Candida parapsilosis: from Genes to the Bedside

Abstract

SUMMARY Patients with suppressed immunity are at the highest risk for hospital-acquired infections. Among these, invasive candidiasis is the most prevalent systemic fungal nosocomial infection. Over recent decades, the combined prevalence of non-albicans Candida species outranked Candida albicans infections in several geographical regions worldwide, highlighting the need to understand their pathobiology in order to develop effective treatment and to prevent future outbreaks. Candida parapsilosis is the second or third most frequently isolated Candida species from patients. Besides being highly prevalent, its biology differs markedly from that of C. albicans, which may be associated with C. parapsilosis’ increased incidence. Differences in virulence, regulatory and antifungal drug resistance mechanisms, and the patient groups at risk indicate that conclusions drawn from C. albicans pathobiology cannot be simply extrapolated to C. parapsilosis. Such species-specific characteristics may also influence their recognition and elimination by the host and the efficacy of antifungal drugs. Due to the availability of high-throughput, state-of-the-art experimental tools and molecular genetic methods adapted to C. parapsilosis, genome and transcriptome studies are now available that greatly contribute to our understanding of what makes this species a threat. In this review, we summarize 10 years of findings on C. parapsilosis pathogenesis, including the species’ genetic properties, transcriptome studies, host responses, and molecular mechanisms of virulence. Antifungal susceptibility studies and clinician perspectives are discussed. We also present regional incidence reports in order to provide an updated worldwide epidemiology summary.

The transcriptional aftermath in two independently formed hybrids of the opportunistic pathogenCandida orthopsilosis

“…To fill in this gap, we here undertook a transcriptomic analysis of two independently formed hybrid strains from the emerging yeast pathogen Candida orthopsilosis (Pryszcz et al 2014; Schröder et al 2016). This yeast belongs to the CTG clade and is phylogenetically placed within the C. parapsilosis sensu lato species complex alongside with the other opportunistic pathogens C. parapsilosis (Pammi et al 2013; Tóth et al 2019) and C. metapsilosis (Tavanti et al 2005). It has been shown that most (~93%) of the clinical isolates of C. orthopsilosis are hybrids between parentals with ~5.1% nucleotide divergence.…”

Utility of two PCR‐RFLP‐based techniques for identification of Candida parapsilosis complex blood isolates

“…The incidence of nosocomial infections caused by Candida has risen significantly in recent decades. Among this genus, C. parapsilosis is the species that has most notably increased in incidence, causing 10%‐25% of candidaemias in neonates and patients in intensive care units 5,17,24 . Candida parapsilosis infections are associated with the use of medical devices, such as central venous catheters, parenteral nutrition administration and healthcare worker contact 5,25‐28 .…”

“…The incidence of invasive candidiasis has increased in recent decades, and Candida parapsilosis is a notable species of Candida . Depending on the geographical area, C. parapsilosis is the second most frequently isolated species, and in some hospitals in Europe, Asia and South America, it has even overtaken Candida albicans in incidence 1‐6 . C. parapsilosis infection predominates in low‐weight neonates, critically ill patients or those with cancer and is associated with the disruption of anatomical barriers by invasive procedures, such as central venous catheter placement, surgery and parenteral nutrition administration 3,5 .…”

“…Depending on the geographical area, C. parapsilosis is the second most frequently isolated species, and in some hospitals in Europe, Asia and South America, it has even overtaken Candida albicans in incidence 1‐6 . C. parapsilosis infection predominates in low‐weight neonates, critically ill patients or those with cancer and is associated with the disruption of anatomical barriers by invasive procedures, such as central venous catheter placement, surgery and parenteral nutrition administration 3,5 . In 2005, the three distinct clades formerly known as C. parapsilosis I, II and III were replaced by a complex of three closely related species: Candida parapsilosis sensu stricto , Candida orthopsilosis and Candida metapsilosis , respectively 7 .…”

“…External acquisition by medical devices is considered an important route of C. parapsilosis infection, and prolonged catheterisation has been demonstrated to be the most important underlying condition, with this factor being of greater relevance to the C. parapsilosis species complex than to C. albicans 2,5,16,17 . In 2015, Barbedo et al observed that the species identified in the catheter was not always responsible for the bloodstream infection, and different cryptic species of the C. parapsilosis complex could be identified in the same patient from both samples 18 …”