Activity in saline of phthalylated or succinylated derivatives of mycobacterial water-soluble adjuvant.
(1/2823)
A water-soluble fraction (WSA) of the cell wall can substitute for mycobacterial cells in Freund complete adjuvant. However, when WSA is administered in saline instead of in a water-in-oil emulsion, its adjuvant activity is very weak, and under certain experimental conditions it can even inhibit the humoral immune response. The data reported in the present study show that after treatment by phthalic or succinic anhydride the adjuvant activity of WSA was markedly changed, since high levels of circulating antibodies were produced when these derivatives were administered with an antigen in an aqueous medium. Moreover, the antigenic determinants of WSA were modified and acylated WSA had no tuberculin-like activity. (+info)
Role of iron in Nramp1-mediated inhibition of mycobacterial growth.
(2/2823)
Innate resistance to mycobacterial growth is mediated by a gene, Nramp1. We have previously reported that Nramp1 mRNA from macrophages of Mycobacterium bovis BCG-resistant (Bcgr) mice is more stable than Nramp1 mRNA from macrophages of BCG-susceptible (Bcgs) mice. Based on these observations and on reports that show that the closely related Nramp2 gene is a metal ion transporter, we evaluated the effect of iron on the growth of Mycobacterium avium within macrophages as well as on the stability of Nramp1 mRNA. The addition of iron to macrophages from Bcgs mice resulted in a stimulation of mycobacterial growth. In contrast, iron increased the capacity of macrophages from Bcgr mice to control the growth of M. avium. When we treated recombinant gamma interferon (IFN-gamma)-activated macrophages with iron, we found that iron abrogated the growth inhibitory effect of IFN-gamma-activated macrophages from Bcgs mice but that it did not affect the capacity of macrophages from Bcgr mice to control microbial growth. A more detailed examination of the effect of iron on microbial growth showed that the addition of small quantities of iron to resident macrophages from Bcgr mice stimulated antimicrobial activity within a very narrow dose range. The effect of iron on the growth inhibitory activity of macrophages from Bcgr mice was abrogated by the addition of catalase or mannitol to the culture medium. These results are consistent with an Fe(II)-mediated stimulation of the Fenton/Haber-Weiss reaction and hydroxyl radical-mediated inhibition of mycobacterial growth. (+info)
A new rapidly growing mycobacterial species, Mycobacterium murale sp. nov., isolated from the indoor walls of a children's day care centre.
(3/2823)
Scotochromogenic mycobacterial isolates from water-damaged parts of indoor building materials of a children's day care centre represented a phenetically and genetically distinct group of strains. A 16S rDNA dendrogram (1243 bp) showed that the closest species to the new strain MA112/96T was Mycobacterium abscessus. Phylogenetic and phenetic analyses (100 characteristics) grouped the new isolates with M. abscessus, Mycobacterium vaccae, Mycobacterium aurum and Mycobacterium austroafricanum. Ribotyping with Pvull restriction distinguished the 5 isolates from the other 12 most closely related species by the major bands at 6.5-7 kb and 13-15 kb. The cell morphology of the new isolates was typical of mycobacteria, electron microscopy revealed a triple-layered cell wall with an irregular electron-dense outer layer. They grew at 10-37 degrees C, with no growth at 45 degrees C in 5 d. The gene encoding the secreted 32 kDa protein, specific to mycobacteria, was detected by PCR. The main whole-cell fatty acids were characterized by high tuberculostearic acid 10Me-C18:0 (17% at 28 degrees C), which increased with increasing growth temperature (22% at 37 degrees C). The other main fatty acids were C18:1 cis9 and C16:0 (21-20% each), followed by, C17:1 cis9 (14%), C16:1 cis10 (8%) and also a high amount of C20 alcohol (9%). alpha-Mycolic acids, keto-mycolates and wax esters were present (C60-C90), MK-9(H2) (90%) and MK-8(H2) were the main menaquinones. The cellular phospholipids were phosphatidylethanolamine, phosphatidylinositol, phosphatidyl inositolmannosides and diphosphatidylglycerol. Polyamine content was low. G+C content was 72.9 mol%. The new isolates are proposed as a new species, Mycobacterium murale sp. nov. The type strain is MA112/96T (= DSM 44340T). (+info)
Enzymatic and immunological characterization of the Mycobacterium fortuitum complex.
