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Antimicrobial Agents and Chemotherapy Jan 2022For the treatment of chronic wounds, acid-oxidizing solutions (AOSs) with broad-spectrum microbicidal activity without disturbing granulation tissue formation have been...
For the treatment of chronic wounds, acid-oxidizing solutions (AOSs) with broad-spectrum microbicidal activity without disturbing granulation tissue formation have been developed. We found AOSs to efficiently kill Mycobacterium ulcerans, the causative agent of Buruli ulcer, which is able to survive harsh decontamination treatments. Topical AOS treatment of Buruli ulcer lesions may support the recommended antibiotic therapy (oral rifampin and clarithromycin), prevent contamination of the environment by the mycobacteria, and control secondary infections, which are a prevalent wound management problem in resource-poor settings where Buruli ulcer is endemic.
Topics: Buruli Ulcer; Clarithromycin; Humans; Mycobacterium ulcerans; Oxidation-Reduction; Rifampin
PubMed: 34662181
DOI: 10.1128/AAC.00870-21 -
Methods in Molecular Biology (Clifton,... 2022As acknowledged by the Clinical and Laboratory Standards Institute (CLSI), there is an insufficient evidence base on which to recommend a standard method for...
As acknowledged by the Clinical and Laboratory Standards Institute (CLSI), there is an insufficient evidence base on which to recommend a standard method for antimicrobial susceptibility testing against M. ulcerans. The agar proportion method has been recognized as the standard method for susceptibility testing against Mycobacterium tuberculosis complex (MTBC) isolates for decades (Woods GL, Engenack NL, Lin G, Turnidge JD (2018) CLSI standards: guidelines for health care excellence. Susceptibility testing of mycobacteria, Nocardia spp., and other aerobic Actinomycetes, 3rd edn. Clinical and Laboratory Standards Institute Copyright©2018 Clinical and Laboratory Standards Institute, Wayne (PA)). While it is more labor-intensive and requires larger amounts of drug or compound than broth-based testing, we recommend the agar proportion method for determination of minimum inhibitory concentrations against M. ulcerans. Herewith we present the method we implemented in our laboratory over the last 2 decades.
Topics: Agar; Anti-Bacterial Agents; Microbial Sensitivity Tests; Mycobacterium ulcerans; Pharmaceutical Preparations
PubMed: 34643913
DOI: 10.1007/978-1-0716-1779-3_18 -
Antimicrobial Agents and Chemotherapy Aug 2020A single dose of Q203 (Telacebec), a phase 2 clinical candidate for tuberculosis, eradicates in a mouse model of Buruli ulcer infection without relapse up to 19 weeks...
A single dose of Q203 (Telacebec), a phase 2 clinical candidate for tuberculosis, eradicates in a mouse model of Buruli ulcer infection without relapse up to 19 weeks posttreatment. Clinical use of Q203 may dramatically simplify the clinical management of Buruli ulcer, a neglected mycobacterial disease.
Topics: Animals; Buruli Ulcer; Disease Models, Animal; Mice; Mycobacterium ulcerans; Tuberculosis
PubMed: 32631818
DOI: 10.1128/AAC.00727-20 -
PLoS Neglected Tropical Diseases Mar 2021Buruli ulcer (BU) is a disabling and stigmatising neglected tropical disease (NTD). Its distribution and burden are unknown because of underdiagnosis and underreporting....
Buruli ulcer (BU) is a disabling and stigmatising neglected tropical disease (NTD). Its distribution and burden are unknown because of underdiagnosis and underreporting. It is caused by Mycobacterium ulcerans, an environmental pathogen whose environmental niche and transmission routes are not fully understood. The main control strategy is active surveillance to promote early treatment and thus limit morbidity, but these activities are mostly restricted to well-known endemic areas. A better understanding of environmental suitability for the bacterium and disease could inform targeted surveillance, and advance understanding of the ecology and burden of BU. We used previously compiled point-level datasets of BU and M. ulcerans occurrence, evidence for BU occurrence within national and sub-national areas, and a suite of relevant environmental covariates in a distribution modelling framework. We fitted relationships between BU and M. ulcerans occurrence and environmental predictors by applying regression and machine learning based algorithms, combined in an ensemble model to characterise the optimal ecological niche for the disease and bacterium across Africa at a resolution of 5km x 5km. Proximity to waterbodies was the strongest predictor of suitability for BU, followed potential evapotranspiration. The strongest predictors of suitability for M. ulcerans were deforestation and potential evapotranspiration. We identified patchy foci of suitability throughout West and Central Africa, including areas with no previous evidence of the disease. Predicted suitability for M. ulcerans was wider but overlapping with that of BU. The estimated population living in areas predicted suitable for the bacterium and disease was 46.1 million. These maps could be used to inform burden estimations and case searches which would generate a more complete understanding of the spatial distribution of BU in Africa, and may guide control programmes to identify cases beyond the well-known endemic areas.
