Strain relatedness of Candida albicans strains isolated from children with leukemia and their bedside parents.

Candida yeasts are occasionally recovered from patients with leukemia in spite of antifungal therapy used during chemotherapy. It is not yet known whether yeasts in these patients are of endogenous or exogenous origin. We examined the strain relatedness of Candida albicans isolated from three patients with leukemia (A, B, and C) and their bedside parents using pulsed-field gel electrophoresis (PFGE), restriction fragment length polymorphism (RFLP) by SmaI digestion, and the Southern hybridization patterns of the RFLPs by the C. albicans-specific probe RPS1. SmaI digestion and Southern hybridization by RPS1 showed identical or similar patterns among Candida isolates in patients A and his mother, although their karyotypes were different. Isolates from patients B and both parents showed identical electrophoretic karyotypes, SmaI digestion patterns, and hybridization patterns. Since electrophoretic karyotypes are more variable than RFLPs and their hybridization patterns, the identity of the last two suggests a close relatedness between strains. Our results also suggest that transmission of yeast strains may have occurred between patient A and his mother and between patient B and her parents. Isolates from patient C and her mother are thought to have originated from different strains, since different patterns were obtained in electrophoretic karyotypes, SmaI digestion patterns, and Southern hybridization patterns.