Proposal of Sphingobacterium allocomposti nom. nov., Mycobacterium chelonae subsp. bovistauri nom. nov. and Lactobacillus delbrueckii subsp. allosunkii nom. nov. as new names with replacement specific or subspecific epithets, respectively, for three illegitimate prokaryotic names Sphingobacterium composti Yoo et al. 2007, Mycobacterium chelonae subsp. bovis Kim et al. 2017 and Lactobacillus delbrueckii subsp. sunkii Kudo et al. 2012; proposal of Christiangramia oceanisediminis comb. nov. and Christiangramia crocea comb. nov. as replacement names respectively for two illegitimate prokaryotic names Gramella oceanisediminis Yang et al. 2023 and Gramella crocea Zhang et al. 2023.

As required by Rule 54 of the International Code of Nomenclature of Prokaryotes, the authors propose the replacement specific epithet 'allocomposti' for the illegitimate prokaryotic name Sphingobacterium composti Yoo et al. 2007, the replacement subspecific epithet 'bovistauri' for Mycobacterium chelonae subsp. bovis Kim et al. 2017 and the replacement subspecific epithet 'allosunkii' for Lactobacillus delbrueckii subsp. sunkii Kudo et al. 2012. Meanwhile, new combinations Christiangramia oceanisediminis and Christiangramia crocea are also proposed as replacements for the illegitimate prokaryotic names Gramella oceanisediminis Yang et al. 2023 and Gramella crocea Zhang et al. 2023, respectively.

Common Features of Environmental Mycobacterium chelonae from Colorado Using Partial and Whole Genomic Sequence Analyses.

Nontuberculous mycobacteria (NTM) are environmentally acquired opportunistic pathogens that cause chronic lung disease in susceptible individuals. While presumed to be ubiquitous in built and natural environments, NTM environmental studies are limited. While environmental sampling campaigns have been performed in geographic areas of high NTM disease burden, NTM species diversity is less defined among areas of lower disease burden like Colorado. In Colorado, metals such as molybdenum have been correlated with increased risk for NTM infection, yet environmental NTM species diversity has not yet been widely studied. Based on prior regression modeling, three areas of predicted high, moderate, and low NTM risk were identified for environmental sampling in Colorado. Ice, plumbing biofilms, and sink tap water samples were collected from publicly accessible freshwater sources. All samples were microbiologically cultured and NTM were identified using partial rpoB gene sequencing. From these samples, areas of moderate risk were more likely to be NTM positive. NTM recovery from ice was more common than recovery from plumbing biofilms or tap water. Overall, nine different NTM species were identified, including clinically important Mycobacterium chelonae. MinION technology was used to whole genome sequence and compare mutational differences between six M. chelonae genomes, representing three environmental isolates from this study and three other M. chelonae isolates from other sources. Drug resistance genes and prophages were common findings among environmentally derived M. chelonae, promoting the need for expanded environmental sampling campaigns to improve our current understanding of NTM species abundance while opening new avenues for improved targeted drug therapies.

Sudapyridine (WX-081) antibacterial activity against Mycobacterium avium, Mycobacterium abscessus, and Mycobacterium chelonae in vitro and in vivo.

