Analysis of dermatophyte flora at a private clinic in Sapporo during the period 1992 to 2001]

Statistical analysis was made of a total of 5530 patients (6798 cases) of dermatophytoses presenting at our private clinic during the period 1992 to 2001. The number of patients and cases represents 8.0% and 9.8% of the entire outpatient population during that time, respectively. Sex ratio (male/female) was 1.5. Among the 6798 dermatophytoses cases, tinea pedis was most frequent (65.8%), followed by tinea unguium (20.7%), tinea cruris (7.2%), tinea corporis (3.9%), tinea manuum (2.4%) and tinea barbae (0.04%). The incidence of tinea unguium increased, whereas that of tinea pedis, tinea cruris, and tinea corporis decreased during this ten year period, and 35.8% of dermatophytoses patients had more than two clinical subtypes simultaneously. Three thousand seven hundred ninety-five dermatophytes were isolated during the survey. : Trichophyton rubrum (TR)(79.4%), Trichophyton mentagrophytes (TM)(19.5%), Microsporum canis (MC)(0.7%), Epidermophyton floccosum (EF) (0.3%), and Microsporum gypseum (MG) (0.1%). Compared with our previous analysis reported for the period 1982 to 1991, the frequency of dermatophytoses increased, especially among aged individuals. Of the clinical subtypes, tinea pedis and tinea unguium were higher, but tinea cruris and tinea corporis were lower, and tinea capitis was not seen in the current survey. Among dermatophytes, TR was increased and other types of fungi were decreased. TR was 4.08 times more common than TM; this ratio is higher than our previous report.     

Dermatophyte flora at the dermatology clinic of Kimitsu Chuo Hospital from 1994 through 1999]

Kimitsu Chuo Hospital is located in the middle of Chiba Prefecture along Tokyo Bay. An epidemiological survey of dermatophytosis was made at the dermatology clinic of the hospital from January 1994 through December 1999. Dermatophytosis patients numbered 2,580 and disease types were composed of: tinea pedis 1,656 (64.2%), tinea unguium 377 (14.6%), tinea corporis 308 (11.9%), tinea cruris 139 (5.4%), tinea manuum 92 (3.6%), tinea capitis 6 (0.2%) and tinea profunda 2 (0.1%). Species frequencies in the 1,610 strains isolated from these patients were as follows: 929 (57.7%) of Trichophyton rubrum, 651 (40.4%) of T. mentagrophytes, 9 (0.6%) of Microsporum gypseum, 8 (0.5%) of M. canis, 8 (0.5%) of Epidermophyton floccosum and 5 (0.3%) of T. violaceum. The ratio of T.R/T.M was 1.43 in all the isolates, and 0.81 in the isolates from tinea pedis. These ratios were lower than those of the epidemiological survey of dermatomycoses in Japan in 1997. T. mentagrophytes was characteristically dominant in this hospital and resulted from a drastic increase in tinea pedis caused by this species in the summer season.     

An epidemiological survey of dermatomycoses in Japan, 2002]

An epidemiological survey of dermatomycoses and the causative fungus flora of dermatophytoses in Japan for 2002 was made on a total number of 72,660 outpatients who visited 14 dermatological clinics throughout Japan. The results were as follows: 1) Dermatophytosis was the most prevalent cutaneous fungal infection (7,994 cases) seen in these clinics, followed by candidiasis (755 cases) and then Malassezia infections (220 cases). 2) Among dermatophytoses, tinea pedis was the most frequent (4,813 cases: male 2,439, female 2,374), then in decreasing order, tinea unguium (2,123 cases: male 1,093, female 1,030), tinea corporis (497 cases: male 281, female 216), tinea cruris (299 cases: male 249, female 50), tinea manuum (248 cases: male 144, female 104) and tinea capitis including kerion (14 cases, male 6, female 8). 3) Tinea pedis and tinea unguium are seen to increase in summer season, among the aged population and among males in each clinic. When compared to the previous surveys (1992 and 1997) by clinical form, t. unguium patients increased from 1.9% of total outpatients in 1992, to 2.0% in 1997, then to 2.9% in 2002. 4) As the causative dermatophyte species, Trichophyton rubrum was the most frequently isolated among all dermatophyte infections except tinea capitis. 5) T. rubrum was isolated from 63.3%(1,431/2,262) of tinea pedis lesions, followed by Trichophyton mentagrophytes (36.6%, 829/2,262), and also 88.8% (325/366) of t. corporis, 95.4% (185/194) of t. cruris and 85.6% (462/540) of t. unguium. 6) Cutaneous candidiasis was seen in 755 cases (1.0%) of 72,660 outpatients. Intertrigo (347 cases) was the most frequent clinical form, followed by erosio interdigitalis (103 cases) and diaper candidiasis (102 cases). It has a tendency to affect the aged being complicated with topical predisposing factors. 7) Cutaneous Malassezia infections and other superficial fungal infections are seen in 220 cases, without any characteristic features by gender or clinical form.     

