Influencia del grupo ecológico sobre la sensibilidad in vitro de los hongos dermatofitos a los antifúngicos

BackgroundDermatophytes can be divided into geophilic (soil), zoophilic (animals) and anthropophilic (humans) strains, depending on the source of the keratin that they use for nutritional purposes.AimsThe in vitro susceptibility of clinical isolates of dermatophyte fungi has been studied in the 3 ecological groups with several antifungal agents for the topical management of dermatophytoses in order to determine their relationship with the ecological group.MethodsA standardised dilution micromethod in a liquid medium was used for the determination of the in vitro antifungal activity of 9 topical antifungal drugs: amorolfine (AMR), bifonazole (BFZ), clotrimazole, econazole, ketoconazole, miconazole, oxiconazole, terbinafine (TRB) and tioconazole. The in vitro activity was obtained against 124 clinical isolates of dermatophyte moulds from the anthropophilic, zoophilic and geophilic ecological groups.ResultsThe in vitro antifungal activity was different depending on the ecological group, although a species-dependent profile was also observed.ConclusionsAzole derivatives showed a similar antifungal profile, being more active against anthropophilic dermatophytes > zoophilic > geophilic. Activity of TRB and AMR was different from that of azole derivatives (zoophilic > anthropophilic > geophilic). A higher in vitro antifungal activity against the 3 ecological groups was observed with TRB and AMR, whilst BFZ was the less active drug.     

The effect of selected human steroid hormones upon the growth of dermatophytes with different adaptation to man

The inhibitory effect exerted by steroid hormones on thein vitro growth characteristics of dermatophytes is poorly understood. As a hypothesis this inhibition could result from fungal adaptation to the human host. Therefore, in this study the susceptibility of representative anthropophilic, zoophilic and geophilic dermatophytes to hormonal inhibition was compared. As a result, in agar dilution assaysprogesterone,testosterone, andestradiol proved to reduce fungal growth, whereashydrocortisone had no such effect. In general, anthropophilic dermatophytes were shown to be more responsive to steroid hormones than geophilic species, suggesting a correlation of steroid susceptibility with adaptation to human skin. However, since fungal response to hormones consisted of growth inhibition and occurred only at steroid concentrations much higher than present in human skin, it cannot be assumed to contribute to this adaptation.     

Eastern Cottontail (<Emphasis Type="Italic">Sylvilagus Floridanus)</Emphasis> as Carrier of Dermatophyte Fungi

Eastern cottontail (Sylvilagus floridanus, fam. Leporidae), introduced into Piedmont (Italy) in the 1960s, was studied as carrier of dermatophyte fungi. Of 216 hair samples collected from animals culled between September 1999 and July 2000 in the Province of Alessandria (Piedmont, Italy) during a pest control project, 57 (26.4%) yielded dermatophyte colonies. As two different species of dermatophytes grew from two samples, a total of 59 fungal isolates (26.5%) were obtained. Six dermatophyte species both geophilic (M. gypseum, M. cookei, Trichophyton ajelloi, T. terrestre) and zoophilic (M. canis, T. mentagrophytes) were identified. No sex-related differences were found but season-related differences were observed. The highest prevalence of dermatophyte-positive samples was recorded in May–September, due to the geophilic fungi whose prevalence decreased during colder and increased during warmer months ( p < 0.001). The presence of zoophilic dermatophytes, T. mentagrophytes, commonly associated with rodents, small mammals and lagomorphs and M. canis, usually correlated with domestic environment, did not change the whole year round. As Eastern cottontail has been showed to be a carrier of dermatophytes transmissible to man (M. canis, T. mentagrophytes and M. gypseum), it may represent a source of infection for gamekeepers, hunters and veterinarians.     

Dermatophytes isolated from patients in University Hospital,Kuala Lumpur,Malaysia

A total of 576 dermatophytes were isolated from patients with a variety of skin infections from January 1993 to May 2000. Ten species of dermatophytes were identified: Epidermophyton floccosum (0.7%), Microsporum audouinii (1.1%), M. canis (3.1%), M. gypseum (0.3%), Trichophyton concentricum(3.5%), T. equinum (0.2%), T. mentagrophytes (36.%), T . rubrum (53.8%), T. verrucosum (0.2) and T. violaceum (1.0%). The body sites most frequently affected by dermatophytes were the buttocks, nails and trunk. Anthropophilic dermatophytes made up 60.1% of the isolates; the most common species was T. rubrum, T. mentagrophytes and M. canis were the two main zoophilic dermatophytes. T. mentagrophytes was isolated from all body sites except the scalp. M. canis was found to be associated with domestic dogs and wasnot isolated from ethnic Malays. The only geophilic dermatophyte was M. gypseum, an uncommon dermatophyte associated with tinea pedis.This revised version was published online in October 2005 with corrections to the Cover Date.     

