Candidaemia in polish hospitals - a multicentre survey

Epidemiological patterns of candidaemia: A comprehensive analysis over a decade

BACKGROUND

The prevalence of fungal bloodstream infections (BSI), especially candidaemia, has been increasing globally during the last decades. Fungal diagnosis is still challenging due to the slow growth of fungal microorganisms and need for special expertise. Fungal polymicrobial infections further complicate the diagnosis and extend the time required. Epidemiological data are vital to generate effective empirical treatment strategies.

OBJECTIVES

The overall aim of this project is to describe the epidemiology of monomicrobial candidaemia and polymicrobial BSI, both with mixed fungaemia and with mixed Candida/bacterial BSIs.

METHODS

We conducted a single-centre retrospective epidemiological study that encompasses 950,161 blood cultures during the years 2010 to 2020. The epidemiology of monomicrobial and polymicrobial candidaemia episodes were investigated from the electronic records.

RESULTS

We found that 1334 candidaemia episodes were identified belonging to 1144 individual patients during 2010 to 2020. Candida albicans was the most prevalent species detected in candidaemia patients, representing 57.7% of these episodes. Nakaseomyces (Candida) glabrata and Candida parapsilosis complex showed an increasing trend compared to previous studies, whereas Candida albicans demonstrated a decrease. 19.8% of these episodes were polymicrobial and 17% presented with mixed Candida/bacterial BSIs while 2.8% were mixed fungaemia. C. albicans and N. glabrata were the most common combination (51.4%) in mixed fungaemia episodes. Enterococcus and Lactobacillus spp. were the most common bacteria isolated in mixed Candida/bacterial BSIs.

CONCLUSIONS

Polymicrobial growth with candidaemia is common, mostly being mixed Candida/bacterial BSIs. C. albicans was detected in more than half of all the candidaemia patients however showed a decreasing trend in time, whereas an increase is noteworthy in C. parapsilosis complex and N. glabrata.

Candida parapsilosis cell wall proteins-CPAR2_404800 and CPAR2_404780-Are adhesins that bind to human epithelial and endothelial cells and extracellular matrix proteins

One of the initial steps necessary for the development of Candida infections is the adherence to the host tissues and cells. Recent transcriptomic studies suggest that, in Candida parapsilosis-a fungal infectious agent that causes systemic candidiasis in immunosuppressed individuals-the adhesion is mediated by pathogen cell-exposed proteins belonging to the agglutinin-like sequence (Als) family. However, to date, the actual interactions of individual members of this family with human cells and extracellular matrix (ECM) have not been characterized in detail. In the current study, we focused attention on two of these C. parapsilosis Als proteins-CPAR2_404800 and CPAR2_404780-that were proteomically identified in the fungal cell wall of yeasts grown in the media suitable for culturing human epithelial and endothelial cells. Both proteins were extracted from the cell wall and purified, and using a microplate binding assay and a fluorescence microscopic analysis were shown to adhere to human cells of A431 (epithelial) and HMEC-1 (endothelial) lines. The human extracellular matrix components that are also plasma proteins-fibronectin and vitronectin-enhanced these interactions, and also could directly bind to CPAR2_404800 and CPAR2_404780 proteins, with a high affinity (KD in a range of 10-7 to 10-8  M) as determined by surface plasmon resonance measurements. Our findings highlight the role of proteins CPAR2_404800 and CPAR2_404780 in adhesion to host cells and proteins, contributing to the knowledge of the mechanisms of host-pathogen interactions during C. parapsilosis-caused infections.

Molecular Investigation of the Fatal Bloodstream Candida orthopsilosis Infection Case following Gastrectomy

Candida orthopsilosis represents a closely related cryptic genospecies of Candida parapsilosis complex-misidentified in routine diagnostic assays. This is emerging in settings where central venous catheters, invasive medical interventions, and echinocandin treatments are most likely to be used. A 59-year-old, non-neutropenic male patient, was admitted to an intensive care unit (ICU) due to respiratory distress syndrome, following a partial gastrectomy. As a result of duodenal stump leakage, re-laparotomy was required, abdominal drains were provided and central line catheters were exchanged. Multiple isolates of Candida orthopsilosis drawn from consecutive blood cultures were identified, despite ongoing echinocandin therapy and confirmed in vitro echinocandins susceptibility of the isolated strain. Species identification was verified via ITS region sequencing. Herein, we report the well-documented—per clinical data and relevant laboratory diagnosis—first case of a bloodstream infection caused by Candida orthopsilosis in Poland.

