Horizontal transmission of Candida parapsilosis candidemia in a neonatal intensive care unit

PCR-based CRISPR/Cas9 system for fluorescent tagging: A tool for studying Candida parapsilosis virulence

Candida parapsilosis is persistent in a hospital environment hence it is often associated with nosocomial infections especially amongst low-birth weight neonates. Genetic modification is therefore important to characterise the physiological and virulence related properties of this fungus. A PCR-based CRISPR/Cas9 system has been adopted to facilitate the generation of fluorescent tagged prototroph isolates. We examined a total of eight fluorescent protein coding genes, out of which three were found to be applicable for simultaneous utilisation. We investigated three clinical isolates of C. parapsilosis in terms of their adherence to silicone and their uptake by J774.2 murine macrophages in competition assays. Interestingly, we found significant differences between them in both experiments where GA1 isolate was significantly less resistant to macrophage uptake and CDC317 was significantly more adherent to silicone material. In silico analysis of the agglutinin-like sequences (Als) exposed remarkable diversity in this protein family and additionally, the thorough analysis of the ALS genes revealed evidence of formation of a new gene by intrachromosomal recombination in the GA1 isolate. Finally, we provide a step by step protocol for the application of the PCR-based CRISPR/Cas9 system for fluorescently labelling C. parapsilosis isolates.

Investigation of clonal relationship in hospital-associated Candida parapsilosis isolates

PURPOSE

We aimed to investigate the clonal relationship and antifungal susceptibility of C. parapsilosis isolated from hospitalized patients and to determine whether it is due to transmission or not and the spread status of resistant isolates.

METHODS

Between January 2017 and June 2019, totally 277 C parapsilosis isolated from blood, urine and catheter samples of adult or pediatric in-patient (intensive care and service) who applied to Mycology laboratory in our hospital were included in the study. All isolates were identified using conventional methods, API 20 C AUX (Biomerieux, France) semi-automated system and confirmed by MALDI-TOF MS Biotyper Smart (Bruker Daltonik GmbH, Germany). Randomly amplified polymorphic DNA (RAPD) PCR method was used for molecular genotyping of isolates. MIC values for fluconazole, anidulafungin and amphotericin B were determined according to the M27-A3 CLSI broth microdilution reference method guideline.

RESULTS

Seven different band patterns (A-G) were detected in 277 isolates by RAPD PCR method. According to the rank order of the isolates, 170 (61.37%) C, 65 (23.47%) A, 18 (6.50%) G, 11 (3.97%) B, six (2.17%) E, two (0.72%) F and one (0.36%) D patterns were determined. When the band patterns of the isolates were evaluated according to the years, it was detected that C pattern continued between 2017 and 2019 and that all isolates continued to spread only as C pattern in 2019. While 211 (76.17%) of the isolates were resistant to fluconazole (≥ 8 µg/ml), two (0.72%) were resistant to amphotericin B (≥ 2 µg/ml) and two (0.72%) were intermediate to anidulafungin.

CONCLUSIONS

It is noteworthy that the spread of the C pattern in C. parapsilosis strains has increased over the years and is the main pattern isolated from the whole hospital. The detection of high fluconazole resistance in C. parapsilosis isolates in our hospital may also be related to the dominant pattern.

Threats from the Candida parapsilosis complex: the surge of multidrug resistance and a hotbed for new emerging pathogens

SUMMARYCandida parapsilosis is a common agent of candidiasis that has gained increased attention in recent years, culminating with its recent consideration as a high-priority fungal pathogen by the World Health Organization. Reasons for this classification are the recent surge in incidence and the alarmingly growing rates of drug and multidrug resistance. In addition, several closely related species such as Candida metapsilosis and Candida orthopsilosis may represent recently emerged opportunistic pathogens originated from environmental niches through interspecies hybridization. Here, I review recent research focused on the potential origin and spread of drug resistance and of emerging species in this complex. I will also discuss open questions regarding the possible implications of human activities in these two epidemiological phenomena.

Candida albicans Horizontal Transmission in COVID-19 Patients Hospitalized in Intensive Care Unit

BACKGROUND

Invasive candidiasis is a predominant mycosis in hospitalized patients, and Candida albicans is the species most often responsible for this infection. Most candidiasis cases originate from endogenous mycobiota; therefore, Candida strains can easily be transferred among hospital patients and personnel. The aim of this study was to assess the possible horizontal transmission of C. albicans in patients with severe COVID-19 infection requiring hospitalization in the intensive care unit.

METHODS

In total, 59 C. albicans strains from 36 patients were collected from blood and lower-respiratory samples. The strains were genotyped using the RAPD method with the OPA-18 primer (5'-AGCTGACCGT-3'). Antifungal susceptibility testing was performed for amphotericin B (AMB), fluconazole (FCZ), voriconazole (VCZ), and anidulafungin (ANF) using the EUCAST method.

RESULTS

C. albicans strains were separated into 13 different groups according to their RAPD pattern. Two predominant clonal clusters of 17 strains isolated from 12 patients and 12 strains from 7 patients were identified, followed by clusters with 6, 4, and 8 strains isolated from 5, 4, and 3 patients, respectively. C. albicans strains were sensitive to AMB, FCZ, VCZ, and ANF, and antifungal susceptibility profiles were similar in all genetic clusters.

CONCLUSIONS

Our study indicates that C. albicans strains can spread horizontally. The routes of transmission for strains in the ward have not been explained due to there being insufficient data. The transmission could have been caused by the unintentional spread of pathogens by medical personnel.

Paradigm Shift: Candida parapsilosis sensu stricto as the Most Prevalent Candida Species Isolated from Bloodstream Infections with Increasing Azole-Non-Susceptibility Rates: Trends from 2015-2022 Survey

Candidemia is the fourth most common healthcare-related bloodstream infection. In recent years, incidence rates of Candida parapsilosis have been on the rise, with differences in prevalence and antifungal susceptibility between countries. The aim of the present study was to evaluate temporal changes in prevalence and antifungal susceptibility of C. parapsilosis among other species causing candidemia. All candidemia episodes from January 2015 to August 2022 were evaluated in order to depict time trends in prevalence of C. parapsilosis sensu stricto among all Candida species recovered from blood cultures as well as fluconazole- and voriconazole-non-susceptibility rates. Secondary analyses evaluated time trends in prevalence and antifungal non-susceptibility according to clinical settings. The overall prevalence of C. parapsilosis was observed to increase compared to the prevalence of other Candida species over time (p-trend = 0.0124). From 2019, the number of C. parapsilosis sensu stricto isolates surpassed C. albicans, without an increase in incidence rates. Overall rates of fluconazole- and voriconazole-non-susceptible C. parapsilosis sensu stricto were both 3/44 (6.8%) in 2015 and were 32/51 (62.7%) and 27/51 (52.9%), respectively, in 2022 (85% cross-non-susceptibility). The risk of detecting fluconazole- or voriconazole-non-susceptibility was found to be higher in C. parapsilosis compared to other Candida species (odds ratio (OR) = 1.60, 95% CI [1.170, 2.188], p-value < 0.0001 and OR = 12.867, 95% CI [6.934, 23.878], p-value < 0.0001, respectively). This is the first study to report C. parapsilosis sensu stricto as the most prevalent among Candida spp. isolated from blood cultures, with worrisome fluconazole- and voriconazole-non-susceptibility rates, unparalleled among European and North American geographical regions.

