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Antimicrobial Agents and Chemotherapy Apr 2020Infections with nontuberculous mycobacteria (NTM) have a poor prognosis in patients with underlying respiratory diseases. Clofazimine (CFZ) showed both experimental and...
Infections with nontuberculous mycobacteria (NTM) have a poor prognosis in patients with underlying respiratory diseases. Clofazimine (CFZ) showed both experimental and clinical promising results against clinically relevant NTM. However, there are no data on CFZ in combination with the current recommended treatment; therefore, we aimed to study its activity in an aerosol mouse model of In an aerosol infection BALB/c mouse model using strain Chester, we treated 58 mice with four combinations of rifampin (RIF) at 10 mg/kg, CFZ at 25 mg/kg, and clarithromycin (CLR) and ethambutol (EMB) at 100 mg/kg. Treatment efficacy was assessed on the basis of lung CFU counts after 2 (M2) and 4 (M4) months of treatment. At M2, CLR-RIF-EMB was slightly but significantly more efficient than CFZ-RIF-EMB (3.02 ± 0.12 versus 3.55 ± 0.28, respectively, < 0.01), whereas CLR-CFZ-EMB and CLR-CFZ-RIF-EMB dramatically decreased lung CFU counts by 4.32 and 4.47 log, respectively, compared to untreated group. At M4, CLR-RIF-EMB was significantly more efficient than CFZ-RIF-EMB (2 ± 0.53 versus 2.66 ± 0.22, respectively, = 0.01). The addition of CLZ to CLR dramatically decreased the lung CFU count, with CFU counts 5.41 and 5.79 log lower in the CLR-CFZ-EMB and CLR-CFZ-RIF-EMB groups, respectively, than in the untreated group. The addition of CFZ to CLR seems to improve the efficacy of CLR as early as M2 and was confirmed at M4. CFZ, in addition to RIF and EMB, on the other hand, is less effective than CLR-RIF-EMB. These results need to be confirmed by similar studies along with CFZ potential for shortening treatment.
Topics: Aerosols; Animals; Antitubercular Agents; Clarithromycin; Clofazimine; Colony Count, Microbial; Drug Synergism; Ethambutol; Female; Lung; Mice; Mice, Inbred BALB C; Microbial Sensitivity Tests; Mycobacterium avium; Mycobacterium avium-intracellulare Infection; Rifampin; Treatment Outcome
PubMed: 32071046
DOI: 10.1128/AAC.02349-19 -
Journal of Theoretical Biology Feb 2022Mycobacterium avium complex (MAC), is known for colonizing and infecting humans following inhalation of the bacteria. MAC pulmonary disease is notoriously difficult to...
Mycobacterium avium complex (MAC), is known for colonizing and infecting humans following inhalation of the bacteria. MAC pulmonary disease is notoriously difficult to treat and prone to recurrence. Both the incidence and prevalence MAC pulmonary disease have been increasing globally. MAC is well known to form biofilms in the environment. In vitro, these biofilms have been shown to aid MAC in epithelial cell invasion, protect MAC from phagocytosis, and cause premature apoptosis in macrophages. In vivo, the system of interactions between MAC, biofilms and host macrophages is complex, difficult to replicate in vitro and in animal models, has not been fully characterized. Here we present a three-dimensional agent-based model of a lung airway to help understand how these interactions evolve in the first 14 days post-bacterial inhalation. We parameterized the model using published data and performed uncertainty analysis to characterize outcomes and parameters' effects on those outcomes. Model results show diverse outcomes, including wide ranges of macrophage recruitment levels, and bacterial loads and phenotype distribution. Though most bacteria are phagocytosed by macrophages and remain intracellular, there are also many simulations in which extracellular bacteria continue to drive the colonization and infection. Initial parameters dictating host immune levels, bacterial loads introduced to the airway, and biofilm conditions have significant and lasting impacts on the course of these results. Additionally, though macrophage recruitment is key for suppressing bacterial loads, there is evidence of significant excess recruitment that fail to impact bacterial numbers. These results highlight a need and identify a path for further exploration into the inhalation events in MAC infection. Early infection dynamics could have lasting impacts on the development of nodular bronchiectatic or fibrocavitary disease as well as inform possible preventative and treatment intervention targeting biofilm-macrophage interactions.
