Occurrence and genetic variability of Candida parapsilosis sensu lato in Hungary

Genetic Diversity of Candida spp. Isolates Colonizing Twins and Their Family Members

A wide range of options for studying Candida species are available through genetic methods. Twins, particularly monozygotic ones and their families may be fitting subjects for studying those microorganisms. The question is: How specific can yeast flora be in an individual? The study aimed to analyze the strain relatedness among commensal yeasts isolated from various parts of the bodies of healthy people and to compare correlations between the genotypes of the isolates. Yeasts were isolated from 63 twins and their family members (n = 25) from the oral cavity, anus, interdigital space and navel. After species identification, Candida albicans (n = 139), C. parapsilosis (n = 39), C. guilliermondii (n = 25), C. dubliniensis (n = 11) and C. krusei (n = 9) isolates were analyzed using the random amplified polymorphic DNA polymerase chain reaction (RAPD-PCR) optimization method. The similarities between the strains were calculated based on the Dice (Sab) coefficient and are displayed graphically as dendrograms. Using cluster analysis, the following relatedness was distinguished: 13 genotypes and three unique (Un) patterns among C. albicans; 10 genotypes and four Un patterns among C. parapsilosis; three genotypes and one Un pattern among C. guilliermondii and C. dubliniensis; and three genotypes among C. krusei isolates. The presence of identical, similar or both genotypes among the strains isolated from family members shows the transmission of yeasts between ontocenoses in the same person and between individuals. The similarity between the genotypes of C. albicans, C. guilliermondii, C. dubliniensis and C. krusei was more remarkable than between the genotypes of C. parapsilosis in the strains isolated from ontocenoses of the same individual and their family members. The degrees of genetic similarity between Candida spp. strains isolated from monozygotic twins and those obtained from their relatives did not differ.

Clinical Performance of the Novel GenMark Dx ePlex Blood Culture ID Gram-Positive Panel

Rapid identification from positive blood cultures is standard of care (SOC) in many clinical microbiology laboratories. The GenMark Dx ePlex Blood Culture Identification Gram-Positive (BCID-GP) Panel is a multiplex nucleic acid amplification assay based on competitive DNA hybridization and electrochemical detection using eSensor technology. This multicenter study compared the investigational-use-only (IUO) BCID-GP Panel to other methods of identification of 20 Gram-positive bacteria, four antimicrobial resistance genes, and both Pan Candida and Pan Gram-Negative targets that are unique to the BCID-GP Panel.

Rapid identification from positive blood cultures is standard of care (SOC) in many clinical microbiology laboratories. The GenMark Dx ePlex Blood Culture Identification Gram-Positive (BCID-GP) Panel is a multiplex nucleic acid amplification assay based on competitive DNA hybridization and electrochemical detection using eSensor technology. This multicenter study compared the investigational-use-only (IUO) BCID-GP Panel to other methods of identification of 20 Gram-positive bacteria, four antimicrobial resistance genes, and both Pan Candida and Pan Gram-Negative targets that are unique to the BCID-GP Panel. Ten microbiology laboratories throughout the United States collected residual, deidentified positive blood culture samples for analysis. Five laboratories tested both clinical and contrived samples with the BCID-GP Panel. Comparator identification methods included each laboratory’s SOC, which included matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) and automated identification systems as well as targeted PCR/analytically validated real-time PCR (qPCR) with bidirectional sequencing. A total of 2,342 evaluable samples (1,777 clinical and 565 contrived) were tested with the BCID-GP Panel. The overall sample accuracy for on-panel organisms was 89% before resolution of discordant results. For pathogenic Gram-positive targets (Bacillus cereus group, Enterococcus spp., Enterococcus faecalis, Enterococcus faecium, Staphylococcus spp., Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcus lugdunensis, Listeria spp., Listeria monocytogenes, Streptococcus spp., Streptococcus agalactiae, Streptococcus anginosus group, Streptococcus pneumoniae, and Streptococcus pyogenes), positive percent agreement (PPA) and negative percent agreement (NPA) ranged from 93.1% to 100% and 98.8% to 100%, respectively. For contamination rule-out targets (Bacillus subtilis group, Corynebacterium, Cutibacterium acnes, Lactobacillus, and Micrococcus), PPA and NPA ranged from 84.5% to 100% and 99.9% to 100%, respectively. Positive percent agreement and NPA for the Pan Candida and Pan Gram-Negative targets were 92.4% and 95.7% for the former and 99.9% and 99.6% for the latter. The PPAs for resistance markers were as follows: mecA, 97.2%; mecC, 100%; vanA, 96.8%; and vanB, 100%. Negative percent agreement ranged from 96.6% to 100%. In conclusion, the ePlex BCID-GP Panel compares favorably to SOC and targeted molecular methods for the identification of 20 Gram-positive pathogens and four antimicrobial resistance genes in positive blood culture bottles. This panel detects a broad range of pathogens and mixed infections with yeast and Gram-negative organisms from the same positive blood culture bottle.

Nosocomial outbreak of Candida parapsilosis sensu stricto fungaemia in a neonatal intensive care unit in China

BACKGROUND

Candida parapsilosis is a common agent of fungaemia, but few outbreaks of Candida parapsilosis infection have been reported in China.

AIM

To elaborate an outbreak of nosocomial Candida parapsilosis sensu stricto fungaemia in a neonatal intensive care unit (NICU) of a comprehensive hospital in China from July to October 2017.

METHODS

Epidemics and characteristics of fungaemia cases were investigated. Surveillance samples were collected. Vitek 2 Compact System, internal transcribed spacer sequencing, and random amplified polymorphic DNA (RAPD) typing were conducted to identify the isolates. Antifungal susceptibility test was performed for all bloodstream isolates.

