Isolation and drug susceptibility of Candida parapsilosis sensu lato and other species of C. parapsilosis complex from patients with blood stream infections and proposal of a novel LAMP identification method for the species.

Candida parapsilosis complex (CPC) is the third Candida species isolated in blood cultures of patients from our Hospital, following C. albicans and C. tropicalis. From 2006 to 2010, the median annual distribution of CPC was 8 cases/year. Records of 36 patients were reviewed. CPC were 31 (86.1%) C. parapsilosis; 4 (11.1%) C. orthopsilosis; and 1 (2.8%) C. metapsilosis. Clinical characteristics were central venous catheter, 34 (94.4%); parental nutrition, 25 (70%); surgery, 27 (57.9%); prior bacteremia, 20 (51.3%); malignancy, 18 (50%). General mortality was 47.2%. Death was higher in immunosuppressed patients (17 vs. 11; p = 0.003). Three out four (75%) patients with C. orthopsilosis and 14 out 31 (45.2%) with C. parapsilosis died (p = 0.558). Thirty-nine individual isolates were tested for susceptibility to seven antifungal drugs, with MICs values showing susceptibility to all of them. Two isolates, one C. orthopsilosis and one C. parapsilosis, had fluconazole MIC = 4 μg/mL. Differentiation among CPC has implication in caring for patients with invasive candidiasis since there are differences in virulence, pathogenicity and drug susceptibility. A method targeting the topoisomerase II gene based on loop-mediated isothermal amplification (LAMP) was developed. LAMP emerges as a promising tool for the identification of fungal species due to the high sensitivity and specificity. LAMP can be performed at the point-of-care, being no necessary the use of expensive equipment. In our study, the method was successful comparing to the DNA sequencing and proved to be a reliable and fast assay to distinguish the three species of CPC.