Sudapyridine (WX-081) is a structural analog of bedaquiline (BDQ), which shows anti-tuberculosis and non-tuberculous mycobacteria (NTM) activities but, unlike BDQ, did not prolong QT interval in animal model studies. This study evaluated the antibacterial activity of this novel compound against Mycobacterium avium, Mycobacterium abscessus, and Mycobacterium chelonae in vitro and in vivo. The minimum inhibitory concentration (MIC) of WX-081 against three kinds of non-tuberculous mycobacteria (NTM) clinical strains was determined using microplate-based alamarBlue assay (MABA), and the antibacterial activity of WX-081 against NTM in J774A.1 cells and mice was evaluated. MIC ranges of WX-081 against clinical strains of M. avium and M. abscessus were 0.05-0.94 µg/mL, 0.88-7.22 µg/mL (M. abscessus subsp. abscessus), and 0.22-8.67 µg/mL (M. abscessus subsp. massiliense), respectively, which were slightly higher than those of BDQ. For M. avium, M. abscessus, and M. chelonae, WX-081 can reduce the intracellular bacterial load by 0.13-1.18, 0.18-1.50, and 0.17-1.03 log10 colony forming units (CFU)/mL, respectively, in a concentration-dependent manner. WX-081 has bactericidal activity against three NTM species in mice. WX-081 exhibited anti-NTM activity to the same extent as BDQ both in vivo and in vitro. WX-081 is a promising clinical candidate and should be studied further in clinical trials. IMPORTANCE: Due to the rapidly increased cases globally, non-tuberculous mycobacteria (NTM) disease has become a significant public health problem. NTM accounted for 11.57% of all mycobacterial isolates in China, with a high detection rate of Mycobacterium abscessus, Mycobacterium avium, and Mycobacterium chelonae during 2000-2019. Treatment of NTM infection is often challenging, as natural resistance to most antibiotics is quite common among different NTM species. Hence, identifying highly active anti-NTM agents is a priority for potent regimen establishment. The pursuit of new drugs to treat multidrug-resistant tuberculosis may also identify some agents with strong activity against NTM. Sudapyridine (WX-081) is a structural analog of bedaquiline (BDQ), which was developed to retain the anti-tuberculosis efficacy but eliminates the severe side effects of BDQ. This study initially evaluated the antimicrobial activity of this novel compound against M. avium, M. abscessus, and M. chelonae in vitro, in macrophages and mice, respectively.

Fire needle combined with photodynamic therapy for cutaneous infectious granulomatosis caused by mycobacterium chelonae: A case report.

Mycobacterium chelonae is a non-tuberculous mycobacteria, which can cause skin infectious granuloma through cosmetic injection. This disease's treatment requires a combination of sensitive antibiotics and a lengthy treatment cycle. Photodynamic therapy is still effective for patients who are unwilling to take antibiotics orally. In this case, we successfully used fire needle combined with photodynamic therapy to treat skin infectious granulomatosis caused by Mycobacterium chelonei, and achieved satisfactory results. We used fire needle to pretreat cysts and nodules, which improved the diffusion and absorption of locally applied photosensitizers and enhanced the efficacy of photodynamic therapy. However, additional clinical research is necessary to determine the efficacy and safety of fire needle combined with photodynamic therapy for cutaneous infectious granulomatosis.

Mycobacterium chelonae lung disease masquerading as Mycobacterium tuberculosis in a TB endemic country.

Mycobacterium chelonae typically affect skin and soft tissue. Pleural involvement by this organism is exceedingly rare. A young female presented with persistent respiratory complaints along with constitutional symptoms. She had already been treated with standard anti-tubercular therapy with inadequate response and had a recent onset of worsening of her symptoms. A detailed evaluation revealed M. chelonae and she responded well to antimicrobials. We report a case of Mycobacterium chelonae lung disease in an immunocompetent patient and its successful management. High index of suspicion with a correct etiological diagnosis is the need of the hour in current era of drug resistance.

Plasmid-mediated drug resistance in mycobacteria: the tip of the iceberg?

Macrolides, such as clarithromycin, are crucial in the treatment of nontuberculous mycobacteria (NTM). NTM are notoriously innately drug resistant, which has made the dependence on macrolides for their treatment even more important. Not surprisingly, resistance to macrolides has been documented in some NTM, including Mycobacterium avium and Mycobacterium abscessus, which are the two NTM species most often identified in clinical isolates. Resistance is mediated by point mutations in the 23S ribosomal RNA or by methylation of the rRNA by a methylase (encoded by an erm gene). Chromosomally encoded erm genes have been identified in many of the macrolide-resistant isolates, but not in Mycobacterium chelonae. Now, Brown-Elliott et al. (J Clin Microbiol 61:e00428-23, 2023, https://doi.org/10.1128/JCM.00428-23) describe the identification of a new erm variant, erm(55), which was found either on the chromosome or on a plasmid in highly macrolide-resistant clinical isolates of M. chelonae. The chromosomal erm(55) gene appears to be associated with mobile elements; one gene is within a putative transposon and the second is in a large (37 kb) insertion/deletion. The plasmid carrying erm(55) also encodes type IV and type VII secretion systems, which are often linked on large mycobacterial plasmids and are hypothesized to mediate plasmid transfer. While the conjugative transfer of the erm(55)-containing plasmid between NTM has yet to be demonstrated, the inferences are clear, as evidenced by the dissemination of plasmid-mediated drug resistance in other medically important bacteria. Here, we discuss the findings of Brown-Elliott et al., and the potential ramifications on treatment of NTM infections.