FINDINGS

Sixteen neonates were diagnosed as Candida parapsilosis sensu stricto fungaemia during this period. Presenting symptoms included leucopenia, thrombocytopenia, and respiratory crackles. Fifteen cases were cured whereas one case who suffered from severe concomitant diseases died. The isolates were susceptible to fluconazole, amphotericin B, itraconazole, voriconazole, and 5-fluorocytosine. A total of 313 surveillance samples were collected, and Candida parapsilosis sensu stricto was identified from 16 environmental samples and one sample from an ultrasonographer's hand. The colonized locations included wiping cloths, faucets, sinks, operating table, puddles in the bathroom, a ventilator, and an ultrasonic probe. The RAPD patterns of all the Candida parapsilosis sensu stricto isolates from bloodstream and surveillance samples were identical. The outbreak was controlled after a series of infection control measures.

CONCLUSION

Contaminated environment was associated with this outbreak. Close attention to immunocompromised patients, thorough environmental disinfection and hand hygiene should be strengthened in NICU.

[Molecular identification and in vitro antifungal susceptibility of blood isolates of the Candida parapsilosis species complex in Venezuela]

BACKGROUND

Candida parapsilosis is a species complex consisting of Candida parapsilosis sensu stricto, Candida orthopsilosis, and Candida metapsilosis. Studies worldwide have described its epidemiology and susceptibility to antifungal agents.

AIMS

The aims of this study were to carry out the molecular identification of blood isolates belonging to the Candida parapsilosis species complex, and to determine their in vitro susceptibility to antifungals of systemic use.

METHODS

A study of 86 strains of C. parapsilosis species complex collected in 2008-2011 and obtained from the Candidaemia Surveillance Network of Mycology Department of the Rafael Rangel National Institute of Hygiene, was made. Secondary alcohol-dehydrogenase gene amplification was performed using polymerase chain reaction, and the products were analysed by restriction fragments length polymorphisms using the enzyme BanI. Susceptibility tests were performed using Etest^®, following the manufacturer's instructions with modifications.

RESULTS

Of the 86 isolates studied, 81 (94.2%) were C. parapsilosis sensu stricto, 4 (4.6%) C. orthopsilosis, and one (1.2%) C. metapsilosis. C. parapsilosis isolates were susceptible to amphotericin B and caspofungin, showing low rates of resistance to fluconazole and voriconazole. C. orthopsilosis and C. metapsilosis were susceptible to all the antifungals tested.

CONCLUSIONS

The results obtained in Venezuela provide for the first time important information about the distribution of C. parapsilosis species complex in cases of candidaemia, and support the need for continuing surveillance programs, including molecular discrimination of species and antifungal susceptibility tests, which may guide specific therapy.

Molecular study of the Candida parapsilosis complex in Sfax, Tunisia

Candida parapsilosis, which was previously considered to be a complex of three genetically distinct groups, has emerged as a significant agent of nosocomial infections. Recently, this complex was separated into three species: C. parapsilosis sensu stricto, C. orthopsilosis, and C. metapsilosis In Tunisia, data pertaining to these fungi are limited. Thus, the purpose of our study was to determine by BanI PCR-RFLP and ITS sequencing, the occurrence of Candida parapsilosis complex among 182 isolates identified as C. parapsilosis by phenotypical methods. C. parapsilosis sensu stricto represented 94.5% of all isolates, while C. metapsilosis and. C. orthopsilosis were identified in 3.3% and 2.2%, respectively. Sequence analysis of internal transcribed spacer region confirmed and revealed only one genotype among the C. parapsilosis sensu stricto strains, three genotypes among six C. metapsilosis strains and two genotypes among four C. orthopsilosis strains.

First isolation of Candida metapsilosis in Kuwait, an emerging global opportunistic pathogen

Invasive infections due to uncommon and rare yeast species are increasing worldwide in prevalence and are associated with high mortality rates. Here, we describe the first isolation and characterization of Candida metapsilosis cultured from the blood sample of a 10-year-old Saudi girl, who suffered from a neurodegenerative disorder, in Kuwait. The yeast isolate was identified by sequencing of ITS region and D1/D2 domains of rDNA. The report extends the geographic distribution of C. metapsilosis to the Middle East and highlights the emerging role of uncommon yeast species causing infections in susceptible hosts.

Candida parapsilosis (sensu lato) isolated from hospitals located in the Southeast of Brazil: Species distribution, antifungal susceptibility and virulence attributes

