Indigenous case of disseminated histoplasmosis from the Penicillium marneffei endemic area of China.

This is the first indigenous case of disseminated histoplasmosis reported from the Penicillium marneffei endemic area in southern China. It was diagnosed by histopathology of tissue, gross and microscopic morphology of the culture and PCR assay of the isolated fungus. Successful antifungal treatment was with itraconazole 400 mg/day for 5 months. This case suggests that histoplasmosis should be an important differential diagnosis in immunocompromised patients in southern China and South East Asia (the only endemic area for P. marneffei).

Malassezia folliculitis in China.

Superficial Malassezia folliculitis was diagnosed in 1-1.5% of all dermatology patients seen in a Dermatology Out-Patient clinic in Urumqi City, Xinjiang province, west China. It was most prevalent in healthy, middle-aged males in the warm seasons. This disease, first reported in 1969, is usually diagnosed as a systemic disease of immuno-compromised patients. Our findings indicate it is a relatively common superficial skin disease that can be managed with ketoconazole or itraconazole.

The effects of temperature, pH, and salinity on the growth and dimorphism of Penicillium marneffei.

Penicillium marneffei is an important thermal dimorphic fungus that is endemic to Southeast Asia and China and causes penicilliosis, an AIDS-defining disease. Dimorphic switching is considered an important growth characteristic associated with its pathogenicity. In recent years, the molecular mechanisms underlying both dimorphic switching and monomorphic growth have been studied. However, little is known about the physical and chemical factors that impact either dimorphic switching or monomorphic growth of this organism. Further, the natural history of the disease is unclear. Our experiments focus upon the effects of temperature, pH and salinity on both growth phases of P. marneffei. We compared 11 isolates of P. marneffei and found that all could grow at a wide temperature range (8.0-39.8 degrees C), but growth was dramatically inhibited at 40 degrees C. The morphological switch from hyphae to yeast growth was initiated at 32 degrees C. However, the sensitivity to elevated temperatures during this transition varied among isolates. Both hyphae and yeast growth forms grew much better at acidic (pH 5, 6) and neutral pH than at alkaline conditions. While similar sensitivities were observed at high concentrations of NaCl and CaCl(2), in general, yeast cells displayed a greater sensitivity to both compounds. Our data demonstrate that isolate differences occur in growth patterns. Importantly, the growth requirements defined in our study may shed light on the environmental conditions that favor its survival, a subject that is not completely resolved in the current literature.

Identification of a novel gene, URE2, that functionally complements a urease-negative clinical strain of Cryptococcus neoformans.

A urease-negative serotype A strain of Cryptococcus neoformans (B-4587) was isolated from the cerebrospinal fluid of an immunocompetent patient with a central nervous system infection. The URE1 gene encoding urease failed to complement the mutant phenotype. Urease-positive clones of B-4587 obtained by complementing with a genomic library of strain H99 harboured an episomal plasmid containing DNA inserts with homology to the sudA gene of Aspergillus nidulans. The gene harboured by these plasmids was named URE2 since it enabled the transformants to grow on media containing urea as the sole nitrogen source while the transformants with an empty vector failed to grow. Transformation of strain B-4587 with a plasmid construct containing a truncated version of the URE2 gene failed to complement the urease-negative phenotype. Disruption of the native URE2 gene in a wild-type serotype A strain H99 and a serotype D strain LP1 of C. neoformans resulted in the inability of the strains to grow on media containing urea as the sole nitrogen source, suggesting that the URE2 gene product is involved in the utilization of urea by the organism. Virulence in mice of the urease-negative isolate B-4587, the urease-positive transformants containing the wild-type copy of the URE2 gene, and the urease-negative vector-only transformants was comparable to that of the H99 strain of C. neoformans regardless of the infection route. Virulence of the URE2 disruption stain of H99 was slightly reduced compared to the wild-type strain in the intravenous model but was significantly attenuated in the inhalation model. These results indicate that the importance of urease activity in pathogenicity varies depending on the strains of C. neoformans used and/or the route of infection. Furthermore, this study shows that complementation cloning can serve as a useful tool to functionally identify genes such as URE2 that have otherwise been annotated as hypothetical proteins in genomic databases.

Outbreak of Trichophyton verrucosum in China transmitted from cows to humans.

Twenty percent of 1000 dairy cows were infected with Trichophyton verrucosum in a newly established dairy farm in western China. The disease was transmitted to 30 of 100 animal workers. The source of the outbreak is unknown but it is suspected that naïve cattle which were transported from Holland to China became infected after they arrived in Xinjiang province (West China) where the fungus is endemic in nature, prepuberty school children and various livestock.

Current topics of tinea capitis in China.

Tinea capitis is one type of superficial fungal infection which is found all over the world. The major etiologic agent of tinea capitis varies in different areas. Tinea capitis in China has unique characteristics. The epidemiology, transmission and therapy of child and adult tinea capitis in China are reviewed in this paper.