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PloS One 2016Ivory Coast is a West African country with the highest reported cases of Buruli ulcer, a disabling subcutaneous infection due to Mycobacterium ulcerans. However, the...
BACKGROUND
Ivory Coast is a West African country with the highest reported cases of Buruli ulcer, a disabling subcutaneous infection due to Mycobacterium ulcerans. However, the prevalence of environmental M. ulcerans is poorly known in this country.
METHODS
We collected 496 environmental specimens consisting of soil (n = 100), stagnant water (n = 200), plants (n = 100) and animal feces (n = 96) in Ivory Coast over five months in the dry and wet seasons in regions which are free of Buruli ulcer (control group A; 250 specimens) and in regions where the Buruli ulcer is endemic (group B; 246 specimens). After appropriate total DNA extraction incorporating an internal control, the M. ulcerans IS2404 and KR-B gene were amplified by real-time PCR in samples. In parallel, a calibration curve was done for M. ulcerans Agy99 IS2404 and KR-B gene.
RESULTS
Of 460 samples free of PCR inhibition, a positive real-time PCR detection of insertion sequence IS2404 and KR-B gene was observed in 1/230 specimens in control group A versus 9/230 specimens in group B (P = 0.02; Fisher exact test). Positive specimens comprised seven stagnant water specimens, two feces specimens confirmed to be of Thryonomys swinderianus (agouti) origin by real-time PCR of the cytb gene; and one soil specimen. Extrapolation from the calibration curves indicated low inoculums ranging from 1 to 102 mycobacteria/mL.
CONCLUSION
This study confirms the presence of M. ulcerans in the watery environment surrounding patients with Buruli ulcer in Ivory Coast. It suggests that the agouti, which is in close contacts with populations, could play a role in the environmental cycle of M. ulcerans, as previously suggested for the closely related possums in Australia.
Topics: Animals; Cote d'Ivoire; DNA, Bacterial; Feces; Mycobacterium ulcerans; Real-Time Polymerase Chain Reaction; Soil Microbiology
PubMed: 26982581
DOI: 10.1371/journal.pone.0151567 -
PLoS Neglected Tropical Diseases Nov 2013Mycobacterium ulcerans, a slow-growing environmental bacterium, is the etiologic agent of Buruli ulcer, a necrotic skin disease. Skin lesions are caused by mycolactone,...
BACKGROUND
Mycobacterium ulcerans, a slow-growing environmental bacterium, is the etiologic agent of Buruli ulcer, a necrotic skin disease. Skin lesions are caused by mycolactone, the main virulence factor of M. ulcerans, with dermonecrotic (destruction of the skin and soft tissues) and immunosuppressive activities. This toxin is secreted in vesicles that enhance its biological activities. Nowadays, it is well established that the main reservoir of the bacilli is localized in the aquatic environment where the bacillus may be able to colonize different niches. Here we report that plant polysaccharides stimulate M. ulcerans growth and are implicated in toxin synthesis regulation.
METHODOLOGY/PRINCIPAL FINDINGS
In this study, by selecting various algal components, we have identified plant-specific carbohydrates, particularly glucose polymers, capable of stimulating M. ulcerans growth in vitro. Furthermore, we underscored for the first time culture conditions under which the polyketide toxin mycolactone, the sole virulence factor of M. ulcerans identified to date, is down-regulated. Using a quantitative proteomic approach and analyzing transcript levels by RT-qPCR, we demonstrated that its regulation is not at the transcriptional or translational levels but must involve another type of regulation. M. ulcerans produces membrane vesicles, as other mycobacterial species, in which are the mycolactone is concentrated. By transmission electron microscopy, we observed that the production of vesicles is independent from the toxin production. Concomitant with this observed decrease in mycolactone production, the production of mycobacterial siderophores known as mycobactins was enhanced.
CONCLUSIONS/SIGNIFICANCE
This work is the first step in the identification of the mechanisms involved in mycolactone regulation and paves the way for the discovery of putative new drug targets in the future.
Topics: Macrolides; Mycobacterium ulcerans; Proteomics; Reverse Transcriptase Polymerase Chain Reaction
PubMed: 24244764
DOI: 10.1371/journal.pntd.0002502 -
FEMS Microbiology Ecology Jun 2016Mycobacterium ulcerans(MU) is the causative agent of Buruli ulcer, an emerging human infectious disease. However, both the ecology and life cycle of MU are poorly...