Monitoring of airborne fungi during the second wave of COVID-19 in selected wards of the referral university hospital in southeastern Iran

Microbiological monitoring of the air hospital is essential for prevention and control, due to the possible airborne route of infection transmission, especially in high-risk wards. This study aimed to monitor the airborne fungi during the second wave of the COVID-19 pandemic in selected wards of the biggest university educational hospital in Kerman, southeastern Iran. This study was conducted in 11 different wards, separated into the patient room and nursing station, of the Afzalipour hospital from May to August 2021. Fungal isolates were characterized to the species level by conventional and sequencing methods. Out of 93 obtained fungal colonies, 70 (75.3%) isolates were filamentous and 23 (24.7%) isolates were yeast. Aspergillus species were the predominant fungal isolates among the filamentous colonies (n=19; 27.1%), and Naganishia albida (formerly Cryptococcus albidus) was identified as the most common yeast isolate (n=13/23; 56.8%). The infectious ward was the most contaminated unit (n=19/93), while the least contaminated units were the neonatal intensive care unit (n=3/93), and oncology (n=3/93). The statistical findings displayed that the number of fungal isolates in patients' rooms is significantly higher than in nurses' stations (p-value=0.013). Our study demonstrated the presence of diverse fungal species in all wards of the hospital. Considering the presence of airborne fungi in hospitals and related public health problems is one of the critical issues for health systems management. In this regard, efficient monitoring of airborne fungi might play an influential role in hospital infection control and surveillance, particularly in high-risk hospitalization patients in critical wards.

Candida parapsilosis sensu stricto Antifungal Resistance Mechanisms and Associated Epidemiology

Fungal diseases cause millions of deaths per year worldwide. Antifungal resistance has become a matter of great concern in public health. In recent years rates of non-albicans species have risen dramatically. Candida parapsilosis is now reported to be the second most frequent species causing candidemia in several countries in Europe, Latin America, South Africa and Asia. Rates of acquired azole resistance are reaching a worrisome threshold from multiple reports as in vitro susceptibility testing is now starting also to explore tolerance and heteroresistance to antifungal compounds. With this review, the authors seek to evaluate known antifungal resistance mechanisms and their worldwide distribution in Candida species infections with a specific focus on C. parapsilosis.

Improved RAPD Method for Candida parapsilosis Fingerprinting

Recently, methods based on the analysis of arbitrarily amplified target sites of genome microorganisms have been extensively applied in microbiological studies, and especially in epidemiological studies. The range of their application is limited by problems with discrimination and reproducibility resulting from a lack of standardized and reliable methods of optimization. The aim of this study was to obtain optimal parameters of the Random Amplified Polymorphic DNA (RAPD) reaction by using an orthogonal array as per the Taguchi and Wu protocol, modified by Cobb and Clark for Candida parapsilosis isolates. High Simpson’s index values and low Dice coefficients obtained in this study indicated a high level of interspecies DNA polymorphism between C. parapsilosis strains, and the optimized RAPD method proved useful in the microbiological and epidemiological study.

Systemic Candidosis Diagnostic Test with Candida Score and Monocyte Count in Premature Infants with Late-Onset Sepsis: Research in Low Resources Country

Abstract Introduction: Candida is the cause of most systemic fungal infections that plays a role in the pathophysiology of sepsis in newborns, especially in premature infants with late-onset sepsis. The candida score can be used to assess the occurrence of systemic candidosis where a candida score 2.5 can accurately identify patients who are at high risk for candidiasis infection. Monocytes also play an important role in preventing candida invasion. Materials and methods: This study used a cross sectional research design. Data was collected from premature infants with late-onset sepsis being suspected of systemic candidosis in neonatology inpatient ward. It was submitted from the period of November-December 2021. It takes a minimum of 31 samples to meet the criteria to process and analyze the data. The data obtained were processed and analyzed using the Receiver Operating Characteristic (ROC) method to obtain the Area Under Curve (AUC) value. Based on the AUC curve, the search for the most optimal intersection is carried out to obtain the sensitivity and specificity values. Results: Of the 31 research subjects, the number of subjects with positive PCR results was 27 (76.93%) while negative were 4 respondents (12.9%). The mean value of PCR density in the positive group of subjects was 76.93 and the range was 40.23 122.78. Meanwhile, in the group of subjects who were negative, the PCR density value was 0. The results of the candida score diagnostic test showed that the sensitivity obtained was 81%. Higher sensitivity and specificity 70% were found in the combined examination of candida scores and monocyte counts according to cut-off compared with separate examinations. Conclusions: The combined examination of candida score and monocyte count can be used as a diagnostic test for systemic candidosis in premature infants with late-onset sepsis, and could be used to consider the initiation of empirical antifungal therapy, either prophylactically or therapeutically, especially in limited laboratory facilities in Indonesia.

A case of Candida metapsilosis conjunctivitis in a neonate admitted to the cardiac heart intensive care unit

Harmless commensal Candida species, especially uncommon and rare ones may rarely cause a serious infection. Candida metapsilosis is a recently described yeast that is phenotypically indistinguishable from Candida parapsilosis and molecular methods are essential for its identification. We report the first case of Candida conjunctivitis due to C. metapsilosis obtained from the eye discharge of a 40-day-old girl with congenital heart disease admitted to the cardiac intensive care unit (CICU). The yeast isolate was identified by sequencing the entire ITS1-5.8 rRNA-ITS2 region. Antifungal susceptibility testing performed according to the CLSI M27-A3 showed that the isolate was susceptible to amphotericin B, fluconazole, itraconazole, voriconazole, clotrimazole, nystatin, terbinafine, 5-fluorocytosine, and caspofungin. Differentiation of the fungal new species allows us the accurate diagnosis and treatment, and a better understanding the microbial epidemiology.

Evolution of Fluconazole Resistance Mechanisms and Clonal Types of Candida parapsilosis Isolates from a Tertiary Care Hospital in South Korea

We investigated the evolution of fluconazole resistance mechanisms and clonal types of Candida parapsilosis isolates from a tertiary care hospital in South Korea. A total of 45 clinical isolates, including 42 collected between 2017 and 2021 and 3 collected between 2012 and 2013, were subjected to antifungal susceptibility testing, sequencing of fluconazole resistance genes (ERG11, CDR1, TAC1, and MRR1), and microsatellite typing. Twenty-two isolates carried Y132F (n = 21; fluconazole MIC = 2 to >256 mg/L) or Y132F+R398I (n = 1; fluconazole MIC = 64 mg/L) in ERG11 and four isolates harbored N1132D in CDR1 (fluconazole MIC = 16 to 64 mg/L). All 21 Y132F isolates exhibited similar microsatellite profiles and formed a distinct group in the dendrogram. All four N1132D isolates displayed identical microsatellite profiles. Fluconazole MIC values of the Y132F isolates varied depending on their MRR1 mutation status (number of isolates, year of isolation, and MIC): K177N (n = 8, 2012 to 2020, 2 to 8 mg/L); K177N + heterozygous G982R (n = 1, 2017, 64 mg/L); K177N + heterozygous S614P (n = 2, 2019 to 2020, 16 mg/L); and K177N + homozygous S614P (n = 10, 2020 to 2021, 64 to > 256 mg/L). Our study revealed that Y132F in ERG11 and N1132D in CDR1 were the major mechanisms of fluconazole resistance in C. parapsilosis isolates. Furthermore, our results suggested that the clonal evolution of Y132F isolates persisting and spreading in hospital settings for several years occurred with the acquisition of heterozygous or homozygous MRR1 mutations associated with a gradual increase in fluconazole resistance.

