Discovery of a novel hsp65 genotype within Mycobacterium massiliense associated with the rough colony morphology

The synergetic effect of sitafloxacin-arbekacin combination in the Mycobacterium abscessus species

Mycobacterium abscessus species (MABS) is the most commonly isolated rapidly growing mycobacteria (RGM) and is one of the most antibiotic-resistant RGM with rapid progression, therefore, treatment of MABS is still challenging. We here presented a new combination treatment with sitafloxacin that targeted rough morphotypes of MABS, causing aggressive infections. Thirty-four clinical strains of MABS were isolated from various clinical samples at the Juntendo university hospital from 2011 to 2020. The susceptibility to a combination of sitafloxacin and antimicrobial agents was compared to that of the antimicrobial agents alone. Out of 34 MABS, 8 strains treated with sitafloxacin-amikacin combination, 9 of sitafloxacin-imipenem combination, 19 of sitafloxacin-arbekacin combination, and 9 of sitafloxacin-clarithromycin combination showed synergistic effects, respectively. Sitafloxacin-arbekacin combination also exhibited the synergistic effects against 10 of 22 Mycobacterium abscessus subspecies massiliense (Mma) strains and 8 of 11 Mycobacterium abscessus subspecies abscessus (Mab) strains, a highly resistant subspecies of MABS. The sitafloxacin-arbekacin combination revealed more synergistic effects in rough morphotypes of MABS (p = 0.008). We demonstrated the synergistic effect of the sitafloxacin-arbekacin combination against MABS. Further, this combination regimen might be more effective against Mab or rough morphotypes of MABS.

The synergetic effect of Imipenem-clarithromycin combination in the Mycobacteroides abscessus complex

Background

Nontuberculous mycobacteria (NTM) are ubiquitous organisms and the incidence of NTM infections has been increasing in recent years. Mycobacteroides abscessus (M. abscessus) is one of the most antimicrobial-resistant NTM; however, no reliable antibiotic regimen can be officially advocated. We evaluated the efficacy of clarithromycin in combination with various antimicrobial agents against the M. abscessus complex.

Results

Twenty-nine clinical strains of M. abscessus were isolated from various clinical samples. Of the isolates, 10 (34.5%) were of M. abscessus subsp. abscessus, 18 (62.1%) of M. abscessus subsp. massiliense, and 1 (3.4%) of M. abscessus subsp. bolletii. MICs of three antimicrobial agents (amikacin, imipenem, and moxifloxacin) were measured with or without clarithromycin. The imipenem-clarithromycin combination significantly reduced MICs compared to clarithromycin and imipenem monotherapies, including against resistant strains. The association between susceptibility of the M. abscessus complex and each combination of agents was significant (p = 0.001). Adjusted residuals indicated that the imipenem-clarithromycin combination had the synergistic effect (adjusted residual = 3.1) and suppressed the antagonistic effect (adjusted residual = − 3.1). In subspecies of M. abscessus complex, the association with susceptibility of M. abscessus subsp. massiliense was similarly statistically significant (p = 0.036: adjusted residuals of synergistic and antagonistic effect respectively: 2.6 and − 2.6). The association with susceptibility of M. abscessus subsp. abscessus also showed a similar trend but did not reach statistical significance.

Conclusion

Our data suggest that the imipenem-clarithromycin combination could be the recommended therapeutic choice for the treatment of M. abscessus complex owing to its ability to restore antimicrobial susceptibility.

PCR amplification of the erm(41) gene can be used to predict the sensitivity of Mycobacterium abscessus complex strains to clarithromycin

