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      Molecular analysis of Mycobacterium isolates from extrapulmonary specimens obtained from patients in Mexico

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          Abstract

          Background

          Little information is available on the molecular epidemiology in Mexico of Mycobacterium species infecting extrapulmonary sites in humans. This study used molecular methods to determine the Mycobacterium species present in tissues and body fluids in specimens obtained from patients in Mexico with extrapulmonary disease.

          Methods

          Bacterial or tissue specimens from patients with clinical or histological diagnosis of extrapulmonary tuberculosis were studied. DNA extracts from 30 bacterial cultures grown in Löwenstein Jensen medium and 42 paraffin-embedded tissues were prepared. Bacteria were cultured from urine, cerebrospinal fluid, pericardial fluid, gastric aspirate, or synovial fluid samples. Tissues samples were from lymph nodes, skin, brain, vagina, and peritoneum. The DNA extracts were analyzed by PCR and by line probe assay (INNO-LiPA MYCOBACTERIA v2. Innogenetics NV, Gent, Belgium) in order to identify the Mycobacterium species present. DNA samples positive for M. tuberculosis complex were further analyzed by PCR and line probe assay (INNO-LiPA Rif.TB, Innogenetics NV, Gent, Belgium) to detect mutations in the rpoB gene associated with rifampicin resistance.

          Results

          Of the 72 DNA extracts, 26 (36.1%) and 23 (31.9%) tested positive for Mycobacterium species by PCR or line probe assay, respectively. In tissues, M. tuberculosis complex and M. genus were found in lymph nodes, and M. genus was found in brain and vagina specimens. In body fluids, M. tuberculosis complex was found in synovial fluid. M. gordonae, M. smegmatis, M. kansasii, M. genus, M. fortuitum/M. peregrinum complex and M. tuberculosis complex were found in urine. M. chelonae/M. abscessus was found in pericardial fluid and M. kansasii was found in gastric aspirate. Two of M. tuberculosis complex isolates were also PCR and LiPA positive for the rpoB gene. These two isolates were from lymph nodes and were sensitive to rifampicin.

          Conclusion

          1) We describe the Mycobacterium species diversity in specimens derived from extrapulmonary sites in symptomatic patients in Mexico; 2) Nontuberculous mycobacteria were found in a considerable number of patients; 3) Genotypic rifampicin resistance in M. tuberculosis complex infections in lymph nodes was not found.

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          Most cited references24

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          Pulmonary disease due to nontuberculous mycobacteria.

          Nontuberculous mycobacteria (NTM) are increasingly associated with pulmonary disease. This is a worldwide phenomenon and one that is not related just to better diagnostic techniques or HIV infection. The mode of transmission of NTM is not well defined, but environmental exposure may be the major factor. While most exposed and infected individuals never acquire NTM disease, some ostensibly immunocompetent persons will. Although our understanding of the pathogenesis of NTM disease is incomplete, we believe that both host and mycobacterial factors are involved. Among the former, interferon-gamma"trafficking" may well play a central role. When disease occurs, it is likely to present in one of three prototypical forms: a tuberculosis-like pattern often affecting older male smokers with COPD; nodular bronchiectasis classically occurring in middle-aged or older women who never smoked and present with cough; and hypersensitivity pneumonitis following environmental exposure. While Mycobacterium avium complex has been described with all three forms, many other NTM can produce one or another of them; variants of these prototypes also exist. Diagnosis of NTM disease relies on microbiology and chest CT scanning, and criteria to aid diagnosis are available. Treatment of disease depends on the species involved, extent and form of disease, and overall condition of the patient. Surgery for localized disease may be useful for those species expected to be refractory to medical therapy. Observation without treatment may be appropriate for some patients with slowly progressive disease that is expected to be particularly difficult to treat.
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            The new mycobacteria: an update.

            The continuous evolution of mycobacterial taxonomy may represent a source of confusion for laboratories and clinicians. Apart from the obvious pathogenic strains of the Mycobacterium tuberculosis complex, Mycobacterium leprae and Mycobacterium ulcerans, the role of other mycobacteria may be associated with varying conditions ranging from contamination to specific disease processes. Of the more than 120 mycobacterial species recognized currently, very few have not been reported as pathogenic in humans or animals. Although the attempt to keep pace with the steadily increasing number of mycobacterial species seems hopeless, a careful review of the recent literature relevant to the newly described species may be advantageous. The aim of this present update is to provide epidemiological and clinical information along with major phenotypic and genotypic characteristics of the species described in the last 3 years.
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              Identification of the causative organism of tuberculous lymphadenitis in ethiopia by PCR.

              Tuberculous lymphadenitis (TBLN) is a common form of extrapulmonary tuberculosis with multiple differential diagnoses. Demonstration of the etiologic agent by smear microscopy or culture of fine needle aspirate (FNA) specimens is often unsuccessful. FNA specimens from 40 patients presenting at a rural health center in South Ethiopia and diagnosed as positive for TBLN on the basis of clinical and cytological criteria were analyzed for mycobacterial DNA by PCR. Thirty (75%) had cervical lymphadenitis and 11 (27.5%) were seropositive for human immunodeficiency virus (HIV). Three primer sets were initially used to identify the causative agent at the genus (antigen 85 complex), complex (IS6110 insertion sequence), and species (pncA gene and allelic variation) levels. Among the forty TBLN cases, 35 (87.5%) were positive by PCR at the genus and complex levels. Based on PCR for detection of allelic variation at position 169, 24 (68.6%) of the 35 were positive for Mycobacterium tuberculosis and 6 (17.1%) were positive for M. bovis. These six were positive in additional PCR assays using the JB21-JB22 primer set, which is highly specific for M. bovis. Five (14.1%) showed amplification for both M. tuberculosis and M. bovis with the allele-specific primer set. Cooccurrence of pyrazinamide (PZA)-sensitive and -resistant M. tuberculosis in those five cases was indicated, since all were negative in assays with the JB21-JB22 primer set. This feature was seen in 3 of 11 HIV-positive and 2 of 29 HIV-negative individuals (P < 0.001). among 35 PCR-positive cases of TBLN from southern Ethiopia, 29 (82.9%) were caused by M. tuberculosis and six (17.1%) were caused by M. bovis.
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                Author and article information

                Journal
                BMC Clin Pathol
                BMC Clinical Pathology
                BioMed Central
                1472-6890
                2009
                9 March 2009
                : 9
                : 1
                Affiliations
                [1 ]Department of Microbiology, Faculty of Medicine, Juárez University of Durango State, Durango, Mexico
                [2 ]Department of Pharmacology, Faculty of Medicine, Juárez University of Durango State, Durango, Mexico
                [3 ]Regional Laboratory of Epidemiological Reference, Mexican Social Security Institute, Guadalajara, Mexico
                [4 ]Medical Research Unit, Mexican Social Security Institute, Zacatecas, México
                [5 ]Department of Pathology, Faculty of Medicine, Juárez University of Durango State, Durango, Mexico
                [6 ]Department of Microbiology and Parasitology, University Center of Health Sciences, University of Guadalajara, Guadalajara, Mexico
                [7 ]R&D Diagnostics, Innogenetics NV, Gent, Belgium
                Article
                1472-6890-9-1
                10.1186/1472-6890-9-1
                2660362
                19272158
                01f7e47e-8cd6-4198-8624-849c1707f2e6
                Copyright © 2009 Alvarado-Esquivel et al; licensee BioMed Central Ltd.

                This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

                History
                : 13 July 2008
                : 9 March 2009
                Categories
                Research Article

                Pathology
                Pathology

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