Topics: Africa; Buruli Ulcer; Climate; Ecosystem; Humans; Models, Theoretical; Mycobacterium ulcerans
PubMed: 33657104
DOI: 10.1371/journal.pntd.0009157 -
Frontiers in Immunology 2022Buruli ulcer is a neglected tropical disease that is characterized by non-fatal lesion development. The causative agent is There are no known vectors or transmission...
Buruli ulcer is a neglected tropical disease that is characterized by non-fatal lesion development. The causative agent is There are no known vectors or transmission methods, preventing the development of control methods. There are effective diagnostic techniques and treatment routines; however, several socioeconomic factors may limit patients' abilities to receive these treatments. The Bacillus Calmette-Guérin vaccine developed against tuberculosis has shown limited efficacy, and no conventionally designed vaccines have passed clinical trials. This study aimed to generate a multi-epitope vaccine against from the major facilitator superfamily transporter protein using an immunoinformatics approach. Twelve genome assemblies were analyzed, resulting in the identification of 11 CD8 and 7 CD4 T-cell epitopes and 2 B-cell epitopes. These conserved epitopes were computationally predicted to be antigenic, immunogenic, non-allergenic, and non-toxic. The CD4 T-cell epitopes were capable of inducing interferon-gamma and interleukin-4. They successfully bound to their respective human leukocyte antigens alleles in docking studies. The expected global population coverage of the T-cell epitopes and their restricted human leukocyte antigens alleles was 99.90%. The population coverage of endemic regions ranged from 99.99% (Papua New Guinea) to 21.81% (Liberia). Two vaccine constructs were generated using the Toll-like receptors 2 and 4 agonists, LprG and RpfE, respectively. Both constructs were antigenic, non-allergenic, non-toxic, thermostable, basic, and hydrophilic. The DNA sequences of the vaccine constructs underwent optimization and were successfully cloned with the pET-28a(+) plasmid. The vaccine constructs were successfully docked to their respective toll-like receptors. Molecular dynamics simulations were carried out to analyze the binding interactions within the complex. The generated binding energies indicate the stability of both complexes. The constructs generated in this study display severable favorable properties, with construct one displaying a greater range of favorable properties. However, further analysis and laboratory validation are required.
Topics: Humans; Epitopes, B-Lymphocyte; Epitopes, T-Lymphocyte; HLA Antigens; Mycobacterium ulcerans; Neglected Diseases; Bacterial Vaccines; Buruli Ulcer
PubMed: 36426350
DOI: 10.3389/fimmu.2022.1023558 -
The American Journal of Tropical... Sep 2019Buruli ulcer is an infectious disease provoking chronic, disabling skin ulcers in mammals and humans. Buruli ulcer is caused by , an environmental mycobacterium...
Buruli ulcer is an infectious disease provoking chronic, disabling skin ulcers in mammals and humans. Buruli ulcer is caused by , an environmental mycobacterium synthesizing a toxin called mycolactone responsible for the pathogenicity. The reservoirs and the modes of transmission of remain elusive, limiting the prophylaxis capabilities in rural areas in endemic countries. In Australia, several studies have demonstrated the probable role of possums as reservoirs. In Côte d'Ivoire, some studies have speculated on the potential role of grasscutters in the transmission cycle of . In this study, we detected -specific sequences in rectal contents and spleens collected in wild grasscutters hunted in Buruli ulcer-endemic area in Côte d'Ivoire, but not in farmed negative control animals and in domesticated animals, namely, pigs, goats, cattle, and dogs, living in close contact with the local population. Some grasscutters exhibited the same sequence pattern in the feces and spleen. These observations confirm the asymptomatic gut carriage of in this mammal species. Moreover, these observations suggest the dissemination of from the gut to the spleen in grasscutters. These observations suggest that, in some mammals, is not only an inoculated pathogen but also a translocating invasive pathogen.