Mycobacterium chelonae Cutaneous Infection: An Important Differential Diagnosis in the Immunosuppressed Patient with Chronic Ulcers.

In 2018, a 38-year-old woman was referred to our hospital with some nodules and nonhealing ulcers on her left thigh that had been present for 18 months. Her medical history included rheumatoid arthritis (RA) being treated with 20-mg prednisone for the last 8 years. There was no history of trauma, surgery, or cosmetic procedure on the leg. Physical examination revealed multiple lesions on her left thigh, including nodules, surrounded by erythema, some of them being covered with a fine white-yellowish scale and hyperpigmented macules. Central atrophy was evident in some lesions. She also had one ulcer with purulent discharge (Figure 1). An infectious disease and vasculitis were considered in the differential diagnoses. Biopsy and culture were conducted from the lesion. A Ziehl-Neelsen stain was obtained from the ulcer's discharge with visible acid-fast bacilli (Figure 2). Light microscopy examination revealed a mixed granuloma with lymphocytes, neutrophils, and giant cells in the dermis (Figure 3). The culture was positive for M. chelonae sensitive to clarithromycin. Treatment with clarithromycin was initiated (500 mg, twice a day) for 8 weeks, with healing of some of the lesions. She was advised to continue antibiotic treatment for 4 more weeks and to report to our hospital after its completion, but she never returned and was lost on follow-up.

Emergence of Inducible Macrolide Resistance in Mycobacterium chelonae Due to Broad-Host-Range Plasmid and Chromosomal Variants of the Novel 23S rRNA Methylase Gene, erm(55).

Macrolides are a mainstay of therapy for infections due to nontuberculous mycobacteria (NTM). Among rapidly growing mycobacteria (RGM), inducible macrolide resistance is associated with four chromosomal 23S rRNA methylase (erm) genes. Beginning in 2018, we detected high-level inducible clarithromycin resistance (MICs of ≥16µg/mL) in clinical isolates of Mycobacterium chelonae, an RGM species not previously known to contain erm genes. Using whole-genome sequencing, we identified a novel plasmid-mediated erm gene. This gene, designated erm(55)P, exhibits <65% amino acid identity to previously described RGM erm genes. Two additional chromosomal erm(55) alleles, with sequence identities of 81% to 86% to erm(55)P, were also identified and designated erm(55)C and erm(55)T. The erm(55)T is part of a transposon. The erm(55)P allele variant is located on a putative 137-kb conjugative plasmid, pMchErm55. Evaluation of 133 consecutive isolates from 2020 to 2022 revealed 5 (3.8%) with erm(55). The erm(55)P gene was also identified in public data sets of two emerging pathogenic pigmented RGM species: Mycobacterium iranicum and Mycobacterium obuense, dating back to 2008. In both species, the gene appeared to be present on plasmids homologous to pMchErm55. Plasmid-mediated macrolide resistance, not described previously for any NTM species, appears to have spread to multiple RGM species. This has important implications for antimicrobial susceptibility guidelines and treatment of RGM infections. Further spread could present serious consequences for treatment of other macrolide-susceptible RGM. Additional studies are needed to determine the transmissibility of pMchErm55 and the distribution of erm(55) among other RGM species.

A bronchoscopy-associated pseudo-outbreak of Mycobacterium chelonae and Mycobacterium mucogenicum associated with contaminated ice machine water and ice.

A pseudo-outbreak of bronchoscopy-associated Mycobacterium chelonae and M. mucogenicum was traced to contaminated ice machine water and ice. A nonsterile ice bath was used to cool uncapped, sterile, saline syringes used to slow procedural bleeding. Joining the growing evidence of bronchoscopy pseudo-outbreaks, our investigation describes several lessons for future prevention.

[Nontuberculous mycobacterial infection after tattooing caused by Mycobacterium chelonae]. / Nichttuberkulöse Mykobakteriose nach Tätowierung durch Mycobacterium chelonae.