Candida parapsilosis (sensu lato), which represents a fungal complex composed of three genetically related species - Candida parapsilosis sensu stricto, Candida orthopsilosis and Candida metapsilosis, has emerged as an important yeast causing fungemia worldwide. The goal of the present work was to assess the prevalence, antifungal susceptibility and production of virulence traits in 53 clinical isolates previously identified as C. parapsilosis (sensu lato) obtained from hospitals located in the Southeast of Brazil. Species forming this fungal complex are physiologically/morphologically indistinguishable; however, polymerase chain reaction followed by restriction fragment length polymorphism of FKS1 gene has solved the identification inaccuracy, revealing that 43 (81.1%) isolates were identified as C. parapsilosis sensu stricto and 10 (18.9%) as C. orthopsilosis. No C. metapsilosis was found. The geographic distribution of these Candida species was uniform among the studied Brazilian States (São Paulo, Rio de Janeiro and Espírito Santo). All C. orthopsilosis and almost all C. parapsilosis sensu stricto (95.3%) isolates were susceptible to amphotericin B, fluconazole, itraconazole, voriconazole and caspofungin. Nevertheless, one C. parapsilosis sensu stricto isolate was resistant to fluconazole and another one was resistant to caspofungin. C. parapsilosis sensu stricto isolates exhibited higher MIC mean values to amphotericin B, fluconazole and caspofungin than those of C. orthopsilosis, while C. orthopsilosis isolates displayed higher MIC mean to itraconazole compared to C. parapsilosis sensu stricto. Identical MIC mean values to voriconazole were measured for these Candida species. All the isolates of both species were able to form biofilm on polystyrene surface. Impressively, biofilm-growing cells of C. parapsilosis sensu stricto and C. orthopsilosis exhibited a considerable resistance to all antifungal agents tested. Pseudohyphae were observed in 67.4% and 80% of C. parapsilosis sensu stricto and C. orthopsilosis isolates, respectively. The secretion of phytase (93% versus 100%), aspartic protease (88.4% versus 90%), esterase (20.9% versus 50%) and hemolytic factors (25.6% versus 40%) was detected in C. parapsilosis sensu stricto and C. orthopsilosis isolates, respectively; however, no phospholipase activity was identified. An interesting fact was observed concerning the caseinolytic activity, for which all the producers (53.5%) belonged to C. parapsilosis sensu stricto. Collectively, our results add new data on the epidemiology, antifungal susceptibility and production of potential virulence attributes in clinical isolates of C. parapsilosis complex.

Differential sensitivity of the species of Candida parapsilosis sensu lato complex against statins

Candida parapsilosis sensu stricto, Candida orthopsilosis and Candida metapsilosis are human fungal pathogens with clinical importance. The recently reclassified three closely related species have significant variation in virulence, clinical prevalence and susceptibility characteristics to different antifungal compounds. The aim of this study was to investigate the in vitro activity of atorvastatin and fluvastatin against C. metapsilosis, C. orthopsilosis and C. parapsilosis. Susceptibility tests showed that C. parapsilosis was the most sensitive while C. orthopsilosis was the least susceptible species to both drugs. On the basis of the differential sensitivity, we developed a simple, reliable and highly cost-effective plate assay to distinguish these closely related species. Applying this method, 54 isolates belonging to the C. parapsilosis sensu lato complex deposited in Szeged Microbial Collection could be sorted into the three species with 100 % probability.

Characterization of virulence properties in the C. parapsilosis sensu lato species

The C. parapsilosis sensu lato group involves three closely related species, C. parapsilosis sensu stricto, C. orthopsilosis and C. metapsilosis. Although their overall clinical importance is dramatically increasing, there are few studies regarding the virulence properties of the species of the psilosis complex. In this study, we tested 63 C. parapsilosis sensu stricto, 12 C. metapsilosis and 18 C. orthopsilosis isolates for the ability to produce extracellular proteases, secrete lipases and form pseudohyphae. Significant differences were noted between species, with the C. metapsilosis strains failing to secrete lipase or to produce pseudohyphae. Nine different clinical isolates each of C. parapsilosis sensu stricto, C. orthopsilosis and C. metapsilosis were co-cultured with immortalized murine or primary human macrophages. C. parapsilosis sensu stricto isolates showed a significantly higher resistance to killing by primary human macrophages compared to C. orthopsilosis and C. metapsilosis isolates. In contrast, the killing of isolates by J774.2 mouse macrophages did not differ significantly between species. However, C. parapsilosis sensu stricto isolates induced the most damage to murine and human macrophages, and C. metapsilosis strains were the least toxic. Furthermore, strains that produced lipase or pseudohyphae were most resistant to macrophage-mediated killing and produced the most cellular damage. Finally, we used 9 isolates of each of the C. parapsilosis sensus lato species to examine their impact on the survival of Galleriamellonella larvae. The mortality rate of G. mellonella larvae infected with C. metapsilosis isolates was significantly lower than those infected with C. parapsilosis sensu stricto or C. orthopsilosis strains. Taken together, our findings demonstrate that C. metapsilosis is indeed the least virulent member of the psilosis group, and also highlight the importance of pseudohyphae and secreted lipases during fungal-host interactions.

Analysis of inteins in the Candida parapsilosis complex for simple and accurate species identification

Inteins are coding sequences that are transcribed and translated with flanking sequences and then are excised by an autocatalytic process. There are two types of inteins in fungi, mini-inteins and full-length inteins, both of which present a splicing domain containing well-conserved amino acid sequences. Full-length inteins also present a homing endonuclease domain that makes the intein a mobile genetic element. These parasitic genetic elements are located in highly conserved genes and may allow for the differentiation of closely related species of the Candida parapsilosis (psilosis) complex. The correct identification of the three psilosis complex species C. parapsilosis, Candida metapsilosis, and Candida orthopsilosis is very important in the clinical setting for improving antifungal therapy and patient care. In this work, we analyzed inteins that are present in the vacuolar ATPase gene VMA and in the threonyl-tRNA synthetase gene ThrRS in 85 strains of the Candida psilosis complex (46 C. parapsilosis, 17 C. metapsilosis, and 22 C. orthopsilosis). Here, we describe an accessible and accurate technique based on a single PCR that is able to differentiate the psilosis complex based on the VMA intein. Although the ThrRS intein does not distinguish the three species of the psilosis complex by PCR product size, it can differentiate them by sequencing and phylogenetic analysis. Furthermore, this intein is unusually present as both mini- and full-length forms in C. orthopsilosis. Additional population studies should be performed to address whether this represents a common intraspecific variability or the presence of subspecies within C. orthopsilosis.