Effect of temperature, humidity and minor injury to the penetration of dermatophytes into human stratum corneum]

We evaluated the minimum period for penetration of Trichophyton mentagrophytes into human stratum corneum using an experimental model of tinea pedis. Fungal elements were applied to the surface of stratum corneum which were obtained from a healthy human heel, and samples were incubated under a designated condition of temperature and humidity. Thirty-five degrees, which is the approximate temperature of the surface of human skin, seemed more suitable for penetration than 27C. The result also indicated that humidity was a more significant factor than temperature. In the following examination using T. mentagrophytes and T. rubrum, the minimum period for penetration at 100% humidity was 1 day with the former and 1.5 days with the latter. At 95% humidity, T. mentagrophytes penetrated into human stratum corneum on day 1.5 and T. rubrum penetrated on day 4. Humidity of the 4th interdigital space in daily life was calculated to be below 95% using a hygro-thermometer. Therefore, to wash the feet daily can prevent development of tinea pedis. When we applied fungal elements to a cut side of stratum corneum, fungi penetrated within a day at 100% and 95% humidity. In addition, fungi were able to penetrate at below 85% humidity, which they were unable to do when applied them to the surface side. We stress that minor injury of stratum corneum is also a significant factor of the development of tinea pedis.     

Prevalence and patient's consciousness of tinea pedis and onychomycosis]

Epidemiological studies on tinea pedis and onychomycosis have been performed across Europe and East Asia. The prevalence of these conditions was 20%, respectively, and it increased with advancing age, more men than women had fungal infection of the feet. The prevalent predisposing factors were sports participation, average temperature, and family history of tinea pedis. The predisposing diseases were hypercholesterolemia, cardiovascular disease, diabetes mellitus, and osteoarticular disease. We conducted an epidemiological investigation to determine the prevalence and circumstances of untreated and unsuspected tinea pedis and onychomycosis. The results showed that the prevalence of occult athlete's foot was 25%, and that 59% of those cases were complicated by tinea unguium. The characteristics of patients with occult athlete's foot included a higher proportion of men and a tendency toward a low clinical score together with a high severity score. In the patient background, a strong correlation was observed between a positive KOH test result and characteristics such as past history of tinea pedis and/or onychomycosis, age, disposition of toes, and predisposing disease, as well as the type of shoes worn daily. We suspected that a patient's local and systemic conditions affected each other, creating good conditions for tinea pedis and onychomycosis so that the prevalence has increased. More understanding of occult athlete's foot will lead to prevention and improvement in treatment and diagnosis.     

Statistical study of dermatomycosis - observations in Sendai National Hospital over a 30 year period]

A statistical 30-year study of dermatomycosis in Sendai National Hospital (1968-1997) revealed many changes in the prevalent diseases: Tinea pedis and tinea unguium constantly increased during this period, and the ratio of the former associated with nail infection finally reached 30% of all tinea pedis patients. On the contrary, tinea corporis and cruris showed a remarkable decreasing tendency. Patient age distribution of each disease also showed distinctive changes, generally increasing in the older generation and decreasing in the younger. The number of patients with tinea pedis and unguium gradually increased among the middle and older generations, with the peak of the age-distribution curve shifting upward year after year. On the other hand, cases of tinea cruris among the younger generation were few in the latest years, and middle-age patients remained at a low number. In the first stage of this study the kinds of atiologic dermatophytes consisted of multiple species, but after middle period the isolation of Epidermaphyton floccosum decreased. Microsporum canis appeared first in 1976 but in the recent several years has completely disappeared. In the last few years of the period studied Trichophyton rubrum and Trichophyton mentagrophytes were the only isolates found from among all types of dermatophytoses. Infantile candidiasis remarkably increased in 1970-1975 but thereafter decreased rapidlly. Candidial intertrigo also increased in the same period but did not decrease as much thereafter and continued at the same intermediate level. The number of other types of candidiases were not greatly changed throughout the 30-year period. Malassezia infection also showed no remarkable changes, and only 20 cases of sporothrichosis were found. One case of the deep seated form of cutaneous aspergillosis was found, and this was also true of chromomycosis caused by Fonceaea pedrosoi.     

