Phenotypic characterization of enzymatic activity of clinical dermatophyte isolates from animals with and without skin lesions and humans

Abstract

Profile of enzymes characteristic of individual species, genus or ecological types of dermatophytes is possibly dependent upon factors related to the host. The relationship between each enzyme and the occurrence of skin lesions in animals and humans or asymptomatic animal carriers varies on whether the infection is caused by Trichophyton mentagrophytes, Trichophyton verrucosum or Microsporum canis. Interestingly, only keratinase seems to be correlated with the appearance of dermatophyte infections, irrespective of the pathogen species, and elastase is a characteristic enzyme for dermatophyte strains infecting humans. Haemolysis seems to be dependent on host factors and is more common in the case of human dermatophyte isolates.

In search of the source of dermatophytosis: Epidemiological analysis of Trichophyton verrucosum infection in llamas and the breeder (case report)

“…Stress, wrong diet, unfavourable environment, heat and humidity, concurrent infection by external parasites, age, genetics and overcrowding may predispose asymptomatic carriers to development of dermatophyte infection (Havlickova et al, ). In such cases, the medical history is not able to reveal the source of asymptomatic infections (Gnat, Łagowski, Nowakiewicz, & Zięba, ; Gnat, Łagowski, Nowakiewicz, & Zięba, ). On the other hand, the identification of the species of animal from which the infection may have spread is not sufficient due to the changing reservoirs of zoophilic dermatophytes (Brasch & Zaldua, ; Gnat, Łagowski, Nowakiewicz, Trościańczyk, et al, ; Ohst, Kupsch, & Graser, ; Weitzman & Summerbell, ).…”

The host range of dermatophytes, it is at all possible? Phenotypic evaluation of the keratinolytic activity of Trichophyton verrucosum clinical isolates

“…Keratin renders animals more robust against both abiotic stress and, which is its most important function, microbial attack . Although only a few species of prokaryotic organisms, that is, Bacillus licheniformis or Bacillus subtilis, are equipped with enzymes with keratin degradation activity, these enzymes commonly occur in dermatophytes, that is, Trichophyton verrucosum, Trichophyton mentagrophytes, Trichophyton equinum, Trichophyton gallinae, Microsporum canis and many more, but rarely in other eukaryotic microorganisms, that is, Aspergillus niger, Aspergillus flavus, Penicillium purpurogenum or Fusarium solani . Thus, microbial degradation of keratin is not widespread in nature outside the dermatophyte group, and keratin can serve as an efficient defence even against microbial attack …”

“…They include actually nine genera, and most of the dermatophytes belong to Trichophyton , Microsporum , Nannizzia and Arthroderma genera, and three ecological groups: anthropophilic, zoophilic and geophilic, that is, associated with humans, animals and soil, respectively . An active dermatophytosis in animals is not common, but many animals can be dermatophyte carriers . Furthermore, main factors that can predispose animals to an infection are stress, diet, poor environmental conditions (heat, humidity and overcrowding), age and genetic predispositions .…”

“…Our knowledge about the range of potentially pathogenically useful enzymes produced by dermatophytes is constantly growing, and several of them with well‐known properties have been characterised at the molecular level . Indeed, a biological characteristic of dermatophytes is their main ability to invade keratinised tissues by producing keratinases as key enzymes in pathogenesis …”

“…It has been demonstrated that keratinases serve not only the nutritional functions but also the most important virulence factors of dermatophytes in the first stage of infection . In addition, there is a direct relationship between their activity and the formation of clinical signs and the intensity of the disease course . It is also possible that the range of activity of keratinases from various dermatophytes is limited to specific species of animals and groups of people …”