MixInYeast: A Multicenter Study on Mixed Yeast Infections

Invasive candidiasis remains one of the most prevalent systemic mycoses, and several studies have documented the presence of mixed yeast (MY) infections. Here, we describe the epidemiology, clinical, and microbiological characteristics of MY infections causing invasive candidiasis in a multicenter prospective study. Thirty-four centers from 14 countries participated. Samples were collected in each center between April to September 2018, and they were sent to a reference center to confirm identification by sequencing methods and to perform antifungal susceptibility testing, according to the European Committee on Antimicrobial Susceptibility Testing (EUCAST). A total of 6895 yeast cultures were identified and MY occurred in 150 cases (2.2%). Europe accounted for the highest number of centers, with an overall MY rate of 4.2% (118 out of 2840 yeast cultures). Of 122 MY cases, the most frequent combinations were Candida albicans/C. glabrata (42, 34.4%), C. albicans/C. parapsilosis (17, 14%), and C. glabrata/C. tropicalis (8, 6.5%). All Candida isolates were susceptible to amphotericin B, 6.4% were fluconazole-resistant, and two isolates (1.6%) were echinocandin-resistant. Accurate identification of the species involved in MY infections is essential to guide treatment decisions.

Candidemia in Children with Malignancies: Report from the Infection Working Group of the Hellenic Society of Pediatric Hematology-Oncology

Candidemia is an important cause of morbidity and mortality especially in immunocompromised and hospitalized patients. We retrospectively collected data of candidemia cases that occurred in the seven Hematology-Oncology Departments/Units of Greece and the Stem Cell Transplant Unit between 2015 and 2019. In total, 19 episodes of candidemia in 19 patients were recorded. The majority of the patients (78.9%) had at least one risk factor for candidemia. The most frequent risk factors associated with candidemia observed in our patients were prolonged duration of hospitalization (30 days, range 1–141), presence of a central venous catheter at diagnosis of candidemia (73.7%) and antibiotics use during the last two weeks (84.2%). Candida parapsilosis was the most common species isolated accounting for 42.1%, followed by C. albicans (26.3%) and C. famata (15.8%). Nearly all of the patients (84.2%) received antifungal monotherapy with liposomal amphotericin B or echinocandins. The central venous catheter was removed in 78.6% of patients and the median time between the first positive blood culture and catheter removal was 3 days (range 1–9). Mortality at 28 days was 26.3%. In conclusion, a predominance of non-albicans species was observed in our study in conformity with the global trend.

Multilocus Sequence Typing Reveals a New Cluster of Closely Related Candida tropicalis Genotypes in Italian Patients With Neurological Disorders

Candida tropicalis is a pathogenic yeast that has emerged as an important cause of candidemia especially in elderly patients with hematological malignancies. Infections caused by this species are mainly reported from Latin America and Asian-Pacific countries although recent epidemiological data revealed that C. tropicalis accounts for 6-16.4% of the Candida bloodstream infections (BSIs) in Italy by representing a relevant issue especially for patients receiving long-term hospital care. The aim of this study was to describe the genetic diversity of C. tropicalis isolates contaminating the hands of healthcare workers (HCWs) and hospital environments and/or associated with BSIs occurring in patients with different neurological disorders and without hematological disease. A total of 28 C. tropicalis isolates were genotyped using multilocus sequence typing analysis of six housekeeping (ICL1, MDR1, SAPT2, SAPT4, XYR1, and ZWF1) genes and data revealed the presence of only eight diploid sequence types (DSTs) of which 6 (75%) were completely new. Four eBURST clonal complexes (CC2, CC10, CC11, and CC33) contained all DSTs found in this study and the CC33 resulted in an exclusive, well-defined, clonal cluster from Italy. In conclusion, C. tropicalis could represent an important cause of BSIs in long-term hospitalized patients with no underlying hematological disease. The findings of this study also suggest a potential horizontal transmission of a specific C. tropicalis clone through hands of HCWs and expand our understanding of the molecular epidemiology of this pathogen whose population structure is still far from being fully elucidated as its complexity increases as different categories of patients and geographic areas are examined.