Mycobacterium ulcerans(MU) is the causative agent of Buruli ulcer, an emerging human infectious disease. However, both the ecology and life cycle of MU are poorly understood. The occurrence of MU has been linked to the aquatic environment, notably water bodies affected by human activities. It has been hypothesized that one or a combination of environmental factor(s) connected to human activities could favour growth of MU in aquatic systems. Here, we testedin vitrothe growth effect of two ubiquitous polysaccharides and five chemical components on MU at concentration ranges shown to occur in endemic regions. Real-time PCR showed that chitin increased MU growth significantly providing a nutrient source or environmental support for thebacillus, thereby, providing a focus on the association between MU and aquatic arthropods. Aquatic environments with elevated population of arthropods provide increased chitin availability and, thereby, enhanced multiplication of MU. If calcium very slightly enhanced MU growth, iron, zinc, sulphate and phosphate did not stimulate MU growth, and at the concentration ranges of this study would limit MU population in natural ecosystems.
Topics: Buruli Ulcer; Calcium; Chitin; Ecosystem; Humans; Iron; Mycobacterium ulcerans; Phosphates; Real-Time Polymerase Chain Reaction; Zinc
PubMed: 27020062
DOI: 10.1093/femsec/fiw067 -
Methods in Molecular Biology (Clifton,... 2022Mycobacterium ulcerans is a slow-growing environmental bacterium that causes a severe skin disease known as Buruli ulcer (BU). Rapid detection of M. ulcerans in clinical...
Mycobacterium ulcerans is a slow-growing environmental bacterium that causes a severe skin disease known as Buruli ulcer (BU). Rapid detection of M. ulcerans in clinical specimens is essential for early diagnosis so that patients can be treated appropriately as soon as possible. This chapter describes suitable methods for the extraction of M. ulcerans DNA from the most common specimens submitted to the laboratory for confirmation of BU: swabs, fresh tissue biopsies, and fixed tissue sections. The resulting DNA extracts may be used for downstream procedures including standard gel-based PCR and real-time PCR assays. Protocols for direct detection of M. ulcerans DNA by real-time PCR are described in Chapter 8 .
Topics: Buruli Ulcer; DNA, Bacterial; Humans; Mycobacterium ulcerans; Nucleic Acid Amplification Techniques; Real-Time Polymerase Chain Reaction
PubMed: 34643901
DOI: 10.1007/978-1-0716-1779-3_6 -
PLoS Neglected Tropical Diseases Sep 2020Buruli ulcer (BU) is an emerging ulcerative skin disease caused by infection with Mycobacterium ulcerans. Efforts to control its spread have been hampered by our limited...
Buruli ulcer (BU) is an emerging ulcerative skin disease caused by infection with Mycobacterium ulcerans. Efforts to control its spread have been hampered by our limited understanding of M. ulcerans reservoirs and transmission, and the factors leading to the emergence of BU disease in a particular region. In this report we investigate an anecdotal link between damming the Mapé River in Cameroon and the emergence of BU in the Health Districts bordering Lake Bankim, the impoundment created by the Mapé dam. We used bacterial population genomics and molecular dating to find compelling support for a 2000 M. ulcerans introduction event that followed about 10 years after the filling of the newly created impoundment in 1988. We compared the genomic reconstructions with high-resolution satellite imagery to investigate what major environmental alterations might have driven the emergence of the new focus.
Topics: Buruli Ulcer; Cameroon; Humans; Lakes; Mycobacterium ulcerans; Phylogeny
PubMed: 32886658
DOI: 10.1371/journal.pntd.0008501 -
The Medical Journal of Australia May 2019
Topics: Buruli Ulcer; DNA, Bacterial; Humans; Mycobacterium ulcerans; Polymerase Chain Reaction
PubMed: 30802309
DOI: 10.5694/mja2.50046 -
PLoS Neglected Tropical Diseases Apr 2014Transmission of M. ulcerans, the etiological agent of Buruli ulcer, from the environment to humans remains an enigma despite decades of research. Major transmission...
Transmission of M. ulcerans, the etiological agent of Buruli ulcer, from the environment to humans remains an enigma despite decades of research. Major transmission hypotheses propose 1) that M. ulcerans is acquired through an insect bite or 2) that bacteria enter an existing wound through exposure to a contaminated environment. In studies reported here, a guinea pig infection model was developed to determine whether Buruli ulcer could be produced through passive inoculation of M. ulcerans onto a superficial abrasion. The choice of an abrasion model was based on the fact that most bacterial pathogens infecting the skin are able to infect an open lesion, and that abrasions are extremely common in children. Our studies show that after a 90d infection period, an ulcer was present at intra-dermal injection sites of all seven animals infected, whereas topical application of M. ulcerans failed to establish an infection. Mycobacterium ulcerans was cultured from all injection sites whereas infected abrasion sites healed and were culture negative. A 14d experiment was conducted to determine how long organisms persisted after inoculation. Mycobacterium ulcerans was isolated from abrasions at one hour and 24 hours post infection, but cultures from later time points were negative. Abrasion sites were qPCR positive up to seven days post infection, but negative at later timepoints. In contrast, M. ulcerans DNA was detected at intra-dermal injection sites throughout the study. M. ulcerans was cultured from injection sites at each time point. These results suggest that injection of M. ulcerans into the skin greatly facilitates infection and lends support for the role of an invertebrate vector or other route of entry such as a puncture wound or deep laceration where bacteria would be contained within the lesion. Infection through passive inoculation into an existing abrasion appears a less likely route of entry.