Dermatophytosis of the external auditory meatus]

Dermatophytosis of the external auditory meatus is believed to be a fairly rare disease. In the past three and a half years we have had seven cases of dermatophytosis in the external auditory meatus. All cases except one were associated with tinea of other lesions. Case 1: A 44-year-old man had tinea of the auricle, tinea pedis and tinea unguium. Case 2: A 14-year-old boy, the son of case 1 had no tinea elsewhere on his body, including the auricle. He scratched the auditory meatus with an earpick which his father had used. Case 3: A 62-year-old man had tinea of the auricle, tinea pedis and tinea unguium. Case 4: A 50-year-old man had tinea of the auricle, tinea pedis and tinea unguium. Case 5: A 36-year-old man had tinea of the auricle, tinea pedis, tinea unguium and tinea cruris. Case 6: A 30-year-old woman had tinea of the auricle. Case 7: A 68-year-old man had tinea of the auricle, tinea pedis, tinea unguium and tinea manuum. Endoscopic examination (except for cases 4 and 7) revealed dry cerumen from cartilaginous to bony region of the external auditory meatus. Direct examination using KOH method of the cerumen in all cases demonstrated numerous fungal elements. Fungal cultures identified Trichophyton rubrum except for cases 3 and 6. All cases were successfully treated with oral itraconazole or terbinafine. We suggest that tinea of the external auditory meatus is frequently associated with that of the auricle.     

1997 Epidemiological survey of dermatophytoses in Japan]

An epidemiological investigation on dermatophytoses in Japan for the year 1997 was carried out with the following results. The number of dermatomycoses patients visiting the fourteen cooperating institutes that year was 8,284. New outpatients with this condition accounted for 13.3% of all new outpatients in these institutes. Dermatophytoses patients numbered 7,314 and were composed of: tinea pedis 4,901 (63.8%), tinea unguium 1,592 (20.7%), tinea corporis 557 (7.2%), tinea cruris 395 (5.1%), tinea manuum 215 (2.8%), tinea capitis 12, kerion celsi 3, tinea barbae 1 and granuloma trichophyticum 1. Of these, 117 were children under 15 years of age. Species and incidences of the 2,273 strains isolated from the patients with dermatophytoses were as follows: Trichophyton (T.) rubrum 1,628 (71.6%), T. mentagrophytes 617 (27.2%), Epidermophyton floccosum 9 (0.4%), Microsporum (M.) canis 2, M. gypseum 2, T. glabrum 1, and 15 undetermined strains. Candidiasis was found in 714 individuals: intertrigo 302, erosio interdigitalis 108, erythema infantum 85, oral candidiasis 51, paronychia et onychia 51, genital candidiasis 50, onychomycosis 15 and other atypical forms of candidiasis 39. Patients with tinea versicolor numbered 242 and those with malassezia folliculitis 15. There were nine cases of deep dermal mycoses. The results of superficial dermatophytoses for the year 1997 differed from those of 1991-92 in the following points: tinea corporis and tinea cruris were lower in number, while tinea unguium had increased in ratio and number continuously. M. canis infection tended to decrease. In the age distribution of tinea, in every clinical form the peak of distribution curve gradually shifted to a more elderly age group.     

Analysis of the dermatophyte species isolated in the British Isles between 1980 and 2005 and review of worldwide dermatophyte trends over the last three decades.

