Intraspecific variability of growth and ochratoxin A production by Aspergillus carbonarius from different foods and geographical areas

Ochratoxin A (OTA) is a nephrotoxic mycotoxin naturally found in a wide range of food commodities throughout the world. Aspergillus carbonarius is the most important source of OTA in food commodities such as wine, grapes and dried vine fruits and is also responsible for the formation of OTA in coffee. The aim of this study was to determine the simultaneous effect of three culture media (Czapek Yeast Extract Broth (CYB); Synthetic Grape Juice Medium (SGM) and White grape juice (WGJ)) at three water activity (a_w) levels (0.90; 0.95 and 0.98-0.99), and three incubation temperatures (15 °C, 25 °C and 35 °C) on the growth and OTA production by 16 strains of A. carbonarius. The strains were mainly isolated from grapes from areas with a Mediterranean climate. All the strains were confirmed for identity by sequencing of the calmodulin gene. The assay was performed in microtiter plates, determining the absorbance at 530 nm and the concentration of OTA after 1, 2, 4 and 10 days of incubation. No significant differences were observed in absorbance values between the strains. The highest absorbance values were recorded in CYB at 0.99 a_w and at 0.95 a_w after 10 days of incubation at 25 °C and 35 °C. None of the strains were able to grow at 0.90 a_w and 15 °C in any culture media after 10 days of incubation. OTA concentration was statistically higher at 15 °C than at 25 °C or 35 °C. The highest significant OTA values were obtained at 0.98-0.99 a_w and the best culture media for OTA production was CYB, followed by WGJ and SGM. While strains isolated from Mediterranean climate foods had a similar behavior despite being isolated from different geographical areas, OTA concentration produced by one Robusta coffee strain from Thailand was statistically higher at 25 °C than at 15 °C. This would suggest that the type of food matrices and consequently the adaptation of A. carbonarius strains to different climatic conditions would have a greater influence on the ecophysiology of the strains than only their geographical origin.

Impact of some environmental factors on growth and ochratoxin A production by Aspergillus niger and Aspergillus welwitschiae

Ochratoxin A (OTA) is a nephrotoxic mycotoxin which may contaminate various foods and feed products worldwide. Aspergillus niger is one of the species responsible for OTA contamination in grapes and derived products. This species has recently been split into A. niger and Aspergillus welwitschiae. Both species can not be distinguished by phenotypic or extrolite profiles and to date there is no ecophysiological information of A. welwitschiae. The aim of this study was to determine the effects of water activity (a_w) (0.90; 0.95 and 0.98-0.99), culture media (Yeast Extract Sucrose Broth (YESB); Synthetic Grape Juice Medium (SGM); White grape juice (WGJ)) and temperature (15 °C, 25 °C and 35 °C) on the growth and OTA production of four strains of A. niger and six strains of A. welwitschiae. The assay was performed in microtiter plates, determining the absorbance at 530 nm and the concentration of OTA at 1, 2, 4 and 10 days. No significant differences were observed in absorbance and OTA values between the two species under study. The highest absorbance values were recorded in YESB, followed by SGM and WGJ. Absorbance values increased with increasing a_w and temperature. The highest OTA values were obtained at 0.98-0.99 a_w and the best culture media for OTA production was YESB, followed by WGJ and SGM. The studied strains of A. niger produced the highest mean OTA level at 25 °C whereas A. welwitschiae strains produced the highest mean OTA concentration at 15 °C, although not differing significantly from concentration produced at 25 °C. To our knowledge, this is the first report on the impact of some environmental factors on growth and OTA production by A. welwitschiae.

Trichophyton erinacei in pet hedgehogs in Spain: Occurrence and revision of its taxonomic status

Hedgehogs have increased in popularity as pets in Spain but there are no data of infection rates of this exotic animal with dermatophytes in our country. During the period of 2008-2011 a total of 20 pet hedgehogs (19 African pygmy hedgehogs and 1 Egyptian long-eared hedgehog) suspected of having dermatophytoses were studied. This is the first survey of the occurrence of T. erinacei in household hedgehogs in Spain. The T. erinacei infection rate was 50% (9 out of 19 African pygmy hedgehogs, and the one Egyptian long-eared hedgehog surveyed). Morphological identification of the isolates was confirmed by molecular analysis. All the strains had the same ITS sequence and showed 100% sequence similarity to T. erinacei type strain CBS 511.73 (AB 105793). The Spanish isolates were confirmed as T. erinacei urease positive. On the basis of ITS sequences, T. erinacei is a species close to but separate from the taxa included in the A. benhamiae complex. Review of the current literature on DNA-based methods for identification of species included in this complex has highlighted the urgent need to reach a consensus in species circumscription and classification system accepted by all mycologists.

