Pirjo Torkko

Mycobacteria and Fungi in Moisture-Damaged Building Materials

ABSTRACT In contrast to the growth of fungi, the growth of mycobacteria in moisture-damaged building materials has rarely been studied. Environmental mycobacteria were isolated from 23% of samples of moisture-damaged materials (n = 88). The occurrence of mycobacteria increased with increasing concentrations of fungi. Mycobacteria may contribute to indoor exposure and associated adverse health effects.

Mycobacterium arosiense sp. nov., a slowly growing, scotochromogenic species causing osteomyelitis in an immunocompromised child.

A yellow-pigmented, scotochromogenic, slowly growing mycobacterial strain, designated T1921(T), was isolated from the disseminated osteomyelitic lesions of a 7-year-old child with an underlying partial gamma interferon receptor alpha-1 deficiency. Hybridization by the line probe assay indicated the presence of a Mycobacterium species. Sequencing of the 16S rRNA gene, the internally transcribed spacer (ITS) region and the hsp65 and rpoB genes revealed that strain T1921(T) could be differentiated from all recognized species of the genus Mycobacterium. Phylogenetic analysis based on the 16S rRNA gene indicated that strain T1921(T) was related most closely to Mycobacterium intracellulare, whereas analysis based on the ITS and hsp65 and rpoB genes indicated that it was most closely related to Mycobacterium avium. Phenotypic tests were not able to differentiate strain T1921(T) from similar slowly growing mycobacteria. Strain T1921(T) is considered to represent a novel species of the genus Mycobacterium, for which the name Mycobacterium arosiense sp. nov. is proposed. The type strain is T1921(T) (=DSM 45069(T) =ATCC BAA-1401(T)).

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).

Mycobacterium xenopi and related organisms isolated from stream waters in Finland and description of Mycobacterium botniense sp. nov.

Three scotochromogenic Mycobacterium xenopi-like organisms were isolated from stream waters in Finland. These strains grew at 36-50 degrees C but not at 30 degrees C. One of the three strains was fully compatible with the M. xenopi type strain according to GLC-MS, biochemical tests, and 16S rDNA and 16S-23S rDNA internal transcribed spacer (ITS) sequencing. Two of the strains closely resembled M. xenopi in lipid analyses and biochemical tests, but analysis by GLC-MS verified the presence of two new marker fatty acids (2,4,6,x-tetramethyl-eicosanoic acid and 2,4,6,x,x-pentamethyl-docosanoic acid). The 16S rDNA and ITS region sequences of these two strains differed from those of M. xenopi and other previously described mycobacterial sequences. Therefore, the strains are regarded as new species of slow-growing mycobacteria, for which the name Mycobacterium botniense sp. nov. is proposed. The chemical, physical and microbiological quality of the water reservoirs of M. xenopi and M. botniense are described. As far as is known, this is the first time that M. xenopi has been isolated from natural waters. The strains of M. botniense sp. nov. (E347T and E43) have been deposited in the ATCC as strains 700701T and 700702, respectively.

Characterization of Mycobacterium bohemicum Isolated from Human, Veterinary, and Environmental Sources

ABSTRACT 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 ofM. bohemicum.