Infections of the skin, hair and nails by dermatophyte fungi are common in developed and developing countries alike. However, the species involved and the resulting clinical entities vary both geographically and with time. We have surveyed 15,333 dermatophytes obtained from primary isolations at the Mycology Reference Laboratory, Bristol, UK from 1980 through 2005. Several striking trends in dermatophyte prevalence were apparent over this period. The relative frequencies of isolations of Microsporum canis (cat and dog ringworm), Trichophyton verrucosum (cattle ringworm), T. mentagrophytes var. mentagrophytes (rodent ringworm) and Epidermophyton floccosum (a cause of human groin and foot infections) all decreased by 90%. Conversely, the contributions of T. tonsurans and T. violaceum (two anthropophilic scalp-infecting species) to total dermatophyte isolations increased by 1000% over the same period. Finally, T. rubrum and T. mentagrophytes var. interdigitale, the two common causes of foot infection comprised 80% of all dermatophytes isolated in 1980 and 90% of isolations in 2005. Similar trends in dermatophyte prevalence were evidenced throughout the British Isles, based on the voluntary reporting of isolations from a large number of British laboratories at 5-yearly intervals over the same period. The implications of these changing patterns of dermatophyte species, and the clinical entities they produce are discussed in the context of a review of worldwide dermatophyte isolations over the last three decades, with emphasis on the causal agents of tinea capitis.     

Statistical study of dermatomycosis for 30 years (1968-1997) in sendai national hospital]

A statistical study on dermatomycoses for the 30 years from 1968 to 1997 in the dermatologic section of Sendai National Hospital was carried out with the following results. The total number of dermatomycosis patients was 14,259 and accounted for 9.59% of all new outpatients during this period. These cases of dermatomycoses were composed of the following: dermatophytoses 10,656, candidiasis 3,287, malassezia infection 566, sporothrichosis 20, aspergillosis 7, and chromomycosis 1. Annual changes in number of dermatophytoses varied in each clinical type: tinea corporis and tinea cruris had increased by the end of the 1970s, and there after decreased gradually until recent years. Tinea pedis and tinea unguium, on the contrary, increased after the 1980s. Age distribution of all clinical forms of dermatophytoses changed gradually, and its peak of the distribution curve shifted to an older site each year, while the number of younger generation patients decreased. Mycologically Trichophyton (T.) rubrum was mainly isolated from all types of dermatophytoses, and T. mentagrophytes followed. The ratio of these two species (R/M) in tinea pedis was 1.25, and the ratio of T. mentagrophytes was relatively high. Epidermophyton floccosum was continuously isolated, but its frequency in recent years has decreased. Microsporum canis infection increased from the middle period of this research, but after 1990 decreased gradually. The other dermatophytes were found sporadically. In recent years the species isolated have become more simplified. Among candidiasis, infantile candidiasis increased dramatically in the 1970s but soon decreased. Intertrigo type also increased in the same period and then decreased to an intermediate level. Paronychia, onychia and erosio interdigitale were constantly found in small numbers, while malassezia infection remained at a constant level and was found more in male patients.     

1996 epidemiological survey of dermatophytoses in Japan. Epidemiological Investigation Committee for Human Mycoses in the Japanese Society for Medical Mycology]

An epidemiological investigation on dermatophytoses in Japan for the year 1996 was carried out with the following results. The number of dermatomycoses patients visiting the fifteen cooperating institutes that year was 8,402. New outpatients with this condition accounted for 13.1% of all new outpatients in these institutes. Dermatophytoses patients numbered 7,395 and were composed of: tinea pedis 4,764 (64.4%), tinea unguium 1,487 (20.1%), tinea corporis 558 (7.5%), tinea cruris 369 (5.0%), tinea manuum 195 (2.6%), tinea capitis 11, kerion Celsi 7, tinea barbae 1 and other forms 3. Of these, 113 were children under 15 years of age. Species and incidences of the 2,615 strains isolated from the patients with dermatophytoses were as follows: Trichophyton (T.) rubrum 1,828 (69. 9%), T. mentagrophytes 743 (28.4%) Epidermophyton floccosum 20 (0. 8%), Microsporum (M.) canis 13 (0.5%), M. gypseum 5, T. violaceum 2, and 4 undetermined strains. Candidiasis was found in 722 individuals: intertrigo 299, erosio interdigitalis 95, erythema infantum 89, oral candidiasis 63, paronychia et onychia 56, genital candidiasis 56, onychomycosis 24, chronic mucocutaneous candidiasis 1 and other atypical forms of candidiasis 39. Patients with tinea versicolor numbered 265 and those with Malassezia folliculitis 15. There were five cases of deep dermal mycoses: three of sporotrichosis, one of chromomycosis and one of aspergillosis. The results of superficial dermatophytoses for the year 1996 differed from those of 1991-92 in the following points: Tinea corporis and tinea cruris were lower in number, while tinea unguium had increased in ratio and number. M. canis infection tended to decrease gradually. In the age-distribution of tinea, in every clinical form the peak of distribution curve shifted to a more elderly age group.     

