Candida parapsilosis in domestic laundry machines

Candida parapsilosis, although a human commensal, acts as an opportunistic pathogen associated with nosocomial infections, with a rising incidence worldwide. Its ecological characteristics are poorly understood. Human-made environments within dwellings, such as dishwashers and water distribution systems, represent major sources of fungi such as C. parapsilosis. Here, we investigated the presence of members of the C. parapsilosis complex in 99 washing machines in various dwellings in the city of Mersin, Turkey. We sampled three sites in each washing machine: (i) the washing powder drawers, (ii) fabric softener drawers, and (iii) rubber seals around the washing machine doors. Additionally, we recorded the type of cleanser used by each customer. Of note, 25.3% of sampled washing machines harbored C. parapsilosis strains, later identified as the members of the C. parapsilosis sensu stricto via internal transcribed spacer (ITS) sequencing. Out of the 29 isolates obtained, biofilm-forming ability and proteinase and esterase activities were recorded in 14, 11, and 4 of the isolates, respectively. Our results suggest that the washing machines investigated abundantly harbored C. parapsilosis sensu stricto; however, no single preferred isolation site or association with cleanser type was observed (P > .05). Furthermore, C. parapsilosis isolates grew at temperatures ranging from 10°C to 37°C, at pH values ranging from 4 to 10, and were found to tolerate 5-10% NaCl. Domestic laundry appliances as a potential source of C. parapsilosis infections are discussed.