Distribution, virulence attributes and antifungal susceptibility patterns of Candida parapsilosis complex strains isolated from clinical samples

It was recently proposed that Candida parapsilosis represents a complex composed of three closely related species, i.e., C. parapsilosis sensu stricto, C. orthopsilosis, and C. metapsilosis. The aim of this study was to describe the distribution of C. parapsilosis complex isolates among clinical samples. We also evaluated antifungal susceptibility profiles, in vitro presence of lipase and secreted aspartyl proteinase, as well as their ability to grow in total parenteral nutrition (TPN) solution, and biofilm production. A total of 413 non-C. albicans Candida isolates were obtained from various clinical samples between 2010 and 2011 in a Turkish Tertiary Care Hospital. Of them, 42 were identified as members of the C. parapsilosis complex. Among these, 38 (90.5%) were C. parapsilosis sensu stricto, 3 (7.1%) C. metapsilosis, and 1 (2.4%) C. orthopsilosis. All isolates recovered from blood were found to be C. parapsilosis sensu stricto and C. metapsilosis. In phenotypic tests, all 42 isolates grew in TPN solution and, although 26.2% of C. parapsilosis sensu stricto-isolates were capable of forming biofilms in vitro, neither C. orthopsilosis nor C. metapsilosis isolates were able to do so. Acid proteinase activity was detected in 31% of isolates and lipase activity in 33%. All isolates were sensitive to voriconazole, caspofungin, and anidulafungin, with only a single C. parapsilosis sensu stricto isolate showing dose-dependent susceptible to fluconazole. While the number of C. metapsilosis and C. orthopsilosis isolates remained low, there were no significant differences in antifungal MIC as compared to C. parapsilosis sensu stricto.

Prevalence and antifungal susceptibility of Candida parapsilosis complex isolates collected from oral cavities of HIV-infected individuals

At present, few data are available on the prevalence and antifungal susceptibility of Candida parapsilosis complex isolates from HIV-infected individuals. The C. parapsilosis complex comprises three species, C. parapsilosis sensu stricto, C. metapsilosis and C. orthopsilosis. Fifteen of 318 Candida isolates were identified as members of the C. parapsilosis complex by PCR and restriction fragment length polymorphism (RFLP). The prevalence of C. parapsilosis complex isolates was 4.7 %, 2.2 % being identified as C. parapsilosis sensu stricto and 2.5 % as C. metapsilosis, while no C. orthopsilosis was isolated. This is believed to be the first study that has identified isolates of C. metapsilosis obtained from the oral cavity of HIV-infected individuals. Antifungal susceptibility tests indicated that all the isolates were susceptible to amphotericin B (AMB), fluconazole (FLC), ketoconazole (KTC), itraconazole (ITC), voriconazole (VRC) and caspofungin (CASPO). Although isolates of C. parapsilosis sensu stricto and C. metapsilosis were susceptible to FLC, isolates of C. metapsilosis showed a tendency for higher MICs (≥1.0 µg ml(-1)). Based upon the frequency of candidiasis and the fact that certain isolates of the C. parapsilosis complex respond differently to FLC therapy, our data may be of therapeutic relevance with respect to susceptibility and potential resistance to specific antifungal agents. Our data suggest that C. metapsilosis can be a human commensal; its importance as a pathogen has yet to be confirmed.

Epidemiology and echinocandin susceptibility of Candida parapsilosis sensu lato species isolated from bloodstream infections at a Spanish university hospital

OBJECTIVES

The aims of this work were to study the epidemiological profiles, differences in echinocandin susceptibilities and clinical relevance of the Candida parapsilosis sensu lato species isolated from proven fungaemia cases at La Fe University Hospital of Valencia (Spain) from 1995 to 2007.

RESULTS

The prevalence of these species was: C. parapsilosis sensu stricto, 74.4%; Candida orthopsilosis, 23.54%; and Candida metapsilosis, 2.05%. The incidence of the species complex as agents of fungaemia remained stationary until 2005 and doubled in 2006. The incidence of C. orthopsilosis showed an increasing trend during the study period, while C. parapsilosis sensu stricto incidence diminished. Also, an important epidemiological change was observed starting in 2004, when 86.5% of the C. parapsilosis sensu lato strains were found in adult patients, while before that year only 13.5% of the isolates were found in this population.

CONCLUSIONS

Echinocandin drug susceptibility testing using the CLSI M27-A3 document showed a wide range of MIC values (0.015-4 mg/L), with micafungin being the most potent in vitro inhibitor followed by anidulafungin and caspofungin (MIC geometric mean of 0.68, 0.74 and 0.87 mg/L, respectively). C. metapsilosis was the most susceptible species of the complex to anidulafungin and micafungin in vitro (MIC(50) for anidulafungin and micafungin: 0.06 mg/L), while there were no differences between C. parapsilosis sensu lato species when caspofungin MIC(50)s were compared (MIC(50) 1.00 mg/L). Differences in caspofungin in vitro susceptibility were observed between the different clinical service departments of La Fe Hospital.

RAPD-SCAR marker and genetic relationship analysis of three Demodex species (Acari: Demodicidae)

For a long time, classification of Demodex mites has been mainly based on their hosts and phenotype characteristics. The study was the first to conduct molecular identification and genetic relationship analysis for six isolates of three Demodex species by random amplified polymorphic DNA (RAPD) and sequence-characterized amplified region (SCAR) marker. Totally, 239 DNA fragments were amplified from six Demodex isolates with 10 random primers in RAPD, of which 165 were polymorphic. Using a single primer, at least five fragments and at most 40 in the six isolates were amplified, whereas within a single isolate, a range of 35-49 fragments were amplified. DNA fingerprints of primers CZ 1-9 revealed intra- and interspecies difference in six Demodex isolates, whereas primer CZ 10 only revealed interspecies difference. The genetic distance and dendrogram showed the intraspecific genetic distances were closer than the interspecific genetic distances. The interspecific genetic distances of Demodex folliculorum and Demodex canis (0.7931-0.8140) were shorter than that of Demodex brevis and D. canis (0.8182-0.8987). The RAPD-SCAR marker displayed primer CZ 10 could be applied to identify the three Demodex species. The 479-bp fragment was specific for D. brevis, and the 261-bp fragment was specific for D. canis. The conclusion was that the RAPD-SCAR multi-marker was effective in molecular identification of three Demodex species. The genetic relationship between D. folliculorum and D. canis was nearer than that between D. folliculorum and D. brevis.

