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International Journal of... 2023Difficult-to-treat mycobacterial infections are increasing globally. There is an urgent need of new treatment alternatives for multidrug-resistant Mycobacterium... (Review)
Review
Difficult-to-treat mycobacterial infections are increasing globally. There is an urgent need of new treatment alternatives for multidrug-resistant Mycobacterium tuberculosis (MTB), as well as nontuberculous mycobacteria such as the Mycobacterium abscessus complex (MABC) and Mycobacterium avium complex (MAC). Recently, new carbapenems and combinations of carbapenems with β-lactamase inhibitors have become available, but activity data in vitro against mycobacteria are so far scarce. Therefore, we performed a systematic review collating the minimum inhibitory concentrations (MICs) of carbapenems, with or without a β-lactamase inhibitors for MTB, MABC, and MAC. The databases PubMed and Web of Science were searched for the relevant articles in English up until September 21, 2022. Screening of studies was performed by two independent reviewers. MIC data by recommended methods with at least five individual MICs were included. Data were reported as MIC range, MIC, modal MIC, and/or histograms when individual MICs were available. The study protocol was registered at PROSPERO (CRD42021258537). After screening, a total of 75 studies with MIC data for carbapenems with or without β-lactamase inhibitors were included in the review. For MTB, the oral carbapenem tebipenem combined with the β-lactamase inhibitor clavulanic acid resulted in the most significant reduction of MICs. For MABC, the addition of avibactam to tebipenem resulted in a 64-fold reduction of modal MIC. Data were insufficient for the analysis of MAC. Carbapenems, and in particular the novel oral compound tebipenem, in combination with clavulanic acid for MTB and avibactam for MABC may be an untapped potential for difficult-to-treat mycobacterial infections.
Topics: Humans; beta-Lactamase Inhibitors; Mycobacterium abscessus; Mycobacterium avium Complex; Mycobacterium tuberculosis; Carbapenems; Penicillins; Clavulanic Acid; Microbial Sensitivity Tests; Anti-Bacterial Agents; Mycobacterium Infections, Nontuberculous
PubMed: 37721224
DOI: 10.4103/ijmy.ijmy_131_23 -
Journal of Infection in Developing... Nov 2023Accurate identification of pathogens that cause pulmonary infections is essential for effective treatment and hastening recovery in adults diagnosed with pneumonia. At...
INTRODUCTION
Accurate identification of pathogens that cause pulmonary infections is essential for effective treatment and hastening recovery in adults diagnosed with pneumonia. At present, despite metagenomic next-generation sequencing (mNGS) technology has been widely used in clinical practice for pathogen identification, the clinical significance and necessity of detecting pathogen in bronchoalveolar lavage fluid (BALF) for pneumonia-stricken adults remain ambiguous.
METHODOLOGY
In this study, 80 patients suffering from pulmonary infection were enrolled, who were admitted to the Affiliated Changzhou Second People's Hospital of Nanjing Medical University between January 2020 and September 2022. The diagnostic performances of mNGS and conventional methods (CM) were systematically analyzed based on BALF samples, and we further investigated the influence of mNGS and CM in diagnosis modification and treatment.
RESULTS
We found a significantly higher positive rate for the mNGS method in contrast to CM. Bacteria were the most common pathogens, and Streptococcus pneumoniae was the most commonly identified pathogen. Candida albicans and Epstein-Barr virus were the most frequently identified fungus and virus. Atypical pathogens such as Mycobacterium tuberculosis, virus Nontuberculous mycobacteria, and Chlamydia psittaci were also identified. A total of 77 patients were identified with mixed infections by mNGS. As the disease progressed and recurrent antibiotic treatment persisted, significant dynamic changes in the clinical manifestation from the BALF samples could be found by mNGS.
CONCLUSIONS
This study underscores the efficacy of mNGS in detecting pathogens in BALF samples from patients suffering pulmonary infections. Compared with the CM, mNGS significantly enhanced the positive diagnosis ratio, particularly in diagnosing Mycobacterium tuberculosis, atypical pathogens, and viral or fungal infections.
