Association between Candida biofilm-forming bloodstream isolates and the clinical evolution in patients with candidemia: An observational nine-year single center study in Mexico

Candida Isolation During COVID-19: Microbiological Findings of a Prospective Study in a Regional Hospital

BACKGROUND

Prolonged hospitalization due to the COVID-19 pandemic gathered risk factors for developing invasive candidiasis.

AIM

To describe Candida spp. isolated from patients with clinical suspicion of COVID treated in a public hospital specialized in COVID-19 during the pandemic, considering the susceptibility profiles and the risk factors related to the species detected in a positive yeast culture.

METHODS

From different samples of 33 patients with comorbidities, 42 clinical isolates were identified by VITEKⓇ MS Plus. Antifungal susceptibility testing was performed using VITEKⓇ 2 Compact with the AST-YS08 card.

RESULTS

The most frequently identified species were C. albicans and C. glabrata, which were also the most common co-infections, Saprochaete capitata, an uncommon yeast was isolated in one patient. 85% of the co-infections were COVID positive and 100% of patients with a co-infection required mechanical ventilation (MV) which has been described as one of the major predisposing factors to candidiasis. Candida species vary in their response to treatment. In this study, 44% of isolates identified as C. glabrata were fluconazole-resistant, which were also immediately susceptible to caspofungin; this profile limits therapeutic options and emphasizes the importance of evaluating the susceptibility profile.

CONCLUSIONS

This work highlights the increase in isolation of different Candida species during COVID-19 and the importance of establishing criteria to declare Candida colonization or infection and the correct etiological identification to establish an agent-based antifungal treatment, to reduce the spreading risk of Candida spp. in the hospital environment, mortality, time, and cost of hospitalization.

Antifungal susceptibility and virulence determinants profile of candida species isolated from patients with candidemia

Candida is the most prevalent fungal bloodstream infection (BSI) with a high mortality rate among hospitalized patients. Another concern facing physicians is rising global incidence of drug-resistant Candida. This study aimed to characterize the prevalence, antifungal susceptibility, biofilm formation, and virulence genes (HWP1, ALS1, SAP2) of different Candida spp. isolated from patients with candidemia. 52 isolates of Candida spp. were identified from blood cultures by chromogenic Candida agar and confirmed by the VITEK 2 system. Isolates were tested for antifungal susceptibility by disk diffusion and VITEK 2 system. Biofilm formation and investigated genes were detected by the Congo red method and conventional PCR, respectively. Candida spp. caused 2.3% of detected BSIs, of which 32.7% were caused by Candida albicans (C. albicans) and 67.3% by non-albicans Candida (NAC), with the predominance of C. tropicalis (25%), followed by C. parapsilosis (17.3%), and C. krusei (13.5%). The susceptibility rates to fluconazole, voriconazole, caspofungin, micafungin, amphotericin B, and flucytosine were 64.7%, 76.5%, 100.0%, 100%, 100.0%, and 100.0% in C. albicans, while 53.6%, 71.4%, 91.4%, 91.4%, 94.3%, and 94.3% in NAC, respectively. Biofilm production, HWP1, ALS1, and SAP2 were detected in 70.6%, 82.4%, 76.5%, and 52.9% of C. albicans and 74.3%, 85.7%, 80.0%, and 48.6% of NAC, respectively. There is remarkable shift to NAC BSIs and high azole resistance. Antifungal stewardship and analysis of risk factors associated with this shift are needed.

Systematic Characterization of Epidemiology, Antifungal Susceptibility, Risk Factors and Outcomes of Candidaemia: A Six-Year Chinese Study

Background

Candida bloodstream infection (BSI), the fourth most common nosocomial BSI, is an urgent global health challenge with the tremendous growth in antifungal resistance rate and mortality rate.

Purpose

To establish the epidemiology, species distribution, risk factors, and 30-day mortality of candidaemia among 115 patients in this 6-year surveillance study.

Materials and Methods

We retrospectively analyzed the clinical characteristics, epidemiology, antifungal susceptibility patterns, and risk factors for morbidity and mortality of 115 candidaemia cases diagnosed in one tertiary care hospital from January 2016 through December 2021.

