| Background:Dermatophytosis is an infection of the shin,hair,or nail caused by dermatophytes,also known as tinea,including tinea capitis,tinea corporis,tinea cruris, tinea manus,tinea pedis,and tinea unguium.Dermatophytosis is a common skin infection,which may be harmful to the body and decrease people's life quality.In recent years,a tendency has been noted that the incidence of some dermatophytosis is increasing.The tinea capitas,which used to be rare for one time,has been emerged because of people's craziness for pets raising.It is suggested that the etiologic agents of dermatophytosis not only vary with the site of the infection,but also differ to some extent according to the city and country of occurrence.The geographical distribution of the anthropophilic and zoophilic dermatophytes is dynamic and subject to change by population shifts due to migration,health habits,standards of living or travel,and the passage of time as well.However,the real recent prevalence and incidence of dermatophytoses and their most common etiologic agents among children in Lanzhou district are largely unknown in most cases.Objective:1.To investigate the prevalence and pathogenic fungi species of dermatophytoses among children in Lanzhou district.To estimate the size of therapeutic problem and to prevent the transmission of such infections with adequate preventive measures.2.To observe the keratinolytic activities of predominant pathogenic fungi species and compare the keratinolytic activities of different strains of the same species among isolates from different positions.To initially discuss the relation between the clinical manifestations and keratinolytic activity. Methods:During October 2007 and September 2008,314 cases(aged≤14 years old) from Lanzhou area attending our dermatology department were clinically suspected to have dermatomycoses.A portion of each specimen was mounted in 10% KOH and examined microscopically for the presence of dermatophytes.The remaining portion was inoculated on two slopes of sabouraud glucose agar.The clinical informations of each patient were recorded and analyzed.The tested strains were inoculated on mediums containing different keratin to promote production of keratinases.Keratin-azure was used to value keratinolytic activity.Keratin degradation was measured in a spectrophotometer at 595nm using uninoculated substrate buffer as a negative control.An increase of 0.01 in the absorbency was considered equal to one keratinase unit.Results:1.Out of a total of 314 children with clinical evidence of dermatomycoses,278(88.54%)cases were positive results by microscopy or culture or both.197(62.74%) strains of dermatophytes were isolated,including M.canis 190 strains(96.45%),T.rubrurn 6 strains(3.05%),and M.gypseum 1 strain(0.50%).Of all dermatophytoses,there were tinea capitis 186(66.54%),tinea corporis 84(29.78%), tinea pedis 6(2.15%),and tinea unguium 3(1.08%).2.The keratinolytic activities in M.canis induced by purified human hair were higher than those induced by human dander(p=0.023).The keratinolytic activities of M.canis isolated from tinea capitis were higher than those of tinea corporis(p=0.037),and tinea alba were similar to kerion in keratinolytic activities(p=0.078).There were no significant differences among the keratinolytic activities of M.canis isolated from different position (p=0.695).Conclusion:1.In Lanzhou district,tinea capitis is of the highest prevalence among children,and M.canis is the most common pathogenic fungi.2.Human hair is a fine substrate for inducing keratinase production.3.The keratinolytic activities of M. canis from different position may be unlikeliness. |
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