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Tuberculosis (Edinburgh, Scotland) May 2024Mycobacteroides abscessus (Mab, also known as Mycobacterium abscessus) causes opportunistic pulmonary and soft tissue infections that are difficult to cure with existing...
Mycobacteroides abscessus (Mab, also known as Mycobacterium abscessus) causes opportunistic pulmonary and soft tissue infections that are difficult to cure with existing treatments. Omadacycline, a new tetracycline antibiotic, exhibits potent in vitro and in vivo activity against Mab. As regimens containing multiple antibiotics are required to produce a durable cure for Mab disease, we assessed efficacies of three three-drug combinations in a pre-clinical mouse model of pulmonary Mab disease to identify companion drugs with which omadacycline exhibits the highest efficacy. Additionally, we assessed the susceptibility of Mab recovered from mouse lungs after four weeks of exposure to the three triple-drug regimens. Among the three-drug regimens, omadacycline + imipenem + amikacin produced the largest reduction in Mab burden, whereas omadacycline + imipenem + linezolid exhibited the most effective early bactericidal activity. Omadacycline + linezolid + clofazimine, a regimen that can be administered orally, lacked early bactericidal activity but produced a gradual reduction in the lung Mab burden over time. The robust efficacy exhibited by these three regimens in the mouse model supports their further evaluation in patients with Mab lung disease. As we were unable to isolate drug-resistant Mab mutants at the completion of four weeks of treatment, these triple-drug combinations show promise of producing durable cure and minimizing selection of resistant mutants.
Topics: Humans; Animals; Mice; Mycobacterium abscessus; Linezolid; Mycobacterium Infections, Nontuberculous; Mycobacterium tuberculosis; Anti-Bacterial Agents; Tetracyclines; Imipenem; Drug Combinations; Microbial Sensitivity Tests
PubMed: 38364332
DOI: 10.1016/j.tube.2024.102482 -
Microbiology Spectrum Mar 2024is a non-tuberculous mycobacterium, causing lung infections in cystic fibrosis patients. During pulmonary infection, switches from smooth (Mabs-S) to rough (Mabs-R)...
is a non-tuberculous mycobacterium, causing lung infections in cystic fibrosis patients. During pulmonary infection, switches from smooth (Mabs-S) to rough (Mabs-R) morphotypes, the latter being hyper-virulent. Previously, we isolated the gene as differentially expressed during S-to-R transition. encodes a pleiotropic transcription factor that falls under the superfamily of nucleoid-associated proteins. Here, we used two functional genomic methods, RNA-seq and chromatin immunoprecipitation-sequencing (ChIP-seq), to elucidate the molecular role of Lsr2 in the pathobiology of . Transcriptomic analysis shows that Lsr2 differentially regulates gene expression across both morphotypes, most of which are involved in several key cellular processes of , including host adaptation and antibiotic resistance. These results were confirmed through quantitative real-time PCR, as well as by minimum inhibitory concentration tests and infection tests on macrophages in the presence of antibiotics. ChIP-seq analysis revealed that Lsr2 extensively binds the genome at AT-rich sequences and appears to form long domains that participate in the repression of its target genes. Unexpectedly, the genomic distribution of Lsr2 revealed no distinctions between Mabs-S and Mabs-R, implying more intricate mechanisms at play for achieving target selectivity.IMPORTANCELsr2 is a crucial transcription factor and chromosome organizer involved in intracellular growth and virulence in the smooth and rough morphotypes of . Using RNA-seq and chromatin immunoprecipitation-sequencing (ChIP-seq), we investigated the molecular role of Lsr2 in gene expression regulation along with its distribution on genome. Our study demonstrates the pleiotropic regulatory role of Lsr2, regulating the expression of many genes coordinating essential cellular and molecular processes in both morphotypes. In addition, we have elucidated the role of Lsr2 in antibiotic resistance both and , where mutant strains display heightened sensitivity to antibiotics. Through ChIP-seq, we reported the widespread distribution of Lsr2 on genome, revealing a direct repressive effect due to its extensive binding on promoters or coding sequences of its targets. This study unveils the significant regulatory role of Lsr2, intricately intertwined with its function in shaping the organization of the genome.
Topics: Humans; Mycobacterium abscessus; Mycobacterium; Mycobacterium Infections, Nontuberculous; Anti-Bacterial Agents; Transcription Factors
PubMed: 38353553
DOI: 10.1128/spectrum.03528-23 -
ChemMedChem Mar 2024Nα-aroyl-N-aryl-phenylalanine amides (AAPs) are RNA polymerase inhibitors with activity against Mycobacterium tuberculosis and non-tuberculous mycobacteria. We observed...