We report the case of a healthy young man who presented to our clinic with itchy skin lesions in the area of a tattoo on the back of the left hand. Bioptic and cultural confirmation of the pathogens led to the diagnosis of Mycobacterium chelonae infection. We initiated antibiotic therapy using azithromycin and linezolid with good response. Our case underlines that besides allergic skin reactions, infections as a complication after tattooing should also be included in the differential diagnosis.

Rare, Atypical Mycobacterium Infection of the Hand in Immunocompetent Individuals.

We present two cases of immunocompetent individuals diagnosed with nontuberculous infections of the hand caused by organisms rarely seen in the clinical setting: Mycobacterium heckeshornense and Mycobacterium chelonae. In the first case, a 50-year-old male presented with tenosynovitis of left long finger. He was subsequently found to have a Mycobacterium heckeshornense infection that was resolved with multiple surgeries and a long-term regimen of several antibiotics. The second case was a 29-year-old female with a history of a trivial hand injury infected with Mycobacterium chelonae. She was successfully treated with surgical debridement and antibiotics over the course of eight months. It is important to recognize the increasing prevalence of these two species of bacteria as human pathogens that can result in infections of the extremities even in immunocompetent individuals. (Journal of Surgical Orthopaedic Advances 32(1):055-058, 2023).

Efficacy of PBTZ169 and pretomanid against Mycobacterium avium, Mycobacterium abscessus, Mycobacterium chelonae, and Mycobacterium fortuitum in BALB/c mice models.

Objectives: We aimed to evaluate the activity of PBTZ169 and pretomanid against non-tuberculous mycobacteriosis (NTM) in vitro and in vivo. Methods: The minimum inhibitory concentrations (MICs) of 11 antibiotics, against slow-growing mycobacteria (SGMs) and rapid-growing mycobacteria (RGMs) were tested using the microplate alamarBlue assay. The in vivo activities of bedaquiline, clofazimine, moxifloxacin, rifabutin, PBTZ169 and pretomanid against four common NTMs were assessed in murine models. Results: PBTZ169 and pretomanid had MICs of >32 µg/mL against most NTM reference and clinical strains. However, PBTZ169 was bactericidal against Mycobacterium abscessus (3.33 and 1.49 log10 CFU reductions in the lungs and spleen, respectively) and Mycobacterium chelonae (2.29 and 2.24 CFU reductions in the lungs and spleen, respectively) in mice, and bacteriostatic against Mycobacterium avium and Mycobacterium fortuitum. Pretomanid dramatically decreased the CFU counts of M. abscessus (3.12 and 2.30 log10 CFU reductions in the lungs and spleen, respectively), whereas it showed moderate inhibition of M. chelonae and M. fortuitum. Bedaquiline, clofazimine, and moxifloxacin showed good activities against four NTMs in vitro and in vivo. Rifabutin did not inhibit M. avium and M. abscessus in mice. Conclusion: PBTZ169 appears to be a candidate for treating four common NTM infections. Pretomanid was more active against M. abscessus, M. chelonae and M. fortuitum than against M. avium.

Nontuberculous mycobacteria isolation from sputum specimens: A retrospective analysis of 1061 cases.