Species Identification of Dermatophytes by MALDI-TOF MS

MALDI-TOF (matrix-assisted laser desorption/ionization time-of-flight) mass spectrometry (MS) is a new tool for the identification of microorganisms, inclusive of dermatophytes. The technique is faster, more straightforward, and powerful when compared to conventional dermatophyte identification methods (culture and microscopy). Accurate species identification in dermatophytes is not only essential to survey epidemiologic situations, but also for an appropriate medical treatment and to locate the source of infection (zoophilic or anthropophilic). Multiple platforms from a number of well-established commercial manufacturers (Andromas SAS, Bruker Daltonics, bioMérieux) have been used for dermatophyte identification with different success. Independent from the platform used, all of the studies reviewed here report on problems with the identification of phylogenetically closely related anthropophilic and zoophilic dermatophyte species. Thus, supplementation of the databases/libraries as well as standardized extraction protocols and cultivation methods are the precondition required for optimal species identification.     

Investigation of keratinophilic fungi from soils in Western Australia a preliminary survey

In order to determine which species of geophilic dermatophytes were present in Western Australian soils 299 samples were investigated. These samples were collected from a range of locations, 208 from towns throughout the state and 91 samples from the Perth Metropolitan area.Most samples were collected from areas frequented by people and animals, such as home gardens, parks and animal yards.Of the total 299 soils, 271 (90.6 %) yielded keratinophilic fungi. A total of 181 dermatophytes were isolated, and there were 205 isolations of other keratinophilic fungi. Microsporum gypseum (30.7 %) was the most prevalent dermatophyte recovered from soil followed byMicrosporum cookei (21.7 %) and thenTrichophyton ajelloi (8.0 %). No other dermatophytes were recovered.Chrysosporium indicum was the most common of all the keratinophilic fungi and was isolated from 50.1 % of the samples. Mixed growth was obtained from 33.5 % of the soil samples.     

Favus of the Scalp: An Overview and Update

Tinea capitis favosa, a chronic inflammatory dermatophyte infection of the scalp, affects over 90% of patients with anthropophilic Trichophyton schoenleinii. T. violaceum, T. verrucosum, zoophilic T. mentagrophytes (referred to as ‘var. quinckeanum’), Microsporum canis, and geophilic M. gypseum have also been recovered from favic lesions. Favus is typically a childhood disease, yet adult cases are not uncommon. Interestingly, favus is less contagious than other dermatophytoses, although intrafamilial infections are reported and have been widely discussed in the literature. Clinical presentation of T. schoenleinii infections is variable: this fungus can be isolated from tinea capitis lesions that appear as gray patches, but symptom-free colonization of the scalp also occurs. Although in the past T. schoenleinii was the dominant fungus recovered from dermatophytic scalp lesions, worldwide the incidence has decreased except in China, Nigeria, and Iran. Favus of the glabrous skin and nails are reported less frequently than favus of the scalp. This review discusses the clinical features of favus, as well as the etiological agents, global epidemiology, laboratory diagnosis, and a short history of medical mycology.     

Dermatophytes isolated from patients in University Hospital,Kuala Lumpur,Malaysia

A total of 576 dermatophytes were isolated from patients with a variety of skin infections from January 1993 to May 2000. Ten species of dermatophytes were identified: Epidermophyton floccosum (0.7%), Microsporum audouinii (1.1%), M. canis (3.1%), M. gypseum (0.3%), Trichophyton concentricum (3.5%), T. equinum (0.2%), T. mentagrophytes (36.1%), T. rubrum (53.8%), T. verrucosum (0.2) and T. violaceum (1.0%). The body sites most frequently affected by dermatophytes were the buttocks, nails and trunk. Anthropophilic dermatophytes made up 60.1% of the isolates; the most common species was T. rubrum, T. mentagrophytes and M. canis were the two main zoophilic dermatophytes. T. mentagrophytes was isolated from all body sites except the scalp. M. canis was found to be associated with domestic dogs and was not isolated from ethnic Malays. The only geophilic dermatophyte was M. gypseum, an uncommon dermatophyte associated with tinea pedis.     