Prospective multicenter study of the epidemiology, molecular identification, and antifungal susceptibility of Candida parapsilosis, Candida orthopsilosis, and Candida metapsilosis isolated from patients with candidemia

A 13-month prospective multicenter study including 44 hospitals was carried out to evaluate the epidemiology of Candida parapsilosis complex candidemia in Spain. Susceptibility to amphotericin B, flucytosine, fluconazole, itraconazole, voriconazole, posaconazole, anidulafungin, caspofungin, and micafungin was tested by the microdilution colorimetric method. A total of 364 C. parapsilosis complex isolates were identified by molecular methods: C. parapsilosis (90.7%), Candida orthopsilosis (8.2%), and Candida metapsilosis (1.1%). Most candidemias (C. parapsilosis, 76.4%; C. orthopsilosis, 70.0%; C. metapsilosis, 100%) were observed in adults. No C. orthopsilosis or C. metapsilosis candidemias occurred in neonates. C. parapsilosis was most frequent in adult intensive care unit (28.8%), surgery (20.9%), and internal medicine (19.7%) departments; and C. orthopsilosis was most frequent in hematology (28.6%), pediatrics (12.0%), and neonatology (11.5%) departments. The geographic distribution of C. orthopsilosis and C. metapsilosis was not uniform. According to CLSI clinical breakpoints, all C. orthopsilosis and C. metapsilosis isolates were susceptible to the nine agents tested. Resistance (MICs > 1 mg/liter) was observed only in C. parapsilosis: amphotericin B, posaconazole, itraconazole, and caspofungin (0.3% each), anidulafungin (1.9%), and micafungin (2.5%). Applying the new species-specific fluconazole and echinocandin breakpoints, the rates of resistance to fluconazole for C. parapsilosis and C. orthopsilosis increased to 4.8% and 0.3%, respectively; conversely, for C. parapsilosis they shifted from 1.9 to 0.6% (anidulafungin) and from 2.5 to 0.6% (micafungin). Our study confirms the different prevalence of C. parapsilosis complex candidemia among age groups: neither C. orthopsilosis nor C. metapsilosis was isolated from neonates; interestingly, C. metapsilosis was isolated only from adults and the elderly. The disparity in antifungal susceptibility among species could be important for therapy.

Isolates from hospital environments are the most virulent of the Candida parapsilosis complex

Background

Candida parapsilosis is frequently isolated from hospital environments, like air and surfaces, and causes serious nosocomial infections. Molecular studies provided evidence of great genetic diversity within the C. parapsilosis species complex but, despite their growing importance as pathogens, little is known about their potential to cause disease, particularly their interactions with phagocytes. In this study, clinical and environmental C. parapsilosis isolates, and strains of the related species C. orthopsilosis and C. metapsilosis were assayed for their ability to induce macrophage cytotocixity and secretion of the pro-inflammatory cytokine TNF-α, to produce pseudo-hyphae and to secrete hydrolytic enzymes.

Results

Environmental C. parapsilosis isolates caused a statistically significant (p = 0.0002) higher cell damage compared with the clinical strains, while C. orthopsilosis and C. metapsilosis were less cytotoxic. On the other hand, clinical isolates induced a higher TNF-α production compared with environmental strains (p < 0.0001). Whereas the amount of TNF-α produced in response to C. orthopsilosis strains was similar to the obtained with C. parapsilosis environmental isolates, it was lower for C. metapsilosis strains. No correlation between pseudo-hyphae formation or proteolytic enzymes secretion and macrophage death was detected (p > 0.05). However, a positive correlation between pseudo-hyphae formation and TNF-α secretion was observed (p = 0.0119).

Conclusions

We show that environmental C. parapsilosis strains are more resistant to phagocytic host defences than bloodstream isolates, being potentially more deleterious in the course of infection than strains from a clinical source. Thus, active environmental surveillance and application of strict cleaning procedures should be implemented in order to prevent cross-infection and hospital outbreaks.

[Matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry vs conventional methods in the identification of Candida non-albicans]

INTRODUCTION

Candida infection has become a major health problem worldwide. The epidemiology of Candidaemia has substantially changed by the emergence of the species Candida non-albicans. This variation is particularly important in the choice of prophylaxis and empirical treatment. The methods based on biochemical and molecular biology have limitations for the correct identification of Candida species. The aim of this study is to demonstrate the ability of the MALDI-TOF mass spectrometry for the identification of these species and compare it with the technology used today.

METHODS

We included all isolates collected over 2 years (n=73) of Candida non-albicans from non-invasive samples. The identification was carried out by Vitek-2 systems YST and API CAUX. The MALDI-TOF identifications were made with Confidence Axima system (Shimadzu Corporation) using the Shimadzu Launchpad software and database SARAMIS (AnagnosTec GmbH). Discrepancies were resolved by SeptiFast LightCycler multiplex PCR, specific PCR C. glabrata and enzymatic digestion with BanI SADH fragment in isolates of C. parapsilosis.