Topics: Animals; Biofilms; Immunity, Innate; Mycobacterium avium; Mycobacterium avium Complex; Phenotype
PubMed: 34717938
DOI: 10.1016/j.jtbi.2021.110949 -
Microbes and Infection 2020Macrophages are major pathogen-killing cells. Mycobacteria can represent a serious threat to human health, in particular Mycobacterium tuberculosis and, less so, the...
Macrophages are major pathogen-killing cells. Mycobacteria can represent a serious threat to human health, in particular Mycobacterium tuberculosis and, less so, the opportunistic Mycobacterium avium. They can cause disseminated infections because of their capacity to survive and proliferate within macrophage phagolysosomes. Accumulating evidence indicates that the regulation of miRNA expression is implicated in the mechanisms of defense of macrophages against mycobacterial infections. Nevertheless, the precise contribution of miRNAs is largely unknown. The present study analyzes the expression profile of miRNAs during M. avium infection of macrophages by means of microarrays. We detected that the levels of 23 miRNAs were significantly changed ≥2.5-fold 24 h after M. avium infection. In particular, MiR-125a-5p was found to be highly expressed as part of the known immunological response of macrophages to bacterial or viral infections. MiR-125a-5p overexpression inhibited the expression of target signal transducers and activators of transcription 3 (STAT3) in THP-1 cells. Conversely, inhibitors of miR-125a-5p had the opposite effect. Silencing of STAT3 significantly enhanced the level of autophagy in both uninfected and M. avium-infected cells. Overexpression of miR-125a-5p significantly increased autophagy and decreased M. avium survival within THP-1 cells. Instead, co-transfection with miR-125a-5p mimic and a human STAT3 expressing construct reversed the effects: autophagy decreased and intracellular bactericidal survival was improved. Taken together, our findings indicate that miR-125a-5p participates in the regulation of innate host defenses by targeting STAT3 and enhancing autophagy levels. The results reported here contribute to a better understanding of host defense mechanisms against mycobacterial infections and offer some clues about their control.
Topics: 3' Untranslated Regions; Autophagy; Gene Expression Regulation; Host-Pathogen Interactions; Humans; Macrophages; MicroRNAs; Microbial Viability; Mycobacterium avium; STAT3 Transcription Factor; THP-1 Cells
PubMed: 31349052
DOI: 10.1016/j.micinf.2019.07.002 -
Virulence 2015Mycobacterium avium subspecies hominissuis (MAH) is an opportunistic pathogen and causes nontuberculous infections in immune compromised individuals, an emerging problem...
Mycobacterium avium subspecies hominissuis (MAH) is an opportunistic pathogen and causes nontuberculous infections in immune compromised individuals, an emerging problem that has been recognized worldwide. Understanding the pathogenesis of this organism is important as better treatment and prevention options are needed. Microaggregates form when two or more bacterial cells join at a surface. MAH forms micgroaggregates to promote its entry in to epithelial cells and cause infection. The mechanisms involved in the interaction between the microaggregate and the host are becoming clearer as the molecules involved in this process are being uncovered. Microaggregate Invasion Protein-1 (MIP-1) is now described as having a major role in the invasion of epithelial cells by MAH.
Topics: Animals; Epithelial Cells; Female; Humans; Mycobacterium avium
PubMed: 26364883
DOI: 10.1080/21505594.2015.1088633 -
Infection and Immunity Apr 2019Members of the complex (MAC) are characterized as nontuberculosis mycobacteria and are pathogenic mainly in immunocompromised individuals. MAC strains show a wide...