Results

Of the 115 candidaemia cases, the most prevalent species were Candida tropicalis (33.0%), followed by Candida albicans (27.8%), Candida parapsilosis complex (19.1%), and others. The overall incidence was 0.21 cases/1000 admissions. The overall crude resistance rate of Candida spp. against azoles was 20.0% (23/115), while Candida tropicalis showed a significant increase in the resistance rate to azoles (from 1/6, 16.7% in 2017 to 6/10, 60.0% in 2021). Multivariate analyses demonstrated that hematological malignancy and neutropenia were significantly associated with Candida tropicalis BSI than Candida non-tropicalis BSI. Candida albicans BSI had a significantly higher rate of previous surgery than Candida non-albicans BSI. Candida parapsilosis BSI had a significantly higher rate of receiving total parenteral nutrition (TPN). The overall 30-day mortality rate was 27.0% (31/115). The presence of high age-adjusted Charlson comorbidity index (aCCI), neutropenia, and septic shock were factors independently associated with increased 30-day mortality.

Conclusion

Candida tropicalis are emerging as the predominant isolate in candidaemia. Of note, the unexpectedly increased resistance rate to azoles in Candida tropicalis BSI was observed. The aCCI scores, neutropenia, and septic shock were independently associated with 30-day mortality. Prompt, adequate antifungal treatment among high-risk patients may lead to a reduction in mortality.

Prediction of Prognostic Risk Factors in Patients with Invasive Candidiasis and Cancer: A Single-Centre Retrospective Study

Background

Invasive candidiasis is a common cancer-related complication with a high fatality rate. If patients with a high risk of dying in the hospital are identified early and accurately, physicians can make better clinical judgments. However, epidemiological analyses and mortality prediction models of cancer patients with invasive candidiasis remain limited.

Method

A set of 40 potential risk factors was acquired in a sample of 258 patients with both invasive candidiasis and cancer. To begin, risk factors for Candida albicans vs. non-Candida albicans infections and persistent vs. nonpersistent Candida infections were analysed using classic statistical methods. Then, we applied three machine learning models (random forest, logistic regression, and support vector machine) to identify prognostic indicators related to mortality. Prediction performance of different models was assessed by precision, recall, F1 score, accuracy, and AUC.

Results

Of the 258 patients both with invasive candidiasis and cancer included in the analysis. The median age of patients was 62 years, and 95 (36.82%) patients were older than 65 years, of which 178 (66.28%) were male. And 186 (72.1%) patients underwent surgery 2 weeks before data collection, 100 (39.1%) patients stayed in ICU during hospitalisation, 99 (38.4%) patients had bacterial blood infection, 85 (32.9%) patients had persistent invasive candidiasis, and 41 (15.9%) patients died within 30 days. The usage of drainage catheter and prolonged length of hospitalisation are the dominant risk factors for non-Candida albicans infections and persistent Candida infections, respectively. Risk factors, such as septic shock, history of surgery within the past 2 weeks, usage of drainage tubes, length of stay in ICU, total parenteral nutrition, serum creatinine level, fungal antigen, stay in ICU during hospitalisation, and total bilirubin level, were significant predictors of death. The RF model outperformed the LR and SVM models. Precision, recall, F1 score, accuracy, and AUC for RF were 64.29%, 75.63%, 69.23%, 89.61%, and 91.28%.

Conclusions

In this study, the machine learning-based models accurately predicted the prognosis of cancer and invasive candidiasis patients. The algorithm could be used to help clinicians in high-risk patients' early intervention.

The relationship between biofilm formation and mortality in patients with Candida tropicalis candidemia

BACKGROUND

Biofilm formation by Candida species is an influential virulence factor in candidemia pathogenesis. We investigated the relationship between biofilm formation of Candida tropicalis isolates with the clinical characteristics and mortality outcomes in patients with candidemia.