Synergistic Activity of the Human Lactoferricin-Derived Peptide hLF1-11 in Combination with Caspofungin against Candida Species

Candida species are the main fungal opportunistic pathogens causing systemic infections that are often associated with drug resistance and biofilm production on medical devices. The pressing need for new antifungal agents led to an increased interest in the use of combination therapies. The present study was aimed at investigating potential synergistic activity of the human lactoferrin-derived hLF1-11 peptide with caspofungin against caspofungin-resistant or -susceptible C. albicans, C. parapsilosis, and C. glabrata strains. Synergism was evaluated by the checkerboard assay, measuring cellular metabolic activity against Candida planktonic and sessile cells. A fractional inhibitory concentration (FIC) index of ≤0.5 was interpreted as synergy. Synergism was evaluated by killing assays on planktonic cells. A cell viability assay was performed with biofilm formation inhibition and preformed biofilm. Synergy for killing and viability assays was defined as a ≥2-log-CFU/mL reduction in comparison with the most active constituent. hLF1-11 and caspofungin exerted (i) synergistic effects against planktonic cells of all the tested strains, yielding drastic caspofungin MIC reduction, (ii) synergistic effects on the inhibition of biofilm formation against biofilm producer strains, yielding caspofungin BIC reduction, and (iii) synergistic effects on preformed biofilm assessed by measuring metabolic activity (FIC range, 0.28 to 0.37) against biofilm-producing strains and by cell viability assay in C. albicans SC5314. The synergistic effect observed between caspofungin and hLF1-11 against Candida spp. is of potential clinical relevance, representing a promising novel approach to target caspofungin-resistant Candida species infections. Further studies elucidating the mechanisms of action of such a synergistic effect are needed. IMPORTANCE The present study describes a synergistic effect between a conventional antifungal drug, caspofungin, and a synthetic peptide derived from human lactoferrin, hLF1-11, against Candida species. These yeasts are able to cause severe systemic fungal infections in immunocompromised hosts. In addition, they can form biofilms in medical implanted devices. Recently, caspofungin-resistant Candida strains have emerged, thus highlighting the need to develop different therapeutic strategies. In in vitro studies, this drug combination is able to restore sensitivity to caspofungin in caspofungin-resistant strains of Candida species, both in free-living cells and in cells organized in biofilms. This synergism could represent a promising novel approach to target infections caused by caspofungin-resistant Candida species.

Characterization and functional analysis of zinc trafficking in the human fungal pathogen Candida parapsilosis

The zinc restriction and zinc toxicity are part of host defence, called nutritional immunity. The crucial role of zinc homeostasis in microbial survival within a host is established, but little is known about these processes in the opportunistic human fungal pathogen Candida parapsilosis. Our in silico predictions suggested the presence of at least six potential zinc transporters (ZnTs) in C. parapsilosis-orthologues of ZRC1, ZRT3 and ZRT101-but an orthologue of PRA1 zincophore was not found. In addition, we detected a species-specific gene expansion of the novel ZnT ZRT2, as we identified three orthologue genes in the genome of C. parapsilosis. Based on predictions, we created homozygous mutant strains of the potential ZnTs and characterized them. Despite the apparent gene expansion of ZRT2 in C. parapsilosis, only CpZRT21 was essential for growth in a zinc-depleted acidic environment, in addition we found that CpZrc1 is essential for zinc detoxification and also protects the fungi against the elimination of murine macrophages. Significantly, we demonstrated that C. parapsilosis forms zincosomes in a Zrc1-independent manner and zinc detoxification is mediated by the vacuolar importer CpZrc1. Our study defines the functions of C. parapsilosis ZnTs, including a species-specific survival and zinc detoxification system.

Characteristics of Biofilms Formed by C. parapsilosis Causing an Outbreak in a Neonatal Intensive Care Unit

Background: We dealt with the occurrence of an outbreak of Candida parapsilosis in a neonatal intensive care unit (NICU) in September 2020. There have been several reports of C. parapsilosis outbreaks in NICUs. In this study we describe our investigation into both the transmission route and the biofilm of C. parapsilosis. Methods: C. parapsilosis strains were detected in three inpatients and in two environmental cultures in our NICU. One environmental culture was isolated from the incubator used by a fungemia patient, and another was isolated from the humidifier of an incubator that had been used by a nonfungemia patient. To prove their identities, we tested them by micro satellite analysis. We used two methods, dry weight measurements and observation by electron microscopy, to confirm biofilm. Results: Microsatellite analysis showed the five C. parapsilosis cultures were of the same strain. Dry weight measurements and electron microscopy showed C. parapsilosis formed biofilms that amounted to clumps of fungal cells. Conclusions: We concluded that the outbreak happened due to horizontal transfer through the humidifier of the incubator and that the C. parapsilosis had produced biofilm, which promoted an invasive and infectious outbreak. Additionally, biofilm is closely associated with pathogenicity.

Continuing Shifts in Epidemiology and Antifungal Susceptibility Highlight the Need for Improved Disease Management of Invasive Candidiasis

Invasive candidiasis (IC) is a systemic life-threatening infection of immunocompromised humans, but remains a relatively neglected disease among public health authorities. Ongoing assessments of disease epidemiology are needed to identify and map trends of importance that may necessitate improvements in disease management and patient care. Well-established incidence increases, largely due to expanding populations of patients with pre-disposing risk factors, has led to increased clinical use and pressures on antifungal drugs. This has been exacerbated by a lack of fast, accurate diagnostics that have led treatment guidelines to often recommend preventative strategies in the absence of proven infection, resulting in unnecessary antifungal use in many instances. The consequences of this are multifactorial, but a contribution to emerging drug resistance is of primary concern, with high levels of antifungal use heavily implicated in global shifts to more resistant Candida strains. Preserving and expanding the utility and number of antifungals should therefore be of the highest priority. This may be achievable through the development and use of biomarker tests, bringing about a new era in improved antifungal stewardship, as well as novel antifungals that offer favorable profiles by targeting Candida pathogenesis mechanisms over cell viability.

Fungi of the human eye: Culture to mycobiome

The focus of the current review is multi-fold and compares the diversity and abundance of fungi on the ocular surface by the conventional culture-based method with the more sensitive, high throughput, culture-independent NGS method. The aim is to highlight the existence of a core ocular mycobiome and explore the transition of the ocular fungal microbiota from the normal eye to the diseased eye. PubMed, Google Scholar and Medline were used to search for publications and reviews related to cultivable fungi and the mycobiome of the normal and diseased eye. The conventional cultivable approach and the NGS approach confirm that the eye has its own mycobiome and several confounding factors (age, gender, ethnicity etc.) influence the mycobiome. Further, dysbiosis in the mycobiome appears to be associated with ocular diseases and thus impacts the health of the human eye. Considering that the mycobiome of the eye is influenced by several confounding factors and also varies with respect to the disease status of the eye there is a need to extensively explore the mycobiome under different physiological conditions, different ethnicities, geographical regions etc. Such studies would unravel the diversity and abundance of the mycobiomes and contribute to our understanding of ocular health. Research focused on ocular mycobiomes may eventually help to build a targeted and individualized treatment.