Six-Year Follow-up of Slaughterhouse Surveillance (2008-2013): The Catalan Slaughterhouse Support Network (SESC)

Meat inspection has the ultimate objective of declaring the meat and offal obtained from carcasses of slaughtered animals fit or unfit for human consumption. This safeguards the health of consumers by ensuring that the food coming from these establishments poses no risk to public health. Concomitantly, it contributes to animal disease surveillance. The Catalan Public Health Protection Agency (Generalitat de Catalunya) identified the need to provide its meat inspectors with a support structure to improve diagnostic capacity: the Slaughterhouse Support Network (SESC). The main goal of the SESC was to offer continuing education to meat inspectors to improve the diagnostic capacity for lesions observed in slaughterhouses. With this aim, a web-based application was designed that allowed meat inspectors to submit their inquiries, images of the lesions, and samples for laboratory analysis. This commentary reviews the cases from the first 6 years of SESC operation (2008-2013). The program not only provides continuing education to inspectors but also contributes to the collection of useful information on animal health and welfare. Therefore, SESC complements animal disease surveillance programs, such as those for tuberculosis, bovine cysticercosis, and porcine trichinellosis, and is a powerful tool for early detection of emerging animal diseases and zoonoses.

Mycobiota and mycotoxin contamination of maize flours and popcorn kernels for human consumption commercialized in Spain

Mycobiota and co-occurrence of aflatoxins, citrinin, ochratoxin A and zearalenone in 30 samples of maize flours and 30 of popcorn kernels purchased in Spain for human consumption were determined. The mycotoxin-producing ability of Aspergillus, Fusarium and Penicillium spp. was also studied. Total fungal counts of maize flours ranged from <10 to 8.4 × 10(4) CFU/g and predominant mycobiota belonged to Aspergillus spp. and Penicillium spp. In popcorn kernels samples the most frequent species were Aspergillus spp., Mucorales, Fusarium spp. and Penicillium spp. Aflatoxins were produced by Aspergillus flavus and Aspergillus parasiticus, citrinin by Penicillium citrinum and Penicillium verrucosum, ochratoxin A by Aspergillus niger and patulin by Aspergillus clavatus and Penicillium griseofulvum. Identification of all the mycotoxin-producing strains as well as some Aspergillus spp. difficult to identify using phenotypic characters only was also performed by molecular methods. Aflatoxins were detected in 14 maize flours and 2 popcorn kernels samples, while ochratoxin A was detected in 4 maize flours and 10 popcorn samples. Co-occurrence of aflatoxins and ochratoxin A was found in the 4 ochratoxin-positive maize flour samples. Citrinin and zearalenone were not detected. This is the first report of aflatoxins and ochratoxin A contamination in maize flours and popcorn kernels commercialized in Spain.

Pyogranulomatous pleuropneumonia and mediastinitis in ferrets (Mustela putorius furo) associated with Pseudomonas luteola Infection

Between 2008 and 2009, three pet ferrets from different sources presented with acute episode of dyspnoea. Cytological examination of pleural exudates revealed severe purulent inflammation with abundant clusters of rod-shaped microorganisms with a clear surrounding halo. Treatment was ineffective and the ferrets died 2–5 days later. Two ferrets were subjected to necropsy examination, which revealed pyothorax, mediastinal lymphadenopathy and multiple white nodules (1–2 mm) in the lungs. Microscopical examination showed multifocal necrotizing-pyogranulomatous pleuropneumonia and lymphadenitis with aggregates of encapsulated microorganisms, some of which were positively stained by periodic acid–Schiff and alcian blue. In-situ hybridization for Pneumocystis spp., Ziehl–Neelsen staining and immunohistochemistry for distemper, coronavirus and influenza antigen were negative in all cases. Electron microscopically, the bacteria were 2–3 μm long with a thick electron-lucent capsule. Microbiology from one ferret yielded a pure culture of gram-negative bacteria identified phenotypically as Pseudomonas luteola. This speciation was later confirmed by 16S RNA gene amplification.

Chrysosporium guarroi sp. nov. a new emerging pathogen of pet green iguanas (Iguana iguana)

Chrysosporium guarroi sp. nov. represented by five strains isolated from cases of dermatomycosis in pet green iguanas (Iguana iguana) in Spain, is described and illustrated. This taxon is characterized by its ability to grow at temperatures from 15 to 37 degrees C and by the presence of arthroconidia and aleurioconidia. The latter are unicellular, smooth, pyriform or clavate, sessile or borne at the ends of narrow stalks. The analysis of the sequences of the D1/D2 and ITS regions confirm the separation of this new species from others of the genus Chrysosporium.

Dermatomycosis in a pet inland bearded dragon (Pogona vitticeps) caused by a Chrysosporium species related to Nannizziopsis vriesii

A Chrysosporium sp. related to Nannizziopsis vriesii was isolated in pure culture from squames and biopsies of facial lesions in a pet inland bearded dragon (Pogona vitticeps) in Spain. The presence in histological sections of morphologically consistent fungal elements strongly incriminates this fungus as the aetiological agent of infection. Lesions regressed following treatment with oral ketoconazole and topical chlorhexidine and terbinafine until the lizard was lost to follow up 1 month later. The ITS-5.8S rRNA gene of the isolate was sequenced and a search on the GenBank database revealed a high match with the sequences of two Chrysosporium sp. strains recently isolated from green iguanas (Iguana iguana) with dermatomycosis, also in Spain. Phylogenetic analysis of the sequences revealed that all these strains are related to N. vriesii. This is the first report of dermatomycoses caused by a Chrysosporium species related to N. vriesii in a bearded dragon outside North America.