Members of the complex (MAC) are characterized as nontuberculosis mycobacteria and are pathogenic mainly in immunocompromised individuals. MAC strains show a wide genetic variability, and there is growing evidence suggesting that genetic differences may contribute to a varied immune response that may impact the infection outcome. The current study aimed to characterize the genomic changes within isolates collected from single patients over time and test the host immune responses to these clinical isolates. Pulsed-field gel electrophoresis and whole-genome sequencing were performed on 40 MAC isolates isolated from 15 patients at the Department of Medical Microbiology at St. Olavs Hospital in Trondheim, Norway. Isolates from patients (patients 4, 9, and 13) for whom more than two isolates were available were selected for further analysis. These isolates exhibited extensive sequence variation in the form of single-nucleotide polymorphisms (SNPs), suggesting that accumulates mutations at higher rates during persistent infections than other mycobacteria. Infection of murine macrophages and mice with sequential isolates from patients showed a tendency toward increased persistence and the downregulation of inflammatory cytokines by host-adapted strains. The study revealed the rapid genetic evolution of in chronically infected patients, accompanied by changes in the virulence properties of the sequential mycobacterial isolates.
Topics: Adaptation, Biological; Aged; Aged, 80 and over; Animals; Bacterial Proteins; Cells, Cultured; Cytokines; Evolution, Molecular; Female; Genetic Variation; Humans; Macrophages; Male; Mice; Mice, Inbred C57BL; Middle Aged; Mycobacterium avium; Mycobacterium avium-intracellulare Infection; Phylogeny; Polymorphism, Single Nucleotide
PubMed: 30642899
DOI: 10.1128/IAI.00323-18 -
Scientific Reports Nov 2016Mycobacterium avium complex induces macrophage apoptosis. However, the M. avium components that inhibit or trigger apoptosis and their regulating mechanisms remain...
Mycobacterium avium complex induces macrophage apoptosis. However, the M. avium components that inhibit or trigger apoptosis and their regulating mechanisms remain unclear. We recently identified the immunodominant MAV2054 protein by fractionating M. avium culture filtrate protein by multistep chromatography; this protein showed strong immuno-reactivity in M. avium complex pulmonary disease and in patients with tuberculosis. Here, we investigated the biological effects of MAV2054 on murine macrophages. Recombinant MAV2054 induced caspase-dependent macrophage apoptosis. Enhanced reactive oxygen species production and JNK activation were essential for MAV2054-mediated apoptosis and MAV2054-induced interleukin-6, tumour necrosis factor, and monocyte chemoattractant protein-1 production. MAV2054 was targeted to the mitochondrial compartment of macrophages treated with MAV2054 and infected with M. avium. Dissipation of the mitochondrial transmembrane potential (ΔΨ) and depletion of cytochrome c also occurred in MAV2054-treated macrophages. Apoptotic response, reactive oxygen species production, and ΔΨ collapse were significantly increased in bone marrow-derived macrophages infected with Mycobacterium smegmatis expressing MAV2054, compared to that in M. smegmatis control. Furthermore, MAV2054 expression suppressed intracellular growth of M. smegmatis and increased the survival rate of M. smegmatis-infected mice. Thus, MAV2054 induces apoptosis via a mitochondrial pathway in macrophages, which may be an innate cellular response to limit intracellular M. avium multiplication.
Topics: Animals; Apoptosis; Bacterial Proteins; Cytochromes c; Female; Interleukin-6; Macrophages; Membrane Potential, Mitochondrial; Mice; Mice, Inbred C57BL; Mitochondria; Mycobacterium avium; Mycobacterium smegmatis; RAW 264.7 Cells; Reactive Oxygen Species; Survival Rate; Tumor Necrosis Factor-alpha
PubMed: 27901051
DOI: 10.1038/srep37804 -
Polish Journal of Veterinary Sciences Sep 2020Mycobacterium avium subsp. paratuberculosis (MAP) is the cause of paratuberculosis mainly in domestic and wild ruminants; paratuberculosis is also known as Johne's...
