KERATINOPIDLIC FUNGI IN SOILS OF CORRIENTES CI1Y (ARGENTINA)

Keratinophilic fungi were isolated from al/ samples ( 100% of positivity) belonging to the genera Tricbophyton, Penicillium, Microsporum, Chrysosporium, Ctenomyces and Drecbslera. In a few cases there was only one isolation, but mostly there was an association between 2, 3 or 4 different genera, present in the same sample. Mkrosporum was present only in 19,8% of the samples, a value considerably lesser than previous reports for other cities of Argentina. Most of the soil samples were alkoline (mean pH = 7.94), sandy and with the high contents of phosphorus.

through nurnerous surveys carried out on soils from different geograpbic areas with varied climatic conditions, had made possible to assert that soil is the main source of causing agents for superficial, systernic or oportunistic human infections.
Fungi use for growing a variety of substrates which may be organic, inorganic or even particular substances like keratinAmong the numerous pathogenic organisms present in soil samples keratinophilic fungi have been the most frequently found, probably due to its abbility to grow in an ample variety of soils (7,1,10,18,21),but tbe distribution of species seems to depend on humus contents (5).
Pathologies produced by keratinopbilic fungi, like nnea capitis or Tinea corporis may be transferred from man to man by direc or indirect contacts, from animal to animal, from animal to humans and viceversa but also soils bave to be considered as an important source of infection ( 4).
The present work reports on tbe results of a survey taken in Corrientes city (Northeast Argentina) in arder to determine tbe prevalence of keratinophilic fungi in soils samples, comparing them wtth previous reports of other argentine cities. We particularly analyze formerly obtained results for Resistencia (Chaco province) a city located only 16 km from Corrientes, with similar climatic conditions, but separated by a great ecological barrier, the Paraná River.

MATERIAL AND METHODS:
• Collection of soil samples: Samples were taken in each selected area from places most frequented by inhabitants and pets, in arder to improve the possibilities for isolation of keratinopbilic fungi. As it is known, they do not limit to zoophilic, antropophilic or geophilic cycles but establish a triangular movement between substrates.
On the basis of a municipal map the city was divided in 60 areas of 1 sq.km each. Places more frequently visited by inhabitants like parks, shopping centers, etc., ,were defmed on it and later 2 sam"ples were taken from each place, one in summer and one in winter. A total of 116 soil samples were taken because 4 winter samples had to be discarded.
After eliminating the superficiallayer ( about 5 mm) 500 gr. of soil were collected with a sterile spoon and kept in sterile paper envelopes.

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• lsolatlons or keratinophlllc fungl: Isolations of keratinophilic fungi were made according to the Vanbreuseghem method {16)! employing autoclaved fragments of horse hair as hooks and incubated for 45 days at 25° C.
• Cultures: Macro and micromorphological analysis of fungi recovered with the hook were made after 15, 30 and 45 days of incubation at room temperatU:re.
• Physical-chemlcal analysis of the soil: -pH measure: was made by the clorimetric method using Bromothymol blue and phenolphthalein as indicators -Nitrates content: measured by Broy method (3,9).

RESULTS
The results obtained are presented in Table 2 and 3 according to the season when samples were coUected.
Keratinophilic fungi were isolated from 100% of samples collected in winter. In 24/56 samples only one genus was isolated (Penlcllllum in 7 and Trichophyton in 17), but associations between two or three different genera were found in other 32 samples. Keratinophilic fungi were also found in all l ./úratinoplrili fturgi in soils ofCorrimtes City (ArgmtiM) • M.L. Mangi~J~Dra el J.M. Aloftso summer soil samples. In 26 of them only one genus was present (Penlclllium in 1 and Tricbophyton in 25) while associations between 2, 3 or 4 were present in the other 34 samples.
The physical-chemical soil analysis in which dermatophytes were isolated showed a predominance of alkaline pH (mean 7.94), Wtth good contents of phosphorus, all of sandy texture, while contents of nitrates as weU as organic compounds were varied.

DISCUSSION
Human infective forms of fungi are always present in soil, where they may maintain its pathogenical potential for long periods of time since it is its natural habitat (19).
The prevalence of superficial mycoses in the Nortbeast region of Argentina has been historicaUy high. For this reason it was considered of interest to find out the isolation frequency of keratinophilic soil fungi in that area, and comparies on it with similar reports from other geographic regions, to determine whether soil is a significant source of infection or just a simple reservoir from which human infecttons may be acquired depending on particular circunstances.
A prior survey taken in Resistencia (Argentina) showed the presence of keratinophilic fungi in 83 % of soil samples (11), which is a value very similar to ours. Thougb climatic conditions, as well as physical-chemical characteristics of so~ are similar for both cities, there were differences m the species isolated and in its frequencies. We found Mlcrosporum gypseum complex in 23 soil samples (19,8%) which is the lowest value reported so far for our country. Previous informs indicated jso. lation rates of 65.27% for C6rdova (387 soil samples) (15), 84 % for Tucumán (75 samples) (17), 89 % in 100 samples of La Plata (8), 62 % for Santa Fe (12) and 24 % in 60 soil samples of Resistencia (11). In many of these reports the sexual form of M. gypseum (Nanniz:zia gypsea = Ar· tbroderma gypsea) was found, but nol in our case. Tricbopbyton terrestre complex o~ i::, tckomorph A. quadrifidum, was isolated in 82,1..¡ % of winter samples and in 96.76% of summer samples. This value is coincident with former fmdings on the easy development of this fungus in soils of mild climate regions.
Physical-chemical analysis of soil samples from which keratinophilic fungi could be isolated revealed correlation with alkalinity (mean pH: 7.94) and sandy texture. Other soil components showed varied values without correlation with presence or absence of this fungi.
The type of keratin present in certain habitats may incide on qualitative and quantitative results obtained from soil surveys (6). In order to digest this insoluble scleroprotein, fungi have to develop an active alkalinization of substrates and perbaps for this reason isolation of keratinophilic organisms may be facilitated in alkaline soil samplcs. This behaviour may have partially influenced the high isolation rates found by us, but any way, we can affirm that Corrientes city soils present particularly tavourable conditions for survival and development of this fungi.