Trends in antifungal susceptibility of Candida spp. isolated from pediatric and adult patients with bloodstream infections: SENTRY Antimicrobial Surveillance Program, 1997 to 2000

A 14-Year Cohort of Candidemia in the Pediatric Population in a Tertiary Center in Jerusalem: Clinical Characteristics, Antifungal Susceptibility, and Risk Factors for Mortality

Candida spp. can cause bloodstream infection and is associated with significant mortality. The proportion of fluconazole-resistant Candida non-albicans has increased over the years, and empirical fluconazole maybe inappropriate. In this retrospective study, we analyzed clinical characteristics, antifungal resistance patterns, and mortality in children with candidemia treated at a tertiary medical center in Jerusalem between 2009 and 2022. A total of 122 children developed 127 candidemia episodes with 132 Candida isolates. Half the episodes occurred in immunocompromised children. Septic shock was present in 27 (21.3%). Candida non-albicans was responsible for 71/132 (56.5%) episodes; 16/132 (12.1%) of isolates were fluconazole-resistant. The rate of Candida non-albicans was significantly higher in fluconazole-resistant episodes (90 vs. 50.5%, p = 0.02). Prolonged severe neutropenia and previous fluconazole exposure were more frequent in fluconazole-resistant episodes. Thirty-day mortality was 25 (19.7%). Greater mortality, as shown by multivariate analysis, was associated with candidemia contracted in the pediatric intensive care unit (PICU), previous use of azoles or carbapenems, and in the presence of shock. In conclusion, mortality rates in our study were higher than those previously reported. In suspected infection associated with factors which we found to increase the probability of mortality-PICU admission, shock, and earlier azole or carbapenems exposure-empirical antifungals should be considered.

Changing Trends in Antimicrobial Susceptibility Patterns of Bloodstream Infection (BSI) in Secondary Care Hospitals of India

Introduction Bloodstream infection (BSI) and subsequent sepsis are life-threatening medical conditions. The onset of antimicrobial resistance and subsequent multi-drug resistant organisms (MDRO) significantly increase healthcare-associated expenditure with adverse clinical outcomes. The present study was undertaken to identify the trends of BSI in community settings in secondary care hospitals (smaller private hospitals and district hospitals) in the state of Madhya Pradesh in Central India with the support of the Indian Council of Medical Research (ICMR) and National Health Mission, Madhya Pradesh. Methodology The present study was a prospective, longitudinal observational chart review type of study. The study was carried out at 10 secondary care hospitals (eight smaller private hospitals and two government district hospitals) nominated by the State Government as part of the ICMR Antimicrobial Resistance Surveillance and Research Network (AMRSN). The hospitals were nominated depending on the availability of a microbiology laboratory and a full-time microbiologist. Result A total of 6202 blood samples were received from patients with suspected BSI, out of which 693 samples were positive for aerobic culture. Among these, 621 (89.6%) showed bacterial growth and 72 (10.3%) grew Candida species (spp). Out of the 621 bacterial growth samples, Gram-negative bacteria were 406 (65.3%) and Gram-positive bacteria were 215 (34.6%). Among the Gram-negative isolates (406), the predominant isolate was Escherichia coli (115; 28.3%) followed by Klebsiella pneumoniae (109; 26.8%), Pseudomonas aeruginosa (61; 15%), Salmonella spp. (52; 12.8%), Acinetobacter spp. (47; 11.6%) and the other Enterobacter spp. (22; 5.4%). Among the Gram-positive isolates (215), the predominant isolate was Staphylococcus aureus (178; 82.8%) followed by Enterococcus spp. (37; 17.2%). Among the Escherichia coli, third-generation cephalosporin resistance was identified in 77.6%, piperacillin-tazobactam resistance in 45.2%, carbapenem resistance in 23.5% and colistin resistance in 16.5% of cases. Among the Klebsiella pneumoniae, third-generation cephalosporin resistance was identified in 80.7%, piperacillin-tazobactam resistance in 72.8%, carbapenem resistance in 63.3% and colistin resistance in 14% of cases. Among the Pseudomonas aeruginosa, ceftazidime resistance was identified in 61.2%, piperacillin-tazobactam resistance in 55%, carbapenem resistance in 32.8%, and colistin resistance in 38.3% of cases. Among the Acinetobacter spp., piperacillin-tazobactam resistance was identified in 72.7%, carbapenem resistance in 72.3%, and colistin resistance in 9.3% cases. While analyzing the antibiogram for Staphylococcus aureus isolates, methicillin resistance (MRSA) was seen in 70.3% of cases, followed by vancomycin resistance (VRSA) in 8% of cases and linezolid resistance in 8.1%. Among the Enterococcus spp. isolates, linezolid resistance was found in 13.5%, vancomycin resistance (VRE) in 21.6%, and teicoplanin resistance in 29.7% of cases. Conclusion In conclusion, the first-ever study to identify the risk of high-end antibiotics causing significant drug resistance in secondary and tertiary care settings has highlighted the urgent need for more randomized control studies and proactive measures from healthcare authorities and serves as a beacon for future research efforts and underscores the importance of implementing antibiograms to combat the growing threat of antibiotic resistance.