RESULTS

Of the 73 isolates of Candida non-albicans, the biochemical methods conclusively identified 67 to species level and 6 at the genus level. The MALDI-TOF system obtained identifications at the species level in all cases. The correlation in the species of all isolates studied was 85.07%, reaching 94.52% when the correlation was made between the identification obtained by biochemical methods and the methods for the analysis of the discrepancies. In isolates of C. parapsilosis, MALDI-TOF system obtained an identification of C. orthopsilosis. In 3 of them it was confirmed by digestion with BanI SADH fragment.

CONCLUSION

This study has demonstrated the use of mass spectrometry (MALDI-TOF system) to provide the microbiology laboratory with greater efficiency and reliability to identify isolates of Candida non-albicans to species level. It also shows its potential usefulness in identifying related species, such as C. parapsilosis, metapsilosis and orthopsilosis.

Characterization of the Candida parapsilosis complex in East China: species distribution differs among cities

Candida parapsilosis, which was previously considered to be a complex of three genetically distinct groups, has emerged as a significant agent of nosocomial infections. Recently, this complex was separated into three species: C. parapsilosis sensu stricto, C. orthopsilosis and C. metapsilosis. In China, data pertaining to these fungi are limited. In this study, we examined 57 isolates of members of the C. parapsilosis complex collected from four cities in East China, i.e., Nanjing (n = 22), Nanchang (n = 20), Shanghai (n = 12) and Jinan (n = 3). C. parapsilosis sensu stricto represented 71.9% of all isolates, while C. metapsilosis accounted for the remaining 28.1%. C. orthopsilosis could not be identified. A significantly high prevalence of C. metapsilosis was observed in strains recovered from Nanchang, 60% (12/20) of the isolates were C. metapsilosis. Sequence analysis of internal transcribed spacer region revealed two unevenly distributed genotypes among the C. metapsilosis strains. A PCR-restriction fragment length polymorphism assay was described for rapid identification. The strains were susceptible to fluconazole, voriconazole, amphoterincin B and micafungin. Six (15%) isolates of C. parapsilosis sensu stricto and three (18.8%) of C. metapsilosis were found to be dose-dependent susceptible to itraconazole. C. parapsilosis sensu stricto strains were less susceptible to micafungin than C. metapsilosis.

Differentiation of Candida parapsilosis, C. orthopsilosis, and C. metapsilosis by specific PCR amplification of the RPS0 intron

Although Candida parapsilosis is the most prevalent among the 3 species of the *psilosis group, studies applying DNA-based diagnostic techniques with isolates previously identified as C. parapsilosis have revealed that both C. orthopsilosis and C. metapsilosis account for 0-10% of all these isolates, depending on the geographical area. Differences in the degrees of antifungal susceptibility and virulence have been found, so a more precise identification is required. In a first approach, we reidentified 38 randomly chosen clinical isolates, previously identified as C. parapsilosis, using the RPO2 (CA2) RAPD marker. Among them, we reclassified 4 as C. metapsilosis and 5 as C. orthopsilosis. We previously developed a method to identify different pathogen yeast species, including C. parapsilosis, based on the amplification of the RPS0 gene intron. In this work, we extend this approach to the new *psilosis species by partially sequencing their RPS0 gene, including the intron sequence. Based on intron sequences, we designed specific primers capable of identifying C. orthopsilosis and C. metapsilosis species, and we reidentified species among the initial isolates. These new primers have allowed a specific and rapid identification of C. orthopsilosis and C. metapsilosis.

Outbreak of Candida parapsilosis in a neonatal intensive care unit: a health care workers source

Nosocomial neonatal candidiasis is a major problem in infants, which require intensive therapy. The subjects of the present study were three preterm infants admitted to the neonatal intensive care unit of the General Hospital "Dr. Manuel Gea Gonzalez". The infants developed Candida parapsilosis infection on the mean age of 13.6 day of life. Prior to fungemia, infants had received assisted ventilation and hyperalimentation through central venous catheter. Sequence analysis of the internal transcribed spacer gene ruled out other Candida species and revealed that the eight isolates were C. parapsilosis. The isolates were examined based on their molecular relation by random amplified polymorphic DNA analysis. The profiles allowed the identification of two main genotypes of C. parapsilosis as the outbreak cause and as a result of the cross-infection with health care workers' hands. We conclude that C. parapsilosis commonly colonize through horizontal transmission due to the staff's noncompliance of hand hygiene procedures.

Molecular screening for Candida orthopsilosis and Candida metapsilosis among Danish Candida parapsilosis group blood culture isolates: proposal of a new RFLP profile for differentiation

Candida orthopsilosis and Candida metapsilosis are recently described species phenotypically indistinguishable from Candida parapsilosis . We evaluated phenotyping and molecular methods for the detection of these species among 79 unique blood culture isolates of the C. parapsilosis group obtained during the years 2004-2008. The isolates were screened by PCR amplification of the secondary alcohol dehydrogenase-encoding gene ( SADH) followed by digestion with the restriction enzyme Ban I, using C. parapsilosis ATCC 22019, C. orthopsilosis ATCC 96139 and C. metapsilosis ATCC 96144 as controls. Isolates with RFLP patterns distinct from C. parapsilosis were characterized by sequence analysis of the ITS1-ITS2, 26S rRNA (D1/D2) and SADH regions. Restriction patterns for the 3 species with each of 610 restriction enzymes were predicted in silico using 12 available sequences. By PCR-RFLP of the SADH gene alone, four isolates (5.1 %) had a pattern identical to the C. orthopsilosis reference strain. Sequence analysis of SADH and ITS (internal transcribed spacer) regions identified two of these isolates as C. metapsilosis. These results were confirmed by creating a phylogenetic tree based on concatenated sequences of SADH, ITS and 26S rRNA gene sequence regions. Optimal differentiation between C. parapsilosis, C. metapsilosis and C. orthopsilosis was predicted using digestion with NlaIII, producing discriminatory band sizes of: 131 and 505 bp; 74, 288 and 348 bp; and 131, 217 and 288 bp, respectively. This was confirmed using the reference strains and 79 clinical isolates. In conclusion, reliable discrimination was obtained by PCR-RFLP profile analysis of the SADH gene after digestion with NlaIII but not with BanI. C. metapsilosis and C. orthopsilosis are involved in a small but significant number of invasive infections in Denmark.

