1/12. Mycobacterium branderi from both a hand infection and a case of pulmonary disease.Mycobacterium branderi, a potential human pathogen first characterized in 1995, has been isolated from respiratory tract specimens. We report here a case in which M. branderi was the only organism isolated upon culture from a hand infection. This isolate, along with a second isolate from a bronchial specimen, was subjected to conventional identification tests for mycobacterial species. Further analysis by high-performance liquid chromatography (HPLC) of mycolic acids and 16S rRNA gene sequencing was performed, and the antibiotic susceptibility profile was determined for both strains. Biochemical tests and the HPLC pattern were consistent with that of M. branderi and M. celatum, which are very similar. The 16S rRNA gene sequence of both strains corresponded to that of M. branderi and enabled us to confidently differentiate this organism from other closely related species such as M. celatum. This contributes to a further understanding of the status of this species as a potential human pathogen as well as illustrating the need for molecular diagnostics as a complementary method for the identification of rare mycobacterial species.- - - - - - - - - - ranking = 1keywords = chromatography (Clic here for more details about this article) |
2/12. Characterization of Mycobacterium bohemicum isolated from human, veterinary, and environmental sources.Chemotaxonomic and genetic properties were determined for 14 mycobacterial isolates identified as members of a newly described species Mycobacterium bohemicum. The isolates recovered from clinical, veterinary, and environmental sources were compared for lipid composition, biochemical test results, and sequencing of the 16S ribosomal dna (rDNA) and the 16S-23S rDNA internal transcribed spacer (ITS) regions. The isolates had a lipid composition that was different from those of other known species. Though the isolates formed a distinct entity, some variations were detected in the features analyzed. Combined results of the phenotypic and genotypic analyses were used to group the isolates into three clusters. The major cluster (cluster A), very homogenous in all respects, comprised the M. bohemicum type strain, nine clinical and veterinary isolates, and two of the five environmental isolates. Three other environmental isolates displayed an insertion of 14 nucleotides in the ITS region; they also differed from cluster A in fatty alcohol composition and produced a positive result in the Tween 80 hydrolysis test. Among these three, two isolates were identical (cluster B), but one isolate (cluster C) had a unique high-performance liquid chromatography profile, and its gas liquid chromatography profile lacked 2-octadecanol, which was present in all other isolates analyzed. Thus, sequence variation in the 16S-23S ITS region was associated with interesting variations in lipid composition. Two of the isolates analyzed were regarded as potential inducers of human or veterinary infections. Each of the environmental isolates, all of which were unrelated to the cases presented, was cultured from the water of a different stream. Hence, natural waters are potential reservoirs of M. bohemicum.- - - - - - - - - - ranking = 2keywords = chromatography (Clic here for more details about this article) |
3/12. Novel mycobacterium related to Mycobacterium triplex as a cause of cervical lymphadenitis.The mycobacterium avium complex (MAC) is an important cause of cervical lymphadenitis in children, and its incidence appears to be increasing in the united states and elsewhere. In areas where mycobacterium tuberculosis is not prevalent, M. avium causes the vast majority of cases of mycobacterial lymphadenitis, although several other nontuberculous mycobacterial species have been reported as etiologic agents. This report describes the case of a child with cervical lymphadenitis caused by a nontuberculous mycobacterium that could not be identified using standard methods, including biochemical reactions and genetic probes. Direct 16S ribosomal dna sequencing showed greater than 99% homology with Mycobacterium triplex, but sequence analysis of the 283-bp 16S-23S internal transcribed spacer (ITS) sequence showed only 95% identity, suggesting that it is a novel species or subspecies within a complex of organisms that includes M. triplex. Mycolic acid high-performance liquid chromatography analysis also identified this isolate as distinct from M. triplex, and differences in susceptibility to streptomycin and rifampin between this strain and M. triplex were also observed. These data support the value of further testing of clinical isolates that test negative with the MAC nucleic acid probes and suggest that standard methods used for the identification of mycobacteria may underestimate the complexity of the genus Mycobacterium. ITS sequence analysis may be useful in this setting because it is easy to perform and is able to distinguish closely related species and subspecies. This level of discrimination may have significant clinical ramifications, as closely related organisms may have different antibiotic susceptibility patterns.- - - - - - - - - - ranking = 1keywords = chromatography (Clic here for more details about this article) |
4/12. Isolation of a novel sequevar of Mycobacterium flavescens from the synovial fluid of an AIDS patient.This report describes the characterisation of a mycobacterium involved in a case of septic arthritis in an AIDS patient that was treated successfully with specific anti-mycobacterial drugs. The biochemical and cultural features, and the mycolic acid pattern as assessed by high-performance liquid chromatography, were fully compatible with the isolate being Mycobacterium flavescens. However, the isolate's 16S rDNA sequence differed by five nucleotides from the two known sequevars of M. flavescens, thus indicating that this isolate belonged to a new 16S rDNA sequevar.- - - - - - - - - - ranking = 1keywords = chromatography (Clic here for more details about this article) |
