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Query: UMLS:C0026918 (Mycobacterium)
 52,428 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The cell wall of mycobacteria is an efficient permeability barrier that makes mycobacteria naturally resistant to most antibiotics. Liposome swelling assays and planar bilayer experiments were used to investigate the diffusion process of hydrophilic molecules through the cell wall of Mycobacterium chelonae and identify the main hydrophilic pathway. A 59-kilodalton cell wall protein formed a water-filled channel with a diameter of 2.2 nanometers and an average single-channel conductance equal to 2.7 nanosiemens in 1 M potassium chloride. These results suggest that porins can be found in the cell wall of a Gram-positive bacterium. A better knowledge of the hydrophilic pathways should help in the design of more effective antimycobacterial agents.
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PMID:Porins in the cell wall of mycobacteria. 127 10

Cyclosporin A (CsA), which is an immunosuppressive drug of helper T lymphocytes, diminished a resistance of mice to influenza virus infection. Mice inoculated intravenously with trehalose-6,6'-dimycolate (TDM, a glycolipid component of the cell wall of Mycobacterium) in an oil-in-water emulsion (TDM emulsion) recovered the resistance to influenza virus infection impaired by CsA. Number of antibody-producing cells was markedly reduced in CsA- and/or TDM-treated mice. Interferon production in lung of TDM-treated mice was augmented; however, it was extremely reduced not only in CsA-treated mice, but also in CsA- and TDM-treated mice. Activities of natural killer cells of CsA- and/or TDM-treated mice were not different from that of control mice. Numbers of lymphocytes in lung of TDM-treated mice and CsA- and TDM-treated mice were more predominantly increased than that of control mice. Analysis of lung lymphocytes by flow cytometry revealed no difference between the populations of L3T4+ T lymphocytes and Lyt-2.2+ T lymphocytes in CsA- and/or TDM-treated mice and the populations in control mice. However, the population of gamma delta T cell receptor positive (gamma delta TCR+) lymphocytes increased markedly in lung of TDM-treated mice and also CsA- and TDM-treated mice. In vitro experiments showed that macrophage cultures treated with TDM emulsion released a mediator(s) which activates T lymphocytes, but not B lymphocytes. These and our earlier results suggest that the recovered anti-influenza virus resistance of CsA-treated mice by treatment with TDM emulsion was caused by elicitation of macrophages with TDM, then activation of T lymphocytes, especially gamma delta TCR+ lymphocytes.
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PMID:Mechanisms of augmented resistance of cyclosporin A-treated mice to influenza virus infection by trehalose-6,6'-dimycolate. 128 53

When Mycobacterium lepraemurium is grown on the 1% Ogawa yolk medium, it produces a specific odor. This odor was not observed in other easily cultivable acid-fast bacilli. Therefore, identification of the components responsible for the specific odor produced by M. lepraemurium was attempted. The odor components were extracted for overnight with sterilized and distilled water from the Ogawa yolk medium on which M. lepraemurium had been cultivated for two months. The odor components in the extract was adsorbed on refined charcoal. After washing with distilled water for three times, the charcoal was dried. Then the odor components were eluted from the charcoal with ethanol and the eluate was condensed under nitrogen gas flow at 40 degrees C. The condensate was analyzed by Gas-Chromatography-Mass-Spectrum (GC-MS). Phenylethanol and phenylacetic acid were identified as major odor components. A mixture of authentic phenylacetic acid, its methyl and ethyl esters, smelled similar to the odor of cultivated medium of M. lepraemurium. Thus, phenylacetic acid was identified as the key odor component produced by M. lepraemurium. When initial isolation culture of M. lepraemurium from murine leproma was cultivated on the Ogawa yolk medium by adding phenylacetic acid, growth inhibition was brought by the compound.
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PMID:[Specific odor component produced by Mycobacterium lepraemurium on Ogawa yolk medium]. 128 85

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.
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PMID:Biologically distinct subtypes of Mycobacterium avium differ in possession of insertion sequence IS901. 812 98

The occurrence of mycobacteria was studied in 50 biofilm samples from water treatment plants, domestic water supply systems and aquaria. Mycobacteria were found in 90% of the samples and their densities usually ranged between 10(3) and 10(4) cfu/cm2 (maximum density 5.6 x 10(6) cfu/cm2). Organic substances such as plastics and rubber were usually colonized by larger numbers of mycobacteria than inorganic substances such as copper and glass. The highest mycobacterial densities were found on plastic surfaces which were continuously perfused with water at temperatures between 22 and 30 degrees C. The species identified include Mycobacterium chelonae, M. flavescens, M. fortuitum, M. gordonae, M. kansasii, and M. terrae/nonchromogenicum. The occurrence in microcolonies indicate that biofilms may be an important replication site of aquatic mycobacteria.
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PMID:Occurrence of mycobacteria in biofilm samples. 142 46

