Development, characterization, and application of a Candida parapsilosis DNA fingerprinting method

The emergence of new bacterial and fungal pathogens in the hospital setting is of concern. Of the fungi, the isolation of Candida species from sites of infection has increased. Even though C. albicans still represents the most common fungal species isolated, other Candida species, like Candida parapsilosis, have become increasingly prevalent over the past two decades. C. parapsilosis causes superficial to deep infections, but has been recently cited for numerous systemic infections in intensive care units. To better understand the genetic relationships of isolates obtained from patients, a DNA fingerprinting method that has been previously used for other infectious fungi, especially Candida species, was developed for C. parapsilosis. Cp3-13 is a moderately repetitive probe and generates a complex fingerprinting pattern when hybridized to a Southern blot of restriction enzyme digested C. parapsilosis genomic DNA. Comparative analysis of fingerprinting patterns, based upon the presence and absence of bands, allows the assessment of genetic relatedness between isolates.; Characterization of Cp3-13 fingerprinting demonstrated that the method fulfilled the requirements necessary for an effective fingerprinting method. Therefore, the Cp3-13 fingerprinting method was applied to a collection of C. parapsilosis isolates that emanated from five hospitals. The isolates were collected from both neonatal intensive care units and surgery intensive care units from a several patients, health care workers, and the physical hospital environment. Fingerprinting of the isolates revealed that the majority of the isolates fell within a major genetic group of C. parapsilosis . Cluster analyses of the dendrograms generated from the fingerprinting data revealed that isolates from different patients in a single hospital could range from highly related to moderately related. Hospital endemic strains formed clusters of highly related isolates collected over relatively long time spans. The infecting population of C. parapsilosis is diverse: no particular genotype was associated with a geographical locale.; Cp3-13 fingerprinting proved to be an effective method for analyzing the genetic relatedness of strains, not only in the resolution that it provides, but also in reproducibility and archival qualities and will be useful in future epidemiological studies of C. parapsilosis.