In Vitro Antifungal-Drug Susceptibilities of Mycelial and Yeast Forms of Penicillium marneffei Isolates in Cambodia

Abstract

Penicillium marneffei infection is an important disease among human immunodeficiency virus patients inPenicillium marneffei, the only known dimorphic species in the genus Penicillium, was first isolated from an organ of a bamboo rat (Rhizomyces sinensis or Rhizomyces pruinosis) (2). Penicilliosis marneffei has been recognized with increasing frequency in Southeast Asia and Southern China (15,19,20). P. marneffei infection has become the third most common opportunistic infection in AIDS patients in Southeast Asia (17,22). Penicilliosis marneffei was first reported in Cambodia in 2002 (1). We report in vitro susceptibility test results, as determined using Etest strips, for P. marneffei isolates from human immunodeficiency virus-infected patients who presented with disseminated P. marneffei infections. We include the susceptibility test results for P. marneffei isolates from the organs of bamboo rats. Our study is the first from Cambodia to report in vitro susceptibilities of clinical and bamboo rat isolates of P. marneffei to antifungal agents.P. marneffei was isolated from 29 human immunodeficiency virus-infected patients seen at Preah Bat Norodom Sihanouk Hospital, Phnom Penh, Cambodia, from 2002 to 2004. Thirteen P. marneffei isolates were isolated from blood, 12 from skin biopsy specimens, and 4 from respiratory specimens. In all cases, only one specimen type was submitted to the laboratory. Bamboo rats (Rhizomyces pruinosus) were captured in the Mondulkiri province of Cambodia. Five isolates of P. marneffei were isolated from the lungs of 10 bamboo rats. P. marneffei was identified by the appearance of the fungal colonies on Sabouraud dextrose agar at 25°C and by microscopic examination (9).One-week-old slant cultures of the mycelial form on Sabouraud dextrose agar, grown at 25°C, were flooded with deionized distilled water (10 ml/slant), and each slant was scraped with a sterile inoculation wire loop. The suspension of mycelial fragments and conidia was transferred to a glass grinder. After the grinding, a homogenous suspension was adjusted to 1 McFarland standard (11,14). To obtain inocula of the yeast form, brain heart infusion broth (Difco) was inoculated with a fungal suspension prepared from 7-dayold slant cultures. The inoculated brain heart infusion flasks were placed on a water bath shaker (150 rpm) and incubated at 37°C for 7 days, yielding a uniform growth of yeast cells. After incubation, the broth cultures were centrifuged at 15,000 ϫ g for 20 min (4°C). After the broth was discarded, the sediment was washed three times successively with sterile deionized distilled water. The washed yeast cells were suspended in deionized distilled water and adjusted to 1 McFarland standard. Etest strips (AB Biodisk, Solna, Sweden) containing amphotericin B (AMB) (0.002 to 32 g/ml), flucytosine (5FC) (0.002 to 32 g/ml), fluconazole (FLC) (0.016 to 256 g/ml), itraconazole (ITC) (0.002 to 32 g/ ml), and ketoconazole (KTC) (0.002 to 32 g/ml) were used to determine the MICs according to the manufacturer's instructio...

Melanization and morphological effects on antifungal susceptibility of Penicillium marneffei

“…MICs were within the range of values previously reported for this fungus (McGinnis et al 2000; Sar et al 2006). No significant differences of melanized and non-melanized cells in the different culture broths were observed between MICs of antifungal drugs.…”

Penicillium marneffeiInfection in AIDS

“…P. marneffei infection is endemic among HIV-positive patients in many areas in Southeast Asia, including Thailand, Vietnam, Hong Kong, Southern China, Taiwan, India, and Laos [ 6 , 8 , 9 , 12 – 20 ]. So far, all reported cases of P. marneffei infections in AIDS patients have showed epidemiological link with the endemic areas except for one case reported in an African from Ghana who had never been to Southeast Asia [ 21 ].…”

In Vitro Susceptibility of Talaromyces Marneffei In Malaysia: Comparison of Yeast and Mycelial Phases

“…[28] and Sar et al [19] respectively. Some of the yeast and mycelial phases of isolates in this study also showed MIC ≥ 24µg/ml, which correlates to the results mentioned above.…”

“…Internal transcribed spacer (ITS) region of the nuclear rDNA was ampli ed with PCR and detected with direct DNA sequencing to determine the species [18]. The mycelial and yeast form of T. marneffei were obtained as mentioned by Sar et al [19].…”