Low occurrence of patulin- and citrinin-producing species isolated from grapes

AIMS

To assess the ability of fungi isolated from grapes to produce patulin and citrinin.

METHODS AND RESULTS

A total of 446 Aspergillus isolates belonging to 20 species and 101 Penicillium isolates were inoculated in Czapek yeast extract agar and yeast extract sucrose agar and incubated for 7 days at 25 degrees C. Extracts were analysed for patulin and citrinin by thin-layer chromatography. None of the isolates of Aspergillus spp. produced either patulin or citrinin. Patulin was produced by three isolates of Penicillium expansum and two of Penicillium griseofulvum. Citrinin was produced by five isolates of P. expansum, two of Penicillium citrinum and one of Penicillium verrucosum.

CONCLUSIONS

Our results show that the Aspergillus and Penicillium species commonly isolated from grapes are not a source of the mycotoxins, patulin and citrinin.

SIGNIFICANCE AND IMPACT OF THE STUDY

The possibility of co-occurrence of patulin and citrinin with ochratoxin A in grapes and grape products remain low, owing to the low frequency of isolation of potentially producing species.

Study of the effect of water activity and temperature on ochratoxin A production by Aspergillus carbonarius

The effect of water activity (aw) (0.78-0.99) and temperature (15 and 30 degrees C) on growth and production of ochratoxin A (OTA) of six Aspergillus carbonarius strains was studied in two culture media: Czapek yeast autolysate (CYA) agar and yeast extract sucrose (YES) agar, during a period of 30 days. The strains were selected to include different sources and different reported abilities to produce OTA and were characterized by RAPD and ITS-5.8S rDNA sequencing. CYA showed to be better culture medium than YES for OTA production in the isolates tested. OTA concentration was higher at 15 degrees C than at 30 degrees C. At 30 degrees C, ranges for OTA production were more restrictive than those for growth. OTA was produced from 0.86, 0.90 or 0.94 aw depending on the strain. At 15 degrees C, growth and OTA production were detected only in the 0.94-0.99 aw range. The molecular study performed showed that five of the strains were conspecific and no correlation was found between molecular data and the OTA production level or origin. The remaining strain had never been able to produce OTA and will probably represent a new species in the Aspergillus section Nigri. Our results show that A. carbonarius is able to grow and produce OTA in a wide range of water activities at both high and low temperatures.

Ochratoxin A-producing fungi from grapes intended for liqueur wine production

The ochratoxigenic mycobiota of grapes intended for liqueur wines from four Spanish vineyards were studied. The specific wine-making technology of these wines requires overripening of the grapes on the vine or extended post-harvest exposure of the grapes in the sun. In every vineyard, samples were taken at three different developmental stages: veraison, harvesting time and after over-ripening. With the maturation of the berries there was a clear increase of Aspergillus spp. In the last sampling time studied, they were isolated from the 90.3% of the plated berries. Black aspergilli (mainly A. niger aggregate and A. carbonarius) were predominant among the different Aspergillus spp. isolated and constituted 98.5% of the total Aspergillus strains isolated. At harvesting time and after over-ripening, the percentage of colonized berries with A. carbonarius exceeded that of Aspergillus niger aggregate. Due to their low frequency of isolation, Penicillium spp. and Aspergillus spp. outside black aspergilli are not an important source of ochratoxin A in grapes for liqueur wine production. On the contrary, 98.5% of the A. carbonarius isolates screened were able to produce ochratoxin A. Although the possible participation of different ochratoxin A-producing species may occur, our results confirm that A. carbonarius is the most important source of ochratoxin A in liqueur wines, increasing its occurrence along the ripening of grapes.

Mycobiota and ochratoxin A producing fungi from Spanish wine grapes

Grapes from three different regions with a long winemaking tradition in Spain were analysed at different growth stages in order to identify the ochratoxigenic mycobiota during three consecutive seasons. The correlation between meteorological parameters and ochratoxigenic fungi was studied and revealed a significant positive correlation between black aspergilli infection and temperatures in the month preceding each sampling date. No significant correlation was found with either relative humidity or rainfall. Biodiversity indexes were also calculated in this study. Black aspergilli species were the most abundant in grapes before harvest, and among them, Aspergillus carbonarius was the main ochratoxin A (OTA) producer species and represented 78-100% of the isolates tested. The results obtained support the key role of A. carbonarius as the main source of OTA contamination in grapes.

