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Characteristics of Biofilms Formed by C. parapsilosis Causing an Outbreak in a Neonatal Intensive Care Unit
Atsushi Miyake1,2, Kenji Gotoh1,2, Jun Iwahashi1
1Department of Infection Control and Prevention, Kurume University School of Medicine, Kurume 831-0011, Japan.
Background:
We dealt with the occurrence of an outbreak of Candida parapsilosis in a neonatal intensive care unit (NICU) in September 2020. There have been several reports of C. parapsilosis outbreaks in NICUs. In this study we describe our investigation into both the transmission route and the biofilm of C. parapsilosis.
Methods:
C. parapsilosis strains were detected in three inpatients and in two environmental cultures in our NICU. One environmental culture was isolated from the incubator used by a fungemia patient, and another was isolated from the humidifier of an incubator that had been used by a nonfungemia patient. To prove their identities, we tested them by micro satellite analysis. We used two methods, dry weight measurements and observation by electron microscopy, to confirm biofilm.
Results:
Microsatellite analysis showed the five C. parapsilosis cultures were of the same strain. Dry weight measurements and electron microscopy showed C. parapsilosis formed biofilms that amounted to clumps of fungal cells.
Conclusions:
We concluded that the outbreak happened due to horizontal transfer through the humidifier of the incubator and that the C. parapsilosis had produced biofilm, which promoted an invasive and infectious outbreak. Additionally, biofilm is closely associated with pathogenicity.
Insights
Candida parapsilosis outbreaks in neonatal intensive care units (NICUs) can be transmitted via incubator humidifiers. Biofilm formation by this fungus promotes invasive infections, highlighting its pathogenicity.
Area of Science:
- Medical Mycology
- Infectious Disease Epidemiology
- Neonatal Care
Background:
- Reports of Candida parapsilosis outbreaks in neonatal intensive care units (NICUs) are increasing.
- This study investigated a specific outbreak of C. parapsilosis in a NICU in September 2020.
Purpose of the Study:
- To identify the transmission route of C. parapsilosis during the NICU outbreak.
- To investigate the role of biofilm formation in C. parapsilosis pathogenicity.
Main Methods:
- C. parapsilosis strains were isolated from patients and environmental sources (incubator, humidifier).
- Microsatellite analysis was used for strain identification.
- Biofilm formation was assessed using dry weight measurements and electron microscopy.
Main Results:
- All five C. parapsilosis isolates (three patient, two environmental) were identified as the same strain.
- C. parapsilosis demonstrated biofilm formation, appearing as clumps of fungal cells.
- The humidifier of an incubator was identified as a potential transmission source.
Conclusions:
- The outbreak was attributed to horizontal transmission via an incubator humidifier.
- C. parapsilosis biofilm formation contributes to invasive infections and pathogenicity in the NICU setting.
- Biofilm is a significant factor in the infectiousness and virulence of C. parapsilosis.
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