Creation and Assessment of a Clinical Predictive Calculator and Mortality Associated With Candida krusei Bloodstream Infections

Background

Candida krusei bloodstream infection (CK BSI) is associated with high mortality, but whether this is due to underlying comorbidities in affected patients or the organism itself is unknown. Identifying patient characteristics that are associated with CK BSI is crucial for clinical decision-making and prognosis.

Methods

We conducted a retrospective analysis of hospitalized patients with Candida BSI at our institution between 2002 and 2015. Data were collected on demographics, comorbidities, medications, procedures, central lines, vital signs, and laboratory values. Multivariable logistic and Cox regression were used to identify risk factors associated with CK and mortality, respectively.

Results

We identified 1873 individual patients who developed Candida BSI within the study period, 59 of whom had CK BSI. CK BSI was predicted by hematologic malignancy, gastric malignancy, neutropenia, and the use of prophylactic azole antifungals, monoclonal antibodies, and β-lactam/β-lactamase inhibitor combinations. The C-statistic was 0.86 (95% confidence interval, 0.81–0.91). The crude mortality rates were 64.4% for CK BSI and 41.4% for non-CK BSI. Although CK was associated with higher mortality in univariable Cox regression, this relationship was no longer significant with the addition of the following confounders: lymphoma, neutropenia, glucocorticoid use, chronic liver disease, and elevated creatinine.

Conclusions

Six patient comorbidities predicted the development of CK BSI with high accuracy. Although patients with CK BSI have higher crude mortality rates than patients with non-CK BSI, this difference is not significant when accounting for other patient characteristics.

In vitro activity of micafungin against biofilms of Candida albicans, Candida glabrata, and Candida parapsilosis at different stages of maturation

Candida spp. is able to form a biofilm, which is considered resistant to the majority of antifungals used in medicine. The aim of this study was to evaluate the in vitro activity of micafungin against Candida spp. biofilms at different stages of their maturation (2, 6, and 24 h). We assessed the inhibitory effect of micafungin against 78 clinical isolates of Candida spp., growing as planktonic or sessile cells, by widely recommended broth microdilution method. The in vitro effect on sessile cells viability was evaluated by colorimetric reduction assay. All examined strains were susceptible or intermediate to micafungin when growing as planktonic cells. At the early stages of biofilm maturation, from 11 (39.3%) to 20 (100%), tested strains, depending on the species, exhibited sessile minimal inhibitory concentrations (SMICs) of micafungin at ≤ 2 mg/L. For 24-h-old Candida spp. biofilms, from 3 (10.7%) to 20 (100%) of the tested strains displayed SMICs of micafungin at ≤ 2 mg/L. Our findings confirm that micafungin exhibits high potential anti-Candida-biofilm activity. However, this effect does not comprise all Candida species and strains. All strains were susceptible or intermediate to micafungin when growing as planktonic cells, but for biofilms, micafungin displays species- and strain-specific activity. Paradoxical growth of C. albicans and C. parapsilosis was observed. Antifungal susceptibility testing of Candida spp. biofilms would be the best solution, but to date, no reference method is available. The strongest antibiofilm activity of micafungin is observed at early stages of biofilm formation. Possibly, micafungin could be considered as an effective agent for prevention of biofilm-associated candidiasis, especially catheter-related candidaemia.

