Application of the DiversiLab system for tracing the source of the mixed infections caused by Cryptococcus neoformans var. grubii from a patient with systemic lupus erythematosus

摘要

Two strains of Cryptococcus neoformans (PU 66 and PU112) were simultaneously isolated from a patient with systemic lupus erythematosus. We aimed to trace the source of the mixed infections. Multi-locus sequence typing (MLST) and the DiversiLab system analyses were performed on the 2 clinical and 23 environmental C. neoformans from pigeon droppings, 11 from the home (H1) the patient visited, 12 from another home (H2) as control. All the strains were uniformly genotyped as C. neoformans var. grubii VNI. Clinical strain PU66 and all the H1 isolates had the same sequence type (ST) - ST5, while for PU112 a new ST was observed - ST265. However, there was only one single base of 7 MLST loci difference between PU66 and PU112. Sequence types of the H2 strains were ST31 and ST297. DiversiLab analysis showed that strain similarity between the two clinical strains was 96.7%. In relation to environmental samples, the highest strain similarity (99.3%) was observed for PU66 and PU70 (H1). However, none of the environmental isolates had similarity over 98.6% comparing to PU112. One source of the mixed infections has been detected, but another needs further investigation.