Modalidades de la Prueba del Tubo Germinal / Modalities of the Germ Tube Test

Las infecciones por levaduras del género Candida, en la actualidad son cada vez más frecuentes, particularmente cuando se presentan condiciones que inmunosuprimen al paciente, como el Síndrome de Inmunodeficiencia Adquirida y el uso de quimioterápicos e inmunomoduladores, entre otros. Candida albicans es la especie del género que se aísla con mayor frecuencia. Entre las pruebas de identificación para las especies de levaduras del género Candida se encuentran la evaluación de las características macroscópicas de las colonias, pruebas físiológicas, como la prueba del tubo germinal, termotolerancia, auxanograma, zimograma, ureasa y resistencia a la cicloheximida, entre otras. De estas, la prueba del tubo germinal es una prueba sencilla y rápida que puede ejecutarse de varias formas. De manera tradicional se ha realizado en tubo y con suero, aunque también se puede realizar en placa. En este trabajo se revisan las diversas formas de realizar esta prueba y se describe una modalidad adicional, producto de la experiencia diaria en el trabajo de laboratorio, con la ventaja del ahorro de material de vidrio y tiempo.

At the present time, the infections by yeasts of the genera Candida, are more and more frequent, particularly when exists inmunosuprimen conditions, like the Acquired Immunodeficiency Syndrome, the use of quimioterapics and inmunomodulators, among others. Candida albicans is the species most frequently isolated from clinical samples. Among the identification tests of the yeasts species of the genera Candida are the evaluation of colony characteristics, physiological and biochemical tests like the germ tube, termotolerancy, auxonogram, zimogram, urease, resistance to cicloheximide, among others. The germ tube test is a simple and fast test, of which several forms exist to carry out it. The traditional way has been made in tube, with serum, although it´s possible to be made in plate. Here we present the modality to directly make the test of the germ tube between slide and slide cover, with advantage of time saving and glass material saving.

Appropriate Condition of Germ Tube Formation as Presumptive Identification Test for Candida albicans / 대한의진균학회지

BACKGROUND: Candida albicans is the most prevalent species found in human yeast infections. The germ tube test is still frequently used for its rapid presumptive identification. Recently Candida dubliniensis as well as C. albicans has been reported to form germ tubes. OBJECTIVE: The purpose of this study was to evaluate the germ tube test at various conditions for rapid presumptive identification of C. albicans. METHODS: C. albicans ATCC 14053, C. albicans ATCC 18804, C. dubliniensis ATCC MYA 646, and C. dubliniensis KCTC 17427 were tested. Human pooled serum (HPS), HBV, HCV infected patient serum, fetal bovine serum (FBS) and rabbit serum (RS) were used for germ tube test. The germ tube formation was evaluated at different keeping condition of various sera, after mixing with 5 different bacterial suspensions and at various incubation conditions. RESULTS: The germ tube formation of C. albicans was more in the RS or FBS than in the HPS. For the various sera fresh sample was always the best expression of germ-tube forming ability. In the HCV infected patient serum and mixing with Pseudomonas aeruginosa germ tube formation was suppressed. C. dubliniensis did not form germ tube in the HPS, only formed in the FBS or RS. CONCLUSION: For rapid presumptive identification of C. albicans not C. dubliniensis the best selection of serum is the fresh HPS. We recommend the examination with isolated colony free from bacteria after incubation for 2 to 3 hours.

Rapid Identification of Candida albicans by 'Spiking' on Blood and Chocolate Agar Plates / 대한임상미생물학회지

BACKGROUND: Colonial morphology of Candida albicans known as 'spiking' on a primary isolation blood agar plate (BAP) allows rapid and presumptive identification of C. albicans. We evaluated the 'spiking' appearance to identify C. albicans. METHODS: A total of 144 fully identified clinical isolates of yeasts and 10 type strains of yeasts were tested. All isolates obtained from the 5% CO2 incubation on BAP and chocolate agar plate (CHOC) were macroscopically examined for the presence of an irregular margin (spiking). The germ tube test was performed by incubating test organisms in 0.5 mL of pooled human sera. RESULTS: The sensitivity for BAP-spiking, CHOC-spiking and germ tube test were 93.7%, 91.1%, and 98.7%, respectively. The specificity for three methods was 100%. CONCLUSION: Use of the spiking identification on BAP can be useful for the economic and rapid presumptive identification of C. albicans in routine laboratories.

Comparison of Murex Candida albicans CA50 with the Germ Tube Test for Presumptive Identification of Candida albicans / 대한임상병리학회지

BACKGROUND: Rapid and reliable identification of Candida albicans becomes more important because the incidence of yeast infections has increased in recent years. Murex C. albicans 50(CA50) assay was developed for rapid and presumptive identification of C. albicans. We evaluated the CA50 assay to identify C. albicans. METHOD: Seventy four yeast isolates from clinical specimens were tested with CA50 and germ tube test. They were identified to species level by API 20C and chlamydospore agar test. RESULT: Of the 74 isolates, 52 were C. albicans and 22 were non-albicans Candida. The sensitivity and specificity for CA50 were 88.5% and 86.4%, respectively. The sensitivity and specificity of the germ tube test using human serum were 88.5% and 90.9% respectively, and those using fetal bovine serum(FBS) were 92.3% and 90.9% respectively. CONCLUSION: CA50 was a rapid and easy-to-perform test, and it was comparable to germ tube test in regard of sensitivity and specificity.