Nα-aroyl-N-aryl-phenylalanine amides (AAPs) are RNA polymerase inhibitors with activity against Mycobacterium tuberculosis and non-tuberculous mycobacteria. We observed that AAPs rapidly degrade in microsomal suspensions, suggesting that avoiding hepatic metabolism is critical for their effectiveness in vivo. As both amide bonds are potential metabolic weak points of the molecule, we synthesized 16 novel AAP analogs in which the amide bonds are shielded by methyl or fluoro substituents in close proximity. Some derivatives show improved microsomal stability, while being plasma-stable and non-cytotoxic. In parallel with the metabolic stability studies, the antimycobacterial activity of the AAPs against Mycobacterium tuberculosis, Mycobacterium abscessus, Mycobacterium avium and Mycobacterium intracellulare was determined. The stability data are discussed in relation to the antimycobacterial activity of the panel of compounds and reveal that the concept of steric shielding of the anilide groups by a fluoro substituent has the potential to improve the stability and bioavailability of AAPs.
Topics: Microbial Sensitivity Tests; Anti-Bacterial Agents; Mycobacterium tuberculosis; Amides
PubMed: 38329388
DOI: 10.1002/cmdc.202300593 -
Southern African Journal of Infectious... 2024Non-tuberculous mycobacteria (NTM) management comprises prolonged therapy that includes macrolides. Non-tuberculous mycobacteria can cause disease in patients with...
BACKGROUND
Non-tuberculous mycobacteria (NTM) management comprises prolonged therapy that includes macrolides. Non-tuberculous mycobacteria can cause disease in patients with predisposing conditions such as HIV and structural lung disease. Local data on NTM disease and macrolide resistance are scarce, and routine antimicrobial susceptibility testing is currently not performed for NTM in South Africa.
OBJECTIVES
This study aims to characterise NTM isolated at Tshepong National Health Laboratory Service (NHLS) according to species and antimicrobial susceptibility pattern.
METHOD
A retrospective data analysis of NTM isolates from Tshepong NHLS was performed from January to June 2020. GenoType NTM-DR was performed on selected isolates where the assay can confirm the species and determine resistance to macrolides and aminoglycosides.
RESULTS
Of the 194 collected NTM isolates, 183 were included in the study. Patients' ages ranged from 1 day to 81 years (median 36 years). The most common specimen was sputum (84.7%), followed by gastric aspirate (6.6%). The most common NTM isolated were (67.6%), (12.6%), (4.3%), (3.9%), and (3.9%). Macrolide resistance occurred in 2.8% of tested isolates; no aminoglycoside resistance was detected. Although most isolates were from males (62.3%), resistance was observed only in females.
CONCLUSION
predominated, with only two and two isolates showing macrolide resistance; aminoglycoside resistance was absent.
CONTRIBUTION
This study highlights the need for increased awareness of NTM, regular nationwide NTM surveillance, and monitoring of resistance trends to guide future patient management and ensure good treatment outcomes.
PubMed: 38322299
DOI: 10.4102/sajid.v39i1.525 -
Journal of Bacteriology Mar 2024is increasingly recognized for causing infections that are notoriously difficult to treat, owing to its large arsenal of intrinsic antibiotic resistance mechanisms....
UNLABELLED
is increasingly recognized for causing infections that are notoriously difficult to treat, owing to its large arsenal of intrinsic antibiotic resistance mechanisms. Tools for the genetic manipulation of the pathogen are critical for enabling a better understanding of biology, pathogenesis, and antibiotic resistance mechanisms. However, existing methods are largely recombination-based, which are relatively inefficient. Meanwhile, CRISPR/Cas9 has revolutionized the field of genome editing including its recent adaptation for use in mycobacteria. In this study, we report a streamlined and efficient method for rapid genetic disruptions in . Harnessing the CRISPR1 loci from , we have developed a dual-plasmid workflow that introduces Cas9 and sgRNA cassettes in separate steps but requires no other additional factors to engineer mutations in single genes or multiple genes simultaneously or sequentially using multiple targeting sgRNAs. Importantly, the efficiency of mutant generation is several orders of magnitude higher than reported for homologous recombination-based methods. This work, thus, reports the first application of CRISPR/Cas9 for gene editing in and is an important tool in the arsenal for the genetic manipulation of this human pathogen.
IMPORTANCE
is an opportunistic pathogen of increasing clinical importance due to its poor clinical outcomes and limited treatment options. Drug discovery and development in this highly antibiotic-resistant species will require further understanding of biology, pathogenesis, and antibiotic resistance mechanisms. However, existing methods for facile genetic engineering are relatively inefficient. This study reports on the first application of CRISPR/Cas9 for gene editing in using a dual-plasmid workflow. We establish that our method is easily programmable, efficient, and versatile for genetic disruptions in . This is a critical advancement to facilitating targeted gene function studies in this emerging pathogen.
