First report on autochthonous urease-positive Trichophyton rubrum (T. raubitschekii) from South-east Europe

Genotyping of Russian isolates of fungal pathogen Trichophyton rubrum, based on simple sequence repeat and single nucleotide polymorphism

BACKGROUND

The Trichophyton rubrum species group consists of prevalent causative agents of human skin, nail and hair infections, including T rubrum sensu stricto and T violaceum, as well as other less well-established or debatable taxa like T soudanense, T kuryangei and T megninii. Our previous study provided limited evidence in favour of the existence of two genetic lineages in the Russian T rubrum sensu stricto population.

OBJECTIVES

We aimed to study the genetic structure of the Russian population of T rubrum and to identify factors shaping this structure.

METHODS

We analysed the polymorphism of 12 simple sequence repeat (SSR or microsatellite) markers and single nucleotide polymorphism in the TERG_02941 protein-coding gene in 70 T rubrum isolates and performed a phylogenomic reconstruction.

RESULTS

All three types of data provided conclusive evidence that the population consists of two genetic lineages. Clustering, performed by means of microsatellite length polymorphism analysis, was strongly dependent on the number of nucleotide repeats in the 5'-area of the fructose-1,6-bisphosphate aldolase gene. Analysis of molecular variance (AMOVA) on the basis of SSR typing data indicated that 22%-48% of the variability was among groups within T rubrum. There was no clear connection of population structure with types of infection, places of geographic origin, aldolase gene expression or urease activity.

CONCLUSION

Our results suggest that the Russian population of T rubrum consists of two cosmopolitan genetic lineages.

Tinea manuum: A report of 18 cases observed in the metropolitan area of Milan and review of the literature

OBJECTIVE

Tinea manuum is considered in Italy as an uncommon infection, although no recent epidemiological data are available.

METHODS

In the period 2000-2018, we observed in the metropolitan area of Milan 18 patients with mycologically tinea manuum.

RESULTS

The infection was monolateral in all patients and characterised by erythema and scaling; in two patients, each vesicles and pustules were present. Two patients had also onychomycosis of one fingernail. No cases of simultaneous tinea pedis were observed. As far as the job of these patients is concerned, seven of them were masseurs, three barbers, two cattlemen, two masons, one car mechanic, one florist, one maid and one veterinarian. Trichophyton rubrum was isolated in 6 patients, Microsporum canis in 4, Trichophyton gypseum in 3, Trichophyton verrucosum in 3 and Trichophyton violaceum in 2 patients.

CONCLUSION

Masseurs were the most affected. Trichophyton rubrum and Microsporum canis were the most frequent isolated dermatophytes.

Generalized superficial mycosis caused by Trichophyton raubitschekii in China: case report and review of the literature

This is a generalized superficial mycosis case from which Trichophyton raubitschekii was isolated. A male adult was presented with a 3-year history of fingernail and toenail changes, and a 50-day history of severe and multiple skin lesions. He also complained of intense itching. T. raubitschekii was identified from every skin lesion (trunk, extremities and nail) through microscopic examination, physiological experiment and DNA sequencing. Generalized superficial mycosis was diagnosed and treated by administering a combination of oral (terbinafine tablets) and topical (naftifine hydrochloride and ketoconazole cream) antimycotic drugs. After treatment, the patient was cured and no recurrence has been observed.

The first non-African case of Trichophyton rubrum var. raubitschekii or a urease-positive Trichophyton rubrum in Central Europe?

We report a case of a 34-year-old Polish Caucasian male who was diagnosed with tinea manuum caused by Trichophyton rubrum var. raubitschekii. It would be the first described case of a dermatophytosis caused by this fungus in Poland and one of a few cases in Central Europe described so far. Admittedly, it would be the first case in Central Europe with no evidence pointing to African origin. The clinical condition improved after administering itraconazole (daily dose 100 mg orally) supplemented with a topical treatment, while the patient was totally cured after 2 months. The histopathological examination turned out to be highly useful in the diagnostic process. The genetic analysis of the urease gene pointed to a urease-positive T. rubrum rather than T. rubrum var. raubitschekii.

Var. raubitschekii of Trichophyton rubrum as a cause of tinea in Germany

Trichophyton raubitschekii was originally described as a distinct dermatophyte species but is now classified as a variant of Trichophyton rubrum. The variant raubitschekii differs from common strains of T. rubrum with regard to morphology, physiology, epidemiology and patterns of infection. It is mostly found in Africa, Asia and South America, but the literature and our observations reveal that seven patients (four men, three women) with T. rubrum var. raubitschekii-infections were meanwhile seen in Germany. All of them were born in Africa and they suffered from tinea corporis or tinea pedum, but onychomycosis was seen as well. All strains matched the typical characteristics of the variant raubitschekii except that one strain had a minimal capacity to perforate hair. Until now, the strains of T. rubrum var. raubitschekii isolated in Germany were probably imported by migration of the patients and so far no further spreading within Germany was observed. However, such a spreading is likely to occur in the future and therefore a monitoring is needed. This can be achieved only when the variant raubitschekii is looked for in the laboratories and is reported with its full name.