G484S Amino Acid Substitution in Lanosterol 14- Demethylase (ERG11) Is Related to Fluconazole Resistance in a Recurrent Cryptococcus neoformans Clinical Isolate
Five sequential Cryptococcus neoformans isolates recovered from an AIDS patient with recurrent meningitis were analyzed. Four isolates were fluconazole susceptible, while the fifth isolate developed fluconazole resistance. Analysis of the 14-α lanosterol demethylase gene (ERG11) showed a point mutation in the resistant strain responsible for the amino acid substitution G484S.
Objective: The presence of exogenous DNA in commercially available polymerase chain reaction (PCR) reagent preparations is a serious problem when amplifying conserved regions of bacteria. The preferred and currently in-use method of decontamination using 8-methoxypsoralen (8-MOP) and UVA requires re-standardization of decontamination with increasing concentrations of 8-MOP and UVA irradiation timings, if the DNA load of reagents is high due to lot-to-lot differences. The objective of this study was to develop a decontamination method, which would (i) work at the minimum reported concentration of 8-MOP and UVA irridation timings; and (ii) take care of inter-batch DNA-load variability of reagents.