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Microbiology Spectrum Feb 2024pulmonary disease is increasing in prevalence globally, particularly for individuals with cystic fibrosis. These infections are challenging to treat due to a high rate...
pulmonary disease is increasing in prevalence globally, particularly for individuals with cystic fibrosis. These infections are challenging to treat due to a high rate of resistance. Amikacin is critical to treatment, but the development of toxicity, amikacin resistance, and treatment failure are significant challenges. Amikacin has been characterized previously as peak-dependent and extended-interval dosing is commonly used. In our hollow fiber infection model of , amikacin exhibited time-dependent rather than the expected peak-dependent pharmacodynamics. Humanized amikacin exposures with more frequent, short-interval dosing (continuous infusion or every 12 hours) yielded improved microbiological response compared to extended-interval dosing (every 24 hours or 1-3 times per week). Short-interval dosing inhibited growth with a mean (SD) maximum Δlog colony forming units of -4.06 (0.52), significantly more than extended-interval dosing ( = 0.0013) every 24 hours, -2.40 (0.58), or 1-3 times per week, -2.39 (0.38). Growth recovery, an indicator of resistance emergence, occurred at 6.56 (0.70) days with short-interval dosing but was significantly earlier with extended-interval dosing ( = 0.0032) every 24 hours, 3.88 (0.85) days, and 1-3 times per week, 3.27 (1.72) days. Microbiological response correlated best with the pharmacodynamic index of %T > minimum inhibitory concentration (MIC), with an EC for growth inhibition of ~40%T > MIC. We used a previously published population model of amikacin to determine the probability of achieving 40%T > MIC and show that current dosing strategies are far below this target, which may partially explain why treatment failure remains so high for these infections. These data support a cautious approach to infrequent amikacin dosing for the treatment of .IMPORTANCEPulmonary disease caused by complex (MABSC) is increasing worldwide, particularly in patients with cystic fibrosis. MABSC is challenging to treat due to high levels of antibiotic resistance. Treatment requires 2-4 antibiotics over more than 12 months and has a significant risk of toxicity but still fails to eradicate infection in over 50% of patients with cystic fibrosis. Antibiotic dosing strategies have been largely informed by common bacteria such as . The "pharmacodynamic" effects of amikacin, a backbone of MABSC treatment, were thought to be related to maximum "peak" drug concentration, leading to daily or three times weekly dosing. However, we found that amikacin MABSC kill and growth recovery, an indicator of antibiotic resistance, are dependent on how long amikacin concentrations are above the minimum inhibitory concentration, not how high the peak concentration is. Therefore, we recommend a re-evaluation of amikacin dosing to determine if increased frequency can improve efficacy.
Topics: Humans; Amikacin; Mycobacterium abscessus; Cystic Fibrosis; Anti-Bacterial Agents; Microbial Sensitivity Tests; Mycobacterium Infections, Nontuberculous
PubMed: 38236037
DOI: 10.1128/spectrum.03222-23 -
Journal of Clinical Microbiology Apr 2022Clarithromycin resistance in Mycobacterium abscessus subsp. , , and occurs through induction of (41) or mutations in (23S rRNA) genes. Phenotypic detection of...
Clarithromycin resistance in Mycobacterium abscessus subsp. , , and occurs through induction of (41) or mutations in (23S rRNA) genes. Phenotypic detection of clarithromycin resistance is hindered by the need for extended incubation as well as co-occurrence of mixed populations of M. abscessus with different susceptibility profiles. We developed a quantitative EvaGreen-based droplet digital PCR (ddPCR) scheme for rapid detection of full-length or truncated (41) and a probe based ddPCR screening assay for assessment of 23S rRNA mutational resistance. We tested 100 M. abscessus strains, synthetic mixes with different susceptibility profiles, and 13 positive MGIT samples. Truncated and full-length (41) genes were detected in 27/100 and 73/100 strains and 4/13 and 9/13 MGIT samples, respectively yielding a sensitivity and specificity of 100%. Clarithromycin resistance mutations in were detected in 26/100 isolates, i.e., A2058G (18/100), A2058C (7/100), and A2059G (1/100), and in 3/13 MGIT samples, i.e., A2058G (2/13) and A2059G (1/13). A screening assay of ddPCR (A2058A/A2058G probes) showed 100% sensitivity in detecting the wild type or A2058G mutation as well as identifying samples requiring further testing. Upon inclusion of additional ddPCR assays, we were able to detect A2058C and A2059G clarithromycin resistance-conferring mutations in the gene. Our ddPCR scheme can differentiate between full-length and truncated (41) and identify clarithromycin resistance-conferring mutations in the gene from clinical isolates and positive MGIT samples as well as deconvolute and quantitate mixed populations of M. abscessus with different clarithromycin resistance traits.