Effect of pH on ochratoxin A production byAspergillus nigeraggregate species

The effect of pH (2-10) on growth and ochratoxin A (OTA) production by 12 Aspergillus niger aggregate strains was studied in two culture media: Czapek yeast autolysate agar (CYA) and yeast extract sucrose agar (YES), over 30 days. The strains were selected to include different sources, different reported abilities to produce OTA and different ITS-5.8S rDNA RFLP patterns. YES was a better culture medium than CYA for OTA production. In this medium, OTA was produced from pH 2 or 3 to 10 depending on the strain. The results show the ability of A. niger aggregate strains not only to grow, but also to produce OTA over a wide pH range. The results will lead to a better understanding of the role of A. niger aggregate strains in the OTA contamination of several food commodities.

Effect of water activity on ochratoxin A production by Aspergillus niger aggregate species

The effect of water activity (a(w)) (0.82-0.99) on growth and ochratoxin A (OTA) production by twelve Aspergillus niger aggregate strains, cultured in Czapek Yeast Autolysate agar (CYA) and Yeast Extract Sucrose agar (YES), was studied for an incubation period of 30 days. The strains were selected to include diverse sources, different reported abilities to produce OTA and different ITS-5.8 S rDNA Restriction Fragment Length Polymorphism (RFLP) pattern. They were characterized by Random Amplification of Polymorphic DNA (RAPD) and ITS-5.8 S rDNA and 28 S rDNA (D1/D2) sequencing. Regardless of the a(w) value tested, YES was a better culture medium than CYA for OTA production. The a(w) range for OTA production was narrower than that for growth. OTA was produced from 0.90, 0.92, 0.94 or 0.96 to 0.99 a(w) depending on the strain and the culture medium. The molecular study differentiated strains into two groups which corresponded to the RFLP types N and T although it did not distinguish them by their source of isolation or OTA producing abilities. Our results show that A. niger aggregate strains are able to grow and produce OTA over a wide a(w) range. These results will lead to a better understanding of the contribution of A. niger aggregate in OTA contamination of food and feed.

Influence of pH and incubation time on ochratoxin A production by Aspergillus carbonarius in culture media

The effect of pH (2 to 10) and temperature (15 and 30 degrees C) on growth and production of ochratoxin A (OTA) of six strains of Aspergillus carbonarius was studied in two culture media: Czapek yeast autolysate agar and yeast extract sucrose agar. Isolates were selected by their different source and different reported ability to produce OTA. Regardless of the initial pH or the temperature tested, Czapek yeast autolysate agar has been shown to be the best culture medium for OTA production by A. carbonarius. In this medium, OTA was produced from pH 2 to 10 at the two incubation temperatures tested. The results obtained show the ability of A. carbonarius to not only grow but also produce OTA over a wide pH range at high or low temperatures. This may help explain why this species is considered the main OTA source in some substrata.

Comparison of disk diffusion method and broth microdilution method for antifungal susceptibility testing of dermatophytes

The use of the agar diffusion Neo-Sensitabs method to determine antifungal susceptibility of 59 isolates of dermatophytes, namely Epidermophyton floccosum, Microsporum canis, M. gypseum, Trichophyton mentagrophytes, T. rubrum and T. tonsurans to Clotrimazole (CLZ), Itraconazole (ITZ) and Terbinafine (TBF) is described. Results obtained are compared to the minimum inhibitory concentrations (MIC) determined by an adaptation of the NCCLS-M38-A procedure. Using the diffusion method, all strains showed a broad zone of inhibition at the first available reading time (3 or 7 days). Using the broth microdilution method, the geometric mean MIC (microg/ml) with regard to all isolates was < or = 0.03 for TBF, < or = 0.069 for CLZ and < or = 0.919 for ITZ. In both methods, TBF was the most active antifungal agent against all isolates tested. The two methods evaluated were able to detect the resistance of the quality control strains of Aspergillus fumigatus to ITZ. Even though a reference method for testing dermatophytes still has not been developed, our data suggest that the Neo-Sensitabs diffusion method could provide a simple procedure for the antifungal susceptibility testing of dermatophytes in the routine clinical laboratory.

Ochratoxigenic species from Spanish wine grapes

The ochratoxigenic mycobiota of grapes belonging to representative wine regions located along the Mediterranean coast of Spain at different developmental stages was identified. During the development of the berries, the occurrence of Aspergillus spp. increased while the percentage of berries contaminated by non-ochratoxin A (OTA) producing species such as Alternaria spp. and Cladosporium spp. decreased. Penicillium verrucosum, the only confirmed Penicillium spp. that is able to produce OTA, was not isolated. The contamination by OTA-producing species comes from the surface of the berries and not from the inner fruit. Black aspergilli were predominant among the different Aspergillus spp. isolated. All the Aspergillus carbonarius isolates were able to produce OTA at different concentrations. None of the isolates belonging to Aspergillus niger aggregate and to Aspergillus japonicus var. aculeatus were able to produce OTA. These results are a strong evidence of the contribution of A. carbonarius in the OTA contamination in wine grapes, mainly at the last developmental stages of the berries.