Background: In recent years, with the development of laboratory methods, the frequency of nontuberculosis mycobacteria (NTM) infections has increased. The primary aim of this study was to evaluate the clinical significance of therapeutic drug monitoring (TDM) growths in respiratory samples, and the secondary aim was to evaluate the treatment regimens and treatment outcomes of treatment for TDM disease. Methods: This study was a retrospective cohort study. Persons with NTM growth in respiratory samples admitted to the reference hospital between 2009 and 2020 were included in this study. Samples detected as NTM by the immunochromatographic rapid diagnostic test, those requested by the clinicians, species were determined by the hsp65PCRREA method. The subjects were classified into 3 groups: patients with NTM infection who received treatment (135, 12.7%), those followed up without treatment (690, 65.1%), and a last group of patients with Mycobacterium tuberculosis (TB) complex strains were isolated and received TB treatment (236, 22.2%). Initiating NTM treatment was decided in accordance with the American Thoracic Society recommendations. Results: The mean ± standard deviation age of patients was 53.8 ± 16.5 years, and 749 (70.6%) were male. In total, 278 (26.2%) out of 1061 cases had identified, and the most frequent species were MAC (81; Mycobacterium avium: 39, Mycobacterium intracellulare: 39, and MAC: 3), Mycobacterium abscessus (67), Mycobacterium kansasii (48), Mycobacterium fortuitum (23), Mycobacterium chelonae (12), Mycobacterium gordonae (11), and Mycobacterium szulgai (11). In the NTM treatment group, 116 (85.9%) of 135 patients had multiple culture positivity. Previous TB treatment history had 51 (37.8%) of 135 patients, respiratory comorbidities were evident in 37 (27.4%) of 135 patients. Thorax computed tomography imaging in 84 patients revealed nodule 38 (45.2%), consolidation 46 (54.8%), cavity 52 (61.9%), and bronchiectasis 27 (32.1%). Treatment results in the NTM treatment group were as follows: ongoing treatment 14 (10.4%), cure 64 (47.4%), default 33 (24.4%), exitus 19 (14.1%), recurrence 3 (2.2%), and refractory disease 2 (1.5%). Conclusion: This is a large case series evaluating the clinical significance of NTM growths and NTM treatment in Turkey. The clinical significance of NTM growth in respiratory samples is low. Treatment success rates of NTM patients who are treated are low. Treatment defaults and mortality rates are high. New drugs and new regimens are needed.

Healthcare-Associated nontuberculous mycobacterial endocarditis following coronary artery angiography.

Infective endocarditis in a patient with structural heart disease following coronary artery angiography is a rare complication. We report a rare case of Mycobacterium chelonae infective endocarditis following coronary artery angiography in a young male with congenital heart disease. This case illustrates the diagnostic as well as therapeutic challenges we faced when managing this rare infectious entity.

Disseminated Mycobacterium chelonae infection complicating rheumatoid arthritis: A case report and review of the literature.

INTRODUCTION: Rheumatoid arthritis (RA) may predispose patients to opportunistic infections-either from innate immune dysregulation, or as a result of immunosuppressant use to treat the RA. Particularly concerning opportunistic infections are those caused by non-tuberculous mycobacterial (NTM) organisms, the incidence of which has been increasing in epidemiological studies. Despite this, guidelines on the management of patients with RA who develop NTM infections are scarce, particularly with respect to immunosuppressant regimen modulation and duration of antibiotic therapy. CASE REPORT: Herein, we present a case of disseminated Mycobacterium chelonae infection, manifesting as arthralgia and cutaneous nodules. DISCUSSION: In addition, a review of the literature was conducted to Preferred Reporting Items for Systemic Reviews and Meta-Analyses guidelines to identify similar cases in the literature-revealing that all RA-associated M. Chelonae infections occurred in immunosuppressed patients (the majority with corticosteroids or tumor necrosis factor inhibitors), and considerable heterogeneity in management approaches. Further research regarding risk factors, preventative approaches and best management of such NTM infections in vulnerable patients with RA is required in order to establish consensus guidelines and consistency.

Infectious Crystalline Keratopathy Secondary to Mycobacterium chelonae.

PURPOSE: The aim of this study was to describe the clinical presentation and multimodal imaging of a patient diagnosed with infectious crystalline keratitis (ICK) secondary to Mycobacterium chelonae . METHODS: This is a case report of a patient with a crystalline corneal infiltrate imaged with anterior segment optical coherence tomography and in vivo scanning laser confocal microscopy. Bacterial, fungal, acanthamoeba, and acid-fast cultures were performed to identify the causal pathogen. RESULTS: Examination revealed a white stellate opacity in the midstroma underlying the scalloped border of an area of central corneal stromal thinning, consistent with a diagnosis of ICK. Anterior segment optical coherence tomography demonstrated a hyperreflective diamond-shaped opacity located at a depth of 334 µm, which demonstrated multiple stellate projections on in vivo scanning laser confocal microscopy. The acid-fast culture was positive for Mycobacterium chelonae . CONCLUSIONS: Although ICK is most commonly associated with Streptococcus species, it may be secondary to atypical bacteria including Mycobacterium species, underscoring the importance of diagnostic imaging and collecting corneal cultures to identify the pathogenic organism.