Topics: Anti-Bacterial Agents; Clarithromycin; Drug Resistance, Bacterial; Humans; Microbial Sensitivity Tests; Mycobacterium Infections, Nontuberculous; Mycobacterium abscessus; RNA, Ribosomal, 23S
PubMed: 35313731
DOI: 10.1128/jcm.01694-21 -
Tuberculosis (Edinburgh, Scotland) Jan 2022The prevalence of infections by nontuberculous mycobacteria is increasing, having surpassed tuberculosis in the United States and much of the developed world....
The prevalence of infections by nontuberculous mycobacteria is increasing, having surpassed tuberculosis in the United States and much of the developed world. Nontuberculous mycobacteria occur naturally in the environment and are a significant problem for patients with underlying lung diseases such as bronchiectasis, chronic obstructive pulmonary disease, and cystic fibrosis. Current treatment regimens are lengthy, complicated, toxic and they are often unsuccessful as seen by disease recurrence. Mycobacterium abscessus is one of the most commonly encountered organisms in nontuberculous mycobacteria disease and it is the most difficult to eradicate. There is currently no systematically proven regimen that is effective for treating M. abscessus infections. Our approach to drug discovery integrates machine learning, medicinal chemistry and in vitro testing and has been previously applied to Mycobacterium tuberculosis. We have now identified several novel 1-(phenylsulfonyl)-1H-benzimidazol-2-amines that have weak activity on M. abscessus in vitro but may represent a starting point for future further medicinal chemistry optimization. We also address limitations still to be overcome with the machine learning approach for M. abscessus.
Topics: Antitubercular Agents; Bayes Theorem; Drug Discovery; Humans; Machine Learning; Mycobacterium abscessus
PubMed: 35077930
DOI: 10.1016/j.tube.2022.102168 -
PLoS Pathogens Nov 2019Free-living amoebae are thought to represent an environmental niche in which amoeba-resistant bacteria may evolve towards pathogenicity. To get more insights into...
Free-living amoebae are thought to represent an environmental niche in which amoeba-resistant bacteria may evolve towards pathogenicity. To get more insights into factors playing a role for adaptation to intracellular life, we characterized the transcriptomic activities of the emerging pathogen Mycobacterium abscessus in amoeba and murine macrophages (Mϕ) and compared them with the intra-amoebal transcriptome of the closely related, but less pathogenic Mycobacterium chelonae. Data on up-regulated genes in amoeba point to proteins that allow M. abscessus to resist environmental stress and induce defense mechanisms, as well as showing a switch from carbohydrate carbon sources to fatty acid metabolism. For eleven of the most upregulated genes in amoeba and/or Mϕ, we generated individual gene knock-out M. abscessus mutant strains, from which ten were found to be attenuated in amoeba and/or Mϕ in subsequence virulence analyses. Moreover, transfer of two of these genes into the genome of M. chelonae increased the intra-Mϕ survival of the recombinant strain. One knock-out mutant that had the gene encoding Eis N-acetyl transferase protein (MAB_4532c) deleted, was particularly strongly attenuated in Mϕ. Taken together, M. abscessus intra-amoeba and intra-Mϕ transcriptomes revealed the capacity of M. abscessus to adapt to an intracellular lifestyle, with amoeba largely contributing to the enhancement of M. abscessus intra-Mϕ survival.
Topics: Amoeba; Animals; Bacterial Proteins; Macrophages; Mice; Mycobacterium Infections, Nontuberculous; Mycobacterium abscessus; Transcriptome; Virulence; Virulence Factors
PubMed: 31703112
DOI: 10.1371/journal.ppat.1008069 -
International Journal of Molecular... Oct 2021() causes chronic pulmonary infections and is the most difficult non-tuberculous mycobacteria (NTM) to treat due to its resistance to current antimicrobial drugs, with...
() causes chronic pulmonary infections and is the most difficult non-tuberculous mycobacteria (NTM) to treat due to its resistance to current antimicrobial drugs, with a treatment success rate of 45.6%. Thus, novel treatment drugs are needed, of which we identified the drug clomiphene citrate (CC), known to treat infertility in women, to exhibit inhibitory activity against . To assess the potential of CC as a treatment for pulmonary diseases, we measured its efficacy in vitro and established the intracellular activity of CC against in human macrophages. CC significantly inhibited the growth of not only wild-type strains but also clinical isolate strains and clarithromycin (CLR)-resistant strains of . CC's drug efficacy did not have cytotoxicity in the infected macrophages. Furthermore, CC worked in anaerobic non-replicating conditions as well as in the presence of biofilm. The results of this in vitro study on activity suggest the possibility of using CC to develop new drug hypotheses for the treatment of infections.