Mycobacterium avium subsp. paratuberculosis (MAP) is the cause of paratuberculosis mainly in domestic and wild ruminants; paratuberculosis is also known as Johne's disease. This disease is endemic all over the world generating significant economic losses, especially in dairy herds, although, MAP is the cause of infection in many other species including primates. Currently, MAP mycobacteria are recognized as pathogens transmitted by food. They are a potential threat to animal and human health. Infected animals excreting mycobacteria with faeces are the main source of MAP. The development of control strategies and disease control are based on determination of the genetic diversity of the MAP strains causing Johne's disease. This study describes 43 strains isolated from a herd of dairy cows located in northern Poland. The types of MAP were determinted based on the polymorphism analysis of two insertion fragments: IS900 and IS1311. The polymorphism of IS900 was analyzed with the use of a PCR multiplex according to Collins' method and the IS1311 polymorphism with the use of the PCR-REA method. Based on the differences observed, the strains isolated were classified into two MAP types, cattle (C-type) and sheep (S-type), with the predominance of the cattle type.
Topics: Animals; Cattle; DNA, Bacterial; Feces; Female; Molecular Typing; Mycobacterium avium subsp. paratuberculosis; Paratuberculosis; Polymerase Chain Reaction; Prohibitins
PubMed: 33006858
DOI: 10.24425/pjvs.2020.134686 -
Journal of Applied Microbiology Aug 2019A major drawback of using dairy slurry as fertilizer is that it may contains pathogens such as Mycobacterium avium subsp. paratuberculosis (MAP), and it could represent...
AIMS
A major drawback of using dairy slurry as fertilizer is that it may contains pathogens such as Mycobacterium avium subsp. paratuberculosis (MAP), and it could represent a risk to animal and public health. Thus, the aim of this study was to evaluate the fate of MAP and bacterial communities in dairy slurry after chemical treatments.
METHODS AND RESULTS
Cattle slurry, naturally contaminated with MAP, was collected from a dairy herd and divided into 32 glass bottles which were assigned to eight different treatments (control, 3·0% CaO, 0·5% NaOH; 0·087%, 0·11% and 0·14% H SO ; and 1·0 and 2·5% KMnO ). Treated dairy slurry samples were evaluated at 0, 1, 3, 7, 15, 30 and 60-days following treatment application for viable MAP and dairy slurry pH, and in addition temperature in this material was monitored continuously. Bacterial counts were estimated at each sampling time. A Bayesian zero-inflated Poisson mixed model was fitted to assess the effect of each treatment on the count of MAP cells. Model results indicated that only the 3·0% CaO treatment had a statistically important negative effect on MAP counts during the study period. For most treatments, MAP was undetectable immediately after chemical treatment but re-appeared over time, in some replicates at low concentrations. However, in those cases MAP counts were not statistically different than the control treatment. Regarding the fate of the other bacterial populations, the Firmicutes phylum was the dominant population in the un-treated slurry while Clostridia class members were among the most prevalent bacteria after the application of most chemical treatments.
CONCLUSION
Only 3% CaO treatment had a statistically important negative effect on MAP viability in cattle slurry.
SIGNIFICANCE AND IMPACT OF THE STUDY
This study provides evidence of MAP partial control in dairy slurry. This information should be considered as a best management practice to reduce MAP and other pathogens for slurry management on dairy farms.
Topics: Animals; Anti-Bacterial Agents; Bayes Theorem; Calcium Compounds; Cattle; Dairying; Female; Fertilizers; Manure; Mycobacterium avium subsp. paratuberculosis; Oxides
PubMed: 31009147
DOI: 10.1111/jam.14288 -
Journal of Medical Microbiology May 2021complex (MAC) has been reported as the most common aetiology of lung disease involving nontuberculous mycobacteria. Antimicrobial susceptibility and clinical...
