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Multilocus sequence typing for Candida albicans strains from patients with candidaemia

Abstract number: P1700

Shin J.H., Yoon M., Lee J.S., Jung S.I., Kee S., Kim S., Shin M., Suh S., Ryang D.

Objectives: To investigate the clonal stabilities or evolutionary changes of C. albicans isolates from candidaemia patients, and to investigate whether the candidaemia agents diagnosed at our hospital are related to internationally distributed C. albicans lineages, we performed multilocus sequence typing (MLST) of 45 C. albicans isolates from various clinical specimens of 23 patients with candidaemia.

Methods: The internal regions of seven housekeeping genes (AAT1a, ACC1, ADP1, MPIb, SYA1, VPS13, and ZWF1b) were sequenced. The MLST results were compared with the results of Southern blot hybridisation of the C1 fragment of Ca3 as the probe (C1 fingerprinting) and pulsed-field gel electrophoresis (PFGE) analysis. PFGE analysis included restriction endonuclease analysis of genomic DNAs using BssHII (REAG-B) and SfiI (REAG-S).

Results: Overall, the 45 isolates yielded 20 unique diploid sequence types (DSTs) by MLST, 19 different REAG-B patterns, 18 REAG-S patterns, and 21 C1 fingerprinting types. By MLST, 33 isolates from 18 patients belonged to new sequence types (16 distinct DSTs), whereas 12 isolates from 5 patients belonged to the previously described types (4 DSTs). The intra-individual isolates showed minor genetic differences (microevolution) by MLST (5 patients), REAG-B (4 patients), REAG-S (2 patients), and C1 fingerprinting (4 patients). All of four genotyping methods used revealed that two distinct genotypes were shared among 10 isolates from nine patients in a neonatal intensive care unit, suggesting two nosocomial clusters. However, none of the blood isolates from these two clusters showed any microevolution by any of the genotyping methods used.

Conclusion: The present study shows that MLST had similar or greater discriminatory ability than PFGE or C1 fingerprinting, and some of the C. albicans strains that cause candidaemia at our hospital share the same MLST type with strains from other geographic regions of the world. In addition, a genetically stable strain of the C. albicans strains may be responsible for nosocomial cross-infection.

Session Details

Date: 19/04/2008
Time: 00:00-00:00
Session name: 18th European Congress of Clinical Microbiology and Infectious Diseases
Subject:
Location: Barcelona, Spain
Presentation type:
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