ABSTRACT
Objective Trichophyton rubrum strains can cause superficial infection and also deep tissue infection, but relevant animal model has not been reported yet.The aim of this study was to construct an animal model of granuloma infected by T.rubrum. Methods Three T.rubrum strains isolated from clinical granuloma tissues, 2 T.rubrum strains isolated from tinea infection and a standard strain of ATCCMYA4438 were selected.Corticosteroids were given to the Balb/C mice before and after the injection of the T. rubrum and mucin suspension and the mice model of granuloma was established.Direct microcopy, culture and histopathologic method were adopt to verify the infection effects. Results The mice inoculated with the T.rubrum granuloma strains with mucin suspension were examined after 21 days in the condition of applying appropriate dose of glucocorticoids.Direct microscopic examination showed the slender mycelium, fungal culture showed the growth of colony and histopathology showed excessive keratinization of foot tissue, formation of granuloma in the dermis with inflammatory cell infiltration of neutro-philic granulocyte and lymphocytes.However, the mice inoculated with the T.Rubrum tinea strains with mucin suspension showed the negative result. Conclusion The rubrum granuloma mice model can be es-tablished using the clinical isolates of T.rubrum granuloma strains with the mucin and glucocorticoids interventions.
ABSTRACT
Objective Little is known about the role of low oxygen concentration in the formation of the capsule of Cryptococ -cus neoformans .This study was to investigate the effect of hypoxic condition on the capsule size of Cryptococcus neoformans . Methods We cultured 39 Cryptococcus neoformans strains in liquid Sabouraud medium and then incubated them at the normoxic (21%) and hypoxic concentration (1%), respectively.After 72 hours of incubation, we observed the capsules formed at different ox-ygen conditions under the Olympus microscope and the measured their sizes using the Axiovision software . Results Of the total number of Cryptococcus neoformans strains , 30 showed larger capsules in the normoxic than in the hypoxic condition , 17 with statisti-cally significant differences in their diameters (P<0.05), while the other 9 strains exhibited just the opposite results , 4 with statisti-cally significant differences in their diameters ( P<0.05). Conclusion Hypoxia might inhibit the growth of the Cryptococcus neoformans capsule.However, further studies are needed on its correlation with the serum or gene types of the Cryptococcus neofor-mans strain.
ABSTRACT
Objective Candidas rank as the second factor of deep fungal infection .This study aimed to investigate the rela-tionship between Candidas and melanin by screening clinically isolated melanin -producing Candidas . Methods We incubated 360 strains of clinically isolated Candidas with caffeic acid , DOPA agar , and minimal medium at a temperature of 35℃, with Cryptococcus neoformans as the positive control .We observed the changes in the culture media using transmission electron microscopy (TEM) and electron spin resonance ( ESR) spectroscopy . Results Cryptococcus neoforman produced pigmentation in all the three types of medi -um.At 5 days, a standard strain of Candida albicans SC 5314 turned dark brown in the DOPA agar and minimal medium and , at 10 days, 12 and 15 of the 360 Candida strains turned dark brown in the DOPA agar and minimal medium , respectively, which were not shown to be melanin by TEM and ESR spectroscopy . Conclusion Culture media are not reliable enough for the identification of mel-anin-producing Candidas , and the observations need to be further verified by TEM and ESR spectroscopy .