A worldwide increase in the Mycobacterium abscessus (M. abscessus) complex has been observed. Therefore, the aim of the present study was to investigate the diversity of the rrl and erm(41) genes, both of which are associated with macrolide sensitivity in the M. abscessus complex. The current study also examined the efficacy of mass spectrometry as an alternative to molecular testing to classify subspecies of the M. abscessus complex. A total of 14 strains of the M. abscessus complex were obtained, and based on conventional analyses using housekeeping genes, 57% were determined to be M. abscessus subsp. abscessus, 43% were M. abscessus subsp. massiliense, and none were identified as M. abscessus subsp. bolletii. However, depending on the strain, it was not always possible to distinguish between the subspecies by mass spectrometry. Consequently, PCR products for the rrl and erm(41) genes were directly sequenced. Overall, 7.1% of the strains were identified to have a rrl mutation, and 92.9% carried a T at position 28 of erm(41). Results presented here suggest that the principal cause of treatment failure for M. abscessus complex infections is inducible macrolide resistance encoded by the erm(41) gene. From a strictly pragmatic standpoint, the phenotypic function of a putative erm(41) gene is the most important piece of information required by clinicians in order to prescribe an effective treatment. Although PCR amplification of erm(41) is not sufficient to differentiate between the M. abscessus complex subspecies, PCR can be easily and efficiently used to predict the sensitivity of members of the M. abscessus complex to clarithromycin.

New Mycobacteroides abscessus subsp. massiliense strains with recombinant hsp65 gene laterally transferred from Mycobacteroides abscessus subsp. abscessus: Potential for misidentification of M. abscessus strains with the hsp65-based method

It has been reported that lateral gene transfer (LGT) events among Mycobacteroides abscessus strains are prevalent. The hsp65 gene, a chronometer gene for bacterial phylogenetic analysis, is resistant to LGT events, particularly among mycobacterial strains, rendering the hsp65-targeting method the most widely used method for mycobacterial detection. To determine the prevalence of M. abscessus strains that are subject to hsp65 LGT, we applied rpoB typing to 100 clinically isolated Korean strains of M. abscessus that had been identified by hsp65 sequence analysis. The analysis indicated the presence of 2 rough strains, showing a discrepancy between the 2 typing methods. MLST analysis based on the partial sequencing of seven housekeeping genes, erm(41) PCR and further hsp65 PCR-restriction enzyme and polymorphism analysis (PRA) were conducted to identify the two strains. The MLST results showed that the two strains belong to M. abscessus subsp. massiliense and not to M. abscessus subsp. abscessus, as indicated by the rpoB-based analysis, suggesting that their hsp65 genes are subject to LGT from M. abscessus subsp. abscessus. Further analysis of these strains using the hsp65 PRA method indicated that these strains possess a PRA pattern identical to that of M. abscessus subsp. abscessus and distinct from that of M. abscessus subsp. massiliense. In conclusion, we identified two M. abscessus subsp. massiliense rough strains from Korean patients with hsp65 genes that might be laterally transferred from M. abscessus subsp. abscessus. To the best of our knowledge, this is the first demonstration of possible LGT events associated with the hsp65 gene in mycobacteria. Our results also suggest that there is the potential for misidentification when the hsp65-based protocol is used for mycobacterial identification.

Phagosome Escape of Rough Mycobacterium abscessus Strains in Murine Macrophage via Phagosomal Rupture Can Lead to Type I Interferon Production and Their Cell-To-Cell Spread

Mycobacterium abscessus complex (MAB) is a rapidly growing mycobacterium(RGM) whose clinical significance as an emerging human pathogen has been increasing worldwide. It has two types of colony morphology, a smooth (S) type, producing high glycopeptidolipid (GPL) content, and a rough (R) type, which produces low levels of GPLs and is associated with increased virulence. However, the mechanism responsible for their difference in virulence is poorly known. By ultrastructural examination of murine macrophages infected, we found that MAB-R strains could replicate more actively in the macrophage phagosome than the S variants and that they could escape into cytosol via phagosomal rupture. The cytosolic access of MAB-R strains via phagosomal rupture led to enhanced Type I interferon (IFN) production and cell death, which resulted in their cell-to-cell spreading. This behavior can provide an additional niche for the survival of MAB-R strains. In addition, we found that their enhancement of cell death mediated cell spreading are dependent on Type I IFN signaling via comparison of wild-type and IFNAR1 knockout mice. In conclusion, our data indicated that a transition of MAB-S strains into MAB-R variants increased their virulence via enhanced Type I IFN production, which led to enhanced survival in infected macrophage via cell death mediated cell-to-cell spreading. This result provides not only a novel insight into the difference in virulence between MAB-R and -S variants but also hints to their treatment strategy.