Topics: Adult; Humans; Epstein-Barr Virus Infections; Herpesvirus 4, Human; Pneumonia; High-Throughput Nucleotide Sequencing; Streptococcus pneumoniae; Mycobacterium tuberculosis; Sensitivity and Specificity
PubMed: 38064390
DOI: 10.3855/jidc.18696 -
Antimicrobial Agents and Chemotherapy Nov 2023Rifampicin is recommended for the treatment of complex pulmonary disease alongside azithromycin and ethambutol. We evaluated the azithromycin-ethambutol backbone with...
Rifampicin is recommended for the treatment of complex pulmonary disease alongside azithromycin and ethambutol. We evaluated the azithromycin-ethambutol backbone with and without rifampicin in an intracellular hollow fiber model and performed RNA sequencing to study the differences in adaptation. In an hollow fiber experiment, we simulated epithelial lining fluid pharmacokinetic profiles of the recommended 3-drug (rifampicin, ethambutol, and azithromycin) or a 2-drug (ethambutol and azithromycin) treatment. THP-1 cells infected with ATCC700898 were exposed to these regimens for 21 days. We determined intra- and extra-cellular bacterial load- and THP-1 cell densities on days 0, 3, 7, 14, and 21, alongside RNA sequencing. The emergence of macrolide resistance was studied by inoculating intra- and extra-cellular fractions of azithromycin-containing Middlebrook 7H10 agar plates. Complete pharmacokinetic profiles were determined at days 0 and 21. Both therapies maintained stasis of both intra- and extra-cellular bacterial populations for 3 days, whilst regrowth coinciding with the emergence of a macrolide-resistant subpopulation was seen after 7 days. THP-1 cell density remained static. Similar transcriptional profiles were observed for both therapies that were minimally influenced by exposure duration. Transcriptional response was slightly larger during 2-drug treatment. Rifampicin did not add to the antimycobacterial effect to the 2-drug therapy or suppression of emergence resistance. RNA transcription was not greatly altered by the addition of rifampicin, which may be due to strong transcriptional influence of azithromycin and host cells. This questions the role of rifampicin in the currently recommended therapy. These findings should be confirmed in clinical trials.
Topics: Humans; Rifampin; Mycobacterium avium; Anti-Bacterial Agents; Ethambutol; Azithromycin; Macrolides; Drug Resistance, Bacterial; Mycobacterium avium Complex; Mycobacterium avium-intracellulare Infection; Lung Diseases
PubMed: 37877693
DOI: 10.1128/aac.00874-23 -
Microbiology Spectrum Dec 2023represents the most common rapidly growing mycobacterial pathogen in cystic fibrosis and is extremely difficult to eradicate. Essential genes are required for growth,...
represents the most common rapidly growing mycobacterial pathogen in cystic fibrosis and is extremely difficult to eradicate. Essential genes are required for growth, often participate in pathogenesis, and encode valid drug targets for further chemotherapeutic developments. However, assessing the function of essential genes in remains challenging due to the limited spectrum of efficient genetic tools. Herein, we generated a Tet-OFF-based system allowing to knock down the expression of , encoding the mycolic acid transporter in mycobacteria. Using this conditional mutant, we confirm the essentiality of in planktonic cultures, in biofilms, and during infection in zebrafish embryos. Thus, in this study, we developed a robust and reliable method to silence the expression of any gene during host infection.
Topics: Animals; Mycobacterium abscessus; Mycobacterium Infections, Nontuberculous; Zebrafish; Mycobacterium; Gene Expression
PubMed: 37831478
DOI: 10.1128/spectrum.02836-23 -
Virulence Dec 2023subspecies ( ) is increasingly recognized as an emerging bacterial pathogen, particularly in cystic fibrosis (CF) patients and CF centres' respiratory outbreaks. We...
