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Investigation of Candida albicans transmission in a surgical intensive care unit cluster by using genomic DNA typing
A Voss1, M A Pfaller, R J Hollis
1Department of Internal Medicine, University of Iowa College of Medicine, Iowa City 52242, USA.
Abstract:
An apparent outbreak of serious Candida albicans infections (n = 6) occurred in a surgical intensive care unit over a 4-week period. Four patients developed C. albicans bloodstream infections. An additional patient developed catheter-related C. albicans infection; the sixth patient developed an infection of cerebrospinal fluid. C. albicans was isolated from the hands of five health care workers (17%) and the throat of one health care worker (3%) during the outbreak investigation. Karyotyping and restriction endonuclease analysis of genomic DNA with BssHII of 23 C. albicans isolates from patients and the 6 health care worker isolates revealed 9 and 12 different patterns, respectively. Three of six patients appeared to be infected with the same C. albicans strain (two bloodstream infections and one cerebrospinal fluid infection). The hands of a health care worker were colonized with strain that appeared identical to an isolate from a patient prior to infection of the patient. However, restriction endonuclease analysis with SfiI found differences among the isolates determined to be identical by the other two methods. Karyotyping alone does not appear to be sufficient to differentiate between outbreak and control isolates. Restriction endonuclease analysis typing may be a more sensitive method than karyotyping alone in the investigation of a cluster of C. albicans infections. Furthermore, the use of more than one restriction enzyme may be necessary for optimal strain discrimination in restriction endonuclease analysis of genomic DNA.
Insights
An intensive care unit outbreak of Candida albicans infections was investigated. Restriction endonuclease analysis proved more effective than karyotyping for identifying the same fungal strain in patients and healthcare workers.
Area of Science:
- Medical Microbiology
- Infectious Diseases
- Hospital Epidemiology
Background:
- A cluster of serious Candida albicans infections occurred in a surgical intensive care unit.
- Candida albicans is an opportunistic fungal pathogen causing significant healthcare-associated infections.
Purpose of the Study:
- To investigate an outbreak of Candida albicans infections in a surgical intensive care unit.
- To evaluate the effectiveness of different molecular typing methods for strain discrimination.
Main Methods:
- Collected Candida albicans isolates from infected patients and healthcare workers.
- Performed molecular typing using karyotyping and restriction endonuclease analysis (REA) with BssHII and SfiI enzymes.
- Compared typing results to identify potential transmission routes and outbreak strains.
Main Results:
- Six cases of Candida albicans infection were identified, including bloodstream, catheter-related, and cerebrospinal fluid infections.
- Candida albicans was isolated from healthcare workers' hands and throat, suggesting potential transmission.
- REA with BssHII showed similarities between patient and healthcare worker isolates, but SfiI REA revealed differences, indicating greater discriminatory power.
Conclusions:
- Karyotyping alone was insufficient for differentiating outbreak and control isolates.
- Restriction endonuclease analysis is a more sensitive method for investigating Candida albicans outbreaks.
- Using multiple restriction enzymes enhances strain discrimination in REA for epidemiological investigations.