A description of Mycobacterium chelonae subsp. gwanakae subsp. nov., a rapidly growing mycobacterium with a smooth colony phenotype due to glycopeptidolipids

Three rapidly growing mycobacterial strains, MOTTH4W, MOTT36W^T and MOTT68W, were isolated from the sputa of three independent Korean patients co-infected with Mycobacterium yongonense Type II strains. The 16S rRNA gene sequences of all three strains were unique, which were closest to that of Mycobacterium chelonae subsp. bovis KCTC 39630^T (99.9 % similarity). Multilocus sequence typing analysis targeting 10 housekeeping genes including hsp65 and rpoB revealed the distinct phylogenetic location of these strains, which were clustered with M. chelonae subsp. chelonae ATCC 35752^T and M. chelonae subsp. bovis KCTC 39630^T. Phylogenetic analysis based on whole genome sequences revealed a 95.89 % average nucleotide identity (ANI) value with M. chelonae subsp. chelonae, slightly higher than the 95.0 % ANI criterion for determining a novel species. In addition, phenotypic characteristics such as a smooth colony morphology and growth inhibition at 37 °C, distinct MALDI-TOF MS profiles of extracted total lipids due to surface glycopeptidolipids, and distinct drug susceptibility profiles further supported the taxonomic characterization of these strains as representing a novel subspecies of Mycobacterium chelonae. Mycobacterium chelonae subsp. gwanakae subsp. nov. is proposed and the type strain is MOTT36W^T (=KCTC 29127^T=JCM 32454^T).

Description of Mycobacterium chelonae subsp. bovis subsp. nov., isolated from cattle (Bos taurus coreanae), emended description of Mycobacterium chelonae and creation of Mycobacterium chelonae subsp. chelonae subsp. nov

Three rapidly growing mycobacterial strains, QIA-37T, QIA-40 and QIA-41, were isolated from the lymph nodes of three separate Korean native cattle, Hanwoo (Bos taurus coreanae). These strains were previously shown to be phylogenetically distinct but closely related to Mycobacterium chelonae ATCC 35752T by taxonomic approaches targeting three genes (16S rRNA, hsp6 and rpoB) and were further characterized using a polyphasic approach in this study. The 16S rRNA gene sequences of all three strains showed 99.7 % sequence similarity with that of the M. chelonae type strain. A multilocus sequence typing analysis targeting 10 housekeeping genes, including hsp65 and rpoB, revealed a phylogenetic cluster of these strains with M. chelonae. DNA-DNA hybridization values of 78.2 % between QIA-37T and M. chelonae indicated that it belongs to M. chelonae but is a novel subspecies distinct from M. chelonae. Phylogenetic analysis based on whole-genome sequences revealed a 95.44±0.06 % average nucleotide identity (ANI) value with M. chelonae, slightly higher than the 95.0 % ANI criterion for determining a novel species. In addition, distinct phenotypic characteristics such as positive growth at 37 °C, at which temperature M. chelonae does not grow, further support the taxonomic status of these strains as representatives of a novel subspecies of M. chelonae. Therefore, we propose an emended description of Mycobacterium chelonae, and descriptions of M. chelonae subsp. chelonae subsp. nov. and M. chelonae subsp. bovis subsp. nov. are presented; strains ATCC 35752T(=CCUG 47445T=CIP 104535T=DSM 43804T=JCM 6388T=NCTC 946T) and QIA-37T (=KCTC 39630T=JCM 30986T) are the type strains of the two novel subspecies.