Interferon-gamma production in peripheral lymphocytes of patients with tinea pedis: comparison of patients with and without tinea unguium.

The precise mechanism of the host defense that protects the nail from dermatophyte invasion is not known. Recent immunological findings in dermatophytosis suggest the hypothesis that the T helper 1 (Th1) response may play a role in protecting the nail from dermatophyte invasion. Our present study focused on interferon-gamma (IFN-gamma) release in patients with tinea pedis with or without tinea unguium, and pathogenesis of tinea unguium is discussed in relation to the association with a possible deficiency of Th1 response in the host defense mechanism. The production of IFN-gamma by peripheral blood mononuclear cells from the patients with tinea unguium in response to stimulation with trichophytin was not impaired in contrast to that from the patients without tinea unguium. Comparable lymphocyte proliferation to trichophytin was observed in both groups. Normal healthy persons with no clinical evidence of tinea could be divided into two groups based on lymphocyte proliferation and IFN-gamma production in response to trichophytin: high responder and low responder, with high responders being correlated with a clinical history of previous tinea pedis. In this study, a lack of a Th1 response to dermatophyte antigen was not shown in patients with tinea unguium by measuring the release of IFN-gamma, which plays a role in the effector phase of the delayed-type hypersensitivity reaction. A deficiency in the Th1 response to dermatophyte antigen, therefore, does not appear to play an important role in the establishment of tinea unguium.     

Five-hour diagnosis of dermatophyte nail infections with specific detection of Trichophyton rubrum

A rapid two-step DNA extraction method and a multiplex PCR for the detection of dermatophytes in general and Trichophyton rubrum specifically were developed and evaluated with DNA extracted from pure cultures and from clinically diseased nails. DNA from the following dermatophytes was used: Epidermophyton floccosum, Microsporum audouinii, Microsporum canis, Microsporum gypseum, Microsporum nanum, Trichophyton mentagrophytes, Trichophyton rubrum, Trichophyton schoenleinii, Trichophyton soudanense, Trichophyton terrestre, Trichophyton tonsurans, Trichophyton verrucosum, and Trichophyton violaceum. Human DNA and DNA from the following nondermatophyte fungi were included as controls: Alternaria, Aspergillus niger, Candida albicans, Candida glabrata, Candida krusei, Malassezia furfur, Saccharomyces cerevisiae, and Scopulariopsis brevicaulis. A total of 118 nail samples received for routine microscopy and culture for dermatophytes were subsequently tested by the two PCRs separately and in a multiplex format. Using DNA extracted from pure cultures and the pan-dermatophyte PCR, the T. rubrum-specific PCR sequentially and in a multiplex format correctly detected all dermatophytes and additionally correctly identified T. rubrum. Comparison of the traditional diagnostic evaluation (microscopy and culture) of nail samples with PCR on DNA directly extracted from the nails showed excellent agreement between PCR and microscopy, but the number of samples with dermatophyte species identification was increased considerably from 22.9% to 41.5%, mainly due to the identification of T. rubrum by PCR in microscopy-positive but culture-negative samples. In conclusion, this 5-hour diagnostic test was shown to increase not only the speed but also the sensitivity of investigation for nail dermatophytosis.     

Epidemiological investigation of tinea pedis in groups of healthy students, research workers and females wearing boots]

