Discussion
Candida parapsilosis sensu lato and its cryptic species has become the predominant causing candidemia in some pediatric settings, especially in newborns, it is responsible for 17-50% of bloodstream infections episodes (11) and the incidence of fungemia caused by C . orthopsilosis and C. metapsilosis have been increasingly reported in recent years (12, 13). C .metapsilosis is a rare entity in nosocomial Candidainfections. Previous studies adjusted the frequency of infections attributed to C . metapsilosis from 0 to 35.5% of allC . parapsilosis sensu lato around the world (14). Studies suggested that C. parapsilosis sensu stricto andC . orthopsilosis are existed as human commensal, whileC. metapsilosis is an environmental organism (1), accordingly the high rate of isolation of C. metapsilosis in a local area of China has been attributed to have similar exogenous origins (15). Nevertheless, we presented a case of C. metapsilosis associated conjunctivitis in a neonate, which to our knowledge there has been no reported to date, following an extensive literature search. Conjunctivitis is a term broadly used to describe an inflammation of the conjunctiva.
C . parapsilosis sensu lato that can be isolated from soil, plants, domestic animals, insects, seawater and marine environment; can be also isolated from, skin, gastrointestinal tract and mucosal surfaces including eye, vaginal and birth canal (1). That is one of the main species of the microflora of the subungual space (1). Therefore, there is two manners for a neonate to develop C. parapsilosis sensu lato conjunctivitis, one way is eye colonization from mother to neonate via the birth canal and post-antibiotic invasion after use the antibacterial drops in neonate settings, hence Colonization precedes infection; and another is the eye injury through the contact with the colonized hands and fingernail beds of the nursing staff (1). Accordingly, conjunctivitis caused by Candida species in newborn is a common occurrence (2, 16, 17). Anyway, transmission of the organism into the bloodstream and the development of candidemia is possible. A case of horizontal transmission of C . parapsilosistransmitted from the hands of two nurses to the neonate’s conjunctiva and then to the bloodstream (2). Our finding suggests that C .metapsilosis can also be a human commensal, although, more researches are needed.
There are conflicting assessments in context of virulence and antifungal susceptibility pattern of C . metapsilosis (7, 11, 13, 18, 19). Nonetheless this species has been reported as the least virulent member of the C . parapsilosis complex, and the low frequency in clinical settings could be associated with this property and the disability of causing morphological changes and effects on the human cells and tissue culture models. Cell cultures exposed toC . metapsilosis releases the least hydrolytic enzymes and hemolytic factors, and represented the least biofilm production and psuedohyphae formation (14, 18). However, recent data indicated an increasingly important role of C . metapsilosis in human mycoses, especially in blood-stream infections, and its isolation from blood cultures deserves particular attention (15). It seems that a strain-dependent virulence mechanism might contribute to the invasiveness of this commonly non-virulent yeast (15)
It is remarked that accurate discrimination among cryptic species ofC. parapsilosis seems unnecessary due to similar antifungal susceptibility profile to commonly used azoles and amphotericin B. However, concerning to echinocandins, identification to the species level is necessary because of different susceptibility patterns (15). Although It is reported that C . orthopsiloss sensu stricto is less susceptible to amphotericin B, echinocandins, and fluconazole than C . metapsilosis and C . orthopsilosis , Canton et al showed the high susceptibility of these two cryptic species to nine antifungal (13). Hence, accurate characterization and discrimination of these cryptic species are important in the two aspects of epidemiological surveys and antifungal susceptibility pattern.