Background Mycobacterium ulcerans disease, or Buruli ulcer (BU), is an indolent, necrotizing infection of skin, subcutaneous tissue and, occasionally, bones. It is the third most common human mycobacteriosis worldwide, after tuberculosis and leprosy. There is evidence that M. ulcerans is an environmental pathogen transmitted to humans from aquatic niches; however, well-characterized pure cultures of M. ulcerans from the environment have never been reported. Here we present details of the isolation and characterization of an M. ulcerans strain (00-1441) obtained from an aquatic Hemiptera (common name Water Strider, Gerris sp.) from Benin.Methodology/Principal FindingsOne culture from a homogenate of a Gerris sp. in BACTEC became positive for IS2404, an insertion sequence with more than 200 copies in M. ulcerans. A pure culture of M. ulcerans 00-1441 was obtained on Löwenstein-Jensen medium after inoculation of BACTEC culture in mouse footpads followed by two other mouse footpad passages. The phenotypic characteristics of 00-1441 were identical to those of African M. ulcerans, including production of mycolactone A/B. The nucleotide sequence of the 5′ end of 16S rRNA gene of 00-1441 was 100% identical to M. ulcerans and M. marinum, and the sequence of the 3′ end was identical to that of the African type except for a single nucleotide substitution at position 1317. This mutation in M. ulcerans was recently discovered in BU patients living in the same geographic area. Various genotyping methods confirmed that strain 00-1441 has a profile identical to that of the predominant African type. Strain 00-1441 produced severe progressive infection and disease in mouse footpads with involvement of bone.ConclusionStrain 00-1441 represents the first genetically and phenotypically identified strain of M. ulcerans isolated in pure culture from the environment. This isolation supports the concept that the agent of BU is a human pathogen with an environmental niche.
Mycobacterium ulcerans infection, or Buruli ulcer, is the third most frequent mycobacterial disease in humans, often causing serious deformities and disability. The disease is most closely associated with tropical wetlands, especially in west and central Africa. Most investigators believe that the aetiological agent proliferates in mud beneath stagnant waters. Modes of transmission may involve direct contact with the contaminated environment, aerosols from water surfaces, and water-dwelling fauna (e.g. insects). Person-to-person transmission is rare. Trauma at the site of skin contamination by M. ulcerans appears to play an important role in initiating disease. Once introduced into the skin or subcutaneous tissue, M. ulcerans multiplies and produces a toxin that causes necrosis. However, the type of disease induced varies from a localised nodule or ulcer, to widespread ulcerative or non-ulcerative disease and osteomyelitis.Although culture of M. ulceransfrom a patient was first reported in 1948, attempts to culture the mycobacterium from many specimens of flora and fauna have been unsuccessful. Failure to cultivate this organism from nature may be attributable to inadequate sampling, conditions of transport, decontamination and culture of this fastidious heat-sensitive organism, and to along generation time relative to that of other environmental mycobacteria. Nevertheless, recent molecular studies using specific primers have revealed M. ulcerans in water, mud, fish and insects. Although no natural reservoir has been found, the possibility that M. ulcerans may colonise microfauna such as free-living amoebae has not been investigated. The host range of experimental infection by M. ulcerans includes lizards, amphibians, chick embryos, possums, armadillos, rats, mice and cattle. Natural infections have been observed only in Australia, in koalas, ringtail possums and a captive alpaca. The lesions were clinically identical to those observed in humans. Mycobacterium ulcerans infection is a rapidly re-emerging disease in some developing tropical countries. The re-emergence may be related to environmental and socioeconomic factors, for example, deforestation leading to increased flooding, and population expansion without improved agricultural techniques, thus putting more people at risk. Eradication of diseases related to these factors is difficult. Whether wild animals have a role in transmission is an important question that, to date, has been virtually unexplored. To address this question, surveys of wild animals are urgently required in those areas in which Buruli ulcer is endemic. KeywordsAlpacas -Aquatic insects -Buruli ulcer -Environment -Fish -Koalas -Mycobacteria -Mycobacterium ulcerans -Possums-Water. Bev. sci. teck Off.int.Epa.. 20 (1)
Le Tchad oriental est une région d’élevage du dromadaire. La trypanosomose à Trypanosoma evansi (ou surra), maladie transmise mécaniquement par divers insectes hématophages, y est répandue et touche en priorité les cheptels transhumants. Une enquête entomologique a été réalisée dans sept sites représentatifs afin de préciser l’épidémiologie de la maladie dans cette zone. Quatre sites (Koukou Angarana et Djogori au Sud, Oum Chalouba et ouaddi Fira au Nord) ont été associés à une forte prévalence de la maladie et les trois autres (Abdi au Sud, Am sak et ouaddi Fama au Nord) à une faible prévalence. L’enquête s’est basée sur l’utilisation de 15 pièges biconiques Challier- Laveissière et de cinq pièges Nzi avec des relevés à 24 et 48 h. Trois séries de piégeages ont été effectuées afin de tenir compte des variations saisonnières. Divers facteurs pouvant influer sur les captures ont été relevés et inclus dans une analyse statistique multivariée. Au total, 1 272 stomoxes, 945 tabanidés et 226 hippobosques ont été capturés. Chez les tabanidés, l’espèce dominante a été Atylotus agrestis ; les autres espèces ont été Tabanus gratus, T. taeniola et T. biguttatus. Les trois principales espèces de stomoxes identifiées ont été Stomoxys calcitrans, S. sitiens et S. niger. La majorité des hippobosques identifiés ont appartenu à l’espèce Hippobosca camelina. Les principaux facteurs qui expliquaient la variabilité des captures étaient la nature du piège, la saison et la latitude. Le piège Nzi a été plus efficace pour la capture des tabanidés et des stomoxes. La période de capture la plus favorable a été le début de la saison sèche (novembre à janvier) pour Atylotus agrestis, les stomoxes et les hippobosques. Tabanus gratus a été surtout capturé en fin de saison sèche (février à mai) et en saison des pluies (juin à octobre) et Tabanus taeniola en saison des pluies. Les hippobosques ont été plus fréquemment capturés au nord de la zone étudiée et T. gratus et T. taeniola au sud. Une corrélation entre le nombre d’insectes piqueurs capturés en saison sèche et la prévalence du surra a été relevée avec les deux types de piège. La forte prévalence du surra dans les cheptels transhumants s’expliquerait par un effet cumulatif, les animaux étant en contact avec le pic d’Atylotus agrestis au Nord à la fin de la saison des pluies et au début de saison sèche et avec une entomofaune piqueuse se maintenant dans les zones d’accueil du Sud (novembre à juin). Chez les petits transhumants et les semi-sédentaires du Nord, l’impact du surra tiendrait à la nature de la zone fréquentée, celle-ci autorisant ou non le maintien de populations d’insectes hématophages en saison sèche.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.