Signaling through Syk or CARD9 Mediates Species-Specific Anti-Candida Protection in Bone Marrow Chimeric Mice

The spleen tyrosine kinase (Syk) and the downstream adaptor protein CARD9 are crucial signaling molecules in antimicrobial immunity. Candida parapsilosis is an emerging fungal pathogen with a high incidence in neonates, while Candida albicans is the most common agent of candidiasis. While signaling through Syk/CARD9 promotes protective host mechanisms in response to C. albicans, its function in immunity against C. parapsilosis remains unclear. Here, we generated Syk-/- and CARD9-/- bone marrow chimeric mice to study the role of Syk/CARD9 signaling in immune responses to C. parapsilosis compared to C. albicans. We demonstrate various functions of this pathway (e.g., phagocytosis, phagosome acidification, and killing) in Candida-challenged, bone marrow-derived macrophages with differential involvement of Syk and CARD9 along with species-specific differences in cytokine production. We report that Syk-/- or CARD9-/- chimeras rapidly display high susceptibility to C. albicans, while C. parapsilosis infection exacerbates over a prolonged period in these animals. Thus, our results establish that Syk and CARD9 contribute to systemic resistance to C. parapsilosis and C. albicans differently. Additionally, we confirm prior studies but also detail new insights into the fundamental roles of both proteins in immunity against C. albicans. Our data further suggest that Syk has a more prominent influence on anti-Candida immunity than CARD9. Therefore, this study reinforces the Syk/CARD9 pathway as a potential target for anti-Candida immune therapy. IMPORTANCE While C. albicans remains the most clinically significant Candida species, C. parapsilosis is an emerging pathogen with increased affinity to neonates. Syk/CARD9 signaling is crucial in immunity to C. albicans, but its role in in vivo responses to other pathogenic Candida species is largely unexplored. We used mice with hematopoietic systems deficient in Syk or CARD9 to comparatively study the function of these proteins in anti-Candida immunity. We demonstrate that Syk/CARD9 signaling has a protective role against C. parapsilosis differently than against C. albicans. Thus, this study is the first to reveal that Syk can exert immune responses during systemic Candida infections species specifically. Additionally, Syk-dependent immunity to a nonalbicans Candida species in an in vivo murine model has not been reported previously. We highlight that the contribution of Syk and CARD9 to fungal infections are not identical and underline this pathway as a promising immune-therapeutic target to fight Candida infections.

Genetic Manipulation as a Tool to Unravel Candida parapsilosis Species Complex Virulence and Drug Resistance: State of the Art

An increase in the rate of isolation of Candida parapsilosis in the past decade, as well as increased identification of azole-resistant strains are concerning, and require better understanding of virulence-like factors and drug-resistant traits of these species. In this regard, the present review “draws a line” on the information acquired, thus far, on virulence determinants and molecular mechanisms of antifungal resistance in these opportunistic pathogens, mainly derived from genetic manipulation studies. This will provide better focus on where we stand in our understanding of the C. parapsilosis species complex–host interaction, and how far we are from defining potential novel targets or therapeutic strategies—key factors to pave the way for a more tailored management of fungal infections caused by these fungal pathogens.

Transcription Profiles Associated with Inducible Adhesion in Candida parapsilosis

Candida parapsilosis has emerged as a frequent cause of invasive candidiasis with increasing evidence of unique biological features relative to C. albicans As it adapts to conditions within a mammalian host, rapid changes in gene expression are necessary to facilitate colonization and persistence in this environment. Adhesion of the organism to biological surfaces is a key first step in this process and is the focus of this study. Building on previous observations showing the importance of a member of the ALS gene family in C. parapsilosis adhesion, three clinical isolates were cultured under two conditions that mimic the mammalian host and promote adhesion, incubation at 37°C in tissue culture medium 199 or in human plasma. Transcriptional profiles using RNA-seq were obtained in these adhesion-inducing conditions and compared to profiles following growth in yeast media that suppress adhesion to identify gene expression profiles associated with adhesion. Overall gene expression profiles among the three strains were similar in both adhesion-inducing conditions and distinct from adhesion-suppressing conditions. Pairwise analysis among the three growth conditions identified 133 genes that were differentially expressed at a cutoff of ±4-fold, with the most upregulated genes significantly enriched in iron acquisition and transmembrane transport, while the most downregulated genes were enriched in oxidation-reduction processes. Gene family enrichment analysis identified gene families with diverse functions that may have an important role in this important step for colonization and disease.IMPORTANCE Invasive Candida infections are frequent complications of the immunocompromised and are associated with substantive morbidity and mortality. Although C. albicans is the best-studied species, emerging infections by non-albicans Candida species have led to increased efforts to understand aspects of their pathogenesis that are unique from C. albicans C. parapsilosis is a frequent cause of invasive infections, particularly among premature infants. Recent efforts have identified important virulence mechanisms that have features distinct from C. albicans C. parapsilosis can exist outside a host environment and therefore requires rapid modifications when it encounters a mammalian host to prevent its clearance. An important first step in the process is adhesion to host surfaces. This work takes a global, nonbiased approach to investigate broad changes in gene expression that accompany efficient adhesion. As such, biological pathways and individual protein targets are identified that may be amenable to manipulation to reduce colonization and disease from this organism.

Candida parapsilosis Colony Morphotype Forecasts Biofilm Formation of Clinical Isolates

Candida parapsilosis is a frequent cause of fungal bloodstream infections, especially in critically ill neonates or immunocompromised patients. Due to the formation of biofilms, the use of indwelling catheters and other medical devices increases the risk of infection and complicates treatment, as cells embedded in biofilms display reduced drug susceptibility. Therefore, biofilm formation may be a significant clinical parameter, guiding downstream therapeutic choices. Here, we phenotypically characterized 120 selected isolates out of a prospective collection of 215 clinical C. parapsilosis isolates, determining biofilm formation, major emerging colony morphotype, and antifungal drug susceptibility of the isolates and their biofilms. In our isolate set, increased biofilm formation capacity was independent of body site of isolation and not predictable using standard or modified European Committee on Antimicrobial Susceptibility Testing (EUCAST) drug susceptibility testing protocols. In contrast, biofilm formation was strongly correlated with the appearance of non-smooth colony morphotypes and invasiveness into agar plates. Our data suggest that the observation of non-smooth colony morphotypes in cultures of C. parapsilosis may help as an indicator to consider the initiation of anti-biofilm-active therapy, such as the switch from azole- to echinocandin- or polyene-based strategies, especially in case of infections by potent biofilm-forming strains.

Preterm Infants Harbour a Rapidly Changing Mycobiota That Includes Candida Pathobionts

Fungi and the mycobiome are a fundamental part of the human microbiome that contributes to human health and development. Despite this, relatively little is known about the mycobiome of the preterm infant gut. Here, we have characterised faecal fungal communities present in 11 premature infants born with differing degrees of prematurity and mapped how the mycobiome develops during early infancy. Using an ITS1 sequencing-based approach, the preterm infant gut mycobiome was found to be often dominated by a single species, typically a yeast. Candida was the most abundant genus, with the pathobionts C.albicans and C.parapsilosis highly prevalent and persistent in these infants. Gestational maturity at birth affected the distribution and abundance of these Candida, with hospital-associated C.parapsilosis more prevalent and abundant in infants born at less than 31 weeks. Fungal diversity was lowest at 6 months, but increased with age and change of diet, with food-associated Saccharomycescerevisiae most abundant in infants post weaning. This study provides a first insight into the fungal communities present within the preterm infant gut, identifying distinctive features including the prominence of pathobiont species, and the influence age and environmental factors play in shaping the development of the mycobiome.

Candida parapsilosis endocarditis. Report of cases and review of the literature

Introduction

Infective endocarditis (IE) due to Candida species is a rare disease representing about 1-2% of all IE cases and carries a high mortality rate. Given the rarity of the disease, there are no clear guidelines on the type and duration of antifungal therapy. Thus, long-term or even life-long antifungal treatment is commonly used.

Case report

We report two patients with prosthetic valve C. parapsilosis IE and persistent candidemia that failed conservative treatment and ultimately developed heart failure. They underwent prosthetic valve replacement and prolonged antifungal treatment with favorable outcome.

Discussion

Candida IE commonly occurs in the setting of underlying malignancy, chronic liver disease, previous endocarditis, previous antimicrobial exposure, previous abdominal surgery, intravenous drug use, presence of a central venous catheter, and previous cardiac surgery. Both present patients had undergone a cardiac surgery and had a prosthetic heart valve, while one patient had an underlying autoimmune disease that could be associated with higher risk of IE. In both patients transthoracic ultrasound failed to diagnose IE. In our patients, conservative treatment alone was not enough to control the infection, thus, both patients underwent valve replacement and were subsequently treated with antifungals for 6 weeks. Furthermore, both patients were put on long-term antifungal suppression treatment.

