeats (VNTR) called mycobacterial interspersed repetitive units (MIRUs) has been identified for Mycobacterium ulcerans (n = 39), M. marinum (n = 27), and one related organism. Fifteen MIRU loci were identified in the genome of M. marinum and were used to genotype M. ulcerans, M. marinum, and an M. marinum-like organism that is considered a possible missing link between M. marinum and M. ulcerans. Seven MIRU loci were polymorphic, and locus-specific PCRs for four of these loci differentiated seven M. ulcerans genotypes, four M. marinum genotypes, and a unique genotype for the missing link organism. The seven M. ulcerans genotypes were related to six different geographic origins of isolates. All isolates from West and Central Africa, including old and recent isolates, belonged to the same genotype, emphasizing the great spatiotemporal homogeneity among African isolates. Unlike the M. ulcerans genotypes, the four M. marinum genotypes could not be clearly related to the geographic origins of the isolates. According to MIRU-VNTR typing, all M. ulcerans and M. marinum isolates of American origin were closely related, suggesting a common American ancestor for these two pathogenic species on the American continents. MIRU typing has significant potential value for discriminating between reoccurrence and reinfection for M. ulcerans disease.

Bacterial Typing Techniques↗
PubMed2005

Comparative nucleotide sequence analysis of polymorphic variable-number tandem-repeat Loci in Mycobacterium ulcerans.

We analyzed a set of variable-number tandem-repeat (VNTR) loci to assess their nucleotide sequence diversity in isolates of three Mycobacterium ulcerans genotypes. Sequence variants in two loci resulted in intraspecies resolution of Southeast Asian and Asian genotypes in contrast to a homogenous sequence composition among African isolates. Nucleotide sequence polymorphism in repeat units can enhance discrimination of VNTR loci.

Bacterial Typing Techniques↗
PubMed2005

Multilocus variable-number tandem repeat typing of Mycobacterium ulcerans.

The apparent genetic homogeneity of Mycobacterium ulcerans contributes to the poorly understood epidemiology of M. ulcerans infection. Here, we report the identification of variable number tandem repeat (VNTR) sequences as novel polymorphic elements in the genome of this species. A total of 19 potential VNTR loci identified in the closely related M. marinum genome sequence were screened in a collection of 23 M. ulcerans isolates, one Mycobacterium species referred to here as an intermediate species, and five M. marinum strains. Nine of the 19 loci were polymorphic in the three species (including the intermediate species) and revealed eight M. ulcerans and five M. marinum genotypes. The results from the VNTR analysis corroborated the genetic relationships of M. ulcerans isolates from various geographical origins, as defined by independent molecular markers. Although these results further highlight the extremely high clonal homogeneity within certain geographic regions, we report for the first time the discrimination of the two South American strains from Surinam and French Guyana. These findings support the potential of a VNTR-based genotyping method for strain discrimination within M. ulcerans and M. marinum.

Animals↗
PubMed2005

Rapid detection of ofloxacin resistance in Mycobacterium tuberculosis by two low-cost colorimetric methods: resazurin and nitrate reductase assays.

We have evaluated the performance of two rapid, low-cost methods for the detection of ofloxacin (OFX) resistance with 95 Mycobacterium tuberculosis isolates from countries with high multidrug-resistant tuberculosis endemicity. Results obtained by nitrate reductase and resazurin assays showed 100% agreement with those of the proportion method on 7H11 agar using 2 mug of OFX/ml. We confirmed the resistance of all isolates found to be resistant to OFX by the Mycobacterium Growth Indicator Tube system, and complete agreement among all methods was observed. Nitrate reductase and resazurin assays are rapid, simple, low-cost methods and might become inexpensive alternative procedures for rapid detection of OFX resistance in low-resource countries.

Anti-Bacterial Agents↗
PubMed2005

Buruli ulcer recurrence, Benin.

Buruli ulcer is a recognized public health problem in West Africa. In Benin, from 1989 to 2001, the Centre Sanitaire et Nutritionnel Gbemoten (CSNG) treated >2,500 Buruli ulcer patients. From March 2000 to February 2001, field trips were conducted in the Zou and Atlantique regions. The choice of the 2 regions was based on the distance from CSNG and on villages with the highest number of patients treated at CSNG. A total of 66 (44.0%) of 150 former patients treated at CSNG were located in the visited villages. The recurrence rate of CSNG-treated patients after a follow-up period of up to 7 years was low (6.1%, 95% confidence interval [CI] 2.0-15.6). We attribute this low rate to the high quality of Buruli ulcer treatment at an accessible regional center (CSNG). The World Health Organization definition of a Buruli ulcer recurrent case should be revised to include a follow-up period >1 year.

Anti-Bacterial Agents↗
PubMed2005

[Phenotypic and genotypic methods for detecting multidrug resistance in Mycobacterium tuberculosis].

BACKGROUND: Expeditious charactization of drug susceptibility in Mycobacterium tuberculosis is difficult and, calls for the design and evaluation of faster, cheaper and more effective new techniques. OBJECTIVE: The aim of the current study was to compare one genotypic and two phenotypic methods for rapid susceptibility detection of M. tuberculosis. MATERIAL AND METHODS: Twenty-one M. tuberculosis strains were evaluated by phenotypic methodologies of oxidation and reduction of Alamar blue and MTT in the presence of streptomycin, isoniazid, rifampin and ethambutol. In all tests, the proportion method was applied as the comparison standard. By means of receiver operative characteristic (ROC) analysis, the performance, predictive values and threshold values for all drugs were determined. In addition, the performance of PCR and reverse line blot hybridization in establishing predictive values for sensitivity and resistance were compared in contingency tables. RESULTS: The susceptibility patterns established by colorimetric techniques were obtained after seven days of incubation. The performances of these tests were excellent for all drugs-the areas under curves were >0.9, 100% of sensitivity (S) and specificity (E) >80%. The genotypic method of RFLP oligotyping detected multidrug resistance with S of 100% and E of 93%. Conclusion. The results indicated that Alamar blue, MTT and RFLP methodologies are rapid and useful tools for characterizing multidrug resistance in M. tuberculosis, particularly for those patients with high risk of developing multidrug resistant tuberculosis.