Topics: Animals; Asymptomatic Infections; Bacterial Translocation; Buruli Ulcer; Cote d'Ivoire; Disease Reservoirs; Gastrointestinal Tract; Mycobacterium ulcerans; Rodentia; Spleen
PubMed: 31333157
DOI: 10.4269/ajtmh.19-0137 -
Frontiers in Microbiology 2020Buruli ulcer (BU) is a neglected, tropical infectious disease of the skin and the subcutaneous tissue caused by This pathogen has emerged as a new species from a common... (Review)
Review
Buruli ulcer (BU) is a neglected, tropical infectious disease of the skin and the subcutaneous tissue caused by This pathogen has emerged as a new species from a common ancestor with by acquisition of the virulence plasmid pMUM. The plasmid encodes enzymes required for the synthesis of the macrolide toxin mycolactone, which has cytotoxic and immunosuppressive activities. In advanced BU lesions, extracellular clusters of reside in necrotic subcutaneous tissue and are protected from infiltrating leukocytes by the cytotoxic activity of secreted mycolactone. Several lines of evidence indicate that elements of the innate immune system eliminate in many cases the initial inoculum before bacterial clusters can form and that therefore exposure to leads only in a minority of individuals to the characteristic chronic necrotizing BU lesions. It is assumed that phagocytes play a key role in early host defense against . Antibodies against bacterial surface structures seem to have less potential to enhance innate immunity than T 1 cell responses. Precise innate and adaptive immune effector mechanisms leading to protective immunity are however unclear, complicating the development of effective vaccines, the most desired solution to control BU. The tuberculosis vaccine Bacillus Calmette-Guérin (BCG) has limited short-term protective activity against BU. Whether this effect is due to the broad antigenic cross-reactivity between and or is at least partly mediated by a non-specific enhanced responsiveness of innate immune cells to secondary stimulation, recently described as "trained immunity" or "innate immune memory" is unknown but has major implications for vaccine design. Current vaccine research and development activities are focusing on recombinant BCG, subunit vaccines with selected proteins, and the neutralization of mycolactone.
PubMed: 32523571
DOI: 10.3389/fmicb.2020.01018 -
Tropical Medicine and Health May 2021Genotyping is a powerful tool for investigating outbreaks of infectious diseases and it can provide useful information such as identifying the source and route of...
BACKGROUND
Genotyping is a powerful tool for investigating outbreaks of infectious diseases and it can provide useful information such as identifying the source and route of transmission, and circulating strains involved in the outbreak. Genotyping techniques based on variable number of tandem repeats (VNTR) are instrumental in detecting heterogeneity in Mycobacterium ulcerans (MU) and also for discriminating MU from other mycobacteria species. Here, we describe and map the distribution of MU genotypes in Buruli ulcer (BU) endemic communities of the Nyong valley in Cameroon. We also tested the hypothesis of whether the suspected animal reservoirs of BU that share the human microhabitat are shedding contaminated fecal matters and saliva into their surrounding environments.
METHODS
Environmental samples from suspected MU-risk factors and lesion swabs from human patients were sampled in BU-endemic communities and tested for the presence of MU by qPCR targeting three independent sequences (IS2404, IS2606, KR-B). Positive samples to MU were further genotyped by VNTR with confirmation by sequencing of four loci (MIRU1, Locus 6, ST1, Locus 19).
RESULTS
MU was detected in environmental samples including water bodies (23%), biofilms (14%), detritus (10%), and in human patients (73%). MU genotypes D, W, and C were found both in environmental and human samples. The micro geo-distribution of MU genotypes from communities showed that genotype D is found both in environmental and human samples, while genotypes W and C are specific to environmental samples and human lesions, respectively. No obvious focal grouping of MU genotypes was observed at the community scale. An additional survey in the human microhabitat suggests that domestic and wild animals do not shed MU in their saliva and feces in sampled communities.
CONCLUSIONS
VNTR typing uncovered different MU genotypes circulating in the endemic communities of the Akonolinga district. A MU environmental genotype was found in patients, yet the mechanism of contamination remains to be investigated; and recovering MU in culture from the environment remains key priority to enable a better understanding of the mode of transmission of BU. We also conclude that excretions from suspected animals are unlikely to be major sources of MU in the Nyong Valley in Cameroon.
