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Epidemiology of Nontuberculous Mycobacteria in Tuberculosis suspects, Southwest of China, 2017-2022.Frontiers in Cellular and Infection... 2023This study summarizes the epidemiological characteristics, species distribution, and drug sensitivity of clinical nontuberculous mycobacteria (NTM) isolates at the...
OBJECTIVES
This study summarizes the epidemiological characteristics, species distribution, and drug sensitivity of clinical nontuberculous mycobacteria (NTM) isolates at the Public Health Clinical Center of Chengdu, China, from January 2017 to December 2022.
METHODS
We retrospectively analyzed data from patients with clinically isolated NTM strains. Chi-square analysis assessed the rate of strain isolation over 6 years.
RESULTS
The number of samples tested for (MTB) and/or NTM increased each year, while MTB detection decreased and NTM detection rose significantly each year (P=0.03). The average age of NTM patients was 51 ± 17.53 years, with a 14.1% HIV infection rate. The predominant isolates were (MAC) and /, with 96.4% of cases being of Han ethnicity. Amikacin, moxifloxacin, and clarithromycin were effective against and ; linezolid, amikacin, and cefoxitin were effective against /. Over 90% of NTM cases originated from the respiratory tract.
CONCLUSION
The NTM isolation rate in Southwest China has risen in recent years, primarily among elderly patients with a high HIV co-infection rate. The main NTM isolates were MAC and /. Amikacin, moxifloxacin, clarithromycin, and linezolid exhibited strong antibacterial activity against SGM, while amikacin and linezolid displayed relatively better antibacterial activity against RGM. The prevalence of NTM infection may be positively associated with regional economic development and health conditions.
Topics: Humans; Aged; Adult; Middle Aged; Nontuberculous Mycobacteria; Clarithromycin; Amikacin; Linezolid; HIV Infections; Moxifloxacin; Retrospective Studies; Anti-Bacterial Agents; Mycobacterium Infections, Nontuberculous; Tuberculosis; China; Microbial Sensitivity Tests
PubMed: 38029240
DOI: 10.3389/fcimb.2023.1282902 -
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 -
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 -
Journal of Clinical Microbiology Jul 2023Macrolides are a mainstay of therapy for infections due to nontuberculous mycobacteria (NTM). Among rapidly growing mycobacteria (RGM), inducible macrolide resistance is...
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 () 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 genes. Using whole-genome sequencing, we identified a novel plasmid-mediated gene. This gene, designated (55), exhibits <65% amino acid identity to previously described RGM genes. Two additional chromosomal (55) alleles, with sequence identities of 81% to 86% to (55), were also identified and designated (55) and (55). The (55) is part of a transposon. The (55) 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 (55). The e(55) 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 (55) among other RGM species.
Topics: Humans; Anti-Bacterial Agents; Macrolides; Mycobacterium chelonae; Drug Resistance, Bacterial; Clarithromycin; Nontuberculous Mycobacteria; Mycobacterium; Plasmids; Microbial Sensitivity Tests; Mycobacterium Infections, Nontuberculous
PubMed: 37347171
DOI: 10.1128/jcm.00428-23 -
Surgical Case Reports Jul 2023Mycobacterium chelonae, a nontuberculous mycobacterium, commonly causes skin, soft tissue, eye, pulmonary, catheter-related, and post-surgical infections in patients...
BACKGROUND
Mycobacterium chelonae, a nontuberculous mycobacterium, commonly causes skin, soft tissue, eye, pulmonary, catheter-related, and post-surgical infections in patients with immunosuppression or trauma. M. chelonae breast infections are rare, and most cases occur following cosmetic surgery. Here, we report the first case of spontaneous breast abscess due to M. chelonae.
CASE PRESENTATION
A 22-year-old Japanese woman presented at our hospital with swelling and pain in the right breast for the past 2 weeks without any fever. She had a 19-month-old child and stopped breastfeeding 1 month after giving birth. The patient had no history of trauma or breast surgeries, no family history of breast cancer, and was not immunocompromised. Breast ultrasonography revealed a heterogeneous hypoechoic lesion with multiple fluid-filled areas suspected to be abscesses. Dynamic contrast-enhanced magnetic resonance imaging revealed a 64 × 58 × 62 mm, ill-defined, high-signal-intensity lesion with multiple ring enhancements in the upper half of the right breast. The first diagnosis was inflammatory breast cancer or granulomatous mastitis with abscess. A core needle biopsy led to drainage of pus. Gram staining did not reveal any bacteria in the pus, but the colonies from the biopsy grew on blood and chocolate agar cultures. Mass spectrometry detected M. chelonae in these colonies. Histopathological findings revealed mastitis without malignancy. The patient's treatment regimen was oral clarithromycin (CAM) based on susceptibility. Three weeks later, although the pus had reduced, the induration in the breast did not resolve; therefore, multidrug antibiotic treatment was initiated. The patient received amikacin and imipenem infusion therapy for 2 weeks, followed by continuation of CAM. Three weeks later, tenderness in the right breast recurred with slight pus discharge. Hence, minocycline (MINO) was added to the treatment. The patient stopped CAM and MINO treatment 2 weeks later. There was no recurrence 2 years after treatment.
CONCLUSION
We report a case of M. chelonae breast infection and abscess formation in a 22-year-old Japanese woman without obvious risk factors. M. chelonae infection should be considered in cases of intractable breast abscess, even in patients without immunosuppression or trauma.
PubMed: 37405585
DOI: 10.1186/s40792-023-01706-8 -
JAAD Case Reports Jul 2023
PubMed: 37492428
DOI: 10.1016/j.jdcr.2023.06.013 -
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