BACKGROUND: The LightCycler(TM) combines rapid amplification of nucleic acids in glass capillaries with melting curve analysis based on fluorescence resonance energy transfer for the sensitive detection of point mutations in various settings, such as drug resistance and hereditary diseases. Point mutations leading to an altered structure of lanosteroldemethylase, the target enzyme of the fungistatic azoles, are an important mechanism of acquired resistance in Candida albicans. METHODS: We screened 13 fluconazole-resistant C. albicans and 21 fluconazole-resistant C. tropicalis strains (minimum inhibitory concentration >128 mg/L), isolated from patients with AIDS, for the presence of defined point mutations by comparing conventional cycle sequencing with a newly designed LightCycler-based assay. RESULTS: In C. tropicalis, 5 of 21 isolates showed the wild-type sequence, and 8 of 21 showed the homozygous nucleotide exchange thymine to cytosine at position 1554 (T1554C). A heterozygous genotype was detected in 8 of 21 isolates by the LightCycler, but in only 3 of 21 isolates by conventional cycle sequencing. In 2 of 13 C. albicans isolates, a homozygous point mutation leading to an amino acid exchange at position 464 (glycine to serine) was detected in both assays. CONCLUSION: The LightCycler technique offers standardized, fast, sensitive, and reproducible detection of point mutations in different Candida spp.
BACKGROUND: The LightCycler(TM) combines rapid amplification of nucleic acids in glass capillaries with melting curve analysis based on fluorescence resonance energy transfer for the sensitive detection of point mutations in various settings, such as drug resistance and hereditary diseases. Point mutations leading to an altered structure of lanosteroldemethylase, the target enzyme of the fungistatic azoles, are an important mechanism of acquired resistance in Candida albicans. METHODS: We screened 13 fluconazole-resistant C. albicans and 21 fluconazole-resistant C. tropicalis strains (minimum inhibitory concentration >128 mg/L), isolated from patients with AIDS, for the presence of defined point mutations by comparing conventional cycle sequencing with a newly designed LightCycler-based assay. RESULTS: In C. tropicalis, 5 of 21 isolates showed the wild-type sequence, and 8 of 21 showed the homozygous nucleotide exchange thymine to cytosine at position 1554 (T1554C). A heterozygous genotype was detected in 8 of 21 isolates by the LightCycler, but in only 3 of 21 isolates by conventional cycle sequencing. In 2 of 13 C. albicans isolates, a homozygous point mutation leading to an amino acid exchange at position 464 (glycine to serine) was detected in both assays. CONCLUSION: The LightCycler technique offers standardized, fast, sensitive, and reproducible detection of point mutations in different Candida spp.
Authors: M J Espy; J R Uhl; L M Sloan; S P Buckwalter; M F Jones; E A Vetter; J D C Yao; N L Wengenack; J E Rosenblatt; F R Cockerill; T F Smith Journal: Clin Microbiol Rev Date: 2006-01 Impact factor: 26.132
Authors: Andreas Dix; Kristin Czakai; Jan Springer; Mirjam Fliesser; Michael Bonin; Reinhard Guthke; Anna L Schmitt; Hermann Einsele; Jörg Linde; Jürgen Löffler Journal: Front Microbiol Date: 2016-03-21 Impact factor: 5.640