Walderez Gambale

Fungal colonization and succession on newly painted buildings and the effect of biocide

This report describes the sequence of fungal colonization and the influence of biocide incorporation on paint films, determined using quantitative methods. Two buildings were painted with an acrylic paint, with and without an experimental biocide formulation containing a carbamate (carbendazin), N-octyl-2H-isothiazolin-3-one and N-(3,4-dichlorophenyl)N,N-dimethyl urea (total biocide concentration 0.25% w/w). One week after painting, the major groups of organisms detected were yeasts and Cladosporium. The yeast population fell to undetectable levels after the third week and this microbial group was not detected again until the 31st week, after which they increased to high levels on the 42nd week. Aureobasidium showed a pattern similar to the yeasts. The main fungal genera detected over the 42-week period were Alternaria, Curvularia, Epicoccum, Helminthosporium, Coelomycetes (mainly Pestalotia/Pestalotiopsis), Monascus, Nigrospora, Aureobasidium and Cladosporium. The latter was the main fungal genus detected at all times. The physiological factors controlling colonization are discussed. Cladosporium, Aureobasidium, Tripospermum and yeasts on the painted surfaces were all able to grow on mineral salts agar containing 10% sodium chloride. This is the first time that the genus Tripospermum has been reported on painted buildings. The fungal population on biocide-containing surfaces was significantly lower than on non-biocide-containing paint after 13 weeks and continued so to 42 weeks after painting, but there was no statistically significant difference in the level of fungal biodiversity.

The development of a method to evaluate bioreceptivity of indoor mortar plastering to fungal growth

The aim of this work was to develop and standardise an accelerated laboratory test for detecting bioreceptivity of indoor mortar to fungal growth. To determine which fungal species were predominant under field conditions, isolation was carried out using mortar samples collected from 41 buildings in two cities of Sao Paulo State in the South East of Brazil. Cladosporium was found to be the genus most frequently recovered from field specimens. Based on the results of laboratory trials strain C. sphaerospermum was chosen as a test microorganism. Four different mortars, two laboratory-manufactured mortars composed of ordinary Portland cement, high calcium hydrated lime and standardised sand, and two different ready-mixed building mortars from the Brazilian market, were investigated for their susceptibility to colonisation by C. sphaerospermum. Several parameters were tested to determine factors influencing fungal bioreceptivity. The type of mortar, degree of carbonation and pH values of mortars, as well as relative humidity of environment effected colonisation of C. sphaerospermum. All except one mortar samples showed significant fungal growth, however, the growth occurred only at 100% relative humidity. Interaction of C. sphaerospermum with mortar specimens was studied using techniques of scanning and environmental scanning electron microscopy combined with energy dispersive X-ray analysis.

Yeasts isolated from blood and catheter in children from a Public Hospital of São Paulo, Brazil

The great majority of nosocomial fungal infections, especially fungemias, are caused by yeasts, mostly of the genus Candida. In addition, such infections may be associated with intravascular catheters. In this study, 80 yeast strains were isolated from hospitalized children, being 59 from blood cultures and 21 from vascular catheter cultures. The prevalent species in both blood and catheter was C. parapsilosis (32.2% and 48.9%, respectively), followed by C. albicans (16.9% and 28.6%, respectively). Concerning enzyme production, 78.8% of the 80 isolates presented strong proteolytic activity but 78.8% showed no phospholipase activity. We also detected two prevalent “killer” biotypes: 511 and 888. Additionally, in five patients, it was possible to observe that the yeast species, “killer” biotype and proteolytic and phospholipase activity of blood and catheter were similar. In view of this, we suggest a transmission of nosocomial yeast infection from catheter to blood.

Postharvest and stored corn in Brazil: Mycoflora interaction, abiotic factors and mycotoxin occurrence

The mycoflora of 130 samples of postharvest and stored corn was analysed throughout one year. The sample originated from Riberirão Preto, State of São Paulo, Brazil. The influences of abiotic factors (moisture content, relative humidity, temperature, rainfall) and mycotoxin occurrence were also verified. The isolation of the fungi was performed with Potato Dextrose Agar. Fungi were identified by using standard techniques. The determination of mycotoxins (aflatoxins, ochratoxin A, sterigmatocystin, zearalenone, deoxynivalenol and fumonisin B1) was carried out by thin-layer chromatography. The Fusarium spp. was the most dominant fungi (83.8%) followed by Penicillium spp. (55.3%), Aspergillus spp. (40.7%) and 11 other filamentous fungi. All of these were isolated from grains with moisture contents of 12.3-17.8%, an average temperature of 18.4-24.1 degrees C, a relative humidity between 64.0 and 97.5% and rainfall of up to 337 mm. With regard to the number of colony forming units (cfu), Fusarium spp. was the main contaminant, varying from 545 x 10(3) to 1.5 x 10(3). The Simple linear correlation analysis showed significant positive correlation of the Fusarium genus with moisture content of grains, and a significant negative correlation in relation to the minimum and medium temperatures, rainfall and relative humidity. The linear correlation of the Penicillium and Aspergillus genera with the abiotic factors was not significant. In the samples analysed only one contained aflatoxin B1.

