Occurrence of Fusarium oxysporum in the water and air distribution system of four hospitals in Sardinia (Tyrrhenian island, Italy)

VIRGILIO BALMAS; FRANCESCA FANCELLU; SILVANA SANNA; BARBARA SCHERM; ISMAEL MALBRÁN; ANGELA MARCELLO; QUIRICO MIGHELI

Martina Franca

Seminario; 13th European Fusarium Seminar; 2015

National Resarch Council - CNR ISPA

Several Fusarium species are able to infect human host and may cause onychomycosis, paronychia, keratitis, ulcers and dermatomycosis. However, the most alarming reports are related to Fusarium spp. acting as opportunistic pathogens in immunodeficient patients suffering from leukemia, HIV/AIDS, undergoing a chemotherapy, or having overcome an organ transplantation. In particularly serious cases, infections can lead to death. Fusaria belonging to the Fusarium oxysporum species complex (FOSC) are frequently isolated, both in hospital environments as well as from patients affected by fungal infection. A survey on hospital water and air distribution systems, including plumbing, was carried out in order to verify the presence of F. oxysporum in four major Sardinian hospitals. Departments as intensive care, hematology, pulmonology and the transfusion centers were included in the study. Two-hundred-and-seventy-one isolates of F. oxysporum were identified based on their morphology. Moreover, 127 of these were molecularly analysed for partial elongation factor gene sequences (EF-1 a) and/or for nearly full-length sequences of the nuclear ribosomal intergenic spacer region (IGS rDNA). The EF-1a and IGS rDNA gene sequences of 32 of these isolates were edited in Seaview v. 4.4.1 and aligned using the MUSCLE multiple sequence alignment method. The resulting dataset provided the basis to construct a maximum parsimony phylogenetic tree. Five different FOSC haplotypes were described: ST33; ST134; ST126; ST183 and ST172. The most frequently described haplotype was ST33 (67%), isolated at a percentage of 54% from water samples and at 41% from the plumbing system; closely followed by haplotype ST134, which was isolated mainly from sink drains at a 73% frequency. The only air borne isolate found belonged to the ST134 haplotype. A F. oxysporum strain was also isolated from a patient that was hospitalised in the department of intensive care. This isolate belonged to haplotype ST33, a haplotype also present in the water samples collected from the same unit.