Internal Transcribed Spacer (ITS) of rDNA of appendaged and non-appendaged strains of Microsporum gypseum reveals Microsporum appendiculatum as its synonym

Recently a new taxon of geophilic dermatophytes was established as Microsporum appendiculatum Bhat and Mariam, based on the presence of appendaged macroconidia. However, such appendages are already known in the related species Microsporum gypseum. We conducted a survey of soil in central India as a part of a microbial biodiversity project and obtained two strains of M. gypseum with appendaged macroconidia. Using phenotypical characterization in combination with sequencing and restriction fragment length polymorphism (RFLP) of the Internal Transcribed Spacer (ITS) region of rDNA, we found that all strains of appendaged species are identical. Therefore M. appendiculatum is regarded as a synonym of M. gypseum.     

Sensitivity of some strains of the genus Epidermophyton to different antifungal agents

The inhibitory activity of some antifungal agents against 17 strains of genus Epidermophyton have been studied. The behaviour of Epidermophyton stockdaleae against antifungal agents tested is clearly different from that observed in the strains belonging to Epidermophyton floccosum, since all of the latter were sensitive to the antifungal agents used and the geophilic species showed resistance to griseofulvin, isoconazole, natamycin and nystatin, and intermediate sensitivity to ketoconazole and miconazole. The low sensitivity of E. stockdaleae (and other geophilic dermatophytes) to antifungal agents could be a problem in the current therapy if further studies or case reports demonstrate their pathogenic role.     

Mycetes and urban areas

Mycetes are ubiquitous organisms that can cause mycoses in human and animals. The role of animals in the epidemiology of human mycoses in urban areas is multiform, but here will be discuss only two features: A) animals as vectors of mycoses and B) animal substrates as growth factor of pathogenic fungi. A) Animals as vectors of mycoses: this role is important as zoofilic dermatophytes are very important agents of zoonosis; the urban dermatophytozoonoses are prevalent caused by Microsporum canis which is prevalent in cats and dogs. Cats are often asymptomatic carriers. The pattern of human dermatomycoses has changed in Italy during the past century: at the beginning of the century anthropophilic fungi were prevalent while at present the zoophilic fungi are the most important causes. B) Animal substrata as growth factor of pathogenic fungi: soil "animalization" (i.e., the addition of such debris as hair, skin scales, dropping and other organic matters) creates an optimal substratum for the growth and the multiplication of geophilic or saprophyitic fungi, such as Microsporum gypseum and Cryptococcus neoformans. The present human lifestyle, which favours a an overpopulation of birds, wild animals, domestic mammals and sinanthropic together with man in crowded areas seems to favour the formation of environments adapted to the abundant growth of some pathogenic fungi with consequent infection for man and animals. Finally, an environment heavily populated by fungi can cause allergic pulmonary reactions as well as reactions in other organs and tissues. The control of human and animal fungi, and the efficient use of a monitoring system require ample knowledge of mycological problems both in human and veterinary medicine and of efficient laboratories capable of resolving the needs of both disciplines. Close collaboration between veterinarians, doctors and mycologists is necessary in order to resolve health problems linked to mycosis.     

Unusual Species of Dermatophytes: Rarely Identified or New?

Dermatophytes are causing superficial mycosis in animals and humans. Depending on the geophilic, zoophilic or anthropophilic origin of the fungus but also on the immunological status of the patient, symptomatology can widely differ. Nevertheless, each species is currently associated with typical clinical manifestations, even if atypical localizations and/or clinical pictures are sometimes also reported. Diagnostic tools applied to species identification have been changing since the last two decades with the more frequent use of molecular methods currently considered nowadays as reference methods for species identification. It becomes obvious that the algorithm used for the distinction of closely related species needs to combine phenotypic and genomic methods. All these different points are discussed, and the most recent novel species causing or involved in human dermatophytosis are reported.     

