Recurrent isolation of an uncommon yeast, Candida pararugosa, from a sarcoma patient

A yeast was repeatedly isolated from the saliva of a sarcoma patient. A relatively uncommon species, Candida maris, was identified based on the API 20C profile. The yeast species most frequently obtained from the patient's mother and from clinic staff was Candida albicans. A comparison of the yeast obtained from the patient with the type strain of C maris strongly suggested that the former was not representative of C maris. Analysis of partial ribosomal DNA sequences of the patient strain and from the type strain of C maris showed that the two are phylogenetically not closely related. The patient strain was very close to Candida pararugosa, a relatively uncommon asporogenous yeast. DNA reassociation studies among C pararugosa and patient isolates showed that they were conspecific. We could not determine the source of the yeast infection. This case will alert hospital staff to be aware of the possibility of unexpected environmental microorganisms as causes of infections, colonizations and persistent environmental contamination events in immunocompromised patients.