PFGE genotyping plays a major role in the prevention and control of nosocomial candidiasis. It has been estimated that 10-20% of nosocomial bloodstream infections are due to Candida species (Jarvis, 1995) In addition to Candida albicans, Candida parapsilosis is emerging as a prominent bloodstream pathogen in the NICU. A multicenter cohort study demonstrated that NICU patients acquire C. parapsilosis from the hands of health care workers (Saiman et al., 2000, 2001). The use of PFGE technology to characterize isolates of Candida spp. has been successful in establishing that the gastrointestinal tract should be considered as a major endogenous reservoir for these organisms and that gastrointestinal colonization of infants has been strongly associated with sepsis (el-Mohandes et al., 1994) Another application of PFGE is in examining the DNA profiles of sequential yeast isolates recovered from the same infected patient over time to determine if one strain or several strains are involved in the infectious process. Although the antifungal susceptibility pattern of the isolates may vary, this might represent the emergence of resistance to current therapy in the same strain and not the acquisition of new strains (Bennett et al., 2004).
PFGE genotyping of Candida spp. can be performed with or without the restriction enzyme digestion. However, electrophoretic karyotyping analysis without enzyme digestion has been reported to provide sufficient discrimination for epidemiologic investigations (Espinel-Ingroff et al., 1999). When restriction enzymes are used for additional subtyping, BssHII, NotI, and Sfi are recommended for digestion of chromosomal DNA of Candida species (Table 9.1).
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