Cryptococcus neoformans strains isolated from church towers in Rio de Janeiro City, RJ, Brazil

Cryptococcosis has been a significant cause of morbidity and mortality in patients with Aids. Many reservoirs of the agent Cryptococcus neoformans have been reported, but the ecology of this yeast must be elucidated in order to establish surveillance programs and to prevent infections. The objective of this study was to evaluate the presence of C. neoformans in Rio de Janeiro City, RJ, Brazil. Ten churches were selected for sampling and detection of the yeast collecting pigeon dropping, air samples from church towers and neighboring areas during one year. The data demonstrated that C. neoformans has been present in every church selected and was present in 37.8% of 219 pigeon dropping samples. As well as, the yeast was isolated from soil, insects, eggs, pigeon nests and feathers. Fifteen air samples (4.9%) were positive. The growth on C.G.B. medium showed that all strains belonged to C. neoformans var. neoformans, with 98.8% of the strains belonging to serotype A.

Mycoflora of the toxic feeds associated with equine leukoencephalomalacia (ELEM) outbreaks in Brazil

The mycoflora of 39 feed samples associated with 29 Equine Leukoencephalomalacia (ELEM) outbreaks was studied from 1988 to 1990, in Brazil. Microbiological examination indicatedFusarium spp. as the most frequent mold which occurred in 97.4% of samples followed byPenicillium spp. in 61.5% andAspergillus spp. in 35.9%. The moisture content of feed implicated in death of horses was above 15% which can favor the development ofFusarium spp. From the genus,F. moniliforme was the predominant species with an occurrence of 82.0%. Two additional species, not commonly associated with animal toxicosis, were isolated in low frequency,F. proliferatum (12.8%) andF. subglutinans (2.6%). It is important to emphasize that the isolation ofF. proliferatum andF. subglutinans from feed obtained from the epizootic areas has not been documented previously in Brazil.

Molecular identification of Candida dubliniensis isolated from oral lesions of HIV-positive and HIV-negative patients in São Paulo, Brazil

Candida dubliniensis is a new, recently described species of yeast. This emerging oral pathogen shares many phenotypic and biochemical characteristics with C. albicans, making it hard to differentiate between them, although they are genotypically distinct. In this study, PCR (Polymerase Chain Reaction) was used to investigate the presence of C. dubliniensis in samples in a culture collection, which had been isolated from HIV-positive and HIV-negative patients with oral erythematous candidiasis. From a total of 37 samples previously identified as C. albicans by the classical method, two samples of C. dubliniensis (5.4%) were found through the use of PCR. This study underscores the presence of C. dubliniensis, whose geographical and epidemiological distribution should be more fully investigated.

Genotyping by RAPD-PCR analyses of Malassezia furfur strains from pityriasis versicolor and seborrhoeic dermatitis patients.

Malassezia furfur is lypophilic yeast commonly associate with dermatological disorders. In the present work, we described the isolation of 47 M. furfur strains from three groups of patients: pityriasis versicolor (21 isolates), seborrhoeic dermatitis (15 isolates) and seborrhoeic dermatitis of the HIV positive patients (11 isolates). To investigate the identity of the strains at molecular level, DNA genomic of M. furfur strains were prepared and used to RAPD-PCR analyses. RAPD assay were carried out using two decamer primers and bands pattern generated were analyzed by an Unweighted Pair-Group Method (UPGMA). Dendrogram established a distinct differentiation between M. furfur isolates from pityriasis versicolor and seborrhoeic dermatitis patients with or without AIDS. We concluded that RAPD typing presented a high discriminatory power between strains studied in this work and can be applied in epidemiological investigation of skin disease causing by M. furfur.

Extracellular proteolytic activity and molecular analysis of Microsporum canis strains isolated from symptomatic and asymptomatic cats

Resumen Microsporum canis es el principal dermatofito en perros y gatos, siendo agente importante de zoonosis. La literatura informa la existencia de gatos que son portadores asintomaticos de M. canis, debido a la resistencia del portador y a la presencia de cepas con menor virulencia. Este estudio fue realizado para evaluar la actividad queratinolitica, elastinolitica y colagenolitica de M. canis y su relacion con gatos (con y sin sintomas) y para analizar molecularmente las cepas por el metodo de RFLP. Las cepas aisladas de gatos con dermatofitosis tenian actividad queratinasa y elastasa mayores que las cepas aisladas de los gatos asintomaticos (p

Susceptibility of phosphogypsum to fungal growth and the effect of various biocides

Natural gypsum (NG) and phosphogypsum (PG) were tested for resistance to fungal growth based on standard test ASTM D 3273-86, with the recommended mixture of three fungal species, and using the same test modified by the use of a Cladosporium sp. A, isolated from a gypsum plaster ceiling. In the standard test little growth occurred on any of the test specimens. However, abundant fungal growth was produced by the Cladosporium sp. A on phosphogypsum, which was much more susceptible than natural gypsum. Phosphogypsum heated to 600°C to destroy organic residues was resistant to growth of Cladosporium sp. A, as well as other fungi isolated from phosphogypsum panels stored in the environment for 2 years: Cladosporium sp. B, Aspergillus niger and Trichoderma sp. Phosphogypsum moulded in Petri dishes was susceptible to growth of a wide range of fungi, although Fusarium sp. and Rhizopus sp. caused practically no discoloration of the substrate. Six biocides were separately incorporated into the phosphogypsum at concentrations recommended by the suppliers and test specimens incubated on Sabouraud agar inoculated with various fungal isolates. The biocide 2-N-octyl-4-isothiazolin-3-one was the most efficient compound. It prevented the growth of the fungi most likely to cause health problems in buildings, but not that of Helminthosporium sp., isolated from powdered phosphogypsum in the factory. This was the most resistant fungus showing growth on all biocide-containing specimens.