Phylogenetic analysis of Mycobacterium massiliense strains having recombinant rpoB gene laterally transferred from Mycobacterium abscessus

Recent multi locus sequence typing (MLST) and genome based studies indicate that lateral gene transfer (LGT) events in the rpoB gene are prevalent between Mycobacterium abscessus complex strains. To check the prevalence of the M. massiliense strains subject to rpoB LGT (Rec-mas), we applied rpoB typing (711 bp) to 106 Korean strains of M. massiliense infection that had already been identified by hsp65 sequence analysis (603 bp). The analysis indicated 6 smooth strains in M. massiliense Type I (10.0%, 6/60) genotypes but no strains in M. massiliense Type II genotypes (0%, 0/46), showing a discrepancy between the 2 typing methods. Further MLST analysis based on the partial sequencing of seven housekeeping genes, argH, cya, glpK, gnd, murC, pta and purH, as well as erm(41) PCR proved that these 6 Rec-mas strains consisted of two distinct genotypes belonging to M. massiliense and not M. abscessus. The complete rpoB sequencing analysis showed that these 6 Rec-mas strains have an identical hybrid rpoB gene, of which a 478 bp partial rpoB fragment may be laterally transferred from M. abscessus. Notably, five of the 6 Rec-mas strains showed complete identical sequences in a total of nine genes, including the seven MLST genes, hsp65, and rpoB, suggesting their clonal propagation in South Korea. In conclusion, we identified 6 M. massiliense smooth strains of 2 phylogenetically distinct genotypes with a specific hybrid rpoB gene laterally transferred from M. abscessus from Korean patients. Their clinical relevance and bacteriological traits remain to be elucidated.

Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: An update for 2011-2012

This review is the seventh update of the original article published in 1999 on the application of MALDI mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2012. General aspects such as theory of the MALDI process, matrices, derivatization, MALDI imaging, and fragmentation are covered in the first part of the review and applications to various structural types constitute the remainder. The main groups of compound are oligo- and poly-saccharides, glycoproteins, glycolipids, glycosides, and biopharmaceuticals. Much of this material is presented in tabular form. Also discussed are medical and industrial applications of the technique, studies of enzyme reactions, and applications to chemical synthesis. © 2015 Wiley Periodicals, Inc. Mass Spec Rev 36:255-422, 2017.

An in vitro model of granuloma-like cell aggregates substantiates early host immune responses against Mycobacterium massiliense infection

Mycobacterium massiliense (M. mass), belonging to the M. abscessus complex, is a rapidly growing mycobacterium that is known to cause tuberculous-like lesions in humans. To better understand the interaction between host cells and M. mass, we used a recently developed in vitro model of early granuloma-like cell aggregates composed of human peripheral blood mononuclear cells (PBMCs). PBMCs formed granuloma-like, small and rounded cell aggregates when infected by live M. mass. Microscopic examination showed monocytes and macrophages surrounded by lymphocytes, which resembled cell aggregation induced by M. tuberculosis (M. tb). M. mass-infected PBMCs exhibited higher expression levels of HLA-DR, CD86 and CD80 on macrophages, and a significant decrease in the populations of CD4+ and CD8+ T cells. Interestingly, low doses of M. mass were sufficient to infect PBMCs, while active host cell death was gradually induced with highly increased bacterial loads, reflecting host destruction and dissemination of virulent rapid-growing mycobacteria (RGM). Collectively, this in vitro model of M. mass infection improves our understanding of the interplay of host immune cells with mycobacteria, and may be useful for developing therapeutics to control bacterial pathogenesis.

Summary: An in vitro model of granuloma-like cell aggregates infected with Mycobacterium massiliense improves our understanding of the interplay of host immune cells with mycobacteria.

Mycobacterium massiliense Induces Macrophage Extracellular Traps with Facilitating Bacterial Growth