Candida albicans Impairments Induced by Peppermint and Clove Oils at Sub-Inhibitory Concentrations

Members of Candida species cause significant health problems, inducing various types of superficial and deep-seated mycoses in humans. In order to prevent from Candida sp. development, essential oils are more and more frequently applied, due to their antifungal activity, low toxicity if used appropriately, and biodegrability. The aim of the study was to characterize the early alterations in Candida albicans metabolic properties in relation to proteins and chromosomal DNA profiles, after treatment with peppermint and clove oils at sub-inhibitory concentrations. The yeasts were affected by the oils even at a concentration of 0.0075% v/v, which resulted in changes in colony morphotypes and metabolic activities. Peppermint and clove oils at concentrations ranging from 0.015× MIC (minimal inhibitory concentration) to 0.5× MIC values substantially affected the enzymatic abilities of C. albicans, and these changes were primarily associated with the loss or decrease of activity of all 9 enzymes detected in the untreated yeast. Moreover, 29% isolates showed additional activity of N-acetyl-β-glucosaminidase and 14% isolates—α-fucosidase in comparison to the yeast grown without essential oils addition. In response to essential oils at 0.25–0.5× MIC, extensive changes in C. albicans whole-cell protein profiles were noted. However, the yeast biochemical profiles were intact with the sole exception of the isolate treated with clove oil at 0.5× MIC. The alterations were not attributed to gross chromosomal rearrangements in C. albicans karyotype. The predominantly observed decrease in protein fractions and the yeast enzymatic activity after treatment with the oils should be considered as a phenotypic response of C. albicans to the essential oils at their sub-inhibitory concentrations and may lead to the reduction of this yeast pathogenicity.

Antifungal drug resistance among Candida species: mechanisms and clinical impact

The epidemiology of Candida infections has changed in recent years. Although Candida albicans is still the main cause of invasive candidiasis in most clinical settings, a substantial proportion of patients is now infected with non-albicans Candida species. The various Candida species vary in their susceptibility to the most commonly used antifungal agents, and the intrinsic resistance to antifungal therapy seen in some species, along with the development of acquired resistance during treatment in others, is becoming a major problem in the management of Candida infection. A better understanding of the mechanisms and clinical impact of antifungal drug resistance is essential for the efficient treatment of patients with Candida infection and for improving treatment outcomes. Herein, we report resistance to the azoles and echinocandins among Candida species.

Inactivation of human kininogen-derived antimicrobial peptides by secreted aspartic proteases produced by the pathogenic yeast Candida albicans

Ten secreted aspartic proteases (Saps) of Candida albicans cleave numerous peptides and proteins in the host organism and deregulate its homeostasis. Human kininogens contain two internal antimicrobial peptide sequences, designated NAT26 and HKH20. In our current study, we characterized a Sap-catalyzed cleavage of kininogen-derived antimicrobial peptides that results in the loss of the anticandidal activity of these peptides. The NAT26 peptide was effectively inactivated by all Saps, except Sap10, whereas HKH20 was completely degraded only by Sap9. Proteolytic deactivation of the antifungal potential of human kininogens can help the pathogens to modulate or evade the innate immunity of the host.

Molecular epidemiology of Candida albicans and Candida glabrata strains isolated from intensive care unit patients in Poland

Over the last decades, Candida spp have been responsible for an increasing number of infections, especially in patients requiring intensive care. Knowledge of local epidemiology and analysis of the spread of these pathogens is important in understanding and controlling their transmission. The aim of this study was to evaluate the genetic diversity of 31 Candida albicans and 17 Candida glabrata isolates recovered from intensive care unit patients from the tertiary hospital in Krakow between 2011-2012. The strains were typed by random amplified polymorphic DNA (RAPD) polymerase chain reaction using five primers (CD16AS, HP1247, ERIC-2, OPE-3 and OPE-18). The results of the present investigation revealed a high degree of genetic diversity among the isolates. No clonal relationship was found among the C. albicans strains, whereas two C. glabrata isolates were identical. The source of Candida infection appeared to be mostly endogenous; however, the presence of two clonal C. glabrata strains suggested the possibility of cross-transmission of these pathogens. Our study confirmed the high discriminatory power of the RAPD technique in the molecular typing of Candida clinical isolates. This method may be applied to the evaluation of transmission routes of pathogenic fungi on a local level.