PubMed: 34020717
DOI: 10.1186/s41182-021-00330-2 -
Frontiers in Pharmacology 2021Mycolactone is a diffusible lipid toxin produced by the causative agent of Buruli ulcer disease. Altough bacterially derived mycolactone has been shown to traffic from...
Mycolactone is a diffusible lipid toxin produced by the causative agent of Buruli ulcer disease. Altough bacterially derived mycolactone has been shown to traffic from cutaneous foci of infection to the bloodstream, the mechanisms underpinning its access to systemic circulation and import by host cells remain largely unknown. Using biophysical and cell-based approaches, we demonstrate that mycolactone specific association to serum albumin and lipoproteins is necessary for its solubilization and is a major mechanism to regulate its bioavailability. We also demonstrate that Scavenger Receptor (SR)-B1 contributes to the cellular uptake of mycolactone. Overall, we suggest a new mechanism of transport and cell entry, challenging the dogma that the toxin enters host cells via passive diffusion.
PubMed: 34603049
DOI: 10.3389/fphar.2021.733496 -
PloS One 2022Buruli ulcer is a tissue necrosis infection caused by an environmental mycobacterium called Mycobacterium ulcerans (MU). The disease is most prevalent in rural areas...
BACKGROUND
Buruli ulcer is a tissue necrosis infection caused by an environmental mycobacterium called Mycobacterium ulcerans (MU). The disease is most prevalent in rural areas with the highest rates in West and Central African countries. The bacterium produces a toxin called mycolactone which can lead to the destruction of the skin, resulting in incapacitating deformities with an enormous economic and social burden on patients and their caregivers. Even though there is an effective antibiotic treatment for BU, the control and management rely on early case detection and rapid diagnosis to avert morbidities. The diagnosis of Mycobacterium ulcerans relies on smear microscopy, culture histopathology, and PCR. Unfortunately, all the current laboratory diagnostics have various limitations and are not available in endemic communities. Consequently, there is a need for a rapid diagnostic tool for use at the community health centre level to enable diagnosis and confirmation of suspected cases for early treatment. The present study corroborated the diagnostic performance and utility of fluorescent-thin layer chromatography (f-TLC) for the diagnosis of Buruli ulcer.
METHODOLOGY/PRINCIPAL FINDINGS
The f-TLC method was evaluated for the diagnosis of Buruli ulcer in larger clinical samples than previously reported in an earlier preliminary study Wadagni et al. (2015). A total of 449 patients suspected of BU were included in the final data analysis out of which 122 (27.2%) were positive by f-TLC and 128 (28.5%) by PCR. Using a composite reference method generated from the two diagnostic methods, 85 (18.9%) patients were found to be truly infected with M. ulcerans, 284 (63.3%) were uninfected, while 80 (17.8%) were misidentified as infected or noninfected by the two methods. The data obtained was used to determine the discriminatory accuracy of the f-TLC against the gold standard IS2404 PCR through the analysis of its sensitivity, specificity, positive (+LR), and negative (-LR) likelihood ratio. The positive (PPV) and negative (NPV) predictive values, area under the receiver operating characteristic curve Azevedo et al. (2014), and diagnostic odds ratio were used to assess the predictive accuracy of the f-TLC method. The sensitivity of f-TLC was 66.4% (85/128), specificity was 88.5% (284/321), while the diagnostic accuracy was 82.2% (369/449). The AUC stood at 0.774 while the PPV, NPV, +LR, and-LR were 69.7% (85/122), 86.9% (284/327), 5.76, and 0.38, respectively. The use of the rule-of-thumb interpretation of diagnostic tests suggests that the method is good for use as a diagnostic tool.
CONCLUSIONS/SIGNIFICANCE
Larger clinical samples than previously reported had been used to evaluate the f-TLC method for the diagnosis of Buruli ulcer. A sensitivity of 66.4%, a specificity of 88.5%, and diagnostic accuracy of 82.2% were obtained. The method is good for diagnosis and will help in making early clinical decisions about the patients as well as patient management and facilitating treatment decisions. However, it requires a slight modification to address the challenge of background interference and lack of automatic readout to become an excellent diagnostic tool.
Topics: Buruli Ulcer; Chromatography, Thin Layer; Ghana; Humans; Mycobacterium ulcerans; Polymerase Chain Reaction
PubMed: 35917367
DOI: 10.1371/journal.pone.0270235