Human neutrophils have been known to release neutrophil extracellular traps (NETs), antimicrobial DNA structures capable of capturing and killing microbes. Recently, a similar phenomenon has been reported in macrophages infected with various pathogens. However, a role for macrophages extracellular traps (METs) in host defense responses against Mycobacterium massiliense (M. mass) has yet to be described. In this study, we show that M. mass, a rapid growing mycobacterium (RGM), also induces the release of METs from PMA-differentiated THP-1 cells. Intriguingly, this process is not dependent on NADPH oxidase activity, which regulates NET formation. Instead, M. mass-induced MET formation partially depends on calcium influx and requires phagocytosis of high bacterial load. The METs consist of a DNA backbone embedded with microbicidal proteins such as histone, MPO and elastase. Released METs entrap M. mass and prevent their dissemination, but do not have bactericidal activity. Instead, they result in enhanced bacterial growth. In this regard, METs were considered to provide interaction of M. mass with cells and an environment for bacterial aggregation, which may facilitate mycobacterial survival and growth. In conclusion, our results demonstrate METs as an innate defense response against M. mass infection, and suggest that extracellular traps play a multifaceted role in the interplay between host and bacteria.

Mycobacterium massiliense Type II genotype leads to higher level of colony forming units and TNF-α secretion from human monocytes than Type I genotype

Recently, we introduced a novel Mycobacterium massiliense Type II genotype from Korean patients, in which all isolates showed only a rough (R) colony morphotype. In this study, we sought to compare clinical factors and virulence potentials of two genotypes of M. massiliense, Type I and Type II. Patients infected with Type II tend to be younger at infection than those infected with Type I (56.7 vs 62.3, p = 0.051). Type II was more significantly related to R colony type than Type I (34.1% vs 94.1%, p < 0.001). The Type II strain showed significantly more colony forming units (CFUs) and higher levels of TNF-α secretion in infection of human monocytes than the Type I strain. The challenge of extracted glycopeptidolipid (GPL) into human monocytes indicated that the loss of GPL from the cell wall of the Type II genotype led to a higher level of TNF-α secretion in a toll-like receptor 2(TLR2)-dependent manner. Taken together, our data suggest that the M. massiliense Type II genotype shows higher virulence than Type I, which may be due to the induction of TNF-α via the loss of GPL from the Type II cell wall.

New Real-Time PCR Assays for Detection of Inducible and Acquired Clarithromycin Resistance in the Mycobacterium abscessus Group

Members of the Mycobacterium abscessus group (MAG) cause lung, soft tissue, and disseminated infections. The oral macrolides clarithromycin and azithromycin are commonly used for treatment. MAG can display clarithromycin resistance through the inducible erm(41) gene or via acquired mutations in the rrl (23S rRNA) gene. Strains harboring a truncation or a T28C substitution in erm(41) lose the inducible resistance trait. Phenotypic detection of clarithromycin resistance requires extended incubation (14 days), highlighting the need for faster methods to detect resistance. Two real-time PCR-based assays were developed to assess inducible and acquired clarithromycin resistance and tested on a total of 90 clinical and reference strains. A SYBR green assay was designed to distinguish between a full-length and truncated erm(41) gene by temperature shift in melting curve analysis. Single nucleotide polymorphism (SNP) allele discrimination assays were developed to distinguish T or C at position 28 of erm(41) and 23S rRNA rrl gene mutations at position 2058 and/or 2059. Truncated and full-size erm(41) genes were detected in 21/90 and 69/90 strains, respectively, with 64/69 displaying T at nucleotide position 28 and 5/69 containing C at that position. Fifteen isolates showed rrl mutations conferring clarithromycin resistance, including A2058G (11 isolates), A2058C (3 isolates), and A2059G (1 isolate). Targeted sequencing and phenotypic assessment of resistance concurred with molecular assay results. Interestingly, we also noted cooccurring strains harboring an active erm(41), inactive erm(41), and/or acquired mutational resistance, as well as slowly growing MAG strains and also strains displaying an inducible resistance phenotype within 5 days, long before the recommended 14-day extended incubation.

Separation of Mycobacterium abscessus into subspecies or genotype level by direct application of peptide nucleic acid multi-probe- real-time PCR method into sputa samples

Background

Recently, we introduced a novel peptide nucleic acid (PNA) multi-probe real time PCR method targeting the hsp65 gene (hsp65 PNA RT-PCR) to distinguish Mycobacterium abscessus groups.

Methods

Here, we evaluated the usefulness of the hsp65 PNA RT-PCR for the direct identification of the M. abscessus group at the subspecies and genotype levels from sputa samples. The method was applied to total sputa DNA from 60 different patients who were identified as having mycobacterial infections via rpoB PCR restriction analysis of the same cultures.