Topics: Animals; Buruli Ulcer; Disease Models, Animal; Female; Guinea Pigs; Injections, Intradermal; Insect Bites and Stings; Male; Mycobacterium ulcerans; Skin; Wound Infection
PubMed: 24722416
DOI: 10.1371/journal.pntd.0002770 -
Nature Microbiology Feb 2024
Topics: Animals; Humans; Mycobacterium ulcerans; Buruli Ulcer; Culicidae; DNA, Bacterial
PubMed: 38263455
DOI: 10.1038/s41564-023-01554-0 -
PLoS Neglected Tropical Diseases Mar 2015Mycobacterium ulcerans causes Buruli ulcer (BU), a debilitating infection of subcutaneous tissue. There is a WHO-recommended antibiotic treatment requiring an 8-week...
Mycobacterium ulcerans causes Buruli ulcer (BU), a debilitating infection of subcutaneous tissue. There is a WHO-recommended antibiotic treatment requiring an 8-week course of streptomycin and rifampicin. This regime has revolutionized the treatment of BU but there are problems that include reliance on daily streptomycin injections and side effects such as ototoxicity. Trials of all-oral treatments for BU show promise but additional drug combinations that make BU treatment safer and shorter would be welcome. Following on from reports that avermectins have activity against Mycobacterium tuberculosis, we tested the in-vitro efficacy of ivermectin and moxidectin on M. ulcerans. We observed minimum inhibitory concentrations of 4-8 μg/ml and time-kill assays using wild type and bioluminescent M. ulcerans showed a significant dose-dependent reduction in M. ulcerans viability over 8-weeks. A synergistic killing-effect with rifampicin was also observed. Avermectins are well tolerated, widely available and inexpensive. Based on our in vitro findings we suggest that avermectins should be further evaluated for the treatment of BU.
Topics: Administration, Oral; Buruli Ulcer; Ivermectin; Microbial Sensitivity Tests; Mycobacterium ulcerans; Rifampin; Streptomycin
PubMed: 25742173
DOI: 10.1371/journal.pntd.0003549 -
BMC Genomics Jan 2024Buruli ulcer (BU) disease, caused by Mycobacterium ulcerans (MU), and characterized by necrotic ulcers is still a health problem in Africa and Australia. The genome of...
BACKGROUND
Buruli ulcer (BU) disease, caused by Mycobacterium ulcerans (MU), and characterized by necrotic ulcers is still a health problem in Africa and Australia. The genome of the bacterium has several pseudogenes due to recent evolutionary events and environmental pressures. Pseudogenes are genetic elements regarded as nonessential in bacteria, however, they are less studied due to limited available tools to provide understanding of their evolution and roles in MU pathogenicity.
RESULTS
This study developed a bioinformatic pipeline to profile the pseudogenomes of sequenced MU clinical isolates from different countries. One hundred and seventy-two MU genomes analyzed revealed that pseudogenomes of African strains corresponded to the two African lineages 1 and 2. Pseudogenomes were lineage and location specific and African lineage 1 was further divided into A and B. Lineage 2 had less relaxation in positive selection than lineage 1 which may signify different evolutionary points. Based on the Gil-Latorre model, African MU strains may be in the latter stages of evolutionary adaption and are adapting to an environment rich in metabolic resources with a lower temperature and decreased UV radiation. The environment fosters oxidative metabolism and MU may be less reliant on some secondary metabolites. In-house pseudogenomes from Ghana and Cote d'Ivoire were different from other African strains, however, they were identified as African strains.
CONCLUSION
Our bioinformatic pipeline provides pseudogenomic insights to complement other whole genome analyses, providing a better view of the evolution of the genome of MU and suggest an adaptation model which is important in understanding transmission. MU pseudogene profiles vary based on lineage and country, and an apparent reduction in insertion sequences used for the detection of MU which may adversely affect the sensitivity of diagnosis.
Topics: Humans; Africa; Australia; Black People; Mycobacterium ulcerans; Pseudogenes; Buruli Ulcer
PubMed: 38253991
DOI: 10.1186/s12864-024-10001-1