A Study Of Etiology On Tinea Manuum Et Pedis And Onychomycosis In Lanzhou District

Background: Tinea manuum et pedis are a kind of dermatophytosis which invades the hand and foot, onychomycosis is defined as the infection of the nail by fungus. Dermatophyte infections of humans are among the most common forms of skin diseases, which may be harmful to the body and decrease people's life quality. From the previous investigations, it is suggested that the etiologic agents of dermatomycoses not only vary with the site of the infection, but also differ to some extent according to the city, state or country of occurrence. The geographical distribution of the anthropophilic and zoophilic dermatophytes is not static within a district, but dynamic, and subject to change by population shifts due to migration, health habits, standards of living or travel. They also may change with the passage of time. It is well established that an understanding of the prevalence and identity of etiological agents assists in the prevention and treatment of dennatophytoses. However, very few have been published about the prevalence and types of dennatophytoses and what etiologic agents are present in Lanzhou district up to the present.Objective: 1. To investigate the risk factors, incidence and etiological agents of tinea manuum tinea pedis and onychomycosis in Lanzhou district. 2. To inquire into the application of rapid and precise identification for the pathogenic fungus species of T. rubrum by using moluculer methods.Methods: The specimens of clinically suspected patients with dermatomycoses were examined for causative fungi in the Second Hospital of Lanzhou University during January to December of 2006, while the clinical materials of each patient with KOH positive were recorded and analyzed. The total DNAs of 72 isolates of T. rubrum were extracted by using mini-preparation, then the internal transcribed spacer (ITS) region of ribosomal DNA were amplified by using the fungi-universal primers ITS1 (5'-TCCGTAGGTGAACCTGCGG-3'), ITS4 (5'-TCCTCCGCTTATTGATATGC-3'). Moreover, two novel tandem repeat subelements (TRSs), TRS-1 and TRS-2, located in the T. rubrum rDNA nontranscribed spacer (NTS), were amplified from T. rubrum. Then restriction fragment length polymorphisms (RFLP) was performed by three restriction enzymes (Hinf I, Taq I) digesting those production of Polymerase chain reaction (PCR) amplification.Results: 1.One hundred and fifty-three cases are onychomycosis in the 262 patients and107 T. rubrum strains were isolated in the 135 strains of pathogenic fungi. 2. The patterns of 72 strains of T. rubrum were isologous after the primer-pair ITS1 and ITS4 being amplified, and about 690bps were obtained in T. rubrum. 3. The patterns of 72 strains of T. rubrum were isologous after the primer-pair TrNTSC-1 and TrNTSR-1 being amplified, and about 500bps were obtained in T. rubrum. Meanwhile, according to TrNTSF-2 and TrNTSR-4 being amplified, we could separate 3 subgroups within72 strains of T. rubrum. It happened to 6 of the 29 patients that multiple genotypes were involved in T. rubrum on different sites in the same body. 4. The patterns of two restriction enzymes Hinf I and Taq I were respectively identical.Conclusions: 1. T. rubrum was the main dermatophytes isolated on the tinea manuum tinea pedis and onychomycosis of people in Lanzhou district. 2. PCR of ribosomal DNA intergenic spacer regions is a useful method for species identification of common dermatophyte fungi. 3. PCR of TRS-2 in the T. rubrum rDNA nontranscribed spacer (NTS) is a useful method for species identification of T. rubrum, and PCR of TRS-1 in the T. rubrum rDNA nontranscribed spacer (NTS) can differentiate T. rubrum at the level of sub-species, which is valuable for the pathogenic diagnosis and epidemiology survey. The study shows that multiple genotypes are involved in T. rubrum infection on different sites in the same patient. The results suggest that in some cases the infections are due to different strains of fungi. 4. Restriction enzymes Hinf I and Taq I digestion of PCR amplified ITS regions produce unique and easily identifiable fragment patterns for T. rubrum species.