Mycological flora isolated from people in Poland

It has been shown that in Poland the most frequently encountered pathogenic fungi are the zoophilic ones:T. mentagrophytes, M. canis andT. verrucosum. The zoophilic fungi have been isolated in 69.6 % of cases, while the anthropophilic fungi in 30.3 % of cases. In Poland, the most frequently isolated fungus among anthropophilic fungi have beenT. rubrum (36.2 %) andT. violaceum (34.3 %), whereasT. schoenleinii has been found in 5.7 % of cases. The geographical distribution of the anthropophilic fungi indicates that they appear most frequently in the counties of Biaystok (58.2 %), Katowice (40.5 %), and Warsaw (36.5 %), while the zoophilic fungi are found prevalently in the counties of ód (93.0 %), Kielce (84.7 %) and in that of Szczecin (83.8 %). It has been ascertained that the diseased animals and sick persons form the main reservoirs of the pathogenetic fungi. For the prophylactic purposes it is indispensable to promote among the population the sanitary instructions and propagate the principles of personal hygiene, which play a very important role in preventing mycosis. Within the framework of antimycosis campaigns it is necessary to widen the collaboration between the dermatologists and veterinary surgeons.Summary The author came to the conclusion that people in Poland suffer mostly of zoo-philic (69.9 %) than of anthropophilic dermatomycoses (30.3 %).Trichophyton rubrum was observed in 36.2 %,T. violaceum in 24.3 % andT. schoenleinii in 5.7. %. The main reservoir of dermatomycoses in Poland are sick animals and people. In the fight against mycoses of people and animals the collaboration of dermatologists and veterinarians is absolutely necessary.

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Résumé L'auteur a démontré qu'en Pologne chez les hommes la fréquence des dermatomycoses zoophiles est plus haute (69.7 %) que celle des dermatomycoses anthropophiles (30.3 %). Trichophyton rubrum noté dans 36.2 %,Trichophyton violaceum dans 24.3 % etTrichophyton schoenleinii dans 5.7 % cas. Les réservoirs principaux des mycoses en Pologne sont les animaux et les hommes malades. Dans la lutte contre les mycoses chez les hommes et chez les animaux, il est indispensable de constituer une collaboration stricte entre les dermatologues et les véterinaires.

     

A short review on dermatophytoses of animals in Romania

Dermatophytoses of animals in Romania are reviewed. Ringworm infections have been found in cattle (whereT. verrucosum was the only isolated agent), horses (the causative organisms beingT. verrucosum, T. mentagrophytes andM. equinum), cats (dermatophytes isolated:M. canis andT. quinckeanum), dogs (M. canis andM. gypseum), fowlsT. gallinae). From the laboratory animals: guinea pigs (T. mentagrophytes, M. audouinii, T. rubrum), mice (T. quickeanum andT. mentagrophytes), rats (T. mentagrophytes), rabbits (T. mentagrophytes andM. canis) and hamster)T. mentagrophytes). Among the wild animals, only the chamois had a ringworm infection byM. gypseum, other large or smaller wild animals harboring only saprophytically some poozhilic and geophilic dermatophytes.     

Controlling Malaria Using Livestock-Based Interventions: A One Health Approach

Where malaria is transmitted by zoophilic vectors, two types of malaria control strategies have been proposed based on animals: using livestock to divert vector biting from people (zooprophylaxis) or as baits to attract vectors to insecticide sources (insecticide-treated livestock). Opposing findings have been obtained on malaria zooprophylaxis, and despite the success of an insecticide-treated livestock trial in Pakistan, where malaria vectors are highly zoophilic, its effectiveness is yet to be formally tested in Africa where vectors are more anthropophilic. This study aims to clarify the different effects of livestock on malaria and to understand under what circumstances livestock-based interventions could play a role in malaria control programmes. This was explored by developing a mathematical model and combining it with data from Pakistan and Ethiopia. Consistent with previous work, a zooprophylactic effect of untreated livestock is predicted in two situations: if vector population density does not increase with livestock introduction, or if livestock numbers and availability to vectors are sufficiently high such that the increase in vector density is counteracted by the diversion of bites from humans to animals. Although, as expected, insecticide-treatment of livestock is predicted to be more beneficial in settings with highly zoophilic vectors, like South Asia, we find that the intervention could also considerably decrease malaria transmission in regions with more anthropophilic vectors, like Anopheles arabiensis in Africa, under specific circumstances: high treatment coverage of the livestock population, using a product with stronger or longer lasting insecticidal effect than in the Pakistan trial, and with small (ideally null) repellency effect, or if increasing the attractiveness of treated livestock to malaria vectors. The results suggest these are the most appropriate conditions for field testing insecticide-treated livestock in an Africa region with moderately zoophilic vectors, where this intervention could contribute to the integrated control of malaria and livestock diseases.     

Dermatophytosis caused by <Emphasis Type="Italic">Microsporum canis</Emphasis> in Eastern cottontail (<Emphasis Type="Italic">Sylvilagus floridanus</Emphasis>)

Eastern cottontail (Sylvilagus floridanus, fam. Leporidae) has previously been shown to be a potential healthy carrier of dermatophyte fungi both geophilic (Microsporum gypseum, M. cookei, Trichophyton ajelloi, T. terrestre) and zoophilic (M. canis, T. mentagrophytes). In this communication, the first case, to the best of our knowledge, of a symptomatic dermatophyte infection in S. floridanus is described.     