Topics: Humans; CRISPR-Cas Systems; RNA, Guide, CRISPR-Cas Systems; Mycobacterium abscessus; Gene Editing; Plasmids
PubMed: 38319218
DOI: 10.1128/jb.00335-23 -
Journal of Biomedical Science Jan 2024Mycobacterium abscessus, a fast-growing non-tuberculous mycobacterium, is an emerging opportunistic pathogen responsible for chronic bronchopulmonary infections in...
BACKGROUND
Mycobacterium abscessus, a fast-growing non-tuberculous mycobacterium, is an emerging opportunistic pathogen responsible for chronic bronchopulmonary infections in people with respiratory diseases such as cystic fibrosis (CF). Due to its intrinsic polyresistance to a wide range of antibiotics, most treatments for M. abscessus pulmonary infections are poorly effective. In this context, antimicrobial peptides (AMPs) active against bacterial strains and less prompt to cause resistance, represent a good alternative to conventional antibiotics. Herein, we evaluated the effect of three arenicin isoforms, possessing two or four Cysteines involved in one (Ar-1, Ar-2) or two disulfide bonds (Ar-3), on the in vitro growth of M. abscessus.
METHODS
The respective disulfide-free AMPs, were built by replacing the Cysteines with alpha-amino-n-butyric acid (Abu) residue. We evaluated the efficiency of the eight arenicin derivatives through their antimicrobial activity against M. abscessus strains, their cytotoxicity towards human cell lines, and their hemolytic activity on human erythrocytes. The mechanism of action of the Ar-1 peptide was further investigated through membrane permeabilization assay, electron microscopy, lipid insertion assay via surface pressure measurement, and the induction of resistance assay.
RESULTS
Our results demonstrated that Ar-1 was the safest peptide with no toxicity towards human cells and no hemolytic activity, and the most active against M. abscessus growth. Ar-1 acts by insertion into mycobacterial lipids, resulting in a rapid membranolytic effect that kills M. abscessus without induction of resistance.
CONCLUSION
Overall, the present study emphasized Ar-1 as a potential new alternative to conventional antibiotics in the treatment of CF-associated bacterial infection related to M. abscessus.
Topics: Humans; Mycobacterium abscessus; Mycobacterium Infections, Nontuberculous; Anti-Bacterial Agents; Cystic Fibrosis; Peptides; Microbial Sensitivity Tests; Polystyrenes
PubMed: 38287360
DOI: 10.1186/s12929-024-01007-8 -
BMC Infectious Diseases Jan 2024This study aimed to measure the prevalence of resistance to antimicrobial agents, and explore the risk factors associated with drug resistance by using nontuberculous...
OBJECTIVES
This study aimed to measure the prevalence of resistance to antimicrobial agents, and explore the risk factors associated with drug resistance by using nontuberculous Mycobacteria (NTM) isolates from China.
METHODS
A total of 335 NTM isolates were included in our analysis. Broth dilution method was used to determine in vitro drug susceptibility of NTM isolates.
RESULTS
Clarithromycin (CLA) was the most potent drug for Mycobacterium intracellulare (MI). The resistance rate of 244 MI isolates to CLA was 21%, yielding a minimum inhibitory concentrations (MIC) and MIC of 8 and 64 mg/L, respectively. 51% of 244 MI isolates exhibited resistance to amikacin (AMK). For 91 Mycobacterium abscessus complex (MABC) isolates, 6 (7%) and 49 (54%) isolates were categorized as resistant to CLA at day 3 and 14, respectively. The resistance rate to CLA for Mycobacterium abscessus subspecies abscessus (MAA) was dramatically higher than that for Mycobacterium abscessus subspecies massiliense (MAM). Additionally, the percentage of patients presenting fever in the CLA-susceptible group was significantly higher than that in the CLA-resistant group.
CONCLUSIONS
Our data demonstrate that approximate one fifth of MI isolates are resistant to CLA. We have identified a higher proportion of CLA-resistant MAA isolates than MAM. The patients caused by CLA-resistant MI are at low risk for presenting with fever relative to CLA-susceptible group.
Topics: Humans; Nontuberculous Mycobacteria; Mycobacterium avium Complex; Mycobacterium abscessus; China; Amikacin; Clarithromycin; Fever
PubMed: 38262940
DOI: 10.1186/s12879-024-09016-6 -
Frontiers in Microbiology 2023Biofilm formation is a major cause of delayed-graft complications. Similarly to implants, dermal fillers carry the risk of biofilm formation, which can lead to the...