The infection rate, causative dermatophytes, and dermatophyte dissemination of tinea pedis in young healthy Japanese were studied by direct microscopic examination, slant cultures, and foot-press culture method. Questionnaires on subjective symptoms and treatments were also distributed. Among fifty-eight medical students with a mean age of 23.9 years, thirteen (22.4%) showed positive by direct microscopic examination and T. mentagrophytes was more dominant than T. rubrum by slant cultures. In one hundred and sixteen student feet, twelve were infected and disseminating dermatophytes, four were infected but not disseminating, three were not infected but adhering dermatophytes. The infection rate of tinea pedis was thus 24.1%. Among thirty-seven research workers (mean age: 34.8), twenty-one (56.8%) showed positive by direct microscopic examination. All the dermatophytes isolated by slant cultures were T. mentagrophytes. In seventy-four feet, twenty-nine were infected and disseminating, ten were infected but not disseminating, and three were adhering dermatophytes. The infection rate was 64.9%. Among thirty-one females wearing boots (mean age: 21.0), seven (22.6%) were infected and T. mentagrophytes was more dominant. In sixty-two feet, eight were infected and disseminating, one was infected but not disseminating, and five were adhering dermatophytes. The infection rate of tinea pedis was quite high and T.r/T.m rate was low in the three groups. Most of the patients had had no treatment and were disseminating dermatophytes.     

Effects of temperature, humidity, minor injury and washing on penetration of dermatophytes into human stratum corneum]

We evaluated the minimum time for penetration of Trichophyton mentagrophytes into human stratum corneum using an experimental model of tinea pedis. After fungal elements were applied on the surface of stratum corneum obtained from a healthy human heel, samples were incubated under designated conditions of temperature and humidity. The penetration of fungal elements was much faster at 35 degrees C than 27 degrees C despite the fact that the latter is an optimal temperature for fungal growth. At 35 degrees C and 100% humidity the minimum time required for penetration was one day. When we applied fungal elements on an abraded surface of stratum corneum, fungi penetrated within a half day under the same conditions. This suggests that minor injury of stratum corneum is a significant factor for infection. The development of tinea pedis does not occur frequently in daily life. We examined the effect of washing the surface of stratum corneum to which T. mentagrophytes had been applied. The samples were incubated under conditions simulating daily life: i.e. with 80% humidity for 8 hours, and 100% humidity for 16 hours. After washing, nearly all the fungal elements had been removed from the surface of stratum corneum within one day. The data suggests that to prevent tinea pedis, daily washing of soles and interdigital regions is effective.     

Tinea pedis: The etiology and global epidemiology of a common fungal infection

Abstract

Tinea pedis, which is a dermatophytic infection of the feet, can involve the interdigital web spaces or the sides of the feet and may be a chronic or recurring condition. The most common etiological agents are anthropophiles, including Trichophyton rubrum sensu stricto, which is the most common, followed by Trichophyton interdigitale and Epidermophyton floccosum. There has been a change in this research arena, necessitating a re-evaluation of our knowledge on the topic from a multidisciplinary perspective. Thus, this review aimed to provide a solid overview of the current status and changing patterns of tinea pedis. The second half of the twentieth century witnessed a global increase in tinea pedis and a clonal spread of one major etiologic agent, T. rubrum. This phenomenon is likely due to increases in urbanization and the use of sports and fitness facilities, the growing prevalence of obesity and the aging population. For optimal patient care and management, the diagnosis of tinea pedis should be verified by microbiological analysis. In this review, we discuss the epidemiology, clinical forms, complications and mycological characteristics of tinea pedis and we highlight the pathogenesis, prevention and control parameters of this infection.     

Dermatophytes identified at the Australian National Reference Laboratory in Medical Mycology 1966-1982

Over a 17 yr period from 1966 to 1982, 4354 dermatophytes were identified at the Australian National Reference Laboratory in Medical Mycology. The most frequently identified species was Trichophyton rubrum, accounting for 35.3% of identifications, followed by Trichophyton mentagrophytes (26.5%), Trichophyton tonsurans (12.8%), Epidermophyton floccosum (10.7%) and Microsporum canis (8.4%). Specimens taken from the feet were the most common source of the Trichophyton rubrum isolates, followed by specimens from the groin. The highest incidence of T. rubrum and other Trichophyton infections was found in males in the age group 21-30 yr. Microsporum species were most commonly isolated from children aged 10 yr or less. In 1.5% of specimens, more than one fungal species was isolated. In most of these instances a yeast (predominantly Candida species) was found in addition to a Trichophyton species.     

