Gas-chromatographic lipid profiles in identification of currently known slowly growing environmental mycobacteria

The prevalence of non-tuberculous mycobacterial infections in mainland China: Systematic review and meta-analysis

Despite increasing attention towards the non-tuberculous mycobacterial (NTM) diseases, the overall epidemiological information remains unavailable for China. A systematic review and meta-analysis was conducted using data of 105 qualified publications from Chinese mainland. The assay demonstrated that the prevalence of NTM infections among tuberculosis suspects was 6.3% (5.4%-7.4%) in mainland, while the Southeastern region had the highest NTM prevalence at 8.6% (7.1%-10.5%). In Northern China, slow growing mycobacteria (SGM) consistituted 63.7% of all the NTM isolates, while this rate in Southern China was 53.0%. More rapid growing mycobacteria (RGM) were present in southern China than the northern (χ² = 57.996, P < 0.001). According to the coastal provinces' data (from north to south), the NTM prevalence rate and the number of isolated NTM species increased apparently in accordance with geographic latitude. The information obtained in this assay will facilitate the NTM disease diagnosis and screening policy making in China.

Mycobacterium heckeshornense peritonitis in a peritoneal dialysis patient: a case report and review of the literature

We report the first case of peritonitis attributed to Mycobacterium heckeshornense. This is a rare, non-tuberculous mycobacterium that has been reported as an aetiological agent in a growing number and widening spectrum of infections.

Real-time PCR detection of environmental mycobacteria in house dust

Analysing the number and species of microbes in indoor dust is needed for assessment of human exposure to microbes in dwellings. Environmental mycobacteria are common heterotrophic bacteria in both natural and man-made environments and potential inducers of human immune system. Culture of mycobacteria from samples rich with other microbes is difficult due to the slow growth rate of mycobacteria and this has hampered the studies on their role in indoor human exposure. A quantitative, real-time 5'-nuclease (TaqMan) PCR assay was developed to detect environmental mycobacteria in indoor dust samples. The specificity of the primers and the probe targeting the 16S rDNA of mycobacteria, tested with 26 mycobacterial and 10 non-mycobacterial but related species, proved to be high. When tested on 20 indoor dust samples collected from five homes, the assay gave counts varying between 4.8 x 10(4) and 7.2 x 10(6)cell/g, being on average 1.1 x 10(3) times higher than culture. Seasonal variation in the dust counts of mycobacteria was observed by both culture and qPCR. Total of 140 isolates considered as mycobacteria by Ziehl-Neelsen staining and GLC-analyses were subjected to PCR analysis with the mycobacterial primers, and 39 isolates to partial 16S rDNA sequencing. All proved to be mycobacteria and revealed high diversity of mycobacterial species in the dust samples. Majority of the sequences were related to M. terrae and M. avium complexes.

Notes on the characterization of prokaryote strains for taxonomic purposes

Taxonomy relies on three key elements: characterization, classification and nomenclature. All three elements are dynamic fields, but each step depends on the one which precedes it. Thus, the nomenclature of a group of organisms depends on the way they are classified, and the classification (among other elements) depends on the information gathered as a result of characterization. While nomenclature is governed by the Bacteriological Code, the classification and characterization of prokaryotes is an area that is not formally regulated and one in which numerous changes have taken place in the last 50 years. The purpose of the present article is to outline the key elements in the way that prokaryotes are characterized, with a view to providing an overview of some of the pitfalls commonly encountered in taxonomic papers.

Mycobacterium heckeshornense tenosynovitis

We describe the first case of tenosynovitis due to Mycobacterium heckeshornense, a mycobacterium characterized in 2000 and only incriminated in a few previous cases of infections. Molecular identification of this pathogen included 16S rRNA and hsp65 gene sequencing. M. heckeshornense may cause a wide spectrum of human infectious diseases and may be underestimated due to its phenotypic relatedness with Mycobacterium xenopi.

Analysis of fatty acids in sputum from patients with pulmonary tuberculosis using gas chromatography-mass spectrometry preceded by solid-phase microextraction and post-derivatization on the fiber

A method based on solid-phase microextraction (SPME) and post-derivatization on the fiber coupled to gas chromatography-mass spectrometry (GC-MS) was developed for the analysis of fatty acids in sputum from patients with pulmonary tuberculosis. The sputum specimens were digested, hydrolyzed, extracted, derivertized, injected and analyzed without cultivation or isolation of the microorganism. Under optimized conditions, the relative standard deviations (RSD, n=5) for all analytes were below 17% and the limits of detection varied from 1.68 (C(24:0)) to 150.4 microg L(-1) (C(12:0)). Good linearity was observed for all the fatty acids studied except for C(12:0) within a wide concentration range of three orders of magnitudes with the correlation coefficients ranging from 0.91 (C(24:0)) to 0.99 (C(14:0)). Fatty acids in sputum specimens from 21 persons were directly analyzed using the proposed method. The results show that in all the sputum specimens from patients, who were clinically diagnosed with tuberculosis (TB), tuberculosis stearic acid (TBSA) was detected, while in all the sputum samples from persons without TB, TBSA was not found. The possibility of using the proposed method to detect mycobacterium tuberculosis (MTB) via the identification of TBSA in sputum was discussed. The comparison with other methods including sputum culture and microscopy of direct smears indicated that the proposed method is fast and sensitive for the analysis of fatty acids in sputum and offers an alternative for the detection of MTB in sputum.

First case of Mycobacterium heckeshornense lymphadenitis

Mycobacterium heckeshornense is a slow-growing nontuberculous mycobacterium first characterized in 2000. It is reported to cause lung disease and tenosynovitis. We report a case of isolated massive axillary lymphadenopathy in an elderly woman, where histology showed necrotizing granulomata and M. heckeshornense was isolated as the causative organism.