Conclusions

Given the absence of controlled randomized trials, the treatment of Candida endocarditis mostly relies on experts' opinion, and, thus, future studies focusing on the type and duration of antifungal treatment are required.

In vitro synergy of echinocandins with triazoles against fluconazole-resistant Candida parapsilosis complex isolates

INTRODUCTION

Candida parapsilosis (C. parapsilosis) is a common non-albicans Candida species ranked as the second common cause of bloodstream infections. Azole resistance and elevated echinocandin MICs have been reported for these fungi. This study was conducted to determine the interactions between azoles and echinocandins against C. parapsilosis species complex.

MATERIALS AND METHODS

Fifteen fluconazole-resistant clinical isolates of C. parapsilosis complex were included: C. parapsilosis sensu stricto (n = 7), C. orthopsilosis (n = 5) and C. metapsilosis (n = 3). The activity of azoles (fluconazole, itraconazole) and echinocandins (anidulafungin, micafungin) alone and in combination was determined using checkerboard broth microdilution. The results were determined based on the fractional inhibitory concentration index (FICI).

RESULTS

In vitro combination of fluconazole with anidulafungin was found to be synergistic (FICI 0.07-0.37) and decreased the MIC range from 4-64 μg/mL to 0.5-16 μg/mL for fluconazole and from 2-8 μg/mL to 0.125-1 μg/mL for anidulafungin. Similarly, interactions of fluconazole with micafungin (FICI 0.25-0.5), itraconazole with anidulafungin (FICI 0.15-0.37) and itraconazole with micafungin (FICI 0.09-0.37) were synergistic.

CONCLUSION

The combination of fluconazole and itraconazole with either anidulafungin or micafungin demonstrated synergistic interactions against C. parapsilosis species complex, especially against isolates with elevated MIC values. However, the use of these combinations in clinical practice and the clinical relevance of in vitro combination results remain unclear.

Environmental Contamination with Candida Species in Multiple Hospitals Including a Tertiary Care Hospital with a Candida auris Outbreak

BACKGROUND

Environmental sources have been implicated as a potential source for exogenous acquisition of Candida species, particularly the emerging multidrug-resistant Candida auris. However, limited information is available on environmental reservoirs of Candida species in healthcare facilities.

METHODS

During a 6-month period, cultures for Candida species were collected from high-touch surfaces in patient rooms and from portable equipment in 6 US acute care hospitals in 4 states. Additional cultures were collected from sink drains and floors in one of the hospitals and from high-touch surfaces, portable equipment, and sink drains in a hospital experiencing an outbreak due to C. auris. Candida species were identified using matrix-assisted laser desorption/ionization time-of-flight mass spectometry.

RESULTS

Candida species were recovered from patient rooms in 4 of the 6 hospitals. Seven of 147 patient room cultures (4.8%) and 1 of 57 (1.8%) portable equipment cultures were positive, with the most common species being C. parapsilosis. For the hospital where additional sites were sampled, Candida species were recovered from 8 of 22 (36.4%) hospital room floors and 4 of 17 (23.5%) sink drains. In the facility with a C. auris outbreak, Candida species were frequently recovered from sink drains (20.7%) and high-touch surfaces (15.4%), but recovery of C. auris was uncommon (3.8% of high-touch surfaces, 3.4% of sink drains, and 0% of portable equipment) and only present in rooms that currently or recently housed a patient with C. auris.

CONCLUSION

Candida species often contaminate surfaces in hospitals and may be particularly common on floors and in sink drains. However, C. auris contamination was uncommon in a facility experiencing an outbreak, suggesting that current cleaning and disinfection practices can be effective in minimizing environmental contamination.

Candida auris: The recent emergence of a multidrug-resistant fungal pathogen

Candida auris is an emerging multidrug-resistant yeast that causes serious invasive infections with high mortality. It was first discovered in 2009, and since then, individual cases or outbreaks have been reported from over 20 countries on five continents. Controlling C. auris is challenging for several reasons: (1) it is resistant to multiple classes of antifungals, (2) it can be misidentified as other yeasts by commonly available identification methods, and (3) because of its ability to colonize patients perhaps indefinitely and persist in the healthcare environment, it can spread between patients in healthcare settings. The transmissibility and high levels of antifungal resistance that are characteristic of C. auris set it apart from most other Candida species. A robust response that involves the laboratory, clinicians, and public health agencies is needed to identify and treat infections and prevent transmission. We review the global emergence, biology, challenges with laboratory identification, drug resistance, clinical manifestations, treatment, risk factors for infection, transmission, and control of C. auris.

Candida parapsilosis: from Genes to the Bedside

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.

Eicosanoid production by Candida parapsilosis and other pathogenic yeasts

Eicosanoids are bioactive lipid mediators generated in almost all mammalian cells from the oxidation of arachidonic acid and other related twenty-carbon polyunsaturated fatty acids (PUFA). Eicosanoids regulate various physiological functions, including cellular homoeostasis and modulation of inflammatory responses in mammals. The mode of action of these lipid mediators depend on their binding to different G-protein coupled receptors. The three main enzymatic pathways associated with their production are the COX pathway, LOX pathway and cytochrome P450 pathway. Interestingly, investigations have also revealed that several human pathogenic fungi are capable of producing these bioactive lipid mediators; however, the exact biosynthetic pathways and their function in pathogenicity are not yet extensively characterized. The aim of the current review is to summarize the recent discoveries pertaining to eicosanoid production by human pathogenic yeasts with a special focus on the opportunistic human fungal pathogen Candida parapsilosis.

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.

Outbreak of Pichia kudriavzevii fungaemia in a neonatal intensive care unit

PURPOSE

Fungaemia is associated with substantial morbidity and mortality in neonates admitted to neonatal intensive care units (NICUs). We report an outbreak of fungaemia in a NICU due to rare yeast, Pichia kudriavzevii (a teleomorph of Candida krusei). To the best of our knowledge, this is the first report of neonatal sepsis due to P. kudriavzevii.

METHODOLOGY

Between August and September 2014, blood cultures from nine neonates diagnosed with late-onset sepsis in the NICU yielded yeast-like organisms. The molecular identification and typing of these isolates was performed by sequencing the D1/D2 region of 26S rDNA and fluorescent amplified fragment length polymorphism (FAFLP) respectively. Antifungal susceptibility was tested by broth microdilution as per the Clinical Laboratory Standards Institute (CLSI) guidelines. Sampling from environmental sources and the hands of healthcare workers (HCWs) in the NICU was performed.

RESULTS

Of the nine neonates, eight were preterm and six had very low birth weight (VLBW). Thrombocytopenia was present in two neonates. Sequencing identified all the isolates as P. kudriavzevii and FAFLP showed their clonal origin. Antifungal susceptibility testing revealed the susceptibility of all isolates to the antifungals tested. Treatment with voriconazole was advised. However, only seven neonates were treated successfully and discharged after improvement, whereas two were lost for follow-up. Cultures from the environment and the hands of HCWs were negative. The outbreak was controlled by the strict implementation of infection control practices.

CONCLUSION

This study emphasizes the importance of accurate identification of the aetiological agent of sepsis and vigilant monitoring for the possibility of an outbreak in NICUs.