Results

The hsp65 PNA RT-PCR method had higher sensitivity than the multi-probe real-time PCR assay targeting hsp65 (HMPRT-PCR) for the detection of M. abscessus from sputum [96.7 % (29/30 samples) vs. 70 % (21/30 samples); 100 % specificity].

Conclusions

These results suggest that the PNA-based method is feasible for the detection of M. abscessus members not only from cultures but also directly from sputa.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-015-1076-8) contains supplementary material, which is available to authorized users.

Molecular mechanisms of clarithromycin resistance in Mycobacterium abscessus complex clinical isolates from Venezuela

In this study, 26 clinical isolates of Mycobacterium abscessus complex strains were characterised using available identification algorithms for the three species (M. abscessus, M. massiliense and M. bolletii) and the genotypic characteristics of clarithromycin (CLR) resistance were determined. Strains were identified by PCR restriction fragment length polymorphism analysis of the hsp65 and erm(41) gene sequences. Susceptibility to CLR was determined by the broth microdilution method. The mechanism of resistance to this macrolide was evaluated by sequencing the erm(41) and rrl genes. Mutations and/or deletions associated with resistance to CLR as determined in this study were those that have been previously described. No constitutive resistance to CLR was found, however 35% (9/26) of the M. abscessus complex strains tested had a functional inducible erm(41) gene. Based on sequencing of this gene, the strains of M. abscessus were separated into six sequevars, of which only two are consistent with those previously reported. In conclusion, we demonstrated that the low percentage of strains with a resistant phenotype to CLR was due only to an inducible resistance mechanism conferred by the erm(41) gene and not to mutations in the rrl gene. CLR can still be useful for treatment in some Venezuelan patients infected with a member of the M. abscessus group, but drug resistance testing and/or molecular analysis must precede the prescription of this antibiotic.

Development of a peptide nucleic acid-based multiprobe real-time PCR method targeting the hsp65 gene for differentiation among Mycobacterium abscessus strains

Recently, the need to distinguish between members of the Mycobacterium abscessus group has gained increasing attention. Here, we introduced a novel peptide nucleic acid (PNA) real-time PCR method targeting the hsp65 gene in order to distinguish between four subspecies within the M. abscessus group (M. abscessus and 3 types of M. massiliense).

Investigation of the population structure of Mycobacterium abscessus complex strains using 17-locus variable number tandem repeat typing and the further distinction of Mycobacterium massiliense hsp65 genotypes

Mycobacterium abscessus complex is a significant pathogen in patients with non-cystic fibrosis (non-CF). Nevertheless, there is little description of the genetic diversity of this species. The aims of this study were to investigate the distribution of M. abscessus complex isolated from respiratory specimens by variable number tandem repeat (VNTR) typing. The results of 104 clinical isolates from 104 non-CF patients were compared using PFGE, hsp65 genotypes and clarithromycin susceptibility. The allelic diversity (Hunter-Gaston Discriminatory Index) of the 17 loci examined by VNTR typing was high (0.977). We determined that C28 sequevar erm(41) genotypes and clarithromycin-acquired resistance isolates were scattered in the minimum spanning tree. Intriguingly, VNTR typing and PFGE were highly congruent and revealed that there were clear examples of grouping of isolates from different individuals amongst both M. abscessus and M. massiliense, and showed five clusters of distinct identical isolates. Within these clusters, M. massiliense hsp65 type I formed three different clusters. Although the distribution of M. massiliense hsp65 type II-1 was low (9.3 %), M. massiliense hsp65 type II-1 isolates separated from clusters contained hsp65 type I isolates. Thus, M. massiliense hsp65 genotypes could be discriminated by analysing VNTRs with sufficient genetic distance for intra-species-level discrimination.

