Kyoko Yarita

Simple detection method for distinguishing dead and living yeast colonies

A rapid and simple assay was developed for detection of yeast colonies containing dying or dead cells. Methylene blue, phloxin B, rose bengal and trypan blue at concentrations of 5-10 micromol l(-1) were shown to stain non-viable cells in colonies of Saccharomyces cerevisiae, Schizosaccharomyces pombe, Candida albicans and Filobasidium capsuligenum without staining or affecting the viability of living cells of the colonies.

Multiple Scedosporium apiospermum abscesses in a woman survivor of a tsunami in northeastern Japan: a case report

IntroductionScedosporium apiospermum is increasingly recognized as a cause of localized and disseminated mycotic infections in near-drowning victims.Case presentationWe report the case of a 59-year-old Japanese woman who was a survivor of a tsunami in northeastern Japan and who had lung and brain abscesses caused by S. apiospermum. Initially, an aspergillus infection was suspected, so she was treated with micafungin. However, computed tomography scans of her chest revealed lung abscesses, and magnetic resonance images demonstrated multiple abscesses in her brain. S. apiospermum was cultured from her bronchoalveolar lavage fluid, and antimycotic therapy with voriconazole was initiated. Since she developed an increase in the frequency of premature ventricular contractions, an adverse drug reaction to the voriconazole was suspected. She was started on a treatment of a combination of low-dose voriconazole and liposomal amphotericin B. After combination therapy, further computed tomography scans of the chest and magnetic resonance images of her brain showed a demarcation of abscesses.ConclusionsVoriconazole appeared to have a successful record in treating scedosporiosis after a near drowning but, owing to several adverse effects, may possibly not be recommended. Thus, a combination treatment of low-dose voriconazole and liposomal amphotericin B may be a safe and effective treatment for an S. apiospermum infection. Even though a diagnosis of scedosporiosis may be difficult, a fast and correct etiological diagnosis could improve the patients chance of recovery in any case.

Antifungal susceptibility of Aspergillus fumigatus clinical isolates collected from various areas in Japan

Azole resistance among clinical isolates of Aspergillus fumigatus is becoming a serious problem in Europe, but the status in Japan is not yet known in detail. The aim of this study was to determine the present status of azole resistance in A. fumigatus in Japan. We employed 171 clinical isolates of A. fumigatus sensu stricto collected from 1987 to 2008 at the Medical Mycology Research Center, Chiba University, Japan for azole resistance determination. Identification of all isolates were re-examined both from the aspect of morphology and molecular phylogeny. The antifungal susceptibility of these isolates was tested based on the CLSI M38-A2 broth microdilution method. In our collection, only 1 (0.6%) and 2 isolates (1.2%) showed elevated MIC to voriconazole and itraconazole, respectively. Our study disclosed that the frequency of azole resistance in A. fumigatus still remains low in this collection.

Scedosporium aurantiacum brain abscess after near-drowning in a survivor of a tsunami in Japan

Many victims of the tsunami that occurred following the Great East Japan Earthquake on March 11, 2011 developed systemic disorders owing to aspiration pneumonia. Herein, we report a case of tsunami lung wherein Scedosporium aurantiacum was detected in the respiratory tract. A magnetic resonance image of the patients head confirmed multiple brain abscesses and lateral right ventricle enlargement. In this case report, we describe a potential refractory multidrug-resistant infection following a tsunami disaster.

An intrafamilial transmission of Arthroderma benhamiae in Canadian porcupines (Erethizon dorsatum) in a Japanese zoo

An intra-familial transmission of Arthroderma benhamiae in Canadian porcupines (Erethizon dorsatum) housed in a Japanese zoo was studied. The family consisted of an adult couple and two offspring (a male and a female). The porcupettes, born in Japan, showed severe hair loss while the parent animals, imported from the USA. (male) and Canada (female), showed mild symptoms or were asymptomatic. Morphologically identical Tricophyton spp. isolates were recovered within seven days from quills of all animals on chloramphenicol-supplemented potato dextrose agar plates incubated at 37 degrees C. Two representative colonies from each animal were identified as Arthroderma benhamiae Americano-European race based on mating type (+) and the internal transcribed spacer (ITS) 1-5.5S-ITS 2 region of the rRNA gene sequences (AB236404-AB236408). The present cases constituted the second isolation of dermatophytes from porcupines. There were two different ITS types, i.e., the predominant one isolated from all animals and a secondary one recovered from only the mother porcupine. The sequences have never been recorded in Japan or in the GenBank database to the best of our knowledge. In addition, they were located at a cluster involving the type strain and mating strains of A. benhamiae Americano-European race and its F1 progeny. In contrast, 28 rodents (eight species) and three insectivora (1 species) exhibited in the petting zoo were negative for any dermatophytes as determined by culture.

Fatal Fungemia with Scedosporium prolificans in a Patient with Acute Myeloid Leukemia

Scedosporium prolificans (S. prolificans) is a type of mold, which rarely affects immunocompromised people. We treated a 71-year-old woman with acute myeloid leukemia (AML-M5a) with low-dose cytarabine, acralubicin, and filgrastim as the induction therapy. On day 7 after the initiation of chemotherapy, she became febrile and agranulocytic, and developed anal pain ; therefore, we discontinued the chemotherapy on day 8. Broad-spectrum antibiotics, micafungin, and then liposomal amphotericin B were ineffective. The serum concentration of β-D-glucan was 525 pg/mL. She died of multiple organ failure on day 17. S. prolificans was detected from the blood culture on day 13. Physicians should consider Scedosporium spp. infection when principal antifungal agents are ineffective and fungal infection is strongly suspected.

Early death at medium acidification and survival after low pH adaptation in Cryptococcus neoformans

WhenCryptococcus neoformans was grown in yeast nitrogen base (YNB) supplemented with 0.5% glucose, the medium was acidified to below pH 3 during the exponential growth phase, which caused early growth-phase death in susceptible strains. Even in resistant strains, 30–70% cells died if incubated for 2 d in YNB supplemented with 1.5% glucose, whereas the remaining cells survived long. Two types of fatal alterations have been observed in dead cells. In the first type, release of cytoplasm occurred through weakened parts of the cell wall; structures attached to cell walls of dead cells were shown to be rich in proteins by FITC staining, indicating their cytoplasmic origin. In the second type, cells shrank distinctly with no sign of wall rupture. The shrinkage may be due to dysfunction of the plasma membrane at low pH. The mechanism of cell survival in medium below pH 3 was also examined. Aniline blue alone, or calcofluor together with methylene blue, allowed cell wall glucan or chitin and dead cell cytoplasm to be stained simultaneously. In the later stages of incubation, cells showing bright staining for cell wall glucan and chitin emerged. These changes in cell wall synthesis could be considered as an adaptation mechanism to acidification of the medium, because such cells survived longer than cells showing no change in the cell wall staining pattern.

Primary cutaneous mucormycosis caused by Mucor irregularis in an immunocompetent patient

Dear Editor, Mucormycosis, which mainly affects immunocompromised patients, is a rare, life-threatening infection caused by the order Mucorales. Among the six clinical types of mucormycosis, cutaneous mucormycosis is the rarest and is further categorized into two types: (i) the gangrenous type, which only occurs in immunocompromised patients and progresses rapidly, and (ii) the superficial type, which develops in immunocompetent individuals, manifests as erythematous plaques, and progresses slowly. We present a case of superficial cutaneous mucormycosis caused by Mucor irregularis (M. irregularis) involving an immunocompetent patient. A 16-year-oldJapanese boy who was otherwise healthy presented with a 1-year history of a gradually enlarging plaque on his leg. A physical examination demonstrated an erythematous plaque exhibiting slight desquamation on his lower right leg, which he had scraped in a bicycle accident 2 years before (Fig. 1a). A histopathological examination detected a suppurative granuloma containing neutrophils, lymphocytes, and multinucleated giant cells in the dermis (Fig. 1b). Broad, ribbon-like, hyaline, aseptate hyphae were also observed (Fig. 1c). However, fungal hyphae and microvascular thrombosis were not detected in his blood vessels. Skin tissue specimens and skin scales cultured on Sabouraud dextrose agar at 25°C yielded wool-like, light yellow colonies, but no colony growth occurred at 38°C (Fig. 1d). Microscopic examinations of slide cultures detected sporangiophores, which had formed a terminal, globose sporangium. No apophyses were observed (Fig. 1e). These findings were consistent with Mucor fungi, and the isolate was identified as Mucor irregularis based on sequencing of the D1/D2 domain of the large subunit rRNA gene (GenBank accession no. IFM 57177). Before obtaining a diagnosis, we tried itraconazole (100 mg/ day), fluconazole (200 mg/day), and voriconazole (300 mg/day), independently, as empirical therapies, but none of them was effective. However, when we administered high-dose itraconazole (400 mg/day), the patient’s plaque gradually regressed. Itraconazole was administered for a total of 9 weeks (Fig. 1f). No recurrence has been observed for 5 years. M. irregularis was originally known as Rhizomucor variabilis, but it was renamed M. irregularis based on its DNA sequence. Cases of mucormycosis due to M. irregularis are rare, and only 14 cases have been reported in the English-language literature. However, it is worth noting that mucormycosis due to M. irregularis presents with unique clinical features. In contrast to classical mucormycosis, most M. irregularis infections affect immunocompetent patients and do not exhibit angioinvasion, especially in the early stages. Moreover, the majority of M. irregularis infections manifest as the superficial cutaneous type, progress chronically, and persist for several years on exposed sites. It is unknown why M. irregularis infections display these unique features. However, the lower thermotolerance of M. irregularis could be responsible for its lack of angioinvasion. Amphotericin B is the first-line treatment for M. irregularis infections (as well as for other types of mucormycosis), and

Deep Cutaneous Infection with Microsphaeropsis arundinis: Report of two Japanese Cases

© 2015 The Authors. doi: 10.2340/00015555-2091 Journal Compilation

Intra-strain variability of Cryptococcus neoformans can be detected on Phloxin B medium

A method was devised for easy detection of intra‐strain variability of the human pathogenic yeast Cryptococcus neoformans. Cultivation of strains on a medium containing Phloxin B resulted in different coloured colonies. Generally, colonies were either pink or red; however there were also several colony‐colour segregant in which both colours could be observed. A number of these segregants were isolated and analysed. Virulence factors such as the cell and capsule sizes were measured; further temperature sensitivity, growth rates, mating‐types and melanin production were also studied. Segregants were examined by random amplified polymorphic DNA (RAPD) fingerprinting and electrophoretic karyotyping by pulsed‐field gel electrophoresis (CHEF). They showed both phenotypic and genotypic differences. The main differences appeared in phenotypic characters and RAPD patterns; while the chromosomal patterns remained unchanged. Reversion frequency analysis revealed that the reason for this segregation could be due to phenotypic switching. The physiological reason for the colour changes was also investigated and was attributed to the differential ability of the cells to accumulate Phloxin B either into their capsules or into their cells. The method described here is potentially applicable for the detection of strain heterogeneity in both basic and clinical microbiology laboratories.