The N-Terminus of Human Lactoferrin Displays Anti-biofilm Activity on Candida parapsilosis in Lumen Catheters

Candida parapsilosis is a major cause of hospital-acquired infection, often related to parenteral nutrition administered via catheters and hand colonization of health care workers, and its peculiar biofilm formation ability on plastic surfaces. The mortality rate of 30% points to the pressing need for new antifungal drugs. The present study aimed at analyzing the inhibitory activity of the N-terminal lactoferrin-derived peptide, further referred to as hLF 1-11, against biofilms produced by clinical isolates of C. parapsilosis characterized for their biofilm forming ability and fluconazole susceptibility. hLF 1-11 anti-biofilm activity was assessed in terms of reduction of biofilm biomass, metabolic activity, and observation of sessile cell morphology on polystyrene microtiter plates and using an in vitro model of catheter-associated C. parapsilosis biofilm production. Moreover, fluctuation in transcription levels of genes related to cell adhesion, hyphal development and extracellular matrix production upon peptide exposure were evaluated by quantitative real time RT-PCR. The results revealed that hLF 1-11 exhibits an inhibitory effect on biofilm formation by all the C. parapsilosis isolates tested, in a dose-dependent manner, regardless of their fluconazole susceptibility. In addition, hLF 1-11 induced a statistically significant dose-dependent reduction of preformed-biofilm cellular density and metabolic activity at high peptide concentrations only. Interestingly, when assessed in a catheter lumen, hLF 1-11 was able to induce a 2-log reduction of sessile cell viability at both the peptide concentrations used in RPMI diluted in NaPB. A more pronounced anti-biofilm effect was observed (3.5-log reduction) when a 10% glucose solution was used as experimental condition on both early and preformed C. parapsilosis biofilm. Quantitative real time RT-PCR experiments confirmed that hLF 1-11 down-regulates key biofilm related genes. The overall findings suggest hLF 1-11 as a promising candidate for the prevention of C. parapsilosis biofilm formation and to treatment of mature catheter-related C. parapsilosis biofilm formation.

Healthcare workers' hands as a vehicle for the transmission of virulent strains of Candida spp.: A virulence factor approach

BACKGROUND

Although the majority of Candida infections are thought to come from endogenous sources, the healthcare workers' (HCWs) hands are being increasingly reported as vehicles for the transmission of pathogens. The aim of the present study was to evaluate the susceptibility of yeast isolated from the HCWs' hands and ICU (Intensive Care Unit) surfaces to antifungal agents and to determine the virulence potential and the genetic similarity between the same.

METHODS

The susceptibility of yeasts from the HCWs' hands (n = 57) and ICU surfaces (n = 98) to conventional antifungals (fluconazole, voriconazole, amphotericin B and micafungin) was evaluated using the broth microdilution assay accordance with CLSI M27-A3. Additionally, some virulence factors such as adhesion and biofilm capacity on abiotic surfaces and on endothelial cells were evaluated, as well as germ tube formation. The similarity among yeast isolates were evaluated by the RAPD technique using the P4, OPA18 and OPE18 primers.

RESULTS

Five species of Candida were found on the HCWs' hands (C. albicans, C. parapsilosis (sensu stricto), C. glabrata, C. tropicalis and C. krusei) and two on ICU surfaces (C. albicans and C. parapsilosis (sensu stricto)). The isolates from hands had higher resistance rates, with C. glabrata having the highest indices (100% FLU; 100% MFG). The similarity of C. albicans from HCWs and ICU surfaces was ≥80% according to the three primers analyzed. Candida spp. from hands had a greater potential for adhesion and biofilm formation on abiotic surfaces (p < 0.05). C. albicans from ICU surfaces had the greatest potential of adhesion on endothelial cells after 2 and 24 h, and presented high filamentation in SEM images and formed more and larger germ tubes (p < 0.05).

CONCLUSION

the present study showed the significant virulence potential of yeasts transmitted in the hospital environment for the first time. Additionally, healthy people working in the ICU can carry these yeasts, which are capable of surviving in hospital surfaces, on their hands, offering a risk to patients, especially those who are immunocompromised.

Colonization and Succession within the Human Gut Microbiome by Archaea, Bacteria, and Microeukaryotes during the First Year of Life

Perturbations to the colonization process of the human gastrointestinal tract have been suggested to result in adverse health effects later in life. Although much research has been performed on bacterial colonization and succession, much less is known about the other two domains of life, archaea, and eukaryotes. Here we describe colonization and succession by bacteria, archaea and microeukaryotes during the first year of life (samples collected around days 1, 3, 5, 28, 150, and 365) within the gastrointestinal tract of infants delivered either vaginally or by cesarean section and using a combination of quantitative real-time PCR as well as 16S and 18S rRNA gene amplicon sequencing. Sequences from organisms belonging to all three domains of life were detectable in all of the collected meconium samples. The microeukaryotic community composition fluctuated strongly over time and early diversification was delayed in infants receiving formula milk. Cesarean section-delivered (CSD) infants experienced a delay in colonization and succession, which was observed for all three domains of life. Shifts in prokaryotic succession in CSD infants compared to vaginally delivered (VD) infants were apparent as early as days 3 and 5, which were characterized by increased relative abundances of the genera Streptococcus and Staphylococcus, and a decrease in relative abundance for the genera Bifidobacterium and Bacteroides. Generally, a depletion in Bacteroidetes was detected as early as day 5 postpartum in CSD infants, causing a significantly increased Firmicutes/Bacteroidetes ratio between days 5 and 150 when compared to VD infants. Although the delivery mode appeared to have the strongest influence on differences between the infants, other factors such as a younger gestational age or maternal antibiotics intake likely contributed to the observed patterns as well. Our findings complement previous observations of a delay in colonization and succession of CSD infants, which affects not only bacteria but also archaea and microeukaryotes. This further highlights the need for resolving bacterial, archaeal, and microeukaryotic dynamics in future longitudinal studies of microbial colonization and succession within the neonatal gastrointestinal tract.

Antifungal Immunological Defenses in Newborns

Newborns are prone to fungal infections, largely due to Candida species. The immunological basis for this vulnerability is not yet fully understood. However, useful insights can be gained from the knowledge of the maturation of immune pathways during ontogeny, particularly when placed in context with how rare genetic mutations in humans predispose to fungal diseases. In this article, we review these most current data on immune functions in human newborns, highlighting pathways most relevant to the response to Candida. While discussing these data, we propose a framework of why deficiencies in these pathways make newborns particularly vulnerable to this opportunistic pathogen.

Opioid Dependent Malingerer with Self-Induced Sepsis

A 21-year-old woman was admitted to the emergency department (ED) with severe sepsis. Both the mechanism of infection and organisms discovered were unusual.

Secular Trends of Candidemia in a Large Tertiary-Care Hospital From 1988 to 2000: Emergence ofCandida parapsilosis

Objective:

To analyze the secular trends of candidemia in a large tertiary-care hospital to determine the overall incidence, as well as the incidence by ward and by species, and to detect the occurrence of outbreaks.

Design:

Retrospective descriptive analysis. Secular trends were calculated using the Mantel-Haenszel test.

Setting:

A large tertiary-care referral center in Spain with a pediatric intensive care unit (ICU) to which more than 500 children with congenital cardiac disease are admitted annually.

Patients:

All patients with candidemia occurring from 1988 to 2000 were included. Cases were identified from laboratory records of blood cultures.

Results:

There were 331 episodes of candidemia. The overall incidence of nosocomial candidemia was 0.6 episode per 1,000 admissions and remained stable throughout the study period (P= .925). The species most frequently isolated wasCandida albicans, but the incidence ofC. parapsilosiscandidemia increased (P= .035). In the pediatric ICU, the incidence ofC. parapsilosiswas 5.6 episodes per 1,000 admissions and it was the predominant species. Outbreaks occurred occasionally in the pediatric ICU, suggesting nosocomial transmission.

