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Journal of Clinical Microbiology Oct 2023Macrolides, such as clarithromycin, are crucial in the treatment of nontuberculous mycobacteria (NTM). NTM are notoriously innately drug resistant, which has made the...
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 and , 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 gene). Chromosomally encoded genes have been identified in many of the macrolide-resistant isolates, but not in . 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 variant, (55) which was found either on the chromosome or on a plasmid in highly macrolide-resistant clinical isolates of . The chromosomal (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 (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 (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.
Topics: Humans; Anti-Bacterial Agents; Mycobacterium chelonae; Macrolides; Drug Resistance, Bacterial; Clarithromycin; Mycobacterium; Mycobacterium Infections, Nontuberculous; Nontuberculous Mycobacteria; Chromosomes
PubMed: 37724858
DOI: 10.1128/jcm.00628-23 -
Infection and Drug Resistance 2023To evaluate the resolution of chromosomal virulence D () as a novel marker for mycobacterial species identification.
OBJECTIVE
To evaluate the resolution of chromosomal virulence D () as a novel marker for mycobacterial species identification.
METHODS
A segment of (652 bp) was amplified by PCR from 63 mycobacterial reference strains, 163 nontuberculous mycobacterial clinical isolates, and 16 complex (MTBC) clinical isolates. A phylogenetic tree based on the reference strains was constructed by the neighbor-joining and IQ-tree methods. Comparative sequence analysis of the homologous gene efficiently differentiated the species within the genus . Slowly growing (SGM) and rapidly growing (RGM) were separated in the phylogenetic tree based on the gene.
RESULTS
The sequence discrepancies were obvious between and , and , and and , none of which could be achieved by 16S ribosomal RNA (rRNA) homologous gene alignment. Furthermore, manifested larger intraspecies diversity among members of subspecies. A total of 174 of the 179 (97.21%) clinical isolates, consisting of 12 mycobacterial species, were identified correctly by blast. Four subsp. were identified as subsp. by . MTBC isolates were indistinguishable, because they showed 99.84%-100% homology.
CONCLUSION
Homologous is a promising gene marker for identifying mycobacterial species, and could be used for highly accurate species identification among mycobacteria.
PubMed: 37719646
DOI: 10.2147/IDR.S422191 -
Translational Vision Science &... Sep 2023In vitro evaluation of rose bengal (RB) photoactivated by our custom-built green light-emitting diode (LED) source for the growth inhibition of bacterial strains and...
PURPOSE
In vitro evaluation of rose bengal (RB) photoactivated by our custom-built green light-emitting diode (LED) source for the growth inhibition of bacterial strains and rapidly growing mycobacterial (RGM) isolates in infectious keratitis.
METHODS
Six corneal clinical bacteria isolates were included in this study: two Gram-positive bacteria (methicillin-resistant Staphylococcus aureus [MRSA] and Staphylococcus epidermidis), two Gram-negative bacteria (Pseudomonas aeruginosa and Serratia marcescens), and two RGM (Mycobacterium chelonae and Mycobacterium abscessus). Microorganisms were cultured and incubated at specific conditions and prepared in suspensions to adjust their concentration to 104 cells/mL. Different treatments were conducted in triplicates: Group I, no treatment; Group II, treated with 0.1% rose bengal alone (exposed to dark for 30 minutes); Group III, exposed to custom green LED for 30 minutes (12.87 J/cm2); and Group IV, treated with 0.1% rose bengal and exposed to custom green LED for 30 minutes. Agar plates were incubated at specific conditions and photographed after growth for pixel analyses.
RESULTS
Complete growth inhibition of all bacteria and RGM was observed in Group IV. MRSA and S. epidermidis in Group II also showed complete growth inhibition.
CONCLUSIONS
The custom-built green LED presented good activity by photoactivating RB and inhibiting micro-organism growth. For the first time, we demonstrated the expressive growth inhibition effect of RB against S. epidermidis, RGM, and S. marcescens. Clinical treatment with RB may offer an alternate adjunct therapy for corneal surface infections.
TRANSLATIONAL RELEVANCE
Validating in vitro the custom-built green LED encourages the clinical application for the treatment of infectious keratitis.
Topics: Rose Bengal; Methicillin-Resistant Staphylococcus aureus; Mycobacterium; Cornea
PubMed: 37703035
DOI: 10.1167/tvst.12.9.9 -
Cureus Aug 2023We present a case report on disseminated cutaneous infection with a sporotrichoid pattern in an immunocompetent patient. The aim of this report is to contribute to the...
We present a case report on disseminated cutaneous infection with a sporotrichoid pattern in an immunocompetent patient. The aim of this report is to contribute to the existing knowledge on the clinical presentation and management of this uncommon presentation.
PubMed: 37692700
DOI: 10.7759/cureus.43170 -
Microbiology Spectrum Sep 2023The clinical utility of rifamycins against non-tuberculous mycobacterial (NTM) disease is limited by intrinsic drug resistance achieved by ADP-ribosyltransferase Arr. By...
The clinical utility of rifamycins against non-tuberculous mycobacterial (NTM) disease is limited by intrinsic drug resistance achieved by ADP-ribosyltransferase Arr. By blocking the site of ribosylation, we recently optimized a series of analogs with substantially improved potency against . Here, we show that a representative member of this series is significantly more potent than rifabutin against major NTM pathogens expressing Arr, providing a powerful medicinal chemistry approach to expand the antimycobacterial spectrum of rifamycins. IMPORTANCE Lung disease caused by a range of different species of non-tuberculous mycobacteria (NTM) is difficult to cure. The rifamycins are very active against which causes tuberculosis (TB), but inactive against many NTM species. Previously, we showed that the natural resistance of the NTM to rifamycins is due to enzymatic inactivation of the drug by the bacterium. We generated chemically modified versions of rifamycins that prevent inactivation by the bacterium and thus become highly active against Here, we show that such a chemically modified rifamycin is also highly active against several additional NTM species that harbor the rifamycin inactivating enzyme found in , including , , and . This finding expands the potential therapeutic utility of our novel rifamycins to include several currently difficult-to-cure NTM lung disease pathogens beyond
PubMed: 37681986
DOI: 10.1128/spectrum.01900-23 -
Skinmed 2023In 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...