Dermatophytes isolated from symptomatic dogs and cats in Tuscany,Italy during a 15-year-period

Between January, 1, 1986 and December, 31, 2000, dermatological specimens from 10.678 animals (7.650 cats and 3.028 dogs) were examined for dermatophytes. All the animals presented clinical signs of ringworm. Two thousand-four hundred fifty-six of the 10.678 (23%) examined animals scored positive for dermatophytes, 566 out of 3.028 canine (18.7%) and 1890 out of 7.650 feline specimens (24.7%). Microsporum canis constituted 83% and 97% of the isolated dermatophytes respectively in dogs and cats, M. gypseum represented 13% and 2.6% and T. mentagrophytes 5.5% and 0.2%. A sexual predisposition for mycotic infections was not observed. The animals with less than 1 year of age were more frequently infected. Canine toy breeds showed a significantly higher (P < 0.001) prevalence of infections by M. canis. Microsporum gypseum was mostly recorded from sporting (hunting) breeds [such as T. mentagrophytes (6.7%)]. Microsporum canis was isolated from long-haired cats with a ratio of 2:1 versus short-haired cats, while M. gypseum and T. mentagrophytes were never recovered from Persian cats. The annual distribution of the infections in dogs showed a significantly higher incidence for M. gypseum in summer versus winter and spring, while the recovery rate of M. canis from cats was very significantly higher in fall and winter than in summer and spring. Trichophyton mentagrophytes did not show a similar seasonal distribution.This revised version was published online in October 2005 with corrections to the Cover Date.     

Dermatophytoses in Animals

Dermatophytoses are one of the most frequent skin diseases of pets and livestock. Contagiousness among animal communities, high cost of treatment, difficulty of control measures, and the public health consequences of animal ringworm explain their great importance. A wide variety of dermatophytes have been isolated from animals, but a few zoophilic species are responsible for the majority of the cases, viz. Microsporum canis, Trichophyton mentagrophytes, Trichophyton equinum and Trichophyton verrucosum, as also the geophilic species Microsporum gypseum. According to the host and the fungal species involved, the typical aspect of dermatophytic lesions may be modified. As a consequence, an accurate clinical examination, a good differential diagnosis and laboratory analyses are required for a correct identification. Few antifungal agents are available and licenced for use in veterinary practice, and the use of systemic drugs is limited in livestock due to the problems of residues in products intended for human consumption. The high resistance of the dermatophyte arthroconidia in the environment, the multiplicity of host species, and the confinement of animals in breedings are cause of an enzootic situation in many cases. Prevention is difficult, but research development on the immune response to dermatophytes and the use of vaccination, especially in cattle, have brought some interesting results.     

Species diversity of keratinophilic fungi in various soil types

Keratinophilic fungi are a highly specialized, keratin-degrading ecological group. They live in natural environments, mostly in the keratinrich remains of dead animal in the soil. We investigated species diversity in four types of soils with different physico-chemical properties. The strain material was identified based on morphological characters. Different representatives of Chrysosporium and geophilic dermatophytes dominated depending on soil pH. Geophilic dermatophytes were represented by one species, Trichophyton ajelloi, and the Chrysosporium group was represented by Chrysosporium keratinophilum. The frequency of Trichophyton ajelloi increased with an increase in pH, and it reached the maximum in strongly acidic soil (podzol), unlike the Chrysosporium group. The frequency of Chrysosporium keratinophilum was positively correlated with the content of humus, nitrogen, CaCO₃ and phosphorus in the soils.     

Dermatophytes in a population of bank voles and woodmice

A population of bank voles (Clethrionomys glareolus) and wood mice (Apodemus sylvaticus) inhabiting an oak wood in Somerset was examined for dermatophytes at monthly intervals for 2 years. The marked animals were frequently retrapped, allowing a study of host fungus relationship over a period of time. Microsporum persicolor (Sabouraud) Guiart er Grigorakis and Trichophyton mentagrophytes (Robin) Blanchard were isolated from both animal species, but M. persicolor predominated in bank voles and T. mentagrophytes in wood mice. In their most favoured host, both dermatophyte species often persisted for several months, but in the less favoured host they were never isolated at more than one sampling. Males of both animal species were infected more often than females.The existing evidence for the geophilic nature of both fungi is reviewed and shown to be very weak, especially for M. persicolor.This is the first report from Great Britain of T. mentagrophytes infection of wood mice not in contact with human habitation.