Experimental studies on the penetration into the human stratum corneum of the dermatophyte]

We present results on the experimental penetration of Trichophyton mentagrophytes and T. rubrum under designated condition of humidity into human stratum corneum obtained from a healthy human heelregion. When mycelia were applied to the surface side of stratum corneum and then incubated at 100 % humidity, T. mentagrophytes and T. rubrum were observed in the stratum corneum on day 1 and day 1.5, respectively. At 95% humidity, T. mentagrophytes and T. rubrum penetrated on day 1.5 and day 4, and at 90% humidity, they penetrated on day 3 and day 7, respectively. At less than 85% humidity, no fungal elements of either strain were observed in stratum corneum for up to 7 days. These datasuggest that at least 90% humidity is necessary for these two fungi to penetrate into stratum corneum within a few days. However, when T. mentagrophytes was applied to the cutting side of the stratum corneum and thenincubated at more than 70% humidity, the mycelia were able to penetrate within a day. The same results were obtained when T. rubrum was applied on the cutting side and incubated at 95 and 100% humidity. T. rubrum was also able to penetrate into the stratum corneum within several days at 70 and 80% humidity. These results may indicate that not only persistent moisture but also minor injuries of stratum corneum are the most important factors in the development of tinea pedis.     

Phylogenetic classification and species identification of dermatophyte strains based on DNA sequences of nuclear ribosomal internal transcribed spacer 1 regions

The mutual phylogenetic relationships of dermatophytes of the genera Trichophyton, Microsporum, and Epidermophyton were demonstrated by using internal transcribed spacer 1 (ITS1) region ribosomal DNA sequences. Trichophyton spp. and Microsporum spp. form a cluster in the phylogenetic tree with Epidermophyton floccosum as an outgroup, and within this cluster, all Trichophyton spp. except Trichophyton terrestre form a nested cluster (100% bootstrap support). Members of dermatophytes in the cluster of Trichophyton spp. were classified into three groups with ITS1 homologies, with each of them being a monophyletic cluster (100% bootstrap support). The Arthroderma vanbreuseghemii-Arthroderma simii group consists of A. vanbreuseghemii, A. simii, Trichophyton mentagrophytes isolates from humans, T. mentagrophytes var. quinckeanum, Trichophyton tonsurans, and Trichophyton schoenleinii. Arthroderma benhamiae, T. mentagrophytes var. erinacei, and Trichophyton verrucosum are members of the Arthroderma benhamiae group. Trichophyton rubrum and Trichophyton violaceum form the T. rubrum group. This suggests that these "species" of dermatophytes have been overclassified. The ITS1 sequences of 11 clinical isolates were also determined to identify the species, and all strains were successfully identified by comparison of their base sequences with those in the ITS1 DNA sequence database.     

Tinea capitis in a paediatric population

Tinea capitis is an increasing problem in Europe. The pattern of infection is changing with an increase in pathogenic anthropophilic dermatophytes particularly Trichophyton tonsurans. We aimed to determine the frequency of tinea capitis in a paediatric population attending dermatology outpatients and examine the clinical spectrum of disease. A retrospective analysis was performed of all laboratory proven tinea capitis cases presenting to the dermatology outpatient department at The Children's University Hospital, Temple Street over an 18-month period (1st January 2004 to 30th of June 2005 inclusive). Sixty-two children had tinea capitis of whom 53 (85.5%) were of African descent. Thirty-five (56%) were male and 27 female (44%). The average age at presentation was 4.02 years (age range 1-163 months) with five cases occurring in children less than one year of age. The most common pathogen was the anthropophilic dermatophyte Trichophyton tonsurans, accounting for 47 (75.8%) of all cases of tinea capitis. Eight (12.9%) were secondary to Microsporum ferrigineum, 2 (3.2%) secondary to Trichophyton violaceum, both Trichophyton soudanese and Trichophyton verruosum accounted for 1.6% each. The zoophilic organism Microsporum canis was diagnosed in 3 cases (4.8%). Presenting signs included scaling of the scalp (35.47%), scaling of the scalp and alopecia (53.24%), and alopecia and kerion (11.29%/o). The duration of symptoms was recorded in 52 patients with the average duration 8.38 months (range 0.5-72 months). In 20 cases an associated skin involvement on other areas of the body was recorded. All patients at diagnosis were either on no, suboptimal or inappropriate treatment. The prevalence of tinea capitis is increasing in this hospital based cohort. The main pathogen is now Trichophyton tonsurans. Children of African descent are at increased risk of infection. The diagnosis is poorly recognized and needs to be highlighted as a public health issue. There is a need for community based prevalence studies.