Unusual presentation of Microsporum canis in human hair.

This study reports an unusual presentation of Microsporum canis in infected human hair in a three-year-old boy. Infected hairs showed ectothrix colonization with a mass of small conidia and numerous macroconidia typical of the genus Microsporum. The infected hairs also showed strong invasion by hyphae bearing small numbers of arthroconidia. These hyphae were thinner and longer than those normally found in hair and scalp. It is well known that in cases of tinea capitis due to M. canis, ectothrix arthroconidia formation is extrapilary and arises from intrapilary hyphae. In this case it seems that unusual quantities of hyphae were formed, and not all of them broke down into arthroconidia. They appeared to remain in the hair and to produce macroconidia, which were not formed outside the hair in contact with air, but instead seemed to remain in a deeper layer of the hair than the arthroconidia seen.

Urease-positive Trichophyton rubrum strains (previously described as T. raubitschekii): first isolations in Argentina.

The present study reports the first Argentinian human cases of tinea caused by urease-positive Trichophyton rubrum strains (corresponding to isolates previously described as T. raubitschekii) in order to supply geographical data for these strains that are very rarely isolated as agents of dermatophytosis. The two isolates were identified by morphological, cultural, and physiological characteristics. The strains were isolated from cases of tinea corporis and tinea unguium.

Histoplasmosis and Paracoccidioidomycosis in northwestern Argentina III. Epidemiological survey in Vipos, La Toma, and Choromoro - Trancas, Tucumán, Argentina.

The present work was undertaken to obtain epidemiological data on the extent and distribution of Histoplasma capsulatum var. capsulatum and Paracoccidiodes brasiliensis diseases in the Vipos, La Toma and Choromoro areas. Skin test surveys with histoplasmin and paracoccidioidin were carried out in the permanent human population of those localities. Mycological sputum studies and serological tests were performed to skin test reactors to determine if there were signs or symptoms of active mycotic disease. La Toma and Choromoro are highly prevalent areas of histoplasmosis (>30% the histoplasmin positive individuals) whereas Vipos can be relatively considered a highly prevalent area (between 20-30% the histoplasmin reactors) according to the normally accepted range used to define an endemic disease [2]. Early Histoplasma capsulatum infection (<10 years old) is reported for Vipos and Choromoro. La Toma has the highest rate of previous exposure to P. brasiliensis detected in the studied area (10.2%). Vipos residents are not infected with P. brasiliensis.

Antimicrobial susceptibilities of strains of Nocardia brasiliensis isolated from soil of Tucumán.

The activity of antimicrobial agents against soil isolates of N. brasiliensis was studied by determination of the minimum inhibitory concentrations (MICs) and disk diffusion technique, according to the National Committee for Clinical Laboratory Standards (NCCLS). The objectives were: (a) to study the patterns of sensitivity among regional strains of N. brasiliensis isolated from natural sources (soil) of different zones of Tucumán province; (b) to correlate these results with those previously obtained with regional strains of N. brasiliensis isolated from human mycetomas, as a contribution in the evaluation of the importance of the natural reservoir area of the potentially pathogen strains. The results obtained by both methods identified strains of N. brasiliensis from soils with similar patterns of susceptibility to the strains N. brasiliensis isolated from human mycetomas. This showed strains sensitive and resistant to antibiotics. The majority of the isolates of N. brasiliensis from soils showed higher susceptibilities to antibiotics than the strains isolated from human mycetomas. Among the antibiotics studied, cefotaxime, ceftriaxone and gentamicin were the most effective against all the regional strains tested, and these results are correlated with those obtained with regional strains that cause human mycetomas.

Etiology and clinical characteristics of mycotic leukonychia.

The purpose of the present paper is to add to our understanding of the prevalence of mycotic leukonychia. Twenty patients with mycotic leukonychia were studied. Leukonychia with atypical characteristics not previously described or with discordant characteristics relative to the ones that were responsible of this infection were found. Direct microscopic examination and cultures showed that Fusarium spp. were the responsible agents in 10% of the cases and that dermatophytes were implicated in the other 90%, where Trichophyton rubrum was the predominant etiologic agent. In this report we describe the clinical characteristics of the nail infections, the probable predisposing causes of the disease and the evolution of the cases.

Antimicrobial susceptibilities of regional pathogenic strains of Nocardia isolated from mycetomas.

The activity of antimicrobial agents against clinical isolates of Nocardia was studied by determination of the Minimal Inhibitory Concentrations (MICs) and Disk Diffusion Technique, according to the National Committee for the clinical Laboratory Standards (NCCLS). The object was: (a) to determine the 'in vitro' susceptibility of the strains that cause human mycetomas; (b) to determine the presence of different patterns of sensitivity among the regional strains; (c) to evaluate the Disk Diffusion Technique using disks commercially available with the antimicrobial concentrations normally used in the microbiological practice. Comparing the MIC values obtained with the values suggested by the National Committee for Clinical Laboratory Standards for Nocardia spp. (broth microdilution MIC breakpoints), we found that local strains are susceptible to amikacin, cefotaxime, ceftriaxone and TMP-SMZ; moderately susceptible to ampicillin and resistant to ciprofloxacin and erythromycin. The results obtained by both methods showed the presence of different patterns of sensitivity among the regional strains of N. brasiliensis. This showed strains sensitive and resistant to antibiotics. The Disk Diffusion Technique, even if it is not the adequate method to study the sensitivity patterns of different strains against antimicrobial agents, permits the differentiation between strains sensitive and resistant to antibiotics.

Histoplasmosis in northwestern Argentina. II: Prevalence of Histoplasmosis capsulati and paracoccidioidomycosis in the population south of Chuscha, Gonzalo and Potrero in the province of Tucuman.

The present work was undertaken to obtain epidemiological data on the extent and distribution of Histoplasma capsulatum var. capsulatum and Paracoccidiodes brasiliensis infections south of the Chuscha, Gonzalo and Potrero areas of Argentina. Skin tests surveys of the human population with histoplasmin and paracoccidioidin were carried out in the permanent population of those localities. The infection index of the population showed that the area south of Chuscha has a high-prevalence of histoplasmosis capsulati. The Gonzalo and Potrero areas, according to their rates of infection also can be considered to have a relatively high prevalence of this disease. The frequency of individuals infected with P. brasiliensis suggests that the level of exposure to this fungus is considerable, especially in Gonzalo where the frequency of infection was 9.23%. The endemic areas of both diseases can be superimposed, as occurs in the northeastern part of Argentina.

Histoplasmosis in northwestern Argentina. Epidemiological survey of Chuscha and La Higuera in the province of Tucumán.

The present work was undertaken to obtain epidemiological data on the extent and distribution of Histoplasma capsulatum infections in the Chuscha and La Higuera areas. Skin test surveys of the human population with histoplasmin and paracoccidioidin were carried out in 40% of the permanent population of both localities, between 3 and 88 years old. It was found that 53.57% of the population were histoplasmin reactors and 1.86% of the population were paracoccidioidin reactors.

Acid and alkali as aids in differentiation of pathogenic Nocardia and for their isolation from clinical specimens.

The tolerance of Nocardia brasiliensis, Nocardia asteroides and Nocardia caviae to different concentrations of acids and alkalis was studied in this work. The purpose was to determine their use: (a) in the differentiation of species; (b) for decontamination of clinical materials during the isolation of pathogenic Nocardia. The results showed (1) that both 2 M NH3 and 0.05 M H2SO4 solutions are useful for differentiating species. They can also be used as a complementary method for identification. (2) That both 1 M NH3 and 0.05 M H2SO4 solutions were useful for decontamination of clinical materials during the isolation of pathogenic Nocardia.

The efficiency of 1 M NH4Cl and 2 M NaCl for the isolation of pathogenic Nocardia from soil.

The present paper reports an improvement to the classical method of the paraffin bait, by the usage of 1 M NH4Cl or 2 M NaCl to eliminate contaminant microflora of soil. The purpose is to introduce a change in the paraffin bait method in order to reduce time required to isolate pathogenic strains of Nocardia from their natural sources. For this study three main criteria were used: a) Determination of the inhibitory effect of different concentrations of salts on soil microflora; b) The tolerance of Nocardia brasiliensis, Nocardia asteroides and Nocardia caviae (Nocardia otitidis caviarum) strains to these chemical inhibitors; c) Determination of the efficiency of salts in the isolation of Nocardia from soil when strains are grown on paraffin baits.

Physiological and pathogenic characteristics of Nocardia brasiliensis isolated from human mycetomas.

A previous analysis of the physiological properties of Nocardia brasiliensis strains isolated from soil of Tucumán proves that non-pathogenic strains have a different behaviour pattern from the pathogenic strains. In the present paper, 16 Nocardia brasiliensis strains isolated from human mycetomas were studied in the same way. The object is to determine if any of the Nocardia brasiliensis present in soil can produce human mycetomas. The macro and micromorphological, biochemical (17 tests), physiological (4 tests) and pathological characteristics were determined for each of the strains. Experimental pathogenicity was determined using albino Swiss mice by inoculation into the footpads. The strains of Nocardia brasiliensis that cause human mycetomas have the same physiological pattern and experimental pathogenicity as the virulent strains present in soil.

Natural occurrence of Nocardia in soil of Tucumán: physiological characteristics.

This is the first study initiated in Argentina to establish the presence of species of Nocardia from soil samples. These samples were gathered in different areas of Tucumán. Thirty three pathogenic strains of Nocardia were isolated by the paraffin bait method. Out of them, 28 were N. brasiliensis, 3 N. asteroides and 2 N. caviae. N. brasiliensis was widely distributed in the soil of the areas tested. It is proved that N. caviae, so rarely found in other regions of the world, occurs in Tucumán. A detailed study of the morphological and physiological characteristics for identification is discussed.

Relationships between the physiological characteristics and pathogenicity of Nocardia brasiliensis.

The analysis of 19 physiological properties of 28 strains of Nocardia brasiliensis isolated from soil reveal differences which could be of great value in distinguishing pathogenic from nonpathogenic strains.

The experimental pathogenicity in Swiss mice of various strains of Nocardia isolated in soil of Tucumán (Argentina).

The isolation of Nocardia pathogenic for man in soil of Tucumán revealed the convenience of undertaking a study of their virulence, to evaluate any potential danger it may imply. Thirty three strains were studied: 28 N. brasiliensis, 3 N. asteroides and 2 N. caviae by inoculating albino Swiss mice into the footpads and intraperitoneally. The results obtained revealed the existence of Nocardia of variable aggresiveness in the soil of Tucumán.

In vivo determination of phagocytic indices and candidacidal activities of Candida species by rat peritoneal macrophages.

A possible correlation between pathogenesis and phagocytosis is established through comparison of the kinetics of the ingestion of nine Candida species by rat peritoneal macrophages in the early stages of infection. After 3 h of intraperitoneal injection of 6.10(8) yeasts to Sprague-Dawley rats, the phagocytic indices, candidacidal activity and the fate of the yeasts are assayed. Phagocytic indices allow separation of the species into four groups. Candidacidal activity and phagocytic indices are coincidently smaller in the more pathogenic species. Common events occur with the species assayed. All the yeasts can be isolated from blood, spleen and kidneys from the first h, whilst invasion to liver occurs from the second h post-infection.

Candida berkhout species isolated from deep-seated and superficial candidosis. Classification of species with the N. van Uden and H. Buckley key.

The purpose of the present paper is to improve the understanding of the incidence of Candidosis in human infections. 85 species of Candida isolated from deep-seated and superficial Candidosis were studied. Identification was attained using the key of N. van Uden & H. Buckley (22).

In vitro determination of phagocytic indices of Candida berkhout species by rat peritoneal macrophages.

The aims of this investigation were to study and describe the behaviour of 13 different species of Candida, as compared with C. albicans, by means of phagocytosis assays in vitro. Tests were carried out with rat peritoneal macrophages in contact with quantified suspensions of live yeasts. Phagocytic indices, candidacidal activity and filamentation rat were tested microscopically after 3 h incubation at 37 degrees C. The phagocytic indices obtained allowed us to separate the fungi into four groups. Candida albicans and tropicalis belong to Group I; diddensii and shehatae, among others, belong to Group II; sake, krusei, viswanathii, etc., Group III; and C. glaebosa and haploid strains of Pichia ohmeri (C. guilliermondii var. membranaefaciens), Group IV. These data would suggest a possible correlation between pathogenesis and phagocytic indices. There were no evidences of any phagocytes ability to kill yeasts. Candidacidal activity was absent in the species assayed. Yeast lysis may have been observed if our assays would have taken longer than 3 h.