MATERIALS AND METHODS

Thirty-nine C. tropicalis isolates were recovered from patients with candidemia admitted to two university hospitals in Tehran, Iran. Biofilm mass and metabolic activity of C. tropicalis biofilms were assessed in vitro with two colorimetric methods. The sessile minimum inhibitory concentrations (SMICs) were evaluated in vitro by treating preformed biofilms with diluted concentrations of azoles according to CLSI-M27 A3/S4 protocol, followed by metabolic activity quantification. The expressions of ERG11, UPC2, MDR1, and CDR1 genes were also evaluated.

RESULTS

All C. tropicalis isolates produced biofilm. Respectively, higher <7-day and ≥7-day mortality rates were found among cases with high metabolic activity (46.7% vs. 13%, P = 0.03) and high biofilm mass (31.8% vs. 0, P = 0.029). Sessile cells had high resistance to fluconazole, voriconazole, and itraconazole. The azole minimum inhibitory concentrations (MICs) of C. tropicalis sessile were significantly greater than the planktonic minimum inhibitory concentrations (PMICs). In fluconazole-treated biofilms, the expression of ERG11 and UPC2 genes was increased.

CONCLUSION

Our findings highlight the importance of C. tropicalis biofilm formation as an important factor in candidemia pathogenesis and the clinical outcome of patients with candidemia.

Current Aspects in the Biology, Pathogeny, and Treatment of Candida krusei, a Neglected Fungal Pathogen

Fungal infections represent a constant and growing menace to human health, because of the emergence of new species as causative agents of diseases and the increment of antifungal drug resistance. Candidiasis is one of the most common fungal infections in humans and is associated with a high mortality rate when the fungi infect deep-seated organs. Candida krusei belongs to the group of candidiasis etiological agents, and although it is not isolated as frequently as other Candida species, the infections caused by this organism are of special relevance in the clinical setting because of its intrinsic resistance to fluconazole. Here, we offer a thorough revision of the current literature dealing with this organism and the caused disease, focusing on its biological aspects, the host-fungus interaction, the diagnosis, and the infection treatment. Of particular relevance, we provide the most recent genomic information, including the gene prediction of some putative virulence factors, like proteases, adhesins, regulators of biofilm formation and dimorphism. Moreover, C. krusei veterinary aspects and the exploration of natural products with anti-C. krusei activity are also included.

Development of a novel anti-biofilm peptide derived from profilin of Spodoptera frugiperda

Candida yeast infections are the fourth leading cause of death worldwide. Peptides with antimicrobial activity are a promising alternative treatment for such infections. Here, the antifungal activity of a new antimicrobial peptide-PEP-IA18-was evaluated against Candida species. PEP-IA18 was designed from the primary sequence of profilin, a protein from Spodoptera frugiperda, and displayed potent activity against Candida albicans and Candida tropicalis, showing a minimum inhibitory concentration (MIC) of 2.5 µM. Furthermore, the mechanism of action of PEP-IA18 involved interaction with the cell membrane (ergosterol complexation). Treatment at MIC and/or 10 × MIC significantly reduced biofilm formation and viability. PEP-IA18 showed low toxicity toward human fibroblasts and only revealed hemolytic activity at high concentrations. Thus, PEP-IA18 exhibited antifungal and anti-biofilm properties with potential applicability in the treatment of infections caused by Candida species.

Anti-fungal susceptibility and virulence factors of Candida spp. isolated from blood cultures