Rapid molecular differentiation and genotypic heterogeneity among Candida parapsilosis and Candida orthopsilosis strains isolated from clinical specimens in Kuwait

Recent molecular studies have led to the recognition of three distinct species within the Candida parapsilosis complex, namely Candida parapsilosis, Candida orthopsilosis and Candida metapsilosis. As currently available yeast identification systems fail to differentiate these species, there is a paucity of information on their occurrence in different geographical regions. This study describes a simple PCR-based protocol for rapid discrimination among C. parapsilosis, C. orthopsilosis and C. metapsilosis strains by using primers derived from unique sequences within the internally transcribed spacer 1 (ITS1)-5.8 rRNA-ITS2 region. Retrospective analysis of 114 C. parapsilosis-complex isolates recovered from clinical specimens in Kuwait identified 109 as C. parapsilosis, five as C. orthopsilosis and none as C. metapsilosis. The results were further validated by PCR-RFLP patterns of the secondary alcohol dehydrogenase gene fragment. DNA sequencing of the ITS region and the D1/D2 regions of the 28S rRNA gene confirmed the species-specific identification of all five C. orthopsilosis strains. The amplicon length of the intergenic spacer between the 28S and 5S rRNA genes (IGS1) was also species-specific, and PCR-RFLP analyses of the IGS1 region identified two distinct genotypes among the five C. orthopsilosis strains, which corresponded with the ITS region sequence data. The three bloodstream C. orthopsilosis strains were confined to a single genotype. Among 81 randomly selected C. parapsilosis strains, two genotypes were detected by IGS1 region analyses, indicating limited genotypic heterogeneity among C. parapsilosis sensu stricto strains. As far as is known, this is the first report on the identification of C. orthopsilosis from a bloodstream infection in the Arabian Gulf region.

Prevalence, distribution, and antifungal susceptibility profiles of Candida parapsilosis, C. orthopsilosis, and C. metapsilosis in a tertiary care hospital

Candida parapsilosis, an emergent agent of nosocomial infections, was previously made up of a complex of three genetically distinct groups (groups I, II, and III). Recently, the C. parapsilosis groups have been renamed as distinct species: C. parapsilosis sensu stricto, C. orthopsilosis, and C. metapsilosis. In Portugal, no data pertaining to the distribution and antifungal susceptibility of these Candida species are yet available. In the present report, we describe the incidence and distribution of C. parapsilosis sensu stricto, C. orthopsilosis, and C. metapsilosis among 175 clinical and environmental isolates previously identified by conventional methods as C. parapsilosis. We also evaluated the in vitro susceptibilities of the isolates to fluconazole, voriconazole, posaconazole, amphotericin B, and two echinocandins, caspofungin and anidulafungin. Of the 175 isolates tested, 160 (91.4%) were identified as C. parapsilosis sensu stricto, 4 (2.3%) were identified as C. orthopsilosis, and 5 (2.9%) were identified as C. metapsilosis. Six isolates corresponded to species other than the C. parapsilosis group. Interestingly, all isolates from blood cultures corresponded to C. parapsilosis sensu stricto. Evaluation of the antifungal susceptibility profile showed that only nine (5.6%) C. parapsilosis sensu stricto strains were susceptible-dose dependent or resistant to fluconazole, and a single strain displayed a multiazole-resistant phenotype; two (1.3%) C. parapsilosis sensu stricto strains were amphotericin B resistant. All C. orthopsilosis and C. metapsilosis isolates were susceptible to azoles and amphotericin B. A high number of strains were nonsusceptible to the echinocandins (caspofungin and anidulafungin).

Molecular differentiation and antifungal susceptibilities of Candida parapsilosis isolated from patients with bloodstream infections

The genetic heterogeneity and antifungal susceptibility patterns of Candida parapsilosis isolated from blood cultures of patients were investigated in this study. Randomly amplified polymorphic DNA (RAPD) analysis generated 5 unique profiles from 42 isolates. Based on the major DNA fragments of the RAPD profiles, the isolates were identified as RAPD type P1 (29 isolates), P2 (6 isolates), P3 (4 isolates), P4 (2 isolates) and P5 (1 isolate). Sequence analysis of the internal transcribed spacer (ITS) gene of the isolates identified RAPD type P1 as C. parapsilosis, P2 and P3 as Candida orthopsilosis, P4 as Candida metapsilosis, and P5 as Lodderomyces elongisporus. Nucleotide variations in ITS gene sequences of C. orthopsilosis and C. metapsilosis were detected. Antifungal susceptibility testing using Etests showed that all isolates tested in this study were susceptible to amphotericin B, fluconazole, ketoconazole, itraconazole and voriconazole. C. parapsilosis isolates exhibited higher MIC(50) values than those of C. orthopsilosis for all of the drugs tested in this study; however, no significant difference in the MICs for these two Candida species was observed. The fact that C. orthopsilosis and C. metapsilosis were responsible for 23.8 and 4.8 % of the cases attributed to C. parapsilosis bloodstream infections, respectively, indicates the clinical relevance of these newly described yeasts. Further investigations of the ecological niche, mode of transmission and virulence of these species are thus essential.