Identification of immunoreactive proteins of Mycobacterium avium subsp. paratuberculosis

Mycobacterium avium subsp. paratuberculosis (MAP) is the cause of a chronic enteritis of ruminants (bovine paratuberculosis (PTB)--Johne's disease) that is associated with enormous worldwide economic losses for the animal production. Diagnosis is based on observation of clinical signs, the detection of antibodies in milk or serum, or evaluation of bacterial culture from feces. The limit of these methods is that they are not able to detect the disease in the subclinical stage and are applicable only when the disease is already advanced. For this reason, the main purpose of this study is to use the MAP proteome to detect novel immunoreactive proteins that may be helpful for PTB diagnoses. 2DE and 2D immunoblotting of MAP proteins were performed using sera of control cattle and PTB-infected cattle in order to highlight the specific immunoreactive proteins. Among the assigned identifiers to immunoreactive spots it was found that most of them correspond to surface-located proteins while three of them have never been described before as antigens. The identification of these proteins improves scientific knowledge that could be useful for PTB diagnoses. The sequence of the identified protein can be used for the synthesis of immunoreactive peptides that could be screened for their immunoreaction against bovine sera infected with MAP. All MS data have been deposited in the ProteomeXchange consortium with identifier PXD001159 and DOI 10.6019/PXD001159.

Analysis of species and intra-species associations between the Mycobacterium abscessus complex strains using pulsed-field gel electrophoresis (PFGE) and multi-locus sequence typing (MLST)

PFGE and MLST showed that the strains of M. massiliense hsp65 II-1 were clearly separated from the strains of M. massiliense hsp65 I or II-2 as well as the strains of M. abscessus or M. bolletii; thus, M. massiliense hsp6 5II-1 might represent an additional subspecies of M. massiliense.

Mycobacterium massiliense bacteremia as a consequence of M. massiliense pneumonia in a patient with acute lymphoblastic leukemia

A 52-year-old woman with relapsed acute lymphoblastic leukemia was diagnosed with Mycobacterium massiliense pneumonia after 4 months of chemotherapy. She developed M. massiliense bacteremia 1 month later. This is the first report of a proven case of M. massiliense bacteremia as a consequence of M. massiliense pneumonia.

Rough colony morphology of Mycobacterium massiliense Type II genotype is due to the deletion of glycopeptidolipid locus within its genome

Background

Recently, we introduced the complete genome sequence of Mycobacterium massiliense clinical isolates, Asan 50594 belonging to Type II genotype with rough colony morphology. Here, to address the issue of whether the rough colony morphotype of M. massiliense Type II genotype is genetically determined or not, we compared polymorphisms of the glycopeptidolipid (GPL) gene locus between M. massiliense Type II Asan 50594 and other rapidly growing mycobacteria (RGM) strains via analysis of genome databases.

Results

We found deletions of 10 genes (24.8 kb), in the GPL biosynthesis related gene cluster of Asan 50594 genome, but no deletions in those of other smooth RGMs. To check the presence of deletions of GPL biosynthesis related genes in Mycobacterium abscessus − complex strains, PCRs targeting 12 different GPL genes (10 genes deleted in Asan 50594 genome as well as 2 conserved genes) were applied into 76 clinical strains of the M. abscessus complex strains [54 strains (Type I: 33, and Type II: 21) of M. massiliense and 22 strains (rough morphoype: 11 and smooth morphotype: 11) of M. abscessus]. No strains of the Type II genotype produced PCR amplicons in a total of 10 deleted GPL genes, suggesting loss of GPL biosynthesis genes in the genome of M. massiliense type II genotype strains.

Conclusions

Our data suggested that the rough colony morphotype of the M. massiliense Type II genotype may be acquired via deletion events at the GPL gene locus for evolutionary adaptation between the host and pathogen.

Complete Genome Sequence of Mycobacterium massiliense Clinical Strain Asan 50594, Belonging to the Type II Genotype

We report the complete genome sequence of the Mycobacterium massiliense clinical strain Asan 50594, which was grouped into the M. massiliense type II genotype, isolated from a Korean patient. This genome sequence will serve as a valuable reference for understanding the disparity in virulence and epidemiological traits between strains belonging to the Mycobacterium abscessus complex.