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.