Conclusions:

During this 13-year period, the incidence of candidemia remained stable in this hospital, butC. parapsilosisincreased in frequency. Occasional outbreaks of candidemia suggested nosocomial transmission ofCandidaspecies (Infect Control Hosp Epidemiol2005;26:548-552).

Drug resistance mechanisms and their regulation in non-albicans Candida species

Fungal pathogens use various mechanisms to survive exposure to drugs. Prolonged treatment very often leads to the stepwise acquisition of resistance. The limited number of antifungal therapeutics and their mostly fungistatic rather than fungicidal character facilitates selection of resistant strains. These are able to cope with cytotoxic molecules by acquisition of appropriate mutations, re-wiring gene expression and metabolic adjustments. Recent evidence points to the paramount importance of the permeability barrier and cell wall integrity in the process of adaptation to high drug concentrations. Molecular details of basal and acquired drug resistance are best characterized in the most frequent human fungal pathogen, Candida albicans Effector genes directly related to the acquisition of elevated tolerance of this species to azole and echinocandin drugs are well described. The emergence of high-level drug resistance against intrinsically lower susceptibility to azoles in yeast species other than C. albicans is, however, of particular concern. This is due to their steadily increasing contribution to high mortality rates associated with disseminated infections. Recent findings concerning underlying mechanisms associated with elevated drug resistance suggest a link to cell wall and plasma membrane metabolism in non-albicans Candida species.

Candida parapsilosis corneal graft infection from a single eye center: Histopathologic report of 2 cases

Fungal keratitis accounts for 6–53% of all cases of ulcerative keratitis in variable studies. The majority of cases are due to septate fungi. The abnormal cornea in cases of dry eye syndrome, chronic ulceration, erythema multiform and possibly HIV infection is infected more commonly with Candida, most commonly Candida albicans. Candida parapsilosis affects neonates and intensive care unit (ICU) patients and it has been recently found with increasing frequency. In a previous study on mycotic keratitis in our tertiary eye hospital, filamentous fungi were more commonly isolated than yeasts. We are presenting 2 successive cases of corneal graft infection by Candida parapsilosis referred to us from another eye center to attract the attention of ophthalmologists and health workers to such an infection.

Characterization of Virulence-Related Phenotypes in Candida Species of the CUG Clade

Candida species cause a variety of mucosal and invasive infections and are, collectively, the most important human fungal pathogens in the developed world. The majority of these infections result from a few related species within the "CUG clade," so named because they use a nonstandard translation for that codon. Some members of the CUG clade, such as Candida albicans, present significant clinical problems, whereas others, such as Candida (Meyerozyma) guilliermondii, are uncommon in patients. The differences in incidence rates are imperfectly correlated with virulence in animal models of infection, but comparative analyses that might provide an explanation for why some species are effective pathogens and others are not have been rare or incomplete. To better understand the phenotypic basis for these differences, we characterized eight CUG clade species--C. albicans, C. dubliniensis, C. tropicalis, C. parapsilosis, Clavispora lusitaniae, M. guilliermondii, Debaryomyces hansenii, and Lodderomyces elongisporus--for host-relevant phenotypes, including nutrient utilization, stress tolerance, morphogenesis, interactions with phagocytes, and biofilm formation. Two species deviated from expectations based on animal studies and human incidence. C. dubliniensis was quite robust, grouping in nearly all assays with the most virulent species, C. albicans and C. tropicalis, whereas C. parapsilosis was substantially less fit than might be expected from its clinical importance. These findings confirm the utility of in vitro measures of virulence and provide insight into the evolution of virulence in the CUG clade.

Analysis of clinical and environmental Candida parapsilosis isolates by microsatellite genotyping--a tool for hospital infection surveillance

Candida parapsilosis emerged as an important opportunistic pathogen, causing candidaemia worldwide. Nosocomial outbreaks triggered by this species have been frequently described, particularly in cancer patients. For a better understanding of its epidemiology, several typing methods are used and microsatellite analysis has been reported as highly discriminant. The main objective of this work was to study C. parapsilosis isolates by application of microsatellite genotyping to distinguish epidemiologically related strains, compare clinical and environmental isolates and determine possible routes of dispersion of the isolates in the hospital setting. A total of 129 C. parapsilosis isolates from different origins, including hospital environment and hands of healthcare workers, were genotyped using four microsatellite markers. The isolates were recovered from different health institutions. Analysis of C. parapsilosis isolates from hospital environment showed great genotypic diversity; however, the same or very similar genotypes were also found. The same multilocus genotype was shared by isolates recovered from the hand of a healthcare worker, from the hospital environment and from patients of the same healthcare institution, suggesting that these could be possible routes of transmission and that infections due to C. parapsilosis may be mainly related with exogenous transmission to the patient. Examination of sequential isolates from the same patients showed that colonizing and bloodstream isolates had the same multilocus genotype in the majority of cases. We demonstrate that this typing method is able to distinguish clonal clusters from genetically unrelated genotypes and can be a valuable tool to support epidemiologic investigations in the hospital setting.

Therapeutic strategies for invasive fungal infections in neonatal and pediatric patients: an update

INTRODUCTION

Invasive fungal infections (IFIs) in neonatal and pediatric patients are still associated with high morbidity and mortality, increased length of hospital stay and high healthcare cost. Two key components are prerequisite to combat pediatric IFIs; first, definition of the 'at-risk' populations that could benefit the most from prophylactic treatment and second, prompt initiation of effective antifungal therapy.

AREAS COVERED

In this article, updated prevention and targeted therapeutic approaches for IFIs in neonates and immunocompromised children are reviewed. Furthermore, European and American guidelines concerning IFI treatment in neonates and children are compared.

EXPERT OPINION

IFIs in neonates and children present substantial differences from adults in respect to their epidemiology, pharmacokinetics of antifungal agents and dosing as well as absence of interventional Phase III and IV clinical trials for guidance of evidence-based decisions. In the therapeutic armamentarium of these age groups, although amphotericin B formulations remain widely indicated, azoles with broader spectrum activity as well as echinocandins have been added in the updated antifungal treatment algorithm. Recent European guidelines (ESCMID and ECIL) contain specific recommendations for pediatric patients with IFIs. In both age groups, definitive updated guidance for prophylaxis and more importantly targeted treatment need to be further evaluated by large, multicenter, randomized controlled trials.

Different scenarios for Candida parapsilosis fungaemia reveal high numbers of mixed C. parapsilosis and Candida orthopsilosis infections

Nosocomial fungal bloodstream infections (BSI) are increasing significantly in hospitalized patients and Candida parapsilosis has emerged as an important pathogen responsible for numerous outbreaks. The objective of this study was to evaluate C. parapsilosis sensu lato infection scenarios, regarding species distribution and strain relatedness. One hundred isolates of C. parapsilosis sensu lato derived from blood cultures and catheter tips were analysed by multiplex microsatellite typing and by sequencing D1/D2 regions of the ribosomal DNA. Our results indicate that 9.5 % of patients presented infections due to C. parapsilosis and Candida orthopsilosis, 57.1 % due to C. parapsilosis, 28.3 % due to C. orthopsilosis and 4.8 % due to Candida metapsilosis. Eighty per cent of the C. parapsilosis BSIs were due to a single strain that was also identified in the catheter, but in 10 % of the cases C. parasilosis was identified in the catheter but the BSI was due to C. orthopsilosis. There is a significant probability that C. parapsilosis isolates collected from the same patient at more than 3 months interval are of different strains (P = 0.0179). Moreover, several isolates were identified persistently in the same hospital, infecting six different patients. The incidence of polyfungal BSI infections with C. parapsilosis and C. orthopsilosis is reported herein for the first time, emphasizing the fact that the species identified in the catheter is not always responsible for the BSI, thus impacting the treatment strategy. The observation that strains can remain in the hospital environment for years highlights the possible existence of reservoirs and reinforces the need for accurate genotyping tools, such as the markers used for elucidating epidemiological associations and detecting outbreaks.