INTRODUCTION
Biofilm formation is a major cause of delayed-graft complications. Similarly to implants, dermal fillers carry the risk of biofilm formation, which can lead to the development of nodules, chronic inflammatory reactions, abscesses and other complications. In this study, we investigated the late or delayed complications associated with biofilm formation on dermal fillers.
METHODS
In this retrospective analysis, we analyzed all cases of complications caused by filler injections at a single center between January 2017 and December 2022, the majority of which comprised nodule formation and chronic persistent inflammatory reactions. The risk of biofilm formation with fillers was summarized and analyzed based on the results of bacterial culture and pathological examination.
RESULTS
Sixty-one patients were enrolled, including 42 cases of nodule formation, 15 of chronic inflammatory reactions, and 4 of active infection. Bacterial culture of the tissue samples obtained from seven patients after surgical treatment were positive, and comprised four cases of , one case of , one case of and one case of . The corresponding histopathological results indicated extensive mononuclear lymphocyte infiltration, with a giant cell reaction in the fibrous connective tissue.
CONCLUSION
The results of this study suggest that biofilm formation is a significant risk factor for late and delayed complications following filler injection, and is caused by the contamination of resident bacteria and recessive infection at the injection site.
PubMed: 38260874
DOI: 10.3389/fmicb.2023.1297948 -
Journal of Infection in Developing... Dec 2023Mycobacterium abscessus is an opportunistic nontuberculous mycobacteria pathogen; however, the prevalence of nosocomial and community infections is increasing. In...
INTRODUCTION
Mycobacterium abscessus is an opportunistic nontuberculous mycobacteria pathogen; however, the prevalence of nosocomial and community infections is increasing. In January 2016, several bedridden inpatients in the intensive care unit of a hospital had positive sputum smears for acid-fast bacilli, suggesting a mycobacteria outbreak.
METHODOLOGY
Acid-fast bacilli smear microscopy, isolation, and culturing were performed twice using sputa from each suspected intensive care unit inpatient (n = 13); in addition, medical history was obtained for each inpatient with suspected infection. Furthermore, environmental specimens were surveyed, collected, and cultured. We used DNA microarray chip analysis to identify positive mycobacterial isolates at the species level and performed whole-genome sequencing and phylogenetic tree construction.
RESULTS
Seven inpatients had M. abscessus pulmonary infection, confirmed by 2 positive cultures; five of the inpatients had only one positive culture, while one had two negative cultures. Six of 13 ventilator condensate samples were mycobacterial culture-positive, identified as M. abscessus; the other environmental samples were negative. The M. abscessus isolates (15 sputa and 4 environmental samples) clustered together in the phylogenic analysis with only one single-nucleotide polymorphism difference. All patients were symptom-free after 8 months of multi-drug treatment.
CONCLUSIONS
We confirmed a pulmonary M. abscessus outbreak among 12 bedridden patients in the intensive care unit through microbiological, molecular epidemiological, and environmental investigations. The possible infection source was contaminated ventilator condensate. This outbreak reemphasizes the importance of standardized ventilator maintenance and disinfection for preventing ventilator-associated pneumonia and is a reminder that nontuberculous mycobacteria-related ventilator-associated pneumonia is possible.
Topics: Aged; Humans; Inpatients; Pneumonia, Ventilator-Associated; Phylogeny; Mycobacterium Infections, Nontuberculous; Critical Care; Nontuberculous Mycobacteria; Disease Outbreaks; Hospitals
PubMed: 38252721
DOI: 10.3855/jidc.17395 -
Pathogens (Basel, Switzerland) Dec 2023Non-tuberculous Mycobacteria (NTM), previously classified as environmental microbes, have emerged as opportunistic pathogens causing pulmonary infections in...
Non-tuberculous Mycobacteria (NTM), previously classified as environmental microbes, have emerged as opportunistic pathogens causing pulmonary infections in immunocompromised hosts. The formation of the biofilm empowers NTM pathogens to escape from the immune response and antibiotic action, leading to treatment failures. NF1001 is a novel thiopeptide antibiotic first-in-class compound with potent activity against planktonic/replicating and biofilm forms of various NTM species. It is potent against both drug-sensitive and -resistant NTM. It has demonstrated a concentration-dependent killing of replicating and intracellularly growing NTM, and has inhibited and reduced the viability of NTM in biofilms. Combination studies using standard-of-care (SoC) drugs for NTM exhibited synergetic/additive effects, but no antagonism against both planktonic and biofilm populations of and . In summary, the activity of NF1001 alone or in combination with SoC drugs projects NF1001 as a promising candidate for the treatment of difficult-to-treat NTM pulmonary diseases (NTM-PD) and cystic fibrosis (CF) in patients.
PubMed: 38251347
DOI: 10.3390/pathogens13010040