β-Aescin at subinhibitory concentration (sub-MIC) enhances susceptibility of Candida glabrata clinical isolates to nystatin

Aescin (escin) derived from the seeds of horse chestnut (Aesculus hippocastanum L.) is a natural mixture of triterpene saponins exhibiting a wide variety of pharmacological properties, including antiinflammatory, analgesic, and antipyretic activities. However, data concerning antifungal activities of these compounds are limited. This study aims to evaluate the in vitro antifungal susceptibility of Candida glabrata clinical isolates to α-aescin sodium, β-aescin crystalline and β-aescin sodium using the disk diffusion (DD) and broth microdilution (BMD) methods. Moreover, the influence of subinhibitory concentration (0.5×MIC) of β-aescins on the nystatin MIC was also studied. In general, the results obtained by the DD assay correlated well with those obtained by the BMD method. Both β-aescins effectively inhibited the growth of all 24 strains tested. The minimum inhibitory concentration (MIC) values ranging from 8 to 32 μg/ml for β-aescin crystalline, whereas those of β-aescin sodium were slightly lower and ranged from 4 to 16 μg/ml. In contrast, α-aescin sodium was found to be completely ineffective against the strains studied. MIC values of nystatin were reduced 2-16-fold and 2-4-fold in the presence of subinhibitory concentration of β-aescin crystalline and β-aescin sodium, respectively. Results of the present study may suggest the additive interaction between β-aescin and nystatin.

Evaluation of blood culture media for the detection of fungi

The aim of this study was to compare the utility of BACTEC™ Mycosis-IC/F (Mycosis), BACTEC™ Plus Aerobic/F (Aerobic), and BACTEC™ Plus Anaerobic/F (Anaerobic) media in the detection of fungi from simulated (obtained by the inoculation of tested media first with sterile sheep's blood and subsequently with one of 60 clinical yeast isolates) and clinical blood samples, taken during routine diagnostic examination in two hospitals. All tested strains grew on Mycosis as well as Aerobic bottles, and the time to detection obtained for Mycosis was significantly shorter (p < 0.05). The largest differences in the time to positivity was found for Candida glabrata and Cryptococcus neoformans, when Mycosis preceded Aerobic in 20-48 h (mean 35.5 h) and 0.7-64 h (mean 24 h), respectively. On the contrary, C. krusei were detected earlier in Aerobic media. In clinical samples, the detection of C. glabrata was also significantly faster in Mycosis than in Aerobic (29.22 ± 11.48 h compared to 86 ± 40 h). The media complement each other and, in 45% of clinical examination sets, a single positive medium was noted (25% in Mycosis and 19% in Aerobic). The study proved that both Aerobic and Mycosis media serve as the correct condition for the culture of fungi and that they varied significantly in the detection time of clinically important species. This result could suggest that the simultaneous use of Aerobic as well as Mycosis media may improve the time of diagnosis in many patients, especially those infected with C. glabrata or C. neoformans.

Candidaemia observed at a university hospital in Milan (northern Italy) and review of published studies from 2010 to 2014

BACKGROUND

Candida species represent the fourth leading cause of nosocomial bloodstream infections (BSI) worldwide. However, candidaemia rates and species involved vary geographically.

OBJECTIVES

To evaluate the epidemiological pattern, risk factors for mortality and antifungal therapy of Candida BSI over a 5-year period (2008-2012) in a university hospital in northern Italy together with a review of the recent literature concerning candidaemia.

METHODS

A retrospective cohort study cross-linked with microbiology database was performed.

RESULTS

A total of 89 Candida BSI were identified in 42 males (47 %) and 47 females (52.8 %). The median age was 69 years (interquartile range 55-78) with 61.8 % of patients being older than 65 years. Considering all hospitalized patients, the overall incidence rate of candidaemia increased significantly from 2008 to 2012 (from 0.4 to 1.68 episodes per 10,000 patient/days) (p = 0.0001) with a mean linear increase in 5 new cases per year. Candida albicans was the predominant species isolated (64 %) followed by C. glabrata (19.1 %). The latter species was observed with significantly higher frequency in Internal Medicine and Intensive Care Units (ICU). In-hospital crude mortality was 41.6 %.

CONCLUSIONS

Candidaemia is an increasing BSI in our university hospital, in accordance with that observed in northern Italy, and it is still associated with high in-hospital crude mortality.