Aspergillus carbonarius as the main source of ochratoxin A contamination in dried vine fruits from the Spanish market

Ochratoxin A (OTA) can occur in a wide range of foods, but unexpectedly high concentrations have been detected in dried vine fruits of various origins. The European Union has recently established a maximum OTA limit of 10 microg/kg for these foodstuffs. In order to determine the likely origin of OTA, a mycological study of 50 dried fruit samples (currants, raisins, and sultanas) representative of the Spanish market was conducted. Fungal contamination was detected in 49 of 50 (98%) samples. Black aspergilli were isolated from all of the positive samples. Aspergillus niger var. niger was isolated from 98% of the samples, and Aspergillus carbonarius was found in 58% of the samples. One hundred sixty-eight A. niger var. niger isolates and 91 A. carbonarius isolates were screened for their ability to produce OTA. Eighty-eight (96.7%) A. carbonarius isolates and one (0.6%) A. niger var. niger isolate were found to be OTA producers. Black aspergilli were the dominant fungi. Among black aspergilli, A. carbonarius has shown a consistent ability to produce OTA and is the most probable source of this mycotoxin in these substrates.

What is the source of ochratoxin A in wine?

During a microvinification trial using natural mouldy grapes from a research experimental vineyard, ochratoxin A (OTA) contaminated white wine was obtained. Potential OTA-producing mycobiota of grape samples used in this microvinification process was assessed. Only Aspergillus carbonarius isolates were detected as producers of OTA. Our report is a strong evidence of the contribution of A. carbonarius in the OTA contamination in wine.

Occurrence of Malassezia spp. in horses and domestic ruminants

During a study on the occurrence of Malassezia spp. in 112 animals (50 horses, 25 goats, 25 sheep and 12 cows), Malassezia spp. were isolated from 60% of horses, 28% of sheep, 44% of goats and 58% of cows. In these animals, the occurrence of lipid-dependent species (42%) was much greater than the occurrence observed for M. pachydermatis (3%). Among the results obtained, we point out the first isolation of M. sympodialis, M. globosa and M. restricta from sheep, M. pachydermatis, M. furfur, M. sympodialis, M. obtusa, M. globosa and M. restricta from goats and M. furfur, M. slooffiae, M. obtusa, M. globosa and M. restricta from horses. To the authors' knowledge, this survey also states the first description of the presence of M. restricta in animals.

Occurrence of Malassezia spp. in the external ear canals of dogs and cats with and without otitis externa

We studied the lipophilic microbiota of the external ear canals of 332 animals (264 dogs and 68 cats), with and without otitis externa, over an 11-year period from 1988 to 1999. Malassezia pachydermatis was isolated from 62.2% and 50% of dogs with and without otitis externa, respectively, and from 41.2% and 17.6% of cats with and without otitis externa, respectively. In the group of animals studied for lipid-dependent species, these yeasts were isolated from 4.5% of dogs with otitis externa and from 23.1% and 8.9% of cats with and without otitis externa, respectively. M. sympodialis and M. furfur were isolated from cats and M. furfur and M. obtusa from dogs. Our findings show that lipid-dependent Malassezia species may contribute to the etiology of otitis externa in dogs and cats.

An easy screening method for fungi producing ochratoxin A in pure culture

A simple screening method has been developed for detecting ochratoxin production by fungi, based on high-performance liquid chromatographic determinations on extracts obtained from agar plugs cut from pure Petri dish cultures. Two culture media. Yeast Extract Sucrose agar and Czapek Yeast Extract agar, and three extraction solvents (methanol, methylene chloride/formic acid, and methanol/formic acid) were compared. All of the isolates tested produced ochratoxin A in one or both culture media after 7 or 14 days of incubation. Based on the results obtained, the use of both culture media is recommended. As extraction solvent, either methanol or methanol-formic acid could be used. This method also provides quantitative information on the level of ochratoxin produced by the cultures. The simplicity of the method makes it very useful when many fungal isolates need to be screened.

Distribution of ochratoxin A producing strains in the A. niger aggregate

Ochratoxin A (OA) production of 92 isolates belonging to the A. niger aggregate was tested. All these isolates were grouped into the two proposed species A. niger and A. tubingensis, according to their ITS-5.8S rDNA RFLP patterns. The distribution of the isolates into the two species was very similar since 52.2% were classified as pattern T (corresponding to A. tubingensis), and 47.8% were classified as pattern N (corresponding to A. niger). Six out of the 92 isolates studied produced OA. All the OA producing strains were classified as pattern N while none of the isolates classified as pattern T produced OA.

Mycotoxins and toxigenic fungi

Mycotoxins and the fungi that produce them are of increasing importance as causes of human illness, but the diseases produced remain poorly understood at the clinical level. This paper explores four aspects: the increase of interest in ochratoxin A, factors affecting mycotoxin production, toxicology of the major mycotoxins, and the identification of Penicillium species which cause food spoilage and are important in indoor air.

