Evaluation of the Commercial Rapid Trehalose Test (GLABRATA RTT) for the Point of Isolation Identification of Candida glabrata Isolates in Primary Cultures
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Candidaemias account for 10–20% of nosocomial bloodstream infections depending on the study. Whilst Candida albicans remains the most frequently isolated species, Candida glabrata may be responsible for as many as 10–25% of all candidaemias. Moreover, C. glabrata is generally less susceptible to the azole antifungals than the majority of other pathogenic yeast species. Thus, a rapid test for the specific identification of isolates of C. glabrata would be useful for patient management if it could be performed at point of isolation, on primary cultures grown on standard mycological media directly from patient specimens. Under certain conditions, C. glabrata rapidly hydrolyses trehalose into glucose. The GLABRATA RTT kit allows detection of the preformed enzyme responsible for this action. This study has assessed GLABRATA RTT as an identification tool specifically at point of isolation. Sixty test isolates were evaluated: 39 clinical isolates of C. glabrata identified at the UK Mycology Reference Laboratory, examples of the recently described genetic relatives of C. glabrata, Candida nivariensis (n = 6) and Candida bracarensis (n = 1), and a selection of other common pathogenic yeast species (n = 14). The test provided results within 30 min. Although 77% (30/39) of confirmed C. glabrata isolates were correctly identified by GLABRATA RTT (positive trehalase test), 23% (9/39) of isolates gave negative or equivocal results. All other yeast species gave negative results. The performance of GLABRATA RTT in this study is compared to previous evaluations of the test which employed isolates pre-cultured on specialised media and to other existing conventional identification methodologies.
KeywordsCandida glabrata Identification Rapid trehalose test Candidaemia Point of isolation identification
We are grateful to the other members of the Mycology Reference Laboratory for their interest and advice.
Conflict of interest
AMB has previously received travel grants from Biotage AB, Sweden.
- 5.Pappas PG, Kauffman CA, Andes D, Benjamin DK Jr, Calandra TF, Edwards JE Jr, Filler SG, Fisher JF, Kullberg BJ, Ostrosky-Zeichner L, Reboli AC, Rex JH, Walsh TJ, Sobel JD. Infectious Diseases Society of America. Clinical practice guidelines for the management of candidiasis: 2009 update by the Infectious Diseases Society of America. Clin Infect Dis. 2009;48:503–35.PubMedCrossRefGoogle Scholar
- 16.Bishop JA, Chase N, Magill SS, Kurtzman CP, Fiandaca MJ, Merz WG. Candida bracarensis detected among isolates of Candida glabrata by peptide nucleic acid fluorescence in situ hybridization: susceptibility data and documentation of presumed infection. J Clin Microbiol. 2008;46:443–6.PubMedCrossRefGoogle Scholar
- 17.Linton CJ, Borman AM, Cheung G, Holmes AD, Szekely A, Palmer MD, Bridge PD, Campbell CK, Johnson EM. Molecular identification of unusual pathogenic yeast isolates by Large Ribosomal Subunit gene sequencing: 2 years experience at the UK Mycology Reference Laboratory. J Clin Microbiol. 2007;45:1152–8.PubMedCrossRefGoogle Scholar
- 25.Parant F, Freydiere AM, Gille Y, Boiron P, Odds FC. A “one minute” trehalase detection test for the identification of Candida glabrata. J Mycol Med. 2001;11:26–31.Google Scholar
- 28.Marklein G, Josten M, Klanke U, Müller E, Horré R, Maier T, Wenzel T, Kostrzewa M, Bierbaum G, Hoerauf A, Sahl HG. Matrix-assisted laser desorption ionization-time of flight mass spectrometry for fast and reliable identification of clinical yeast isolates. J Clin Microbiol. 2009;47:2912–7.PubMedCrossRefGoogle Scholar
- 29.Quiles-Melero I, García-Rodríguez J, Gómez-López A, Mingorance J. Evaluation of matrix-assisted laser desorption/ionisation time-of-flight (MALDI-TOF) mass spectrometry for identification of Candida parapsilosis, C. orthopsilosis and C. metapsilosis. Eur J Clin Microbiol Infect Dis. 2012;31:67–71.Google Scholar