Phenotypic and Genotypic Characterization of Intestinal Candida spp. in Tunisia

Background: Yeasts naturally colonize the mammalian digestive tract and play an important role in health and disease. This community is composed of commensal yeasts, mostly Candida and Saccharomyces described as a part of the intestinal mycobiome and could be associated with resident or transient flora. Objectives: The aim of our study was to perform the phenotypic and genotypic characterization of culturable Candida isolates present in stool specimens of healthy Tunisian individuals and to evaluate their antifungal susceptibility. Methods: Yeasts were recovered from 46 stool samples cultured on Sabouraud dextrose agar at 37°C. Species were identified using conventional methods and ITS-PCR sequencing. Candida isolates were tested by exploring their tolerance to oxidative stress and extreme acidic conditions. In addition, their biofilm formation ability and in vitro resistance to antifungals was determined by the VITEK 2 system. Results: The identification by sequencing the ITS1-5.8S-ITS2 region of the 56 yeast strains isolated from 37 stool samples revealed that Candida was the dominant genus and was represented by Candida albicans (n = 21), C. parapsilosis (n = 10), C. glabrata (n = 9), and C. krusei (n = 9). In contrast, the other genera, including Trichosporon, Geotrichum, and Rhodotorula, were sporadically occurring. We found that most Candida isolates were able to form biofilms under oxidative stress and extreme pH conditions. Regarding antifungal susceptibility, a higher resistance rate to fluconazole was revealed in comparison to caspofungin and micafungin. However, no resistance was revealed against voriconazole, amphotericin B, and 5-flucytosine. Conclusions: This is the first work-generated data on cultivable yeasts from stool specimens of healthy individuals in Tunisia. Further metagenomic studies with a larger sample size are needed to better characterize the intestinal mycobiota.

Candida Bloodstream Infections: Changes in Epidemiology and Increase in Drug Resistance

The literature on bloodstream infections (BSIs) have predominantly been biased towards bacteria, given their superior clinical significance in comparison with the other types of microorganisms. Fungal pathogens have epidemiologically received relatively less attention, although they constitute an important proportion of BSI aetiologies. In this review, the authors discuss the clinical relevance of fungal BSIs in the context of Candida species, as well as treatment options for the infections, emphasizing the compelling need to develop newer antifungals and strengthen antimicrobial stewardship programmes in the wake of the rapid spread of antifungal resistance.

Trends in Pediatric Candidemia: Epidemiology, Anti-Fungal Susceptibility, and Patient Characteristics in a Children's Hospital

Candida bloodstream infections (CBSIs) have decreased among pediatric populations in the United States, but remain an important cause of morbidity and mortality. Species distributions and susceptibility patterns of CBSI isolates diverge widely between children and adults. The awareness of these patterns can inform clinical decision-making for empiric or pre-emptive therapy of children at risk for candidemia. CBSIs occurring from 2006-2016 among patients in a large children's hospital were analyzed for age specific trends in incidence rate, risk factors for breakthrough-CBSI, and death, as well as underlying conditions. Candida species distributions and susceptibility patterns were evaluated in addition to the anti-fungal agent use. The overall incidence rate of CBSI among this complex patient population was 1.97/1000 patient-days. About half of CBSI episodes occurred in immunocompetent children and 14% in neonatal intensive care unit (NICU) patients. Anti-fungal resistance was minimal: 96.7% of isolates were fluconazole, 99% were micafungin, and all were amphotericin susceptible. Liposomal amphotericin was the most commonly prescribed anti-fungal agent included for NICU patients. Overall, CBSI-associated mortality was 13.7%; there were no deaths associated with CBSI among NICU patients after 2011. Pediatric CBSI characteristics differ substantially from those in adults. The improved management of underlying diseases and antimicrobial stewardship may further decrease morbidity and mortality from CBSI, while continuing to maintain low resistance rates among Candida isolates.

In vitro antifungal susceptibilities of six antifungal drugs against clinical Candida glabrata isolates according to EUCAST

Background and Purpose:

Candida glabrata is the second cause of candidiasis. The mortality rate of C. glabrata infections is about 40%; accordingly, it may be life threatening, especially in immunocompromised hosts. Regarding this, the current study was conducted to evaluate the regional patterns of the antifungal susceptibility of clinical C. glabrataisolated from the patients referring to the health centers located in Ahvaz, Iran

Materials and Methods:

In this study, a total of 30 clinical strains of C. glabrata isolates were recovered from different body sites (i.e., vagina, mouth, and urine). Phenotypic characteristics and molecular methods were used to identify the isolates. The minimum inhibitory concentration (MIC) was determined according to the European Committee on Antimicrobial Susceptibility Testing

Results:

Our findings demonstrated that 20%, 80%, and 6.7% of the isolates were resistant to amphotericin B, terbinafine, and posaconazole, respectively, while all the isolates were found to be fluconazole susceptible dose dependent and susceptible to voriconazole and caspofungin

Conclusion:

Our study suggested that voriconazole had high potency against C. glabrata isolates. Consequently, this antifungal agent can be an alternative drug in the treatment of resistant patients. These results can be helpful for the successful treatment of patients in different regions

The Evolution of Azole Resistance in Candida albicans Sterol 14α-Demethylase (CYP51) through Incremental Amino Acid Substitutions

Recombinant Candida albicans CYP51 (CaCYP51) proteins containing 23 single and 5 double amino acid substitutions found in clinical strains and the wild-type enzyme were expressed in Escherichia coli and purified by Ni²⁺-nitrilotriacetic acid agarose chromatography. Catalytic tolerance to azole antifungals was assessed by determination of the concentration causing 50% enzyme inhibition (IC₅₀) using CYP51 reconstitution assays. The greatest increase in the IC₅₀ compared to that of the wild-type enzyme was observed with the five double substitutions Y132F+K143R (15.3-fold), Y132H+K143R (22.1-fold), Y132F+F145L (10.1-fold), G307S+G450E (13-fold), and D278N+G464S (3.3-fold). The single substitutions K143R, D278N, S279F, S405F, G448E, and G450E conferred at least 2-fold increases in the fluconazole IC₅₀, and the Y132F, F145L, Y257H, Y447H, V456I, G464S, R467K, and I471T substitutions conferred increased residual CYP51 activity at high fluconazole concentrations. In vitro testing of select CaCYP51 mutations in C. albicans showed that the Y132F, Y132H, K143R, F145L, S405F, G448E, G450E, G464S, Y132F+K143R, Y132F+F145L, and D278N+G464S substitutions conferred at least a 2-fold increase in the fluconazole MIC. The catalytic tolerance of the purified proteins to voriconazole, itraconazole, and posaconazole was far lower and limited to increased residual activities at high triazole concentrations for certain mutations rather than large increases in IC₅₀ values. Itraconazole was the most effective at inhibiting CaCYP51. However, when tested against CaCYP51 mutant strains, posaconazole seemed to be the most resistant to changes in MIC as a result of CYP51 mutation compared to itraconazole, voriconazole, or fluconazole.

Barriers and facilitators and the need for a clinical guideline for microbiological diagnostic testing in the hospital: a qualitative and quantitative study

The appropriate use of microbiological investigations is an important cornerstone of antibiotic stewardship programmes, but receives relatively limited attention. This study aimed to identify influencing factors in performing microbiological diagnostic tests and to assess the need for a clinical guideline. We performed a qualitative (focus group) and quantitative (online questionnaire survey) study among medical specialists and residents to identify physicians' considerations in performing microbiological diagnostic tests and to assess the need for a diagnostic guideline. The questionnaire consisted of 14 statements, divided into three categories: knowledge, influencing factors and presence of guidelines. The questionnaire was sent to physicians of the departments of internal medicine, intensive care, paediatrics and pulmonology in five hospitals in the Netherlands. Sub-analyses for medical specialists versus residents and for paediatric versus non-paediatric departments were performed. We included 187 completed questionnaires in our analyses. The physicians reported having adequate knowledge on methods, time-to-result and accuracy, but inadequate knowledge on costs of the tests. Patients' clinical condition, comorbidity, local guidelines and accuracy of tests were appraised as the four most important influencing factors to perform tests. Over 70% (132/187) of physicians reported being interested in a guideline for microbiological diagnostic testing. Fifteen physicians (8.0%) provided additional comments. This study identifies the influencing factors to microbiological testing and shows the demand for a clinical guideline among physicians. IMPORTANCE: Microbiological diagnostic tests are an important cornerstone within antibiotic stewardship programmes [1-5]. These programmes aim to ameliorate the appropriate use of antibiotics and thus improve clinical outcomes of infectious diseases, whilst reducing the emergence of antimicrobial resistance [6]. However, inappropriate microbiological testing is a widely recognised problem [7-12], and influencing factors to testing have not been studied in the past. Our research shows the demand for a clinical guideline among physicians, and it identifies their influencing factors to testing. These results can be used to create a clinical guideline for microbiological diagnostic testing, thus supporting antibiotic stewardship programmes and reducing antimicrobial resistance.

A Prospective, Open-label Study to Assess the Safety, Tolerability and Efficacy of Anidulafungin in the Treatment of Invasive Candidiasis in Children 2 to <18 Years of Age

BACKGROUND

Treatment with an echinocandin is recommended as first-line therapy for patients with invasive candidiasis (ICC) including candidemia. Little is known about the efficacy and safety of anidulafungin in children with ICC.

METHODS

Eligible patients with ICC 2 to <18 years old were enrolled into this prospective, open-label, noncomparative, international study (NCT00761267) and received anidulafungin for 10-35 days (3 mg/kg on day 1, 1.5 mg/kg daily thereafter). Safety was assessed through week 6 follow-up. Efficacy, measured by global response (based on clinical and microbiologic responses), was assessed at end of intravenous treatment (EOIVT), end of treatment, weeks 2 and 6 follow-up.

RESULTS

Forty-nine patients