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G A Land

Publications and source records attributed to G A Land.

13 recordsLinked to original sources
PubMed1991

Evaluation of the Baxter-MicroScan 4-hour enzyme-based yeast identification system.

A new 4-h Yeast Identification Panel (YIP; Baxter-MicroScan, W. Sacramento, Calif.) was compared with the API 20C Yeast Identification System (Analytab Products, Inc., Plainview, N.Y.) in the identification of recent clinical yeast isolates. The YIP had a 94% correlation (288 of 306) in identifying 22 species within the genera Candida, Hansenula, Pichia, Rhodotorula, Saccharomyces, and Torulopsis. Correlation dropped to 65% for those species within the genera of slower growing yeasts, i.e., Blastoschizomyces spp., Crpytococcus spp., Geotrichum spp., Hyphopichia spp., Phaeococcomyces spp., Prototheca spp., and Trichosporon spp. Overall correlation with the API 20C was 92% (365 of 401) for those taxa included in the data base and 85% (373 of 437) for all yeasts encountered in the study. There were 36 (8.2%) discrepant identifications, which were due in part to the limited data base. Expansion of the data base plus the easy inoculation, reading, and rapid results of the YIP should make it an excellent method for yeast identification.

Culture Media↗
PubMed1979

Assimilation of protocatechuic acid and p-hydroxybenzoic acid as an aid to laboratory identification of Candida parapsilosis and other medically important yeasts.

Test for the ability of yeasts isolated from clinical specimens to utilize protocatechuic acid and p-hydroxybenzoic acid were carried out by using techniques that are commonly employed to test assimilation of carbon sources. A total of 60 isolates of Candida parapsilosis and 5 isolates of Candida humicola readily assimilated these two phenolic acids, whereas other Candida species gave uniformly negative results. Cryptococcus albidus, Cryptococcus terreus, and some isolates of Cryptococcus laurentii also assimilated protocatechuate and p-hydroxybenzoate, whereas Cryptococcus neoformans did not. Results of these tests suggest that assimilation of protocatechuate and p-hydroxybenzoate may be a useful characteristic, when used in conjunction with traditional tests, for identifying C. parapsilosis and C. albidus.

Candida↗
PubMed1979

Evaluation of the new API 20C strip for yeast identification against a conventional method.

The new API 20C yeast identification system together with appropriate microscopic morphology determinations achieved a 97% correlation with a rapid conventional method. Whereas a group composed of Candida, Torulopsis, Saccharomyces, and Rhodotorula was identified with ease (98% overall correlation), a second group, containing Cryptococcus, Trichosporon, and Geotrichum species, appeared to give the system the most difficulty (90% correlation). Within this group particular difficulty was encountered in identifying varieties of Cryptococcus albidus, C. terreus, C. laurentii, Trichosporon beigelli, and Geotrichum spp. as to species. The API 20C system should be incubated the full 72 h prescribed by the manufacturer. However, when used in conjunction with appropriate morphological tests, presumptive identifications of some Candida and Torulopsis species may be made at 24 to 48 h. To facilitate identifications of the more difficult group of yeasts, ancillary tests for determining nitrate reductase, urease, and phenol oxidase activities should be considered as additions to the strip. Incorporating the phenol oxidase test would be especially important for identification of Cryptococcus neoformans, a yeast which should be identified as quickly and as accurately as possible. The API 20C system with computer assistance has proved to be an easy-to-inoculate, versatile, and fairly rapid method of yeast identification, giving results comparable to those obtained by conventional methodologies.

Candida↗
PubMed1979

Improved blood culture technique based on centrifugation: clinical evaluation.

A total of 3,335 blood samples from 1,180 patients suspected of having bacteremia were analyzed concurrently by two methods: (i) supplemented peptone broth with sodium polyanethanol sulfonate and a CO2 atmosphere; and (ii) lysis centrifugation at 3,000 X g for 30 min onto a high-density, hydrophobic cushion. The centrifugation technique recovered 80% of the positive cultures as compared with 67% for the broth method. The centrifugation technique showed an apparent increase in the isolation of staphylococcus aureus, Pseudomonas, and yeasts. In almost every instance, the time required for detection of a positive culture was shortest for the centrifugation method. Contamination rates for both systems were comparable (1.4%). Quantitation, offered only by the centrifugation method, proved useful on several occasions in discriminating between an opportunistic infection versus a skin contaminant and in judging efficacy of antimicrobial therapy.

Bacteria↗
PubMed1978

Isolation and rapid identification of yeasts from compromised hosts.

In order to improve the isolation and identification of yeasts in a cancer research hospital, a protocol was developed utilizing an improved blood culture methodology and a four-test schema for rapid yeast identification. The blood culturing technique, based upon centrifugation, has shown a ten-fold increase in isolation of fungi from blood and has provided for: quantitation or organisms, unlimited selection of media and atmospheres for primary culturing, and a 1:200 dilution of microorganisms away from serum antimicrobial factors and antibiotics. The four-test schema, which may be adapted for the identification of any unknown yeast in pure culture, consists of a dye pour plate auxanogram (DPPA), Tween 80-Oxgall-Caffeic acid (TOC), a rapid nitrate-reductase test (swab test) and Urea 'R' Broth. Using this protocol, over 95% of the clinical isolates received were correctly identified within 24 hours and 100% by 48 hours. By using DPPA, a 14 sugar assimilation pattern for each isolate was determined within 12 to 16 hours; and in some cases, as little as 6 hours. Growth on TOC yielded one of the following results: (1) Candida albicans and Candida stellatoidea sequentially produced germ tubes and chlamydospores in 3 hours and 24 hours, respectively; (2) Cryptococcus neoformans produced a brown pigment specific for its identification in 12 hours or less. The swab test gave results on nitrate utilization in less than 15 minutes and urease was detected within 4 hours.

Blood↗
PubMed1978

Rapid urea broth test for yeasts.

A rapid, miniaturized, urea broth test useful for detecting urease activity of yeasts was compared to Christensen urea agar. All urease-producing yeasts tested were positive on both media; however, 60% were reactive in the urea R broth within 30 min, and the remainder were reactive within 4 h. This urea multiwell test may be useful as a rapid screening method for detecting urease-producing yeasts recovered from clinical specimens and as an adjunct test with other rapid methods of yeast identification.

Candida albicans↗
PubMed1978

Immunodiagnosis of histoplasmosis in a compromised host.

Three serological tests for the diagnosis of histoplasmosis were compared for sensitivity and specificity in serum from blood bank donors, patients with histoplasmosis, and infected or noninfected immunosuppressed patients. The histoplasmin latex agglutination test was positive in 9% of the normal patients, 33% of the histoplasmosis patients, and 61% of the noninfected immunosuppressed patients. Since the test is prone to many false-positive results in patients with inflammatory diseases or non-Histoplasma infections, it has limited potential as a screening test among compromised patients. Immunodiffusion and counterimmunoelectrophoresis using a mycelial antigen were found to be more sensitive than either test using a combined yeast and mycelial antigen or a pure yeast phase antigen. Counterimmunoelectrophoresis at pH 7.2 proved to be the test of choice for serodiagnosis of histoplasmosis, resolving 85% of the immunocompetent infected patients and 100% of the infected immunosuppressed patients. Results indicated that counterimmunoelectrophoresis in conjunction with immunodiffusion could be used as a screening protocol to determine infection in incoming patients in a cancer hospital.

Antibodies, Fungal↗
PubMed1977

New culture medium for the presumptive identificaion of Candida albicans and Cryptococcus neoformans.

A new medium composed of Tween 80, oxgall, caffeic acid, and Davis agar (TOC) that provides for the rapid presumptive identification of Candida albicans and Cryptococcus neoformans is described herein. C. albicans is differentiated from other yeasts by the sequential production of germ tubes and chlamydospores. In a comparison with cormeal agar control plates, there was an increase of chlamydospore-forming strains of C. albicans (97.1% versus 87.2%) and a decrease in the time required for chlamydospore formation (24 h versus 48 h). C. neoformans produced a brown pigment of TOC, which is specific for its identification, thus differentiating it from the other yeasts. A comparison of 24-h pigment production by C. neoformans on TOC with that of birdseed agar showed a dark, coffee brown color in the former cultures and a light brown color in the latter. The change in pigmentation of C. neoformans, as well as morphological changes in C. albicans, can be induced within 3 to 12 h and in not more than 24 h on the TOC medium.

Agar↗
PubMed1977

Rapid method for determining nitrate utilization by yeasts.

A test for the nitrate-reductase activity in yeasts has been developed, in which the reaction may be read after only 10 min of incubation. The rapidity of the test is due to the optimization of pH, substrate concentration, and temperature for the reaction.

Culture Media↗
PubMed1975

Factors affecting filamentation in Candida albicans: relationship of the uptake and distribution of proline to morphogenesis.

When glucose was present in high concentration, Candida albicans formed filaments in a phosphate-buffered medium, regardless of the nitrogen source. In lower concentrations of glucose, filamentation occurred only when various members of the glutamate, succinyl, or acetoacetyl-coenzyme A families of amino acids were used as sole nitrogen sources. Yeast morphology could be maintained either by replacing the amino acids in the medium with ammonium chloride or by making the medium high in phosphate or biotin. Studies using [U-14C]proline indicated that proline was catabolized in a manner consistent with the generation of increased cellular reducing potential and that the proline label entered into the Kreb's cycle. A reduction in Kreb's cycle activity was evidenced by an initial increase and then a rapid drop of the total organic acid content of the cells as well as in specific Kreb's cycle intermediates. Filamentation under conditions of low phosphate, high glucose, and increased cellular reduction potential, accompanied by a decrease in Kreb's cycle activity, suggests that morphogenesis in C. albicans is correlated with a Crabtree-like effect, i.e., repression of mitochondrial activity.

Candida albicans↗
PubMed1975

Factors affecting filamentation in Candida albicans: changes in respiratory activity of Candida albicans during filamentation.

Glucose metabolism and respiration of Candida albicans were compared under conditions which permitted either maximal filamentous or maximal yeast growth. Changes in metabolism were monitored by comparing the quantities of ethanol produced, CO2 evolved, and oxygen consumed. Filamenting cultures produced more ethanol and less CO2 than yeasts, with oxygen consumption in the former concomitantly slower than that of the latter. Studies involving cofactors and inhibitors associated with electron transport imply that a transfer of electrons away from flavoprotein is required for maintenance of yeast morphology. Conditions consistent with a buildup of reduced flavoprotein, however, favored filament formation. These changes were expressed metabolically as a shift from an aerobic to a fermentative metabolism. The results presented are consistent with hypotheses correlating filament production with changes in carbohydrate metabolism and an interruption of electron transfer within the cell.

Acridines↗
PubMed1975

Improved auxanographic method for yeast assimilations: a comparison with other approaches.

An improved pour-plate auxanographic method has been developed for determining the assimilation of 14 different carbohydrates by medically important yeasts. Reduction of a dye incorporated into the agar has been correlated with the growth and carbohydrate assimilation of the yeasts, allowing the speciation of many yeasts within 24 to 48 h. This technique has been found to compare more than favorably with existing yeast assimilation techniques, in terms of rapid identification, total cost, and technician time in preparing and inoculating the plates. The dye pour-plate auxanographic technique provides an easier-to-interpret, rapid, and reproducible method of mycological identification for small clinical laboratories.

Agar↗