Antitubercular Agents↗
PubMed2004

Multicenter evaluation of mycobacteria identification by PCR restriction enzyme analysis in laboratories from Latin America and the Caribbean.

The identification of mycobacterial species in clinical isolates is essential for making patient care decisions. Polymerase chain reaction (PCR) restriction enzyme analysis (PRA) is a simple and rapid identification method, based on amplification of 441 bp of the hsp65 gene and restriction with BstEII and HaeIII. As a contribution to the validation of PRA, a multicenter study was performed in eight laboratories located in Argentina, Brazil, Colombia, Chile, and Guadeloupe. Each laboratory received 18 coded isolates from the collection of the Institute of Tropical Medicine (Antwerp, Belgium), representing duplicates of nine laboratory strains: Mycobacterium terrae CIPT 140320001, Mycobacterium scrofulaceum CIPT 140220031, Mycobacterium flavescens ATCC 14474, Mycobacterium triviale ATCC 23292, Mycobacterium nonchromogenicum ATCC 19530, Mycobacterium chitae ATCC 19627, Mycobacterium abscessus ATCC 19977, Mycobacterium kansasii ATCC 12478, and Mycobacterium peregrinum ATCC 14467. A detailed protocol including amplification, enzymatic digestion, and gel preparation was provided to each laboratory. Two laboratories identified correctly all 18 (100%) isolates, one identified correctly 17 (94.5%), two identified 14 (77.7%), one identified 11 (61%), and two identified 8 (44.4%) isolates. Errors detected in laboratories with more than 77% accuracy were associated with electrophoresis running conditions and an unspecific amplicon produced by a single strain. Lower accuracy was mainly related to inappropriate use of DNA markers and insufficient training in interpretation of patterns. In conclusion, the PRA method was readily implemented in some Latin American and Caribbean laboratories of mycobacteria, but improvements in critical points, as gel running conditions and training in interpretiation of patterns, are needed in order to improve accuracy. In others, improvement in critical points is still necessary.

Bacterial Proteins↗
PubMed2004

Rapid alternative methods for detection of rifampicin resistance in Mycobacterium tuberculosis.

OBJECTIVE: To study the performance of three rapid low cost methods for the detection of rifampicin resistance. METHODS: A panel of 20 coded Mycobacterium tuberculosis strains was tested blindly by the low cost methods: nitrate reductase, MTT and resazurin assays, and compared with the results obtained with the gold standard methods: the proportion method on Löwenstein-Jensen medium and the BACTEC TB 460 system. We have also tested two commercial tests: MGIT and INNO LiPA Rif.TB kit. RESULTS: Complete agreement was observed among all methods. CONCLUSION: These three simple methods might become inexpensive alternative procedures for rapid detection of rifampicin resistance in low-resource countries.

Antibiotics, Antitubercular↗
PubMed2004

Newly developed primers for the detection of Mycobacterium avium subspecies paratuberculosis.

Recent publications reported the existence of IS900 like sequences in mycobacteria different from Mycobacterium avium subspecies paratuberculosis (Map). The primers used for IS900 detection of Map have amplified these sequences causing false positive results. In this study, we have developed two new PCR assays for the detection of Map. The first assay is based on the IS900 sequence using primers different from the ones previously reported, the second assay on the f57 sequence. The specificity of the tests was checked by analysis of 190 mycobacterial isolates (74 Map and 116 non-Map isolates). All Map strains were positive and all non-Map strains were negative. Serial dilutions of Map bacteria were used to assess the sensitivity of the assays. We achieved a sensitivity of 1CFU per PCR for both assays. In addition, a PCR-simulating computer programme was used to evaluate the specificity of the new IS900 primers. The combination of the two PCR assays has proven to be useful for the identification of Map but validation on a large range of clinical samples still needs to be done.

Animals↗
PubMed2004

One-tube cell lysis and DNA extraction procedure for PCR-based detection of Mycobacterium ulcerans in aquatic insects, molluscs and fish.

The purpose of this study was to develop a simple procedure for cell lysis and DNA extraction for direct detection of Mycobacterium ulcerans in aquatic insects, gills and intestinal contents of fish, molluscs and human tissue samples using a nested PCR method specific for the insertion sequence IS2404. The simultaneous action of sodium N-lauroyl sarcosine, guanidinium isothiocyanate, chloroform and Tris-saturated phenol on mycobacteria, followed by a DNA purification method using mini-columns fitted with silica-cellulose membranes was successfully employed to extract DNA from cultured bacteria, environmental and human tissue samples. All specimens were collected from Buruli ulcer endemic regions. M. ulcerans DNA was detected in 11 of 57 aquatic insects, one of six molluscs and three of 15 fish, supporting the hypothesis that the fauna of major Buruli ulcer endemic foci in swampy terrain of tropical and subtropical regions can be a source of M. ulcerans infection.

Animals↗