Genetic diversity among Candida albicans isolates associated with vertical transmission in preterm triplets

We report a case of congenital candidiasis in triplets, in the context of premature labor at 25 weeks gestation, without symptomatic vaginitis or chorioamnionitis. All three infants died as a result of prematurity, aggravated by systemic candidiasis. Multi-locus sequence typing confirmed vertical transmission of Candida albicans from the mother to the triplets and revealed a slight diversity among the strains isolated from the neonates.

In Candida parapsilosis the ATC1 gene encodes for an acid trehalase involved in trehalose hydrolysis, stress resistance and virulence

An ORF named CPAR2-208980 on contig 005809 was identified by screening a Candida parapsilosis genome data base. Its 67% identity with the acid trehalase sequence from C. albicans (ATC1) led us to designate it CpATC1. Homozygous mutants that lack acid trehalase activity were constructed by gene disruption at the two CpATC1 chromosomal alleles. Phenotypic characterization showed that atc1Δ null cells were unable to grow on exogenous trehalose as carbon source, and also displayed higher resistance to environmental challenges, such as saline exposure (1.2 M NaCl), heat shock (42°C) and both mild and severe oxidative stress (5 and 50 mM H2O2). Significant amounts of intracellular trehalose were specifically stored in response to the thermal upshift in both wild type and mutant strains. Analysis of their antioxidant activities revealed that catalase was only triggered in response to heat shock in atc1Δ cells, whereas glutathione reductase was activated upon mild oxidative stress in wild type and reintegrant strains, and in response to the whole set of stress treatments in the homozygous mutant. Furthermore, yeast cells with double CpATC1 deletion were significantly attenuated in non-mammalian infection models, suggesting that CpATC1 is required for the pathobiology of the fungus. Our results demonstrate the involvement of CpAtc1 protein in the physiological hydrolysis of external trehalose in C. parapsilosis, where it also plays a major role in stress resistance and virulence.

Systemic Infection Due to Candida parapsilosis in a Domestic Ferret (Mustela putorius furo)

An 18-month-old castrated male ferret (Mustela putorius furo) was presented to the veterinary hospital for acute collapse but died despite initiation of emergency treatment. The body was submitted for a complete postmortem examination. The pathologist determined the ferret was suffering from severe necrotizing encephalitis, necrogranulomatous mediastinal lymphadenitis, and ulcerative dermatitis attributable to systemic Candida parapsilosis. This is the first report of systemic Candida parapsilosis in a ferret.

Emergence of non-albicans Candida species in neonatal candidemia

Background:

Candida species are one of the most common causes of blood stream infections among neonates and account for 9-13% of such infections. Although Candida albicans remains the most common fungal isolate from neonatal candidemia, longitudinal studies have detected a shift towards non-albicans Candida (NAC) species.

Aim:

To examine the prevalence and epidemiology of candidemia among infants admitted to our hospital.

Materials and Methods:

Blood samples were collected from 548 neonates and only those which yielded pure growth of Candida spp. were included in the study. The isolates were identified as per standard mycological techniques and antifungal susceptibility (AFS) was done by disc diffusion method.

Results:

Of the total 132 neonates included in the study, NAC species were responsible for 80.30% cases with C. parapsilosis (25.0%) and C. tropicalis (21.97%) as the most predominant species; whereas 19.70% of cases were caused by C. albicans. AFS results revealed that 65.91, 73.49, and 96.21% isolates were sensitive to fluconazole (FLK), itraconazole (ITR), and amphotericin B (AMB), respectively.

Conclusion:

Candidemia in neonates is an ominous prognostic sign and is an important entity in our hospital. Strict infection control strategies, appropriate preventive and therapeutic measures such as prophylactic antifungal use and a restrictive policy of antibiotic use should be implemented.

Anidulafungin versus caspofungin in a mouse model of candidiasis caused by anidulafungin-susceptible Candida parapsilosis isolates with different degrees of caspofungin susceptibility

Candida parapsilosis isolates occasionally display resistance in vitro to echinocandins and cause breakthrough infections to echinocandins. The degree of the in vivo cross-resistance among echinocandins and the fitness loss associated with caspofungin (CAS) resistance of C. parapsilosis are not well studied. We compared the activities of CAS and anidulafungin (ANF), each given at 2 dosing schedules (high dose or low dose) in a nonneutropenic mouse model of invasive candidiasis (IC) caused by ANF-susceptible isolates of C. parapsilosis with different degrees of susceptibility to CAS (CAS resistant [CAS-R], MIC, >16 mg/liter; CAS intermediate [CAS-I], MIC, 4 mg/liter; and CAS susceptible [CAS-S], MIC, 2 mg/liter). We analyzed tissue fungal burden, histopathology, and weight loss patterns. Increasing CAS resistance was associated with reduced virulence of C. parapsilosis isolates (mortality rates for CAS-S versus CAS-I versus CAS-R, 100% versus 11.1% versus 0%, respectively; P < 0.001). High doses of either echinocandin were active against infection with the CAS-I isolate when assessed by fungal burden reduction and weight gain. In contrast to CAS-S and CAS-I isolates, there was no reduction in fungal burden in mice infected with the CAS-R isolate following treatment with either echinocandin, each given at a high or low dose. Nevertheless, mice infected with the CAS-R isolate had reduced disease severity following echinocandin treatment, suggesting that echinocandins have activity in vivo, even against echinocandin-resistant strains. A complex interplay of residual echinocandin activity, decreased virulence, and/or fitness of isolates with altered cell wall and possible immunomodulatory effects can be encountered in vivo during infection with CAS-resistant C. parapsilosis isolates.

Candida parapsilosis is a significant neonatal pathogen: a systematic review and meta-analysis

BACKGROUND

Candida is the third most common cause of late-onset neonatal sepsis in infants born at <1500 g. Candida parapsilosis infections are increasingly reported in preterm neonates in association with indwelling catheters.

METHODS

We systematically reviewed neonatal literature and synthesized data pertaining to percentage of C. parapsilosis infections and mortality by meta-analyses. We also reviewed risk factors, virulence determinants, antimicrobial susceptibility patterns and outlined clinical management strategies.

RESULTS

C. parapsilosis infections comprised 33.47% (95% confidence interval [CI]: 30.02, 37.31) of all neonatal Candida infections. C. parapsilosis rates were similar in studies performed before the year 2000, 33.53% (95% CI: 30.06, 37.40) (28 studies), to those after 2000, 27.00% (95% CI: 8.25, 88.37) (8 studies). The mortality due to neonatal C. parapsilosis infections was 10.02% (95% CI: 7.66, 13.12). Geographical variations in C. parapsilosis infections included a low incidence in Europe and higher incidence in North America and Australia. Biofilm formation was a significant virulence determinant and predominant risk factors for C. parapsilosis infections were prematurity, prior colonization and catheterization. Amphotericin B remains the antifungal drug of choice and combination therapy with caspofungin or other echinocandins may be considered in resistant cases.

CONCLUSION

C. parapsilosis is a significant neonatal pathogen, comprises a third of all Candida infections and is associated with 10% mortality. Availability of tools for genetic manipulation of this organism will identify virulence determinants and organism characteristics that may explain predilection for preterm neonates. Strategies to prevent horizontal transmission in the neonatal unit are paramount in decreasing infection rates.