Current importance of ochratoxin A-producing Aspergillus spp

Ochratoxin A (OA) is receiving attention worldwide because of the hazard it poses to human and animal health. OA contamination of commodities, such as cereals or pork and poultry meat, is well recognized. Nevertheless, there is an increasing number of articles reporting OA contamination in other food commodities, such as coffee, beer, wine, grape juice, and milk, in the last few years. This continuous and increasing exposure to OA that humans experience is reflected in the high incidence of OA in both human blood and milk in several countries. OA was believed to be produced only by Aspergillus ochraceus and closely related species of section Circumdati and by Penicillium verrucosum; however, in the genus Aspergillus, the production of OA has been recently reported by species outside the section Circumdati. Thus, it has been clearly established as a metabolite of different species of the section Nigri, such as Aspergillus niger and Aspergillus carbonarius. OA production ability by Aspergillus spp. is more widespread than previously thought; therefore, there is the possibility that unexpected species can be new sources of this mycotoxin in their natural substrates.

Evaluation of different preservation and storage methods for Malassezia spp

Freezing at -80 degrees C, lyophilization, preservation in distilled water, and storage in different culture media were performed in order to find a suitable method that allowed a prolonged storage of Malassezia spp. Freezing at -80 degrees C was the only method successful at maintaining all species.

[Taxonomy and identification of the species involved in nosocomial aspergillosis]

Although Aspergillus fumigatus is the most common etiological agent of invasive aspergillosis, other Aspergillus spp. such as A . flavus, A. niger, A. terreus and A. nidulans (Emericella nidulans) among others, have been also implicated. In this article, the taxonomy of the genus Aspergillus and the characteristics of the species most frequently isolated from patients with nosocomial aspergillosis are reviewed.

Atypical lipid-dependent Malassezia species isolated from dogs with otitis externa

During a survey of the occurrence of Malassezia species in the external ear canals of dogs with chronic otitis externa, lipid-dependent Malassezia species were isolated in three dogs. These species were identified as Malassezia furfur and M. obtusa but showed atypical assimilation patterns. To our knowledge, this is the first report of the isolation of lipid-dependent species of the genus Malassezia in association with canine otitis.

[Mycotoxin producing fungi]

Mycotoxins are relatively small molecules characterized by a diversity of chemical structure and a diversity of biological activity. They are often genotypically specific for a group of species, but the same compound can also be formed by fungi belonging to different genera. Most of the mycotoxins known have been recognized as metabolic products of Aspergillus, Penicillium and Fusarium species. This review will be focused on aflatoxins, ochratoxins and fumonisins because of their hazard to animal and human health. The production of these mycotoxins have been usually associated with a small number of species but some recent studies have reported the production of these mycotoxins by some other species. These results show that mycotoxin production is broader than is normally thought, so the possibility can not be ruled out that new species may be a new source of unexpected mycotoxins in their natural substrates.

Otitis externa associated with Malassezia sympodialis in two cats

The lipid-dependent species Malassezia sympodialis was isolated from two cats with otitis externa. To our knowledge, this is the first report of the isolation of lipid-dependent species of the genus Malassezia associated with skin disease in domestic animals.

New PCR method to differentiate species in the Aspergillus niger aggregate

The DNA that encodes the 5.8S gene of the ribosomal RNA and the two intergenic spacers ITS1 and ITS2 of the two proposed type strains of the Aspergillus niger aggregate (A. niger and Aspergillus tubingensis) have been sequenced. By comparison of sequences we have found that both species could be differentiated by RsaI digestion of the PCR products of the mentioned regions. This method could be a useful tool in the identification of strains of the A. niger aggregate, especially in studies that involve a large number of isolates.

Isolation of Malassezia furfur from a cat

During a survey of the occurrence of Malassezia species in the external ear canals of cats without otitis externa, Malassezia furfur was isolated. This is the first report of the isolation of M. furfur from cats.

Nasal granuloma caused by Scedosporium apiospermum in a dog

A 10-month-old male American Staffordshire terrier was presented to the Autonomous University of Barcelona Veterinary Teaching Hospital because of a 6-month history of a mucopurulent bilateral nasal discharge. The dog had not responded to antibiotics. A follow-up X ray revealed a mixed pattern of osteolysis and increased radiodensity confined to the nasal cavity. Histologic sections of the biopsy specimens revealed the presence of granules containing numerous septate hyphae that were hyaline to pale brown and smooth, one-celled, subspherical-to-elongate conidia that were hyaline to brownish green, and bacteria. Cultures yielded numerous colonies belonging to Scedosporium apiospermum. Susceptibility tests were performed on the isolated strain. The isolate was sensitive to ketoconazole, intermediate to clotrimazole, and resistant to amphotericin B, 5-fluorocytosine, fluconazole, and itraconazole. The dog was treated with oral ketoconazole. During the treatment a general improvement in the lesions was observed. To our knowledge, S. apiospermum has not been implicated previously as an etiologic agent of nasal disease in dogs. This report provides its first description as such.