BACKGROUND
subspecies ( ) is increasingly recognized as an emerging bacterial pathogen, particularly in cystic fibrosis (CF) patients and CF centres' respiratory outbreaks. We characterized genomic and phenotypic changes in 15 serial isolates from two CF patients (1S and 2B) with chronic pulmonary M. massiliense infection leading to death, as well as four isolates from a CF centre outbreak in which patient 2B was the index case.
RESULTS
Comparative genomic analysis revealed the mutations affecting growth rate, metabolism, transport, lipids (loss of glycopeptidolipids), antibiotic susceptibility (macrolides and aminoglycosides resistance), and virulence factors. Mutations in 23S rRNA, 4, porin locus and R genes occurred in isolates from both CF patients. Interestingly, we identified two different spontaneous mutation events at the mycobacterial porin locus: a fusion of two tandem porin paralogs in patient 1S and a partial deletion of the first porin paralog in patient 2B. These genomic changes correlated with reduced porin protein expression, diminished C-glucose uptake, slower bacterial growth rates, and enhanced TNF-α induction in mycobacteria-infected THP-1 human cells. Porin gene complementation of porin mutants partly restored C-glucose uptake, growth rate and TNF-α levels to those of intact porin strains.
CONCLUSIONS
We hypothesize that specific mutations accumulated and maintained over time in , including mutations shared among transmissible strains, collectively lead to more virulent, host adapted lineages in CF patients and other susceptible hosts.
Topics: Humans; Anti-Bacterial Agents; Cystic Fibrosis; Genomics; Glucose; Lung; Mutation; Mycobacterium; Mycobacterium abscessus; Tumor Necrosis Factor-alpha; Porins
PubMed: 37221835
DOI: 10.1080/21505594.2023.2215602 -
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 -
Scientific Reports Nov 2023The prevalence of Mycobacterium avium complex-pulmonary disease (MAC-PD) has become a growing concern worldwide, and current treatments involving macrolides...
The prevalence of Mycobacterium avium complex-pulmonary disease (MAC-PD) has become a growing concern worldwide, and current treatments involving macrolides (clarithromycin [CLR] or azithromycin), ethambutol, and rifampicin have limited success, highlighting the need for better therapeutic strategies. Recently, oxazolidinone drugs have been identified as novel anti-tuberculosis drugs effective against drug-resistant M. tuberculosis. However, the effects of these drugs against MAC are still controversial due to limited data. Here, we first evaluated the intracellular anti-MAC activities of two oxazolidinone drugs, linezolid (LZD) and delpazolid (DZD), against 10 macrolide-susceptible MAC strains and one macrolide-resistant M. avium strain in murine bone marrow-derived macrophages (BMDMs) and found that both drugs demonstrated similar potential. The synergistic efficacies with CLR were then determined in a chronic progressive MAC-PD murine model by initiating a 4-week treatment at 8 weeks post-infection. Upon assessment of bacterial burdens and inflamed lesions, oxazolidinone drugs exhibited no anti-MAC effect, and there was no significant difference in the synergistic effect of CLR between LZD and DZD. These findings suggest that oxazolidinone drugs inhibit intracellular bacterial growth, even against macrolide-resistant MAC, but their clinical application requires further consideration.
Topics: Humans; Mice; Animals; Mycobacterium avium Complex; Mycobacterium avium-intracellulare Infection; Oxazolidinones; Anti-Bacterial Agents; Antitubercular Agents; Clarithromycin; Macrolides; Lung Diseases
PubMed: 37996500
DOI: 10.1038/s41598-023-48001-y -
Cureus Jul 2023is a ubiquitous and opportunist agent that may cause infections related to water activities in humans. It causes mainly skin and soft tissue infections, and other...
is a ubiquitous and opportunist agent that may cause infections related to water activities in humans. It causes mainly skin and soft tissue infections, and other forms of presentation are uncommon. A 27-year-old man presented to the Emergency Department of a tertiary hospital due to a cervical foreign-body sensation that evolved into right cervical swelling and consumption symptoms. He was a waiter on a cruise in the Douro river. Weeks after the initial presentation, the diagnosis of infection was made by positive nucleic acid amplification tests (NAAT) in tissues obtained by excisional biopsy of cervical adenopathy. Treatment with rifampicin and clarithromycin was started. The symptoms improved, and there was a decrease in the adenopathy number and size. Although adenitis as initial presentation of the disease is rare, the identification of the agent by NAAT and favorable response to treatment supported the diagnosis.