complex (MAC) has been reported as the most common aetiology of lung disease involving nontuberculous mycobacteria. Antimicrobial susceptibility and clinical characteristics may differ between and . We aimed to evaluate the differences in antimicrobial susceptibility profiles between two major MAC species ( and ) from patients with pulmonary infections and to provide epidemiologic data with minimum inhibitory concentration (MIC) distributions. Between January 2019 and May 2020, 45 and 242 . isolates were obtained from Shanghai Pulmonary Hospital. The demographic and clinical characteristics of patients were obtained from their medical records. The MICs of 13 antimicrobials were determined for the MAC isolates using commercial Sensititre SLOWMYCO MIC plates and the broth microdilution method, as recommended by the Clinical and Laboratory Standards Institute (CLSI; Standards M24-A2). MIC and MIC values were derived from the MIC distributions. had higher resistance rates than for most tested antimicrobials except clarithromycin, ethambutol, and ciprofloxacin. Clarithromycin was the most effective antimicrobial against both the (88.89 %) and (91.32 %) isolates, with no significant difference between the species (=0.601). The MIC of clarithromycin was higher for (32 µg ml) than (8 µg ml). The MIC of rifabutin was more than four times higher for (1 µg ml) than (≤0.25 µg ml). The percentages of patients aged >60 years and patients with sputum, cough, and cavitary lesions were significantly higher than among patients with infection than infections. The pulmonary disease caused by distinct MAC species had different antimicrobial susceptibility, symptoms, and radiographic findings.
Topics: Adult; Aged; Anti-Bacterial Agents; China; Ciprofloxacin; Clarithromycin; Cough; Doxycycline; Drug Resistance, Bacterial; Female; Humans; Lung; Lung Diseases; Male; Microbial Sensitivity Tests; Middle Aged; Mycobacterium avium; Mycobacterium avium Complex; Mycobacterium avium-intracellulare Infection; Radiography; Sputum
PubMed: 33999797
DOI: 10.1099/jmm.0.001358 -
Clinical Microbiology and Infection :... Mar 2019To determine MIC distributions for Mycobacterium chimaera, Mycobacterium intracellulare, Mycobacterium colombiense and Mycobacterium avium, and to derive tentative... (Comparative Study)
Comparative Study
OBJECTIVES
To determine MIC distributions for Mycobacterium chimaera, Mycobacterium intracellulare, Mycobacterium colombiense and Mycobacterium avium, and to derive tentative epidemiological cut-off (ECOFF) values.
METHODS
A total of 683 bacterial isolates (M. chimaera, n = 203; M. intracellulare, n = 77; M. colombiense, n = 68; M. avium, n = 335) from 627 patients were tested by broth microdilution according to CLSI protocol M24-A2 on Sensititre RAPMYCOI plates. MICs were interpreted based on CLSI breakpoints for clarithromycin, and tentative breakpoints for amikacin, moxifloxacin and linezolid. Tentative ECOFFs were determined by visual approximation and the ECOFFinder algorithm.
RESULTS
Modal MIC, MIC and MIC values were within ± one dilution step from the respective aggregated data set for 47/48 (97.9%), 48/48 (100%) and 48/48 (100%) species-drug combinations. Clarithromycin wild-type populations were mostly classified as susceptible (MIC 4-8 mg/L; S ≤8 mg/L). Rifabutin MICs were lower than those of rifampicin. Tentative moxifloxacin, linezolid and amikacin breakpoints split wild-type populations. No ECOFFs could be set for rifampicin, ethambutol, ciprofloxacin, isoniazid, trimethoprim/sulfamethoxazole and doxycycline because of truncation of MIC distributions. Agreement between the visually determined and the modelled 97.5% ECOFFs was 90.9%. All 99.0% ECOFFs were one titre step higher than by visual approximation.
CONCLUSIONS
Drug susceptibility patterns of M. chimaera are comparable to those of closely related species. Except for clarithromycin, breakpoints for Mycobacterium avium-intracellulare complex should be re-evaluated. Statistical determination of the 99.0% ECOFF may be superior to visual approximation.
Topics: Anti-Bacterial Agents; Drug Resistance, Bacterial; Humans; Microbial Sensitivity Tests; Mycobacterium avium; Mycobacterium avium Complex; Mycobacterium avium-intracellulare Infection
PubMed: 29906595
DOI: 10.1016/j.cmi.2018.06.010