Candidemia is one of the most common fungal nosocomial infections worldwide. It causes high mortality and morbidity rate with significant hospital costs due to increased length of hospital stay and costs for anti-fungal treatment. This study aims to investigate anti-fungal drug susceptibility, enzymatic activity and biofilm formation of the Candida spp. isolated from blood cultures. In 2016, a total of 84 clinical Candida isolates were analyzed for minimum inhibitory concentration (MIC) against fluconazole and amphotericin B by agar diffusion E-test (E-strips). Three enzymatic activity tests for phospholipase, proteinase and esterase were performed by using egg yolk agar, bovine serum albumin medium and Tween 80 opacity medium, respectively. Biofilm formation was determined by crystal violet staining. To describing the various Candida distributions cultured, C. albicans was the most frequent species (n=37, 44.1%), followed by C. tropicalis (n=30, 35.7%), C. parapsilosis (n=8, 9.5%), C. glabrata (n=6, 7.1%) and C. guilliermondii (n=3, 3.6%). Regarding anti-fungal drug susceptibility, C. albicans was susceptible to fluconazole (100%). In addition, all clinical Candida isolates were fully susceptible to amphotericin B (100%). The predominant enzyme activity of C. albicans included medium to high levels of phospholipase, proteinase and esterase activities. C. tropicalis displayed esterase activity, while C. glabrata and C. guilliermondii had no phospholipase and proteinase activity. Non-albicans Candida (NAC) i.e. C. tropicalis formed a biofilm at a higher rate than C. albicans. This study revealed the production of virulent factors in Candida strains from candidemia patients.

Candida species isolated from pigeon (Columbia livia) droppings may express virulence factors and resistance to azoles

Even though it is widely known that Cryptococcus spp. may transmit cryptococcosis trough aerosol formed when dried birds (mainly pigeons) droppings are dispersed and become airborne, little is known about the role of these birds in harboring other pathogenic yeasts in their gastrointestinal tract, feathers and beaks, specifically because these animals often stay and reproduce close or even above air conditioner units. Here we evaluated the prevalence of pathogenic yeasts isolated from pigeon droppings collected in the outside area of a University Hospital in Brazil. We also aimed to investigate the pathogenic potential and antifungal susceptibility of Candida species of medical interest isolated from these samples. Therefore, we performed the evaluation of virulence factors attributes expression in vitro, including the ability to adhere to human buccal epithelial cells and biofilm formation and to produce lytic enzymes, such as phospholipases, proteinases and hemolysins. Antifungal susceptibility testing against fluconazole, itraconazole, amphotericin and micafungin was also performed. The Candida genus was the most prevalent in our study, with several medically important species being isolated. Of note, these strains were able to express several virulence factors in vitro, clearly showing their pathogenic potential. Our study was able to demonstrate that Candida spp. isolated from pigeon droppings may express virulence factors in the same manner of clinical isolates, suggesting a pathogenic potential for these yeasts. The fact these strains were collected from the outside area of a tertiary hospital may be of interest, because they may be a source of infection, specifically to immunocompromised hosts.

Fungal infections in pediatric neurosurgery

INTRODUCTION

Invasive mycosis of the central nervous system represent a diverse group of diseases that have gradually emerged as not only opportunistic infections in patients with immune susceptibility due to congenital and acquired deficiency, immunomodulation, solid organ and stem cell transplantation, hematological malignancies, and chronic steroid use but also in selected risk populations such as low weight preterm infants, patients with shunted hydrocephalus and external ventricular drainages, skull base surgery, and head injury.

OBJECTIVES

The purpose of this review is to familiarize the pediatric neurosurgeon with the most common mycosis and their clinical scenarios which can be encountered in the clinical practice, with special emphasis on clinical, radiological, and laboratory diagnosis beyond classical microorganism cultures as well as options in medical and surgical treatment given the high incidence of morbidity and mortality associated with these challenging entities.

METHODS

We conducted an online database review (Ovid, PubMed) gathering relevant English language literature published in the last 20 years with special emphasis on recent breakthroughs in the diagnosis and treatment of invasive mycosis of the CNS as well as reported cases within the pediatric neurosurgical literature and their surgical management.

RESULTS

Fungal agents capable of invading the CNS can behave as aggressive entities with rapid progression manifesting as overwhelming meningoencephalitis with vascular compromise or can lead to space-occupying lesions with abscess formation which require prompt diagnosis by either laboratory identification of the components of these biological agents and their host response or by obtaining tissue specimens for microbiological identification which may not be straightforward due to prolonged culture time.

CONCLUSION

Following a high degree of suspicion with prompt initiation of antifungal agents and reversal of potential immunosuppressant therapies along with neurosurgical evacuation of intracranial collections or removal of infected hardware (CSF shunts) can lead to more optimistic outcomes of these complex clinical scenarios.