PubMed: 37575752
DOI: 10.7759/cureus.41833 -
PLoS Pathogens Aug 2023Mycobacterium abscessus causes severe disease in patients with cystic fibrosis. Little is known in M. abscessus about the roles of small regulatory RNAs (sRNA) in gene...
Mycobacterium abscessus causes severe disease in patients with cystic fibrosis. Little is known in M. abscessus about the roles of small regulatory RNAs (sRNA) in gene regulation. We show that the sRNA B11 controls gene expression and virulence-associated phenotypes in this pathogen. B11 deletion from the smooth strain ATCC_19977 produced a rough strain, increased pro-inflammatory signaling and virulence in multiple infection models, and increased resistance to antibiotics. Examination of clinical isolate cohorts identified isolates with B11 mutations or reduced expression. We used RNAseq and proteomics to investigate the effects of B11 on gene expression and test the impact of mutations found in clinical isolates. Over 200 genes were differentially expressed in the deletion mutant. Strains with the clinical B11 mutations showed expression trends similar to the deletion mutant, suggesting partial loss of function. Among genes upregulated in the B11 mutant, there was a strong enrichment for genes with B11-complementary sequences in their predicted ribosome binding sites (RBS), consistent with B11 functioning as a negative regulator that represses translation via base-pairing to RBSs. Comparing the proteomes similarly revealed that upregulated proteins were strongly enriched for B11-complementary sequences. Intriguingly, genes upregulated in the absence of B11 included components of the ESX-4 secretion system, critical for M. abscessus virulence. Many of these genes had B11-complementary sequences at their RBSs, which we show is sufficient to mediate repression by B11 through direct binding. Altogether, our data show that B11 acts as a direct negative regulator and mediates (likely indirect) positive regulation with pleiotropic effects on gene expression and clinically important phenotypes in M. abscessus. The presence of hypomorphic B11 mutations in clinical strains is consistent with the idea that lower B11 activity may be advantageous for M. abscessus in some clinical contexts. This is the first report on an sRNA role in M. abscessus.
Topics: Mycobacterium abscessus; Virulence; Anti-Bacterial Agents; RNA, Small Untranslated
PubMed: 37603560
DOI: 10.1371/journal.ppat.1011575 -
Nature Communications Sep 2023Tuberculosis continues to pose a serious threat to global health. Mycobacterium tuberculosis, the causative agent of tuberculosis, is an intracellular pathogen that...
Tuberculosis continues to pose a serious threat to global health. Mycobacterium tuberculosis, the causative agent of tuberculosis, is an intracellular pathogen that relies on various mechanisms to survive and persist within the host. Among their many virulence factors, mycobacteria encode Mce systems. Some of these systems are implicated in lipid uptake, but the molecular basis for Mce function(s) is poorly understood. To gain insights into the composition and architecture of Mce systems, we characterized the putative Mce1 complex involved in fatty acid transport. We show that the Mce1 system in Mycobacterium smegmatis comprises a canonical ATP-binding cassette transporter associated with distinct heterohexameric assemblies of substrate-binding proteins. Furthermore, we establish that the conserved membrane protein Mce1N negatively regulates Mce1 function via a unique mechanism involving blocking transporter assembly. Our work offers a molecular understanding of Mce complexes, sheds light on mycobacterial lipid metabolism and its regulation, and informs future anti-mycobacterial strategies.
Topics: Membrane Proteins; Mycobacterium smegmatis; Mycobacterium tuberculosis; Membrane Transport Proteins; ATP-Binding Cassette Transporters
PubMed: 37736771
DOI: 10.1038/s41467-023-41578-y