I compared counting efficacies of CFU-enumerating method for the number of mycobacteria (Mycobacterium intracellulare and M. fortuitum) locating in cultured macrophages with that of microscopic counting method. Zymosan A-induced macrophages from ddY mice were infected with either M. intracellulare or M. fortuitum by incubation in 10% FBS-RPMI 1640 medium containing the organisms for 1 hr, thereafter thoroughly washed to remove extracellular bacilli, and cultured for 3 to 5 days. At intervals, macrophages were thoroughly rinsed and subjected to either CFU-enumeration or microscopic counting, as follows. In the former method, macrophages were lysed with 0.2% Tween 80-distilled water by sonication using Handy Sonic and CFUs were counted on 7H11 agar plates. In the latter method, the number of acid-fast bacilli was counted by microscopy for macrophages after Ziehl-Toda's staining. The number of bacteria by the CFU-enumerating method was much greater than that by the microscopic counting method.
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PMID:[Counting efficacies of the CFU-enumerating method and microscopic counting method for mycobacteria located in cultured macrophages]. 145 68

Mycobacterium xenopi is infrequently recognized as a cause of pulmonary disease. During a 12-year survey (1978-89),. 108 strains of this Mycobacterium were isolated from 90 persons and 6 hot water samples. From 87 patients 89 occasional strains of M. xenopi were isolated, and 3 patients were diagnosed as having pulmonary mycobacteriosis caused by it. The treatment and the response in these three cases were variable, depending on clinical conditions and sensitivity to drugs. Most of the strains isolated came from patients hospitalized at the Barzilai Hospital, Ashkelon, therefore a local environmental contamination was suspected. The suspicion was confirmed by the isolation of this thermophile organism from the hot water samples of the above hospital.
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PMID:Mycobacterium xenopi, a potential human pathogen. 146 88

Gas chromatography-mass spectrometry (GC-MS) was used to detect 2-docosanol, a secondary alcohol characteristic of Mycobacterium xenopi, in 7 of 10 analyzed drinking water samples culture positive for that species. GC-MS was also used to detect tuberculostearic acid. Both of these chemical markers were analyzed as halogenated derivatives in the negative-ion-chemical-ionization mode. The numbers of CFU of M. xenopi were lowest in the three GC-MS-negative samples. The described GC-MS method is useful for the rapid detection of M. xenopi in drinking water.
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PMID:Application of gas chromatography-mass spectrometry for rapid detection of Mycobacterium xenopi in drinking water. 148 79

Between December 5, 1989, and September 25, 1990, Mycobacterium chelonae was isolated from endoscopic or bronchial washings in 14 patients on a single clinical service. A phenotypically unique strain of M. chelonae subspecies abscessus that was highly resistant to cefoxitin (MIC greater than 256 micrograms/ml) and different from 13 control isolates of M. chelonae recovered elsewhere in the hospital was identified in all these patients and the rinse water from the bronchoscope disinfecting machine. None of the outbreak patients had evidence of invasive M. chelonae disease. Aggressive infection control measures on the disinfecting machine, including use of sterile water in the wash and rinse cycles, increasing the 2% alkaline glutaraldehyde exposure time, frequent replacement of the glutaraldehyde, and disinfection of the machine, failed to eradicate the M. chelonae, presumably because of the presence of a biofilm inside the machine. Rinsing the scopes with 70% alcohol after automated disinfection eliminated the outbreak strain. This study demonstrates that automated bronchoscope disinfecting machines may become heavily contaminated with mycobacteria that resist usual disinfection, resulting in a source of bronchoscope contamination.
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PMID:Contamination of flexible fiberoptic bronchoscopes with Mycobacterium chelonae linked to an automated bronchoscope disinfection machine. 155 14

The absence of disease due to Mycobacterium avium in Ugandan patients with AIDS, which we previously observed in a blood culture study, has been confirmed and our observations have been extended to 165 additional clinical isolates. Fourteen soil and water samples from the Ugandan environment have been cultured and revealed a high frequency of isolation of M. avium. The absence of M. avium complex disease in Uganda remains unexplained.
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PMID:Absence of Mycobacterium avium complex disease in patients with AIDS in Uganda. 156 Mar 44


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