Beijing/W Mycobacterium tuberculosis in Italy.
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Adult↗
Biomedical subjects
Enrico Tortoli
Publications and source records attributed to Enrico Tortoli.
A real-time PCR assay for detection of isoniazid resistance in Mycobacterium tuberculosis clinical isolates.
A real-time PCR genotypic assay was developed for the detection of isoniazid (INH) resistance in Mycobacterium tuberculosis. The assay detects mutations C(-15)T and, possibly, G(-24)T in the regulatory region of the inhA gene and proved as sensitive and specific as nucleotide sequencing in all the clinical isolates tested. Our assays mapped the mutations efficiently in 10 out of 35 resistant isolates, thereby covering 29% of all resistant strains.
Antitubercular Agents↗
Impact of genotypic studies on mycobacterial taxonomy: the new mycobacteria of the 1990s.
The advancement of genetic techniques has greatly boosted taxonomic studies in recent years. Within the genus Mycobacterium, 42 new species have been detected since 1990, most of which were grown from clinical samples. Along with species for which relatively large numbers of strains have been reported, some of the new species of mycobacteria have been detected rarely or even only once. From the phenotypic point of view, among the new taxa, chromogens exceed nonchromogens while the numbers of slowly and rapidly growing species are equivalent. Whereas conventional identification tests were usually inconclusive, an important role was played by lipid analyses and in particular by high-performance liquid chromatography. Genotypic investigations based on sequencing of 16S rRNA gene have certainly made the most important contribution. The investigation of genetic relatedness led to the redistribution of the species previously included in the classically known categories of slow and rapid growers into new groupings. Within slow growers, the intermediate branch related to Mycobacterium simiae and the cluster of organisms related to Mycobacterium terrae have been differentiated; among rapid growers, the group of thermotolerant mycobacteria has emerged. The majority of species are resistant to isoniazid and, to a lesser extent, to rifampin. Many of the new species of mycobacteria are potentially pathogenic, and there are numerous reports of their involvement in diseases. Apart from disseminated and localized diseases in immunocompromised patients, the most frequent infections in immunocompetent people involve the lungs, skin, and, in children, cervical lymph nodes. The awareness of such new mycobacteria, far from being a merely speculative exercise, is therefore important for clinicians and microbiologists.
Bacterial Proteins↗
Evaluation of the BDProbeTec ET system for direct detection of Mycobacterium tuberculosis in pulmonary and extrapulmonary samples: a multicenter study.
We evaluated the BDProbeTec ET system (Becton Dickinson, Sparks, Md.), a strand displacement amplification-based technique, for direct detection of Mycobacterium tuberculosis in 867 clinical samples. Of 294 extrapulmonary specimens, 52 had positive results by both BDProbeTec ET and culture and 209 had negative results by both methods; sensitivity and specificity were 76.5 and 95.9%, respectively. After resolution of discrepancies, the sensitivity rose to 77.8%.
Body Fluids↗
Evaluation of INNO-LiPA MYCOBACTERIA v2: improved reverse hybridization multiple DNA probe assay for mycobacterial identification.
INNO-LiPA MYCOBACTERIA (Innogenetics, Ghent, Belgium) is a reverse hybridization DNA probe assay that has been recently improved by increasing the number of identifiable mycobacterial species to 16. Our assessment, performed with 197 mycobacteria belonging to 81 taxa, revealed 100% specificity and sensitivity for 20 out of 23 probes. The probes specific for Mycobacterium fortuitum complex, for the Mycobacterium avium-intracellulare-scrofulaceum group, and for Mycobacterium intracellulare type 2 cross-reacted with several mycobacteria rarely isolated from clinical specimens. The overall sensitivity was 100%, and the overall specificity was 94.4%.
DNA Probes↗
Mycobacterium kansasii, species or complex? Biomolecular and epidemiological insights.
Mycobacterium kansasii is one of the best known nontuberculous mycobacteria and large awareness exists about its involvement in diseases both of immunocompetent and immunocompromised patients. Two phenotypic variants within this species, which differ for the virulence in guinea pig too, have been detected since 1962. It was however following recent progress in genetic studies that a large variability emerged. Major contributions to the disclosure of such findings came from the DNA probes hybridization, the nucleotide sequencing of 16 rDNA and internal transcribed spacer (ITS), and from the analyses of repetitive DNA sequences polymorphism. At present five subtypes of M. kansasii are recognized, defined by the ITS sequence and by the polymorphism revealed by different restriction enzyme technologies. Such variants differ from the epidemiological point of view too, with type i being isolated from humans, type ii both from humans and environment, and types iii, iv and v, from the environment only. A revision of the present taxonomic status of M. kansasii and its splitting into different species or subspecies seems nowadays necessary.
Animals↗
Pseudoepidemic from Mycobacterium gordonae due to a contaminated automatic bronchoscope washing machine.
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Bronchoscopes↗
Mycobacterium palustre sp. nov., a potentially pathogenic, slowly growing mycobacterium isolated from clinical and veterinary specimens and from Finnish stream waters.