(4/2823)
The arylsulfatase isozymes of Mycobacterium fortuitum, M. peregrinum, M. chelonei subsp. chelonei, and M. chelonei subsp. abscessus were examined to determine the isozymal and immunological relationship among the members of the M. fortuitum complex. Cell extracts were subjected to electrophoresis on agarose and polyacrylamide gel, and arylsulfatase activity was localized using beta-naphthyl sulfate as substrate. Unique zymograms were produced for M. fortuitum, M. peregrinum, and M. chelonei which were characteristic for each species. The immunological relationship among the sulfatases was assayed by using immunodiffusion and immunoelectrophoresis followed by sulfatase staining for the enzyme. One of the isozymes of M. fortuitum and M. peregrinum cross-reacted, showing immunological identity. Antisera to sulfatases of M. fortuitum and M. peregrinum did not react with sulfatases of M. chelonei. The characterization of sulfatase isozymes in extracts of organisms in the M. fortuitum complex suggests the division of the M. fortuitum complex into two species, M. fortuitum and M. chelonei, with subspecies designations. (+info)
Evolutionary relationships among diverse bacteriophages and prophages: all the world's a phage.
(5/2823)
We report DNA and predicted protein sequence similarities, implying homology, among genes of double-stranded DNA (dsDNA) bacteriophages and prophages spanning a broad phylogenetic range of host bacteria. The sequence matches reported here establish genetic connections, not always direct, among the lambdoid phages of Escherichia coli, phage phiC31 of Streptomyces, phages of Mycobacterium, a previously unrecognized cryptic prophage, phiflu, in the Haemophilus influenzae genome, and two small prophage-like elements, phiRv1 and phiRv2, in the genome of Mycobacterium tuberculosis. The results imply that these phage genes, and very possibly all of the dsDNA tailed phages, share common ancestry. We propose a model for the genetic structure and dynamics of the global phage population in which all dsDNA phage genomes are mosaics with access, by horizontal exchange, to a large common genetic pool but in which access to the gene pool is not uniform for all phage. (+info)
Central line sepsis in a child due to a previously unidentified mycobacterium.
(6/2823)
A rapidly growing mycobacterium similar to strains in the present Mycobacterium fortuitum complex (M. fortuitum, M. peregrinum, and M. fortuitum third biovariant complex [sorbitol positive and sorbitol negative]) was isolated from a surgically placed central venous catheter tip and three cultures of blood from a 2-year-old child diagnosed with metastatic hepatoblastoma. The organism's unique phenotypic profile and ribotype patterns differed from those of the type and reference strains of the M. fortuitum complex and indicate that this organism may represent a new pathogenic taxon. (+info)
Comparison of the MB/BacT and BACTEC 460 TB systems for recovery of mycobacteria from various clinical specimens.
(7/2823)
A total of 1,830 specimens (75.7% respiratory and 24.3% nonrespiratory) were cultured in parallel with the MB/BacT and BACTEC 460 TB systems and on Lowenstein-Jensen (LJ) medium. Mycobacteria were identified from 173 (6.5%) specimens. The most common species recovered were Mycobacterium tuberculosis complex (65. 9%), Mycobacterium avium complex (22.5%), and Mycobacterium chelonae (9.2%). The recovery rates by individual systems were 96.5, 99.4, and 95.9% for MB/BacT, BACTEC 460 TB, and LJ medium, respectively, for all mycobacteria; the recovery rates were 99.1, 100, and 98.2%, respectively, for M. tuberculosis complex alone. The difference among the recovery rates for all mycobacteria and those for individual species was not significant. The BACTEC 460 TB system detected M. tuberculosis isolates more rapidly than the MB/BacT system (8 versus 11.8 days for smear-positive specimens [P < 0.01] and 18 versus 21 days for smear-negative specimens [P < 0.05]), whereas the MB/BacT system more rapidly detected the nontuberculous mycobacteria (17.1 versus 12.7 days [P < 0.01]). These results indicate that the nonradiometric MB/BacT system is a rapid, sensitive, and efficient method for the recovery of M. tuberculosis and nontuberculous mycobacteria from both pulmonary and extrapulmonary clinical specimens. (+info)
Microbial oxidation and assimilation of propylene.
(8/2823)
Hydrocarbon-utilizing microorganisms in our culture collection oxidized propylene but could not utilize it as the sole source of carbon and energy. When propane-grown cells of Mycobacterium convulutum were placed on propylene, acrylate, the terminally oxidized, three-carbon unsaturated acid, accumulated. A mixed culture and an axenic culture (strain PL-1) that utilized propylene as the sole source of carbon and energy were isolated from soil. Respiration rates, enzyme assays, fatty acid profiles, and 14CO2 incorporation experiments suggest that both the mixed culture and strain PL-1 oxidize propylene via attack at the double bond, resulting in a C2+C1 cleavage of the molecule. (+info)