New Ochratoxigenic Species in the Genus Aspergillus

A total of 176 isolates of the genus Aspergillus were screened for their ability to produce ochratoxin A in yeast extract-sucrose broth and on moistened com. Besides being produced by A. ochraceus and A. alliaceus , ochratoxin A was produced by one isolate of A. fumigatus and one of A. versicolor ; species not previously reported to produce this mycotoxin.

Dermatophytes isolated from domestic animals in Barcelona, Spain

This retrospective study deals with the main samples studied at the Mycology Diagnostic Service of the Faculty of Veterinary Science of Barcelona: animals with suspected dermatophytosis. Over a ten-year period from 1986 to 1995, 136 dermatophytes were identified from dog and cat cultures submitted for identification and from specimens submitted for mycological examination from a variety of other domestic animals. The most frequent dermatophytes isolated were Microsporum canis (55.9%), Trichophyton mentagrophytes var. mentagrophytes (27.2%), Microsporum gypseum (7.4%) and Trichophyton verrucosum (7.4%). The identity of the dermatophytes from dog and cat cultures submitted for identification was M. canis (77.8%), T. mentagrophytes (13.3%) and M. gypseum (8.9%). Dermatophytes were cultured from 15 of 105 (14.3%) canine specimens and 19 of 56 (33.9%) feline specimens submitted for mycological examination during this period. Microsporum canis was the most common species isolated (73.3% and 94.7% respectively). The percentage of positive microscopic examinations of the specimens of hair in culture positive submissions from dogs and cats was 58.8%. There was a high proportion of positive cultures from both dogs and cats less than 1 year of age, and in some breeds of dogs, but there was no significant difference between the sexes. Although dermatophytes were more frequently isolated in autumn and winter months, no significant difference was detected in the seasonal distribution of the canine and feline dermatophytosis. Trichophyton mentagrophytes was the most prevalent dermatophyte in rabbits and T. verrucosum in ruminants. Other isolated species were T. equinum and M. equinum from horses.

[Enzymatic activities of Microsporum canis and Microsporum gypseum strains.]

The presence of 11 enzymatic activities, detected by qualitative methods, and 19 enzymes, semi-quantitatively detected by API ZYM system, in strains belonging to Microsporum canis and Microsporum gypseum has been studied. No pronounced differences were noted between Microsporum canis and Microsporum gypseum, although Microsporum gypseum presented in some cases more intense enzymatic activities than Microsporum canis.

Seasonal study of the fungal biota of the fur of dogs

During a one year period, 944 dogs from the Municipal kennel of Barcelona were examined to detect animals with suspected dermatophytosis. Only a few animals (1.8%) presented skin lesions but none of them had dermatophytosis. A representative number of dogs without visible skin lesions (n = 172), selected at random, were used to carry out a seasonal study of the mycobiota of their fur. Fifteen isolates belonging to the genera Microsporum and Trichophyton were isolated from 14 of the 172 (8.1%) dogs without lesions. The identity of these fungi was Microsporum gypseum (6/15), Trichophyton terrestre (4/15), M. canis (2/15), M. cookei (2/15) and Trichophyton ajelloi (1/15) (one strain each of M. gypseum and T. ajelloi were isolated from one dog). Species of Penicillium (% prevalence = 89.5%), Alternaria (86.6%), Cladosporium (84.9%), Aspergillus (77.3%), Scopulariopsis (65.7%) and Chrysosporium (64.5%) were the most prevalent. No significant differences in the fungal biota were observed with respect to age, gender, hair length or between mixed and pure breed dogs. A large number of isolates, including species belonging to the genera Beauveria, Chrysosporium, Malbranchea and Scopulariopsis, that macroscopically and/or microscopically resemble dermatophytes and may be mistaken for them, produced a red color change in Dermatophyte Test Medium. No significant seasonal difference was detected among the isolates belonging to the most frequently encountered genera, with the exception of Scopulariopsis (higher in summer and autumn) and Chrysosporium (higher in summer). Species from other genera, with lower occurrence also presented significant differences in their seasonal distribution. Arthrinium, Aureobasidium, Chaetomium and Phoma spp. presented maximum prevalence peaks in spring, Fusarium, Paecilomyces, Phoma and Rhizopus spp. in summer and Geotrichum and Mucor spp. in autumn. The Microsporum and Trichophyton species were more frequently isolated in summer.

Dyes as fungal inhibitors: effect on colony enumeration

The effects of three dyes on the colony enumeration of nine fungal strains (including members of the Deuteromycetes and Zygomycetes) in pure and mixed cultures were investigated. Using malt extract agar as basal and control medium, the following dyes and concentrations were assayed: auramine (25 ppm), gentian violet (5 ppm) and malachite green (1 ppm). The chemicals commonly used in commercial media dichloran (2 ppm) and rose bengal (50 ppm) were included in the study as reference mould-spreading inhibitors. Higher counts were usually obtained in the media containing dichloran, rose bengal or auramine, including the control medium in the absence of chemical when the mixed-conidium inocula did not include a spreading mould. Nevertheless in most cases no significant differences were observed between them. Malachite green (1 ppm) performed mainly as a strong inhibitor of spreading moulds, only allowing adequate colony development and recoveries of both Fusarium and Aspergillus strains tested.