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 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.
Topics: Female; Humans; Adult; Ulcer; Diagnosis, Differential; Mycobacterium chelonae; Clarithromycin; Skin Diseases, Infectious; Skin Diseases; Cellulitis
PubMed: 37634109
DOI: No ID Found -
Animal Microbiome Aug 2023Despite the long-established importance of zebrafish (Danio rerio) as a model organism and their increasing use in microbiome-targeted studies, relatively little is...
BACKGROUND
Despite the long-established importance of zebrafish (Danio rerio) as a model organism and their increasing use in microbiome-targeted studies, relatively little is known about how husbandry practices involving diet impact the zebrafish gut microbiome. Given the microbiome's important role in mediating host physiology and the potential for diet to drive variation in microbiome composition, we sought to clarify how three different dietary formulations that are commonly used in zebrafish facilities impact the gut microbiome. We compared the composition of gut microbiomes in approximately 60 AB line adult (129- and 214-day-old) zebrafish fed each diet throughout their lifespan.
RESULTS
Our analysis finds that diet has a substantial impact on the composition of the gut microbiome in adult fish, and that diet also impacts the developmental variation in the gut microbiome. We further evaluated how 214-day-old fish microbiome compositions respond to exposure of a common laboratory pathogen, Mycobacterium chelonae, and whether these responses differ as a function of diet. Our analysis finds that diet determines the manner in which the zebrafish gut microbiome responds to M. chelonae exposure, especially for moderate and low abundance taxa. Moreover, histopathological analysis finds that male fish fed different diets are differentially infected by M. chelonae.
CONCLUSIONS
Overall, our results indicate that diet drives the successional development of the gut microbiome as well as its sensitivity to exogenous exposure. Consequently, investigators should carefully consider the role of diet in their microbiome zebrafish investigations, especially when integrating results across studies that vary by diet.
PubMed: 37563644
DOI: 10.1186/s42523-023-00254-8 -
Internal Medicine (Tokyo, Japan) Apr 2024Mycobacterium chelonae, a rapidly growing mycobacterium found in the natural environment, is known to cause localized lesions in the skin, soft tissue, and bone through...
Mycobacterium chelonae, a rapidly growing mycobacterium found in the natural environment, is known to cause localized lesions in the skin, soft tissue, and bone through traumatic inoculation, but widespread lesions are uncommon. We herein report an immunocompromised 79-year-old man suspected of having polyangiitis granulomatosis due to weight loss, epistaxis, and nasal crusts with impending septal perforation who was subsequently diagnosed with mucocutaneous and bone disease caused by widespread M. chelonae infection. Given these findings, clinicians should be aware of the tendency to develop unusual widespread lesions in immunocompromised patients, which can present a clinical picture similar to systemic vasculitides, such as granulomatosis with polyangiitis.
Topics: Male; Humans; Aged; Mycobacterium chelonae; Granulomatosis with Polyangiitis; Mycobacterium Infections, Nontuberculous; Nasal Septal Perforation; Diagnosis, Differential
PubMed: 37558480
DOI: 10.2169/internalmedicine.2202-23 -
Journal of Infection in Developing... Jul 2023Although non-tuberculous mycobacterium (NTM) infection accounts for only a small proportion of fever of unknown origin (FUO) cases, it has become a more common etiology... (Review)
Review
INTRODUCTION
Although non-tuberculous mycobacterium (NTM) infection accounts for only a small proportion of fever of unknown origin (FUO) cases, it has become a more common etiology in recent years. Therefore, we reviewed FUO patients with underlying NTM infection to better understand its clinical features.
METHODOLOGY
The medical records of patients presenting with FUO and diagnosed with NTM infection admitted to Peking Union Medical College Hospital between January 2016 and June 2021 were reviewed. The clinical information of patients whose follow-up data were available were summarized. Specimens submitted for pathogenic identification were processed by mycobacterial culture, acid-fast staining, and mycobacterial nucleic acid detection. IBM SPSS Statistics v22.0 (SPSS, Inc., Chicago, IL, USA) was used for data analysis.
RESULTS
Fifty-five FUO patients were diagnosed with NTM infection (55/785; 7.0% of FUO cases). Patients were mostly middle-aged men and had a relatively long disease course. Seven, 29, and 54 patients had previously no respondence to glucocorticoids, immunosuppressants, and multiple antibiotics, respectively; their inflammatory indexes were significantly increased; and there was no obvious risk of immunosuppression in this group, who were likely to be T.SPOT-TB negative (33/41; 80.5%). The most commonly identified NTM was Mycobacterium intracellulare followed by Mycobacterium chelonae/abscessus, Mycobacterium kansasii, and Mycobacterium avium.
CONCLUSIONS
Microbiological investigations including culture, acid-fast staining, NTM nucleic acid examination, and next-generation sequencing were performed to confirm the diagnosis of NTM in FUO patients. FUO patients should screen for NTM infections so that this important etiology can be recognized, targeted treatments administered early, and outcomes improved.
Topics: Male; Middle Aged; Humans; Mycobacterium Infections, Nontuberculous; Fever of Unknown Origin; Mycobacterium avium Complex; Mycobacterium; Tuberculosis; Nontuberculous Mycobacteria; Retrospective Studies
PubMed: 37515806
DOI: 10.3855/jidc.17610