Candida parapsilosis, an emerging fungal pathogen

SUMMARY

Candida parapsilosis is an emerging major human pathogen that has dramatically increased in significance and prevalence over the past 2 decades, such that C. parapsilosis is now one of the leading causes of invasive candidal disease. Individuals at the highest risk for severe infection include neonates and patients in intensive care units. C. parapsilosis infections are especially associated with hyperalimentation solutions, prosthetic devices, and indwelling catheters, as well as the nosocomial spread of disease through the hands of health care workers. Factors involved in disease pathogenesis include the secretion of hydrolytic enzymes, adhesion to prosthetics, and biofilm formation. New molecular genetic tools are providing additional and much-needed information regarding C. parapsilosis virulence. The emerging information will provide a deeper understanding of C. parapsilosis pathogenesis and facilitate the development of new therapeutic approaches for treating C. parapsilosis infections.

Genetic variability of Candida albicans isolates in a university hospital in Hungary

The occurrence and genetic variability of Candida albicans isolates in a Hungarian hospital were examined. Among the 103 Candida isolates, 44 (42.7%) proved to be C. albicans species. Comparing with a previous study carried out in 2002, the percentage of infections caused by C. albicans decreased in Hungary in this period with an increasing incidence of non-albicans species, in accordance with the world-wide trend. The genetic variability of the isolates was examined using mitochondrial DNA (mtDNA), restriction fragment length polymorphism (RFLP), random amplified polymorphic DNA (RAPD) analysis and electrophoretic karyotyping. The examined C. albicans isolates could be clustered into four groups based on their mtDNA profiles. The electrophoretic karyotypes of the isolates were mostly identical to that of the reference strain 1006, with the exception of mtDNA type II isolates. RAPD analysis could be used to cluster the isolates into different groups, but this clustering was not in complete agreement with their assignment to mtDNA types. Population genetic analyses of the data indicated low amounts of recombination among these C. albicans strains. None of the isolates exhibited decreased susceptibilities to 5-fluorocytosine.

Geographic distribution and antifungal susceptibility of the newly described species Candida orthopsilosis and Candida metapsilosis in comparison to the closely related species Candida parapsilosis

Candida orthopsilosis and Candida metapsilosis are recently described species, having previously been grouped with the more prevalent species Candida parapsilosis. Current literature contains very little data pertaining to the distributions and antifungal susceptibilities of these Candida species. We determined the species and antifungal susceptibilities of 1,929 invasive clinical isolates from the ARTEMIS antifungal surveillance program collected between 2001 and 2006 and identified as C. parapsilosis using Vitek and conventional methods. Of the 1,929 isolates of presumed C. parapsilosis tested, 117 (6.1%) were identified as C. orthopsilosis and 34 (1.8%) as C. metapsilosis. The percentage of presumed C. parapsilosis isolates found to be C. orthopsilosis varied greatly by region, with the highest percentage (10.9%) from South America and the lowest (0.7%) from Africa. The MIC distributions of the C. orthopsilosis and C. metapsilosis isolates were statistically significantly lower than those of C. parapsilosis for all drugs except fluconazole, for which they were significantly higher (P < 0.001 for all). No C. orthopsilosis or C. metapsilosis isolates were fluconazole resistant, and all were susceptible to caspofungin, anidulafungin, and micafungin.

Prevalence and susceptibility profile of Candida metapsilosis and Candida orthopsilosis: results from population-based surveillance of candidemia in Spain

We describe the prevalences and susceptibility profiles of two recently described species, Candida metapsilosis and Candida orthopsilosis, related to Candida parapsilosis in candidemia. The prevalences of these species (1.7% for C. metapsilosis and 1.4% for C. orthopsilosis) are significant. Differences observed in their susceptibility profiles could have therapeutic importance.

DNA microarray based on arrayed-primer extension technique for identification of pathogenic fungi responsible for invasive and superficial mycoses

An oligonucleotide microarray based on the arrayed-primer extension (APEX) technique has been developed to simultaneously identify pathogenic fungi frequently isolated from invasive and superficial infections. Species-specific oligonucleotide probes complementary to the internal transcribed spacer 1 and 2 (ITS1 and ITS2) region were designed for 24 species belonging to 10 genera, including Candida species (Candida albicans, Candida dubliniensis, Candida famata, Candida glabrata, Candida tropicalis, Candida kefyr, Candida krusei, Candida guilliermondii, Candida lusitaniae, Candida metapsilosis, Candida orthopsilosis, Candida parapsilosis, and Candida pulcherrima), Cryptococcus neoformans, Aspergillus species (Aspergillus fumigatus and Aspergillus terreus), Trichophyton species (Trichophyton rubrum and Trichophyton tonsurans), Trichosporon cutaneum, Epidermophyton floccosum, Fusarium solani, Microsporum canis, Penicillium marneffei, and Saccharomyces cerevisiae. The microarray was tested for its specificity with a panel of reference and blinded clinical isolates. The APEX technique was proven to be highly discriminative, leading to unequivocal identification of each species, including the highly related ones C. parapsilosis, C. orthopsilosis, and C. metapsilosis. Because of the satisfactory basic performance traits obtained, such as reproducibility, specificity, and unambiguous interpretation of the results, this new system represents a reliable method of potential use in clinical laboratories for parallel one-shot detection and identification of the most common pathogenic fungi.

Lodderomyces elongisporus masquerading as Candida parapsilosis as a cause of bloodstream infections

Ten yeast bloodstream isolates identified as Candida parapsilosis by conventional methods grew as turquoise blue colonies on Chromagar media. Subsequent sequence analysis showed that these isolates were the species Lodderomyces elongisporus. To our knowledge, this is the first published report of L. elongisporus as a cause of human disease.