Cryptococcosis in a cat seropositive for feline immunodeficiency virus

A 5-year-old female Siamese cat was presented to the veterinary teaching hospital with a history of bronchopneumonia for 20 days. The cat had not responded to antibacterial chemotherapy and had developed a pronounced submandibular lymphadenopathy. Characteristically encapsulated yeast cells with narrow-necked buds were clearly seen in a fine-needle aspirate of the lymph node with an India ink preparation. Cryptococcus neoformans var. neoformans was identified. Susceptibility tests on the isolated strain were performed using antifungal tablets. The strain was sensitive to amphotericin B, fluconazole, itraconazole and ketoconazole and was resistant to 5-fluorocytosine. The cat was positive for feline immunodeficiency virus. Nevertheless, the cat was treated with ketoconazole for 3 months and apparently recovered. Three months later the animal was presented in a precomatose state. The owners refused to treat the animal and the cat was destroyed.

Ochratoxin A production by strains of Aspergillus niger var. niger

In a survey of the occurrence of ochratoxin A (OA)-positive strains isolated from feedstuffs, two of the 19 isolates of Aspergillus niger var. niger that were studied produced OA in 2% yeast extract-15% sucrose broth and in corn cultures. This is the first report of production of OA by this species.

Mycoflora and Aflatoxin-Producing Strains in Animal Mixed Feeds

The mycoflora of 69 samples of animal mixed feeds were studied. Fungal counts ranged from 10² to 10⁸ CFU/g, the lowest counts corresponding to the samples of rabbit feeds. Seventy-one fungal species belonging to 26 genera were identified. The pre- dominant species were Aspergillus flavus , Fusarium moniliforme , and Penicillium chrysogenum . Thirty-six strains of A. flavus and one strain of A. parasiticus were screened for aflatoxin production in yeast extract-sucrose medium. The final pH, weight of mycelium, and production of aflatoxins were determined after 14 days of incubation. Five strains (13.5%) were aflatoxigenic. No statistical differences were observed in mycelial dry weights and final pH between aflatoxin-producing strains and nonaflatoxigenic strains.

Sodium chloride tolerance in strains of Epidermophyton floccosum and Epidermophyton stockdaleae

The ability of strains of genus Epidermophyton to grow at different concentrations of NaCl (ranged from 0 to 10%) was studied. A reduction in the diameter of colonies was observed as the concentration of NaCl increased. A nearly complete absence of macroconidia were shown even at the lowest concentration assayed. The geophilic species E. stockdaleae tolerated higher concentrations of NaCl (> 7%) than E. floccosum (< 3%).

Detection of human papillomavirus DNA by in situ hybridization and polymerase chain reaction in human papillomavirus equivocal and dysplastic cervical biopsies

One hundred twenty-one paraffin-embedded cervical biopsy specimens were tested for the presence of human papillomavirus (HPV) DNA by in situ hybridization and polymerase chain reaction. By in situ hybridization using probes for HPV types 6/11, 16/18, 31/33/35, 42/43/44, 51/52, and 45/56, HPV DNA was found in none of 20 normal/squamous metaplasia biopsy specimens, in one of 76 HPV equivocal biopsy specimens, in seven of 12 condyloma/mild dysplasia biopsy specimens, and in 12 of 13 moderate/severe dysplasia biopsy specimens. Polymerase chain reaction using HPV L1 consensus sequence primers followed by filter hybridization of the amplification products was positive for HPV DNA in two of 20 normal/squamous metaplasia biopsy specimens, in 23 of 76 HPV equivocal biopsy specimens, in eight of 12 condyloma/mild dysplasia biopsy specimens, and in 12 of 13 moderate/severe dysplasia biopsy specimens. Among biopsies that tested positive by polymerase chain reaction but that were negative by in situ hybridization, the most commonly identified HPV was type 16. We conclude that although HPV equivocal biopsy specimens contain HPV DNA more frequently than histologically normal tissue, the majority of biopsy specimens in this category test negative for HPV DNA. The clinical significance of a positive test for HPV, in the absence of unequivocal histologic changes, remains to be determined.

Comparative study of some factors affecting enumeration of moulds using dilution plate techniques

The influence of dilution plating technique, nature of diluent, culture media and incubation period on the enumeration of moulds have been studied. Three new culture media containing Auramine, Gentian Violet and Malachite Green respectively have been induced in this study. No significant differences were observed between results obtained after 3, 5 and 7 days of incubation. Significantly higher recoveries were obtained using the surface-spread method than pour plate method. Using the first technique no effect of diluent was observed, and among the different culture media studied higher counts were obtained with medium containing Auramine.