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)).

Diagnostic application of genotypic identification of mycobacteria

This study evaluated conventional methods, GLC and three molecular tests, including 16S rRNA sequencing, for the identification of mycobacteria, and the experiences of the authors with the integration of these methods into a diagnostic clinical laboratory were also recorded. Of 1067 clinical isolates of mycobacteria identified by conventional tests, 365 were tested by Accuprobe hybridization assays and PCRs specific for Mycobacterium tuberculosis (MTB) complex or Mycobacterium avium complex (MAC), 202 were tested by 16S rRNA sequencing, and 142 were tested by GLC. Three runs of all tests were performed on a weekly basis. The identifications for 209 MTB complex and 118 MAC isolates obtained by species-specific PCR were in complete agreement with AccuProbe hybridization and conventional test results. The 16S rRNA sequence-based identification, at a similarity of > or =99 %, for 132 of 142 isolates was concordant with the identifications made by the biochemical methods, and for 134 isolates was concordant with the identifications made by GLC at species, group or complex level. 16S rRNA sequencing resulted in fewer incorrectly identified or unidentified organisms than GLC or conventional tests. For the slowly growing non-tuberculous mycobacteria, the mean turnaround times for identification were 4-5 days for 16S rRNA sequencing, 14-29 days for GLC and 22-23 days for conventional methods. Considering the large proportion of some species among clinical isolates, a strategy of initial screening with species-specific PCR (or AccuProbe assays) for the MTB complex and MAC, followed by direct sequencing of the strains that yield negative results, should make 16S rRNA sequencing more affordable for routine application in diagnostic laboratories.

Fluorescence in situ hybridization using peptide nucleic acid probes for rapid detection of Mycobacterium avium subsp. avium and Mycobacterium avium subsp. paratuberculosis in potable-water biofilms

Here, we present for the first time a high-affinity peptide nucleic acid (PNA) oligonucleotide sequence for detecting Mycobacterium avium bacteria, including the opportunistically pathogenic subspecies M. avium subsp. avium, M. avium subsp. paratuberculosis, and M. avium subsp. silvaticum, by the fluorescence in situ hybridization (FISH) method. There is evidence that M. avium subsp. avium especially is able to survive and grow in drinking-water biofilms and possibly transmit via drinking water. The designed PNA probe (MAV148) specificity was tested with several bacterial species, including other mycobacteria and mycolic acid-containing bacteria. From the range of bacterial strains tested, only M. avium subsp. avium and M. avium subsp. paratuberculosis strains were hybridized. The PNA FISH method was applied successfully to detect M. avium subsp. avium spiked in water samples and biofilm established within a Propella biofilm reactor fed with potable water from a distribution supply.

Mycobacterium florentinum sp. nov., isolated from humans

Eight mycobacterial strains isolated during an 11 year period from the sputum of independent patients with various pulmonary disorders and, in one case, from a lymph node of a young girl, were found to present identical features. Phenotypic and genotypic characteristics revealed that the most closely related species to these test isolates were Mycobacterium triplex and Mycobacterium lentiflavum. However, the lipids of the cell wall of the test isolates differed from those of the latter species by TLC and presented unique profiles by both GC and HPLC. Genotypic analysis showed that they had unique 16S rRNA gene and internal transcribed spacer (ITS) sequences, and could be differentiated from all other mycobacterial strains by PCR restriction analysis of hsp65. The strains presented high resistance to antimycobacterial drugs. The name Mycobacterium florentinum sp. nov. is proposed for this taxon, with strain FI-93171T (=DSM 44852T=CIP 108409T) as the type strain.

Mycobacteria in drinking water distribution systems: ecology and significance for human health

In contrast to the notorious pathogens Mycobacterium tuberculosis and M. leprae, the majority of the mycobacterial species described to date are generally not considered as obligate human pathogens. The natural reservoirs of these non-primary pathogenic mycobacteria include aquatic and terrestrial environments. Under certain circumstances, e.g., skin lesions, pulmonary or immune dysfunctions and chronic diseases, these environmental mycobacteria (EM) may cause disease. EM such as M. avium, M. kansasii, and M. xenopi have frequently been isolated from drinking water and hospital water distribution systems. Biofilm formation, amoeba-associated lifestyle, and resistance to chlorine have been recognized as important factors that contribute to the survival, colonization and persistence of EM in water distribution systems. Although the presence of EM in tap water has been linked to nosocomial infections and pseudo-infections, it remains unclear if these EM provide a health risk for immunocompromised people, in particular AIDS patients. In this regard, control strategies based on maintenance of an effective disinfectant residual and low concentration of nutrients have been proposed to keep EM numbers to a minimum in water distribution systems.

Mycobacterium heckeshornense infection in an immunocompetent patient and identification by 16S rRNA sequence analysis of culture material and a histopathology tissue specimen

Mycobacterium heckeshornense is a rare isolate in clinical specimens. We performed simultaneous 16S rRNA sequence analysis of a mycobacterium culture and a histopathology specimen to determine the relevance of M. heckeshornense infection in an immunocompetent patient initially presenting with pneumothorax.

The genetics of nontuberculous mycobacterial infection

The molecular aetiology of familial susceptibility to disseminated mycobacterial disease, usually involving weakly pathogenic strains of mycobacteria, has now been elucidated in more than 30 families. Mutations have been identified in five genes in the interleukin-12-dependent interferon-gamma pathway, highlighting the importance of this pathway in human mycobacterial immunity. Knowledge derived from the study of these rare patients contributes to our understanding of the immune response to common mycobacterial pathogens such as Mycobacterium tuberculosis and Mycobacterium leprae, which remain major public health problems globally. This knowledge can be applied to the rational development of novel therapies and vaccines for these important mycobacterial diseases.