Topics: Anti-Bacterial Agents; Clomiphene; Drug Repositioning; Humans; Macrophages; Mycobacterium Infections, Nontuberculous; Mycobacterium abscessus; THP-1 Cells
PubMed: 34681686
DOI: 10.3390/ijms222011029 -
Nature Communications Aug 2022Mycobacterium abscessus is an emerging multidrug-resistant non-tuberculous mycobacterium that causes a wide spectrum of infections and has caused several local outbreaks...
Mycobacterium abscessus is an emerging multidrug-resistant non-tuberculous mycobacterium that causes a wide spectrum of infections and has caused several local outbreaks worldwide. To facilitate standardized prospective molecular surveillance, we established a novel core genome multilocus sequence typing (cgMLST) scheme. Whole genome sequencing data of 1991 isolates were employed to validate the scheme, re-analyze global population structure and set genetic distance thresholds for cluster detection and taxonomic identification. We confirmed and amended the nomenclature of the main dominant circulating clones and found that these also correlate well with traditional 7-loci MLST. Dominant circulating clones could be linked to a corresponding reference genome with less than 250 alleles while 99% of pairwise comparisons between epidemiologically linked isolates were below 25 alleles and 90% below 10 alleles. These thresholds can be used to guide further epidemiological investigations. Overall, the scheme will help to unravel the apparent global spread of certain clonal complexes and as yet undiscovered transmission routes.
Topics: Genome, Bacterial; Genotype; Multilocus Sequence Typing; Mycobacterium abscessus; Phylogeny; Whole Genome Sequencing
PubMed: 35999208
DOI: 10.1038/s41467-022-32122-5 -
BMC Infectious Diseases Nov 2022The Mycobacterium abscessus complex (MABC) is a group of acid-fast, rapidly dividing non-tuberculous mycobacteria (NTM) that include a number of clinically important... (Review)
Review
The Mycobacterium abscessus complex (MABC) is a group of acid-fast, rapidly dividing non-tuberculous mycobacteria (NTM) that include a number of clinically important subspecies, including M. abscessus, M. bolletii, and M. massiliense. These organisms are prevalent in the environment and are primarily associated with human pulmonary or skin and skin structure infections (SSSI) but may cause more deep-seeded disseminated infections and bacteremia in the immunocompromised. Importantly, these NTM are resistant to most first-line anti-tuberculous agents and, due to intrinsic or acquired resistance, exhibit exceedingly low, variable, and geographically distinct susceptibilities to commonly used antibacterial agents including older tetracyclines, macrolides, aminoglycosides, cephalosporins, carbapenems, and sulfamethoxazole-trimethoprim. Omadacycline is a novel third-generation member of the tetracycline family of antibacterials that has recently been demonstrated to have potent anti-NTM effects and clinical efficacy against MABC, including M. abscessus. The purpose of this review is to present a comprehensive and up-to-date assessment on the body of literature on the role of omadacycline for M. abscessus infections. Specifically, the in vitro and in vivo microbiology, mechanisms of action, mechanisms of resistance, clinical pharmacokinetics, clinical efficacy, adverse effects, dosage and administration, and place in therapy of omadacycline in management of M. abscessus infections will be detailed.
Topics: Humans; Mycobacterium Infections, Nontuberculous; Tetracyclines; Nontuberculous Mycobacteria; Mycobacterium abscessus; Anti-Bacterial Agents
PubMed: 36419143
DOI: 10.1186/s12879-022-07857-7 -
Antimicrobial Agents and Chemotherapy Jun 2023Benzoxaboroles are a new class of leucyl-tRNA synthetase inhibitors. Epetraborole, a benzoxaborole, is a clinical candidate developed for Gram-negative infections and...
Benzoxaboroles are a new class of leucyl-tRNA synthetase inhibitors. Epetraborole, a benzoxaborole, is a clinical candidate developed for Gram-negative infections and has been confirmed to exhibit favorable activity against a well known pulmonary pathogen, Mycobacterium abscessus. However, according to ClinicalTrials.gov, in 2017, a clinical phase II study on the use of epetraborole to treat complicated urinary tract and intra-abdominal infections was terminated due to the rapid emergence of drug resistance during treatment. Nevertheless, epetraborole is in clinical development for nontuberculous mycobacteria (NTM) disease especially for Mycobacterium avium complex-related pulmonary disease (MAC-PD). DS86760016, an epetraborole analog, was further demonstrated to have an improved pharmacokinetic profile, lower plasma clearance, longer plasma half-life, and higher renal excretion than epetraborole in animal models. In this study, DS86760016 was found to be similarly active against M. abscessus , intracellularly, and in zebrafish infection models with a low mutation frequency. These results expand the diversity of druggable compounds as new benzoxaborole-based candidates for treating M. abscessus diseases.