5/12. Acquired predisposition to mycobacterial disease due to autoantibodies to IFN-gamma.Genetic defects in the IFN-gamma response pathway cause unique susceptibility to intracellular pathogens, particularly mycobacteria, but are rare and do not explain mycobacterial disease in the majority of affected patients. We postulated that acquired defects in macrophage activation by IFN-gamma may cause a similar immunological phenotype and thus explain the occurrence of disseminated intracellular infections in some patients without identifiable immune deficiency. macrophage activation in response to IFN-gamma and IFN-gamma production were studied in whole blood and PBMCs of 3 patients with severe, unexplained nontuberculous mycobacterial infection. In all 3 patients, IFN-gamma was undetectable following mitogen stimulation of whole blood, but significant quantities were detectable in the supernatants of PBMCs when stimulated in the absence of the patients' own plasma. The patients' plasma inhibited the ability of IFN-gamma to increase production of TNF-alpha by both autologous and normal donor PBMCs, and recovery of exogenous IFN-gamma from the patients' plasma was greatly reduced. Using affinity chromatography, surface-enhanced laser desorption/ionization mass spectrometry, and sequencing, we isolated an IFN-gamma-neutralizing factor from the patients' plasma and showed it to be an autoantibody against IFN-gamma. The purified anti-IFN-gamma antibody was shown to be functional first in blocking the upregulation of TNF-alpha production in response to endotoxin; second in blocking induction of IFN-gamma-inducible genes (according to results of high-density cDNA microarrays); and third in inhibiting upregulation of HLA class II expression on PBMCs. Acquired defects in the IFN-gamma pathway may explain unusual susceptibility to intracellular pathogens in other patients without underlying, genetically determined immunological defects.- - - - - - - - - - ranking = 1keywords = chromatography (Clic here for more details about this article) |
6/12. infection of bone by mycobacterium fortuitum masquerading as nocardia asteroides.A case of traumatic osteomyelitis of the leg yielded on culture a branching partially acid-fast organism that failed to respond to therapy directed at nocardia asteroides. Subsequent laboratory investigation revealed the organism to be mycobacterium fortuitum. N. asteroides and M. fortuitum can demonstrate similar staining and morphologic patterns microscopically, as well as common colonial and cultural characteristics. Separation can be aided by careful examination of the branching pattern, and can be established by thin-layer chromatography of lipid extracts of the organism. Correct identification of these species in the laboratory is important because of some overlap in their clinical syndromes and because of differences in their susceptibilities to antibiotics.- - - - - - - - - - ranking = 1keywords = chromatography (Clic here for more details about this article) |
7/12. Isolation of the newly described species Mycobacterium celatum from AIDS patients.Mycobacterium celatum is a recently described species which, on the basis of conventional tests, may be misidentified as mycobacterium xenopi or as belonging to the mycobacterium avium complex. Only genomic sequencing or high-performance liquid chromatography of cell wall mycolic acids can presently allow a correct identification of this mycobacterium. Two cases of infection due to M. celatum, in AIDS patients, are described here. The quantitative susceptibility pattern of the isolates to a wide spectrum of drugs is also reported.- - - - - - - - - - ranking = 1keywords = chromatography (Clic here for more details about this article) |
8/12. Characterization of an isolate of the newly described species Mycobacterium interjectum.The phenotypic features of a clinical isolate of the new species Mycobacterium interjectum, identified on the basis of its 16S rRNA gene sequence, are compared with those of the type strain. The differentiation of M. interjectum from Mycobacterium gordonae or mycobacterium scrofulaceum is not achievable on the basis of phenotypic traits usually tested for mycobacterial speciation, but it can be reached by 16S rRNA gene sequencing or by high performance liquid chromatography (HPLC) of cell wall mycolic acids. The former reveals sequence identity with the signature region of the type species, and the latter yields a profile which is easily differentiated from those of the other two species. The unique HPLC profile of M. interjectum is reported here for the first time and so are the MICs of a wide spectrum of drugs.- - - - - - - - - - ranking = 1keywords = chromatography (Clic here for more details about this article) |
9/12. pneumonia and bacteremia due to Mycobacterium celatum masquerading as mycobacterium xenopi in patients with AIDS: an underdiagnosed problem?A newly described species of mycobacteria, Mycobacterium celatum, has rarely been reported as a cause of localized and disseminated human disease and can easily be misidentified as mycobacterium xenopi when identification is based on biochemical testing alone. We report two cases of pneumonia and bacteremia due to M. celatum in patients with AIDS. In one case, diagnosis and initiation of therapy were delayed by misidentification of the infecting organism as M. xenopi. Genomic analysis or high-performance liquid chromatography is necessary to distinguish the two species. The finding in our two cases and a review of existing literature indicate that pulmonary disease may be an important manifestation of infection with M. celatum, especially in patients with AIDS. Further studies are needed to determine the incidence and clinical relevance of this organism in patients with AIDS and the optimal treatment regimens.- - - - - - - - - - ranking = 1keywords = chromatography (Clic here for more details about this article) |
10/12. Phenotypic and molecular characterization of three clinical isolates of Mycobacterium interjectum.Introduction of molecular biology-based technology into an Australian mycobacterial reference laboratory has resulted in the identification of three isolates of Mycobacterium interjectum in the past 12 months. Conventional phenotypic methods failed to identify the species of these isolates, and high-performance liquid chromatography found that only one of the three isolates had a mycolic acid pattern similar to that of the type strain. In contrast, all three isolates were rapidly identified as M. interjectum by 16S rRNA gene sequence analysis. Two isolates were recovered from the lymph nodes of children with cervical lymphadenitis, confirming the pathogenicity of this organism. However, the third isolate was obtained from the sputum of an elderly male with chronic lung disease without evidence of clinical or radiological progression, suggesting that isolation of M. interjectum should not imply disease. With the increasing use of molecular biology-based technology in mycobacterial laboratories, M. interjectum may be recognized more frequently as a pathogen or commensal organism.- - - - - - - - - - ranking = 1keywords = chromatography (Clic here for more details about this article) |
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