Taxonomic studies were performed on a phenotypically homogeneous group of 13 mycobacteria isolated from clinical, veterinary and stream-water samples. The methods applied included chromatographic analyses of bacterial lipids, biochemical tests and sequencing of the 16S rDNA and the internal transcribed spacer 1 (ITS1) region. Positive results in urease, Tween 80 hydrolysis and pyrazinamidase tests and a negative result in a semi-quantitative catalase test, combined with the ability to grow at 42 degrees C, distinguished this group among the yellow-pigmented, slowly growing mycobacteria. Unique fatty acid and mycolic acid profiles in chromatographic analyses and the results of gene sequencing indicated that the novel isolates represent a previously undescribed species, for which the name Mycobacterium palustre sp. nov. is proposed. The fatty acid profile obtained by GLC was characterized by the presence of several methyl-branched fatty acid markers. The most prominent markers were 2-methyleicosanoic, tetracosanoic and hexacosanoic acids. According to 16S rDNA sequencing, M. palustre is phylogenetically closest to Mycobacterium kubicae, a recently described species. M. palustre gives a false-positive result in a hybridization test with the AccuProbe Mycobacterium avium complex. One of the strains was isolated from a lymph-node biopsy from a child with cervical lymphadenitis. Thus, M. palustre should be listed among potential inducers of paediatric lymphadenitis. The veterinary isolates originated from the lymph nodes of slaughter pigs. The majority of the strains were recovered from natural waters, which highlights the role of the environment as a source of potentially pathogenic mycobacteria. The type strain of M. palustre is strain E846T (= DSM 44572T = ATCC BAA-377T).
Animals↗
Human infections due to Mycobacterium lentiflavum.
Three cases of human disease due to Mycobacterium lentiflavum are reported. In the first, the mycobacterium was responsible for chronic pulmonary disease in an elderly woman; in the second, it gave rise to cervical lymphadenitis in a child; and in the third, it caused a liver abscess in a young AIDS patient.
Child, Preschool↗
Evaluation of automated BACTEC MGIT 960 system for testing susceptibility of Mycobacterium tuberculosis to four major antituberculous drugs: comparison with the radiometric BACTEC 460TB method and the agar plate method of proportion.
We evaluated the performance of BACTEC MGIT 960 for automated testing of the susceptibility of 133 strains of Mycobacterium tuberculosis to streptomycin, isoniazid, rifampin, and ethambutol. The BACTEC MGIT 960 results were compared with those obtained with the radiometric BACTEC 460TB system, and when there was disagreement, the method of proportion on agar plates was used as a reference method. Strains resistant to the critical concentration of streptomycin, isoniazid, or ethambutol were also tested with a second, higher concentration. The overall agreement between the two systems was 96.7%, and the 18 discrepancies were resolved in favor of BACTEC 460TB in 11 cases and in favor of BACTEC MGIT 960 in 7, a difference which was not statistically significant. Apart from the assay's low specificity for ethambutol, which was low for the radiometric assay as well, good sensitivity and specificity values characterized BACTEC MGIT 960. The average time required for completion of the test was 2.5 days shorter with BACTEC 460TB. In conclusion, BACTEC MGIT 960 appears to be a suitable replacement for the radiometric method of antimicrobial susceptibility testing of M. tuberculosis. The problem of frequent contamination of BACTEC MGIT 960 tests needs to be quickly resolved; in fact, 14 strains had to be reprocessed because of contamination.
Antitubercular Agents↗
Identification of mycobacteria by using INNO LiPA.
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DNA Probes↗
Inteins in mycobacterial GyrA are a taxonomic character.
The A subunit of DNA gyrase in mycobacteria is frequently subjected to splicing events as its gene, gyrA, harbours an insertion encoding an intein. Investigation of a number of different isolates of Mycobacterium kansasii, Mycobacterium malmoense, Mycobacterium marinum, Mycobacterium ulcerans and Mycobacterium xenopi demonstrated that the presence of GyrA inteins is not random but a taxonomic character specific for a given taxon at a species or subspecies level.
Bacterial Proteins↗
Multicenter evaluation of mycobacteria growth indicator tube (MGIT) compared with the BACTEC radiometric method, BBL biphasic growth medium and Löwenstein---Jensen medium.
OBJECTIVE: To evaluate the new BBL mycobacteria growth indicator tube (MGIT) in comparison with other media. METHODS: MGIT was evaluated in 10 Italian centers on 433 clinical samples, mainly of respiratory origin and mainly smear positive, in comparison with Löwenstein---Jensen and with one or more other methods represented, according to participating centers, by the BACTEC radiometric method or by the biphasic BBL Septi-Chek AFB system. While MGIT and Löwenstein---Jensen were used for all the samples, 285 of them were also inoculated in BACTEC vials and 274 in biphasic bottles. Of these samples, 132 were investigated with all the four methods. RESULTS: Although less rapid and sensitive than the radiometric method, the results of MGIT were equal when compared with the other two media with respect to overall isolation yield; furthermore, it allowed the detection of growth in significantly shorter times. CONCLUSIONS: The results of this study indicate the value of MGIT for the detection of mycobacteria and, thanks to its extreme simplicity of use, its suitability for small and large laboratories. Its combined use with a solid medium can substantially improve the diagnosis of mycobacterial infection.
Journal Article↗