Topics: Animals; Mycobacterium abscessus; Zebrafish; Mycobacterium Infections, Nontuberculous; Anti-Bacterial Agents; Amino Acyl-tRNA Synthetases; Nontuberculous Mycobacteria
PubMed: 37212672
DOI: 10.1128/aac.01567-22 -
Frontiers in Cellular and Infection... 2017is a rapidly growing mycobacterium (RGM) causing serious infections especially among cystic fibrosis patients. Extremely limited therapeutic options against and a rise...
is a rapidly growing mycobacterium (RGM) causing serious infections especially among cystic fibrosis patients. Extremely limited therapeutic options against and a rise in infections with this mycobacterium require novel chemotherapies and a better understanding of how the bacterium causes infection. Different from most RGM, can survive inside macrophages and persist for long durations in infected tissues. We recently delineated differences in the infective programs followed by smooth (S) and rough (R) variants of . Unexpectedly, we found that the S variant behaves like pathogenic slow growing mycobacteria, through maintaining a block on the phagosome maturation process and by inducing phagosome-cytosol communications. On the other hand, R variant infection triggers autophagy and apoptosis, reminiscent of the way that macrophages control RGM. However, the R variant has an exquisite capacity to form extracellular cords, allowing these bacteria to rapidly divide and evade phagocytosis. Therefore, new chemotherapeutic interventions against need to efficiently deal with both the reservoir of intracellular bacilli and the extracellular cords. In this context, we recently identified two chemical entities that were very effective against both populations. Although being structurally unrelated these two chemotypes inhibit the activity of the essential mycolic acid transporter, MmpL3. In this Perspective, we aimed to highlight recent insights into how interacts with phagocytic cells and how the inhibition of mycolic acid transport in this pathogenic RGM could be an efficient means to control both intracellular and extracellular populations of the bacterium.
Topics: Anti-Bacterial Agents; Apoptosis; Bacterial Proteins; Biological Transport; Cystic Fibrosis; Cytosol; Humans; Indoles; Macrophages; Membrane Transport Proteins; Mycobacterium Infections, Nontuberculous; Mycobacterium abscessus; Mycolic Acids; Phagocytosis; Phagosomes; Piperidines
PubMed: 28920054
DOI: 10.3389/fcimb.2017.00388 -
MBio Mar 2021is an opportunistic pathogen whose treatment is confounded by widespread multidrug resistance. The therapeutic use of bacteriophages against infections offers a...
is an opportunistic pathogen whose treatment is confounded by widespread multidrug resistance. The therapeutic use of bacteriophages against infections offers a potential alternative approach, although the spectrum of phage susceptibilities among isolates is not known. We determined the phage infection profiles of 82 recent clinical isolates and find that colony morphotype-rough or smooth-is a key indicator of phage susceptibility. None of the smooth strains are efficiently killed by any phages, whereas 80% of rough strains are infected and efficiently killed by at least one phage. The repertoire of phages available for potential therapy of rough morphotype infections includes those with relatively broad host ranges, host range mutants of phages, and lytically propagated viruses derived from integrated prophages. The rough colony morphotype results from indels in the glycopeptidolipid synthesis genes and , negating reversion to smooth as a common route to phage resistance. Resistance is thus rare, and although mutations in polyketide synthesis, , and can confer resistance, these likely also impair survival The expanded therapeutic repertoire and the resistance profiles show that small cocktails or single phages could be suitable for controlling infections with rough strains. infections in cystic fibrosis patients are challenging to treat due to widespread antibiotic resistance. The therapeutic use of lytic bacteriophages presents a new potential strategy, but the great variation among clinical isolates demands determination of phage susceptibility prior to therapy. Elucidation of the variation in phage infection and factors determining it, expansion of the suite of therapeutic phage candidates, and a greater understanding of phage resistance mechanisms substantially advances the potential for broad implementation of new therapeutic options for infections.
Topics: Bacterial Proteins; Cystic Fibrosis; Host Specificity; Host-Pathogen Interactions; Humans; Mutation; Mycobacteriophages; Mycobacterium Infections, Nontuberculous; Mycobacterium abscessus; Phage Therapy; Phylogeny
PubMed: 33785625
DOI: 10.1128/mBio.03431-20