Aspergillus species identification in the clinical setting

Multiple recent studies have demonstrated the limited utility of morphological methods used singly for species identification of clinically relevant aspergilli. It is being increasingly recognised that comparative sequence based methods used in conjunction with traditional phenotype based methods can offer better resolution of species within this genus. Recognising the growing role of molecular methods in species recognition, the recently convened international working group meeting entitled "Aspergillus Systematics in the Genomic Era" has proposed several recommendations that will be useful in such endeavors. Specific recommendations of this working group include the use of the ITS regions for inter section level identification and the beta-tubulin locus for identification of individual species within the various Aspergillus sections.

Fatal Apophysomyces elegans infection transmitted by deceased donor renal allografts

Two patients developed renal mucormycosis following transplantation of kidneys from the same donor, a near-drowning victim in a motor vehicle crash. Genotypically, indistinguishable strains of Apophysomyces elegans were recovered from both recipients. We investigated the source of the infection including review of medical records, environmental sampling at possible locations of contamination and query for additional cases at other centers. Histopathology of the explanted kidneys revealed extensive vascular invasion by aseptate, fungal hyphae with relative sparing of the renal capsules suggesting a vascular route of contamination. Disseminated infection in the donor could not be definitively established. A. elegans was not recovered from the same lots of reagents used for organ recovery or environmental samples and no other organ transplant-related cases were identified. This investigation suggests either isolated contamination of the organs during recovery or undiagnosed disseminated donor infection following a near-drowning event. Although no changes to current organ recovery or transplant procedures are recommended, public health officials and transplant physicians should consider the possibility of mucormycosis transmitted via organs in the future, particularly for near-drowning events. Attention to aseptic technique during organ recovery and processing is re-emphasized.

Interlaboratory reproducibility of a microsatellite-based typing assay for Aspergillus fumigatus through the use of allelic ladders: proof of concept

An interlaboratory study was performed with the aim of investigating the reproducibility of a multiplex microbial microsatellite-based typing assay for Aspergillus fumigatus in different settings using a variety of experimental and analytical conditions and with teams having variable prior microsatellite typing experience. In order to circumvent problems with exchange of sizing data, allelic ladders are introduced as a straightforward and universally applicable concept for standardization of such typing assays. Allelic ladders consist of mixtures of well-characterized reference fragments to act as reference points for the position in an electrophoretic trace of fragments with established repeat numbers. Five laboratories independently analysed six microsatellite markers in 18 samples that were provided either as DNA or as A. fumigatus conidia. Allelic data were reported as repeat numbers and as sizes in nucleotides. Without the use of allelic ladders, size differences of up to 6.7 nucleotides were observed, resulting in interpretation errors of up to two repeat units. Difficulties in interpretation were related to non-specific amplification products (which were resolved with explanation) and bleed-through of the different fluorescent labels. In contrast, after resolution of technical or interpretive problems, standardization of sizing data by using allelic ladders enabled all participants to produce identical typing data. The use of allelic ladders as a routine part of molecular typing using microsatellite markers provides robust results suitable for interlaboratory comparisons and for deposition in a global typing database.

Early events in macrophage killing of Aspergillus fumigatus conidia: new flow cytometric viability assay

Detailed investigations of macrophage phagocytosis and killing of Aspergillus fumigatus conidia have been limited by technical difficulties in quantifying fungal uptake and viability. In order to study early events in cell pathogen ingestion and killing, we developed a new flow cytometry assay that utilizes the fungus-specific viability dye FUN-1. Metabolically active A. fumigatus conidia accumulate orange fluorescence in vacuoles, while dormant or dead conidia stain green. After incubation within THP-1 cells, recovered conidia are costained with propidium iodide (PI) to discriminate between dormant and dead cells. Flow cytometric measurements of FUN-1 metabolism and PI uptake provide indicators of conidial viability, dormancy, and death. Conidial phagocytosis and killing are also assessed by measurement of green and orange FUN-1 fluorescence within the THP-1 cell population. Compared to previously described methods, this assay has less error introduced by membrane permeability changes and serial dilution of filamentous fungal forms. Results suggest that the THP-1 cells kill conidia rapidly (within 6 h) after exposure. Conidia that are preexposed to human serum are ingested and killed more quickly than are nonopsonized conidia.

Microsporum gypseum complex in Madras, India

In Madras, India, 312 soil samples were collected from different habitats and screened for the presence of keratinophilic fungi especially those belonging to the Microsporum gypseum complex.

Anti-Cryptococcus activity of combination of extracts of Cassia alata and Ocimum sanctum

The paper reports the anti-Cryptococcus activity of combination of ethanolic extracts of leaves of Cassia alata and Ocimum sanctum. The activity of combination of the extracts was heat-stable and worked at acidic pH.

A survey of dermatophytosis in animals in Madras, India

Two hundred and eleven dogs (including strictly house and stray dogs) and 170 cattle in and around the city of Madras, India were screened for the presence of dermatophytosis. 106 strains of dermatophytes (89 strains from dogs and 17 strains from bovines) were isolated. 57/106 strains were Trichophyton mentagrophytes var. mentagrophytes and 42/106 strains were of the Microsporum gypseum complex. 5 strains of T. rubrum and 2 strains of T. simii were also obtained in culture. A predominance of M. gypseum complex isolates was recorded in stray dogs and cattle and T. mentagrophytes var. mentagrophytes and T. rubrum in strictly house dogs. The family history of the owners of the most of the dogs had clear records of dermatophytosis. Further, the owners of the 11 dogs that yielded T. mentagrophytes var. mentagrophytes had either tinea corporis or tinea pedis. The etiological agent of all the 11 human cases was T. mentagrophytes var. interdigitale. Similarly the owners of 4 of the 5 dogs that yielded T. rubrum were known T. rubrum patients. All these patients responded to oral griseofulvin or ketaconozole, but the recurrence of lesions was noted with the cessation of treatment. None of the patients had onychomycosis and the family history of all the patients revealed no reports of T. rubrum infections. The pet dogs were presumed to be the source of re-infection. Reversed transmission of dermatophytes from humans to animals may be the reason for the selective predominance of these organisms in strictly house dogs. They also may act as sources of reinfection. Most of the animals had small, occult, scattered lesions. These lesions may either go unnoticed or are ignored by the owners of the animals. The taxonomic status of T. mentagrophytes and T. mentagrophytes var. interdigitale was aligned to their teleomorph Arthroderma vanbreuseghemii. Our study suggests that the periodic screening and medication of all live-stock are essential for the prevention and management of the public health problem caused by dermatophytes.

Soil dermatophytes in Madras, India, in relation to human ringworm

A total of 269 soil samples collected from different habitats in Madras, India, were screened for the presence of dermatophytes by the hair-baiting technique. Three strains of Trichophyton mentagrophytes and 16 strains of Microsporum gypseum complex were isolated. These strains were subjected to the mating experiment. 2/3 soil isolates of Trichophyton mentagrophytes belonged to Arthroderma vanbreuseghemii (+) mating type, and 1/3 was Arthroderma vanbreuseghemii (-) mating type. Similarly 6/70 clinical strains of Trichophyton mentagrophytes isolated in our previous study also belonged to Arthroderma vanbreuseghemii (+) mating type. These 6 strains were isolated from severe cases of tinea capitis in children belonging to rural Madras. The teleomorphic and mating type homology between the clinical and soil isolates of T. mentagrophytes suggest that soil may act as reservoir for these organisms. The incompatible clinical strains of T. mentagrophytes var. interdigitale and A. vanbreuseghemii showed DNA homology, thereby establishing the epidemiologic link which supports the above findings.

Isolation of Microsporum nanum from a patient with tinea corporis in Madras, India

Microsporum nanum was isolated from a case of tinea corporis in a 16-year-old boy. This is the first recorded case of human ringworm infection caused by M. nanum in India.

ABO blood groups in relation to the infection rate of dermatophytosis

The role of ABO blood groups in the carriage rate of dermatophytosis was studied. Blood grouping was done for 108 culture-proven dermatophytosis patients. Forty-nine patients belonged to blood group A, 54 to blood group O, three to blood group B and two to blood group AB. The incidence of dermatophytosis was found to be high in patients of blood group O and A. However, chronicity of the disease was more frequent in those in blood group A. The control group consisted of 100 healthy subjects. Sixteen out of 29 control subjects belonging to blood group A had a history of skin infections. None of the O blood group control subjects had a history of skin infections. Our study suggests that A blood group subjects may be prone to chronic dermatophytosis.

Mating patterns of dermatophytes of diverse origin in India

The mating patterns of Trichophyton mentagrophytes var. interdigitale (74 isolates) and the Microsporum gypseum complex (17 isolates) of diverse origin and T. rubrum (25 isolates) and T. tonsurans (10 isolates) of clinical origin were studied. The results of the study showed that the teleomorph of the Indian isolates of T. mentagrophytes belong to Arthroderma vanbreuseghemii, undetermined teleomorphs of T. mentagrophytes var. interdigitale (+) mating types, and undetermined teleomorphs of T. mentagrophytes var. interdigitale indeterminate mating types. All the isolates of T. rubrum and T. tonsurans were found to be of the (-) mating type.