Species Distribution, Virulence Factors, and Antifungal Susceptibility Among Candida parapsilosis Complex Isolates Recovered from Clinical Specimens

Abstract

The Candida parapsilosis complex has emerged as an important fungal pathogen. In spite of this, relatively little is known about its characteristics. Thus, the purposes of this study were (1) to determine by BanI-RFLP-assay the occurrence of C. parapsilosis complex species among 81 clinical isolates primarily identified as C. parapsilosis; (2) to evaluate their in vitro production of virulence factors; and (3) to compare their susceptibility profiles, grown as planktonic cells and biofilms, against amphotericin B, fluconazole, voriconazole, and caspofungin by following the Clinical and Laboratory Standards Institute (CLSI) guidelines. Seventy-seven isolates (95%) were identified as C. parapsilosis sensu stricto, 2 (2.5%) as C. orthopsilosis, and 2 (2.5%) as C. metapsilosis. Protease activity was detected in 29 (37.7%) isolates of C. parapsilosis sensu stricto, whereas only 7 (9.1%) exhibited phospholipase activity. None of the C. metapsilosis or C. orthopsilosis was able to produce protease or phospholipase. Biofilm production was detected in 35 (43.2%) isolates, among which 33 were C. parapsilosis sensu stricto and 2 were C. orthopsilosis. Antifungal resistance was uncommon; only one C. metapsilosis was fluconazole resistant. However, biofilm-producing isolates showed a marked resistance to all antifungal agents tested, particularly to voriconazole. This knowledge could be of clinical relevance for guiding therapeutic decisions.

In vitro evaluation of hydrolytic enzyme activity and biofilm formation of Candida parapsilosis species complex from a nosocomial environment

“…Of the seven C. metapsilosis isolates, five produced proteinase, and interestingly, one was found to produce both enzymes. Phospholipase production is not usual for this species; the absence of PL activity in C. metapsilosis isolates has been previously described 13 . Although the role of PL in Candida virulence remains unclear, some authors recognize the secretion of proteinases as an important virulence factor, which is immunogenic during infection and able to promote the degradation of host defense proteins 3 .…”

Candida parapsilosis: from Genes to the Bedside

“…Similarly, additional studies reported that Ͼ88% of C. parapsilosis clinical isolates actively secreted these enzymes (168,(193)(194)(195). On the other hand, others reported a lower number (Ͻ37%) of clinical strains producing hydrolytic proteases (196)(197)(198)(199). Although there is wide variability among C. parapsilosis isolates in terms of Sap production, it is commonly agreed that isolates derived from host surfaces (e.g., skin or vaginal mucosa) are more likely to produce and secrete these enzymes than those obtained from systemic infections or from the environment.…”

“…C. parapsilosis also secretes phospholipases albeit with wide intraspecies variation, with studies reporting that 9 to 90% of clinical isolates produce the enzyme (193,196,198,199). However, their contribution to pathogenicity is still a matter of debate, as there is no direct link between their expression and the degree of virulence.…”

Virulence factors, antifungal susceptibility and molecular mechanisms of azole resistance among Candida parapsilosis complex isolates recovered from clinical specimens

“…So, further studies are needed to better understand the characteristics, including putative virulence traits, drug resistance trends, especially of the two rarely isolated species, C. orthopsilosis and C. metapsilosis . A better knowledge could have clinical relevance, as it may be useful in guiding therapeutic decisions [ 13 ].…”