An outbreak of Candida parapsilosis fungemia involving 17 neonatal intensive care unit (NICU) patients was studied. There were 14 blood culture and nine colonizing isolates from other sites available. The hands of NICU healthcare workers (HCW) yielded eight isolates. Screening of the isolates by random amplified polymorphic DNA (RAPD) method showed only three profiles. Typing by restriction fragment length polymorphism (RFLP) revealed all blood isolates were RFLP subtype VII-1. Among the nine infant colonizing isolates, there were four different RFLP subtypes; four of the isolates were subtype VII-1. Seven of the eight isolates from HCW were RFLP subtype VII-1. The majority of infant colonizers were not found in the blood, suggesting a possible direct spread of the epidemic subtype VII-1 strain from HCW hands to infant blood. The source of the infant colonizing strains is unclear, but non-VII-1 strains may be largely of maternal origin and VII-1 strains from HCW. These findings reinforce prior studies that have implicated HCW hands as the source of nosocomial, including neonatal, fungemia.
Epidemiological studies of Candida parapsilosis have been performed by molecular methods. To compare two prominent methods, 29 isolates, typed by multilocus sequence typing (MLST), were typed by restriction fragment length polymorphism (RFLP). Of the 19 proposed Candida parapsilosis sensu stricto isolates [group I by internally transcribed spacer (ITS1) sequence], the most commonly encountered species, 17 were RFLP type VII-1. The species Candida orthopsilosis (eight isolates) and Candida metapsilosis (two isolates) consisted of five and one other RFLP types, respectively; none were VII-1. None of the non-VII-1 types were in more than one ITS group. VII-1 is the most common RFLP type (176/203 in continuing studies), and C. parapsilosis sensu stricto is similarly dominant in other studies, and cannot be subtyped by RFLP or MLST. RFLP subtype VII-1 and C. parapsilosis sensu stricto appear to be nearly identical; C. orthopsilosis, which can be subtyped by MLST, can also be subtyped by RFLP. C. metapsilosis appears rarely.
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