Comparison of the MUREX C. albicans, Albicans-Sure, and BactiCard Candida test kits with the germ tube test for presumptive identification of Candida albicans

Abstract

The MUREX C. albicans (MC) (Murex Diagnostics), Albicans-Sure (AS) (Clinical Standards Laboratories), and BactiCard Candida (BC) (Remel) test kits were compared with the germ tube (GT) test for the rapid, presumptive identification of Candida albicans. All three test kits detect the enzymes L-proline aminopeptidase and ␤-galactosaminidase in yeast cells grown on culture media and are based on the principle that C. albicans produces both enzymes whereas other yeasts produce only one or neither of the enzymes. The organisms evaluated were fresh clinical isolates identified by methods routinely used in our laboratory (API 20C system and conventional methods) and included 303 C. albicans isolates, 153 Candida glabrata isolates, 70 Candida tropicalis isolates, 36 Candida parapsilosis isolates, 13 isolates of other Candida spp., 5 Cryptococcus neoformans isolates, and 3 Saccharomyces cerevisiae isolates. The MC, AS, BC, and GT tests detected 299 (98.7%), 300 (99.0%), 301 (99.3%), and 287 (94.7%) C. albicans isolates, respectively. There was one false-positive result with both the MC and BC kits and two false-positive results with the GT test. The enzymatic methods evaluated in this study provide rapid and accurate alternatives to the GT test for the presumptive identification of C. albicans.

Comparison of 12 liquid media for germ tube production of Candida albicans and C. tropicalis

“…As a consequence, it seems to make sense to investigate whether there are certain conditions allowing for 100% specificity and 100% sensitivity. In the literature, GTT was reported to have sensitivities between 94.1% and 99%, and specificities between 94.4% and 100% 5,7,10,11,16,18,21,22 …”

“…This test is based on the observation that yeast cells produce short, slender, tube‐like structures (germ tubes) when incubated in serum at 30–37 °C for 2–4 h. It is a simple, rapid, easy‐to‐perform, cheap and well‐known method 4–6 . However, up to 5% of C. albicans isolates were shown to be germ tube negative 2–4,7–11 . It has also been reported that non‐ C. albicans yeasts, i.e.…”

Evaluation of Mueller‐Hinton‐agar as a simple medium for the germ tube production of Candida albicans and Candida dubliniensis

“…However, these liquids often showed less sensitivity than human serum, ranging from 35% for horse serum, 62% for peptone water and TSB, 90% for rabbit serum, to 95% for a mixture of three parts of rabbit serum and two parts of TSB. 8,10,11 An alternative method based on agar media using DalmauÕs technique has been developed. The advantage of this technique is that there is no need for a standardised inoculum and no preparation of smears.…”

“…18 The specificity of the GTT for the presumptive identification of C. albicans was generally high, ranging from 96% to 100%. 6,7,10,11 Candida tropicalis can produce germ tube-like structures, which may be confused with true germ tubes after an extended incubation time of 3 h. Hilmioglu et al found that an incubation time of 2 h resulted in the best specificity. 10 In our own preliminary experiments, incubation of the MH-plates for 3 h at 37°C resulted in the C. tropicalis control strain producing germ tube-like filaments.…”

Comparison of the Rapid Yeast Plus Panel with the API20C Yeast System for Identification of Clinically Significant Isolates of Candida Species

“…Conventional methods for the identification of clinically significant yeasts are time-consuming and labor-intensive. Rapid screening methods, including the ability to produce germ tubes (8,13) and production of the enzymes beta-galactosaminidase and L-proline aminopeptidase (2,4,7,11), may be used to presumptively identify C. albicans. Other rapid screening methods involve the use of differential culture media (1,6,10,12).…”