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Biomedical subjects

I Weitzman

Publications and source records attributed to I Weitzman.

At least 37 records · Page 2Linked to original sources
PubMed1984

Studies in the differentiation between Microsporum ferrugineum Ota and Trichophyton soudanense Joyeux.

A study, conducted with 20 isolates of Microsporum ferrugineum and 12 isolates of Trichophyton soudanense, revealed that some of the discrepancies in the literature regarding their characteristics and differentiation were due to methodology, strain variation and the use of an insufficient number of isolates. We found all isolates of T. soudanense to be urease negative and gelatinase positive (usually by the first week); to produce brown to black colonies on Lowenstein-Jensen medium; to rapidly decompose casein and more slowly tyrosine; to grow well or better at 37 degrees C as compared to room temperature; to produce reflexive branching on cornmeal Tween agar and abundant microconidia on casero medium and to exhibit no sexual reaction with either mating type of arthroderma simii. All but one isolate demonstrated restricted growth on lactose agar and only three isolates perforated hair. In contrast, we found 18 of 20 isolates of M. ferrugineum to be urease positive in urea broth (most isolates were negative on urea agar); all produced light-colored colonies on Lowenstein-Jensen medium; spreading colonies on lactose agar and failed to perforate hair in vitro or to produce reflexive branching. Most isolates manifested poorer to no growth at 37 degrees C compared to room temperature and all but one failed to decompose casein and tyrosine. A few strains produced macroconidia and/or microconidia on casero medium and some reacted sexually with A. simii (a) (-) mating type. Gelatin hydrolysis was variable.(ABSTRACT TRUNCATED AT 250 WORDS)

Culture Media↗
PubMed1984

Phialophora parasitica, an emerging pathogen.

Monoconidial cultures derived from 12 clinical and environmental isolates of Phialophora parasitica were compared with respect to morphologic and physiologic characteristics and response to antifungal agents. No yeast cells were seen in 1- and 3-week-old slide culture preparations. Also, not all of the distinguishing characteristics of this species were displayed by all isolates on all media examined. Although the isolates grew on Sabouraud agar with chloramphenicol and cycloheximide, some inhibition was observed. All cultures were strongly urease-positive and hydrolyzed casein and starch; most decomposed tyrosine but not gelatin. All but one environmental isolate grew well at both 23 and 37 degrees C, but none grew at 40 degrees C. In the sensitivity testing the isolates did not vary much in their response to each drug, although some anomalies were observed. Amphotericin B and miconazole had minimum inhibitory concentrations in the low sensitivity range (2.0-8.0 and 2.5-10 micrograms m-1 respectively), for most isolates, and most isolates were resistant to both 5-fluorocytosine and ketoconazole. Limited observations were made on three other Phialophora species which might be confused with P. parasitica.

Amphotericin B↗
PubMed1983

Evaluation of trichophyton agars for identification of Trichophyton soudanense.

Studies of three monoconidial subcultures of each of 10 isolates of Trichophyton soudanense on seven trichophyton agars revealed variations in growth among the subcultures of each isolate and among the isolates themselves on six agars. In contrast, greater consistency and generally good to excellent growth were noted with all isolates on trichophyton agar 1 (basal medium). These results are contrary to those found with other Trichophyton species and suggest that growth on the trichophyton agars is not a suitable test for the identification of T. soudanense.

Agar↗
PubMed1982

Zygomycosis caused by Cunninghamella bertholletiae: mycologic aspects.

Two isolates of Cunninghamella bertholletiae from confirmed cases of human zygomycosis were studied, and their sexual, asexual, and physiologic characteristics described. Minimal inhibitory concentrations for these two isolates, as well as for six other clinical isolates of C bertholletiae, were determined for amphotericin B, flucytosine, and miconazole using a standardized agar dilution technique. All isolates were found to be susceptible to miconazole, but resistant to flucytosine and amphotericin B.

Amphotericin B↗
PubMed1981

Mycobacterium thermoresistibile: a new pathogen for humans.

The first evidence of the potential pathogenicity of Mycobacterium thermoresistibile is presented. This mycobacterium, initially identified as Mycobacterium gordonae, was isolated repeatedly from sputum, a bronchoscopy specimen. and later, an open lung biopsy. The distinctive characteristics are described, including the unique ability of the organism to grow at 52 degrees C.

Bronchi↗
PubMed1980

Canine tuberculosis.

In a survey of 15,272 canine necropsies, natural infection with Mycobacterium tuberculosis was found to have been diagnosed in eight dogs (0.05%). Clinical findings were anorexia, loss of body weight, lethargy, vomiting, and leukocytosis; radiography revealed pleural and pericardial effusion, ascites, and hepatomegaly. Granulomatous lesions with acid-fast bacilli were consistently found. Mycobacterium tuberculosis was isolated from lesions in the lungs, liver, or lymph nodes of five dogs. All eight dogs had a history of contact with human patients with tuberculosis.

Animals↗
PubMed1980

Isolation in the United States of a culture resembling M. praecox.

A Microsporum culture isolated in the United States, from a clinical case of tinea corporis, was noted to have microscopic features resembling Rivalier's description of Microsporum (Sabouraudites) praecox (11). This unusual finding prompted further taxonomic studies, the results of which suggest that the new isolate may be either the first strain of Microsporum praecox (or a variety thereof) to be isolated in North America or, possibly, a new species.

Adult↗
PubMed1980

Subcutaneous infection with phialophora richardsiae and its susceptibility to 5-fluorocytosine, amphotericin B and miconazole.

Two patients are described with subcutaneous infections due to Phialophora richardsiae. Both were diabetics and originally came from subtropical areas. One of the patients had a cystic lesion which was well encapsulated while the other had a large ulcerating lesion with draining sinus tracts. The organisms were found to be susceptible to cycloheximide but resistant to 5-fluorocytosine, miconazole and amphotericin B. There was some variability in the degree of resistance depending upon whether the primary or secondary phialoconidia were tested. While simple excision appears curative for the solitary cystic type of lesion, therapy of the ulcerating form of the disease remains problematic.

Adult↗
PubMed1979

Pneumonia caused by Cunninghamella bertholletiae complicating chronic lymphatic leukemia.

A case of pneumonia caused by Cunninghamella bertholletiae is described in a patient with chronic lymphatic leukemia. The species of Cunninghamella, a genus in the order Mucorales, are characterized by the formation of conidia on the surface of an inflated conidiophore (vesicle). C. bertholletiae, not C. elegans, is the most appropriate name for this fungus. This zygomycete was resistant by in vitro sensitivity testing to amphotericin B. The source of the infection is not known.

Humans↗
PubMed1979

Rhizopus rhizopodiformis: emerging etiological agent of mucormycosis.

Mucormycosis is caused principally by members of the genus Rhizopus, especially R arrhizus and R. oryzae. Infection attributable to R. rhizopodiformis has rarely been documented. Of 13 cases of mucormycosis diagnosed during a 4-year period (1974 to 1978) at The Mount Sinai Hospital, 6 cases, occurring within 9 months, were caused by R. rhizopodiformis. The six isolates were identified mainly by: growth at 50 degrees C; production of short, sometimes branched, sporangiophores arising from opposite rhizoids; elongated columellae; and small spherical-to-elliptical, smooth-to-finely striated sporangiospores. The possibility that this explosive occurrence of R. rhizopodiformis at our institution was because of nosocomial acquisition was strongly supported by the recovery of this same mycotic agent from adhesive bandages used in the cardiac intensive care unit, where a patient developed subcutaneous R. rhizopodiformis infection after cardiac surgery. The invasive potential of R. rhizopodiformis was manifested by the extensive subcutaneous and systemic infections in each of the six patients, three of whom developed antibody against this mucormycotic agent.

Adult↗
PubMed1978

Mating behaviour of Nannizzia otae (=Microsporum canis).

One hundred and ninety-eight isolates of Microsporum canis, obtained from humans and animals in 12 countries, were paired with the two Japanese tester strains of Nannizzia otae (= M. canis), VUT 74037 (CDC B-2094+) and VUT 74039 (CDC B-2095-). One hundred and forty-one (72%) produced either gymnothecia or pseudogymnothecia in crosses with VUT 74037. Fifty-seven (28%) were nonreactive. None of the paired isolates reacted with VUT 74039. The number of nonreactive isolates decreased to 17% when 104 of the 198 isolates were paired with one additional tester strain of each mating type. All sexually reacting strains, however, belonged to the (-) mating type. Crosses between nonreactive isolates did not result in ascocarp formation. The F1 generations from three different strongly reactive crosses were all characterized by poor ascospore germination. Most of the monoascospore progeny that germinated to form mature colonies were nonreactive in crosses to determine their mating type. Others reacted predominantly as the (+) mating type, thereby precluding the likelihood of an associated lethal factor accounting for the lack of this mating type in our clinical isolates. Several explanations for this phenomenon are presented.

Animals↗
PubMed1976

Is Arthroderma simii the perfect state of Trichophyton Quinckeanum?

Gymnothecia with asci and ascospores developed repeatedly and in abundance whenever Trichophyton quinckeanum isolates X-392 and IMI 140691 were paired with Arthroderma simii 678 A. However, repeatable fertile crosses did not occur when all of our 19 isolates of T. quinckeanum were paired with 10 other isolates of A. simii comprising A and a mating types. Additional crosses between these 19 isolates of T. quinckeanum with A. simii and with A. benhamiae revealed that 11 of the 19 isolates of T. quinckeanum produced fertile gymnothecia only when crossed with A. simii 678 A but not when crossed with another isolate of A. simii of the A mating type nor when crossed with mating type a. All 19 isolates mated with A. benhamiae mating type A; therefore, all of our T. quinckeanum isolates were of the a mating type. Study of asci and random ascospores, selected with a micromanipulator, from crosses between several isolates of T. quinckeanum and A. simii 678 A revealed irregularities in the maturation of ascospores, poor ascospore germination, and a predominance of the A. simii phenotype and mating type for those ascospores that germinated and produced mature colonies. All these reactions are characteristic of interspecific crosses. In contrast, ascus analysis of the F1 progeny of crosses between these same isolates of T. quinckeanum with A. benhamiae revealed regular maturation of ascospores, better germination, and essentially a 1:1 segregation of mating types and parental phenotypes. This study confirms the concept that T. quinckeanum is not an independent species and that it is best considered to be a variety of T. mentagrophytes, as reported by Ajello, Bostick & Cheng (1968). Furthermore, our data indicate that T. mentagrophytes var. quinckeanum appears to be more closely related to A. simii than the granular variety of T. mentagrophytes, since fertile gymnothecia resulted from crosses between T. mentagrophytes var. quinckeanum and A. simii but not between T. mentagrophytes var. mentagrophytes and A. simii. Further implications of this study suggest the importance of extensive ascospore analysis when investigating the perfect states of fungi in order to avoid creating unwarranted new species.

Ascomycota↗