Study on genotype and virulence of Cryptococcus neoformans and Cryptococcus gattii clinical isolates in Guigang, Guangxi Zhuang Autonomous Region / 中华流行病学杂志

<p><b>OBJECTIVE</b>To understand the species, genotypes and mating types of Cryptococcus neoformans and Cryptococcus gattii isolated from clinical samples in Guigang, Guangxi Zhuang Autonomous Region.</p><p><b>METHODS</b>A total of 20 Cryptococcus strains were isolated from clinical samples in Guigang from 2009 to 2012. The biological identification was conducted by polymerase chain reaction (PCR) to amplify internal transcribed spacer (ITS) sequences. The serotypes and mating types of C. neoformans and C. gattii were identified by PCR with serotype-specific and mating type-specific primers. The genotype was characterized by PCR fingerprinting and URA5 gene restriction fragment length polymorphism (URA5-RFLP). Phenotype study included growth test at 37 °C, melanin production test and urease test.</p><p><b>RESULTS</b>Among the 20 strains, 19 (95%) were identified as C. neoformans varieties (var.) grubii (serotype A, mating type α, genotype VN I), and only 1 was identified as C. gattii (mating type α, genotype VG I). The results of virulence test showed that all the strains grew well at 37 °C and positive in both urease test and melanin production test.</p><p><b>CONCLUSION</b>C. neoformans var. grubii (serotype A, genotype VN I and mating type α) was the predominant pathogen causing cryptococcosis in Guigang, and C. gattii strain was also detected.</p>

Study on virulence factors of Candida tropicalis isolated from clinical samples / 中华流行病学杂志

Objective To determine the in vitro production of virulence factors for Candida (C.) tropicalis,including aspartyl proteinases,phospholipases and hemolytic activities,describe the regulation of virulence factors varying with time in C.tropicalis,and analyze the differences in aspartyl proteinases and hemolytic activities of C.tropicalis isolated from anatomically distinct sites.Methods A total of 64 C.tropicalis strains were spot-inoculated onto bovine albumin agar,egg yolk agar and sheep blood agar plates,respectively.Then the plates were incubated for 24,48 and 72 hour at 37 ℃,respectively.The aspartyl proteinases,phospholipase and hemolytic activities were determined at each time point,respectively.Results All the C.tropiclais isolates showed positive aspartyl proteinases and hemolytic activities at each time point,but no phospholipases activity was detected in C.tropicalis.On comparison of aspartyl proteinases and hemolytic activities at different time points,aspartyl proteinases activity at 48 and 72 hour was higher than that at 24 hour.During 72 hour,hemolytic activity of C.tropicalis increased.No statistical significant differences in aspartyl proteinases and hemolytic activities of C.tropicalis were observed among different infection sites (P=0.368 and 0.985).Conclusion The C.tropicalis clinical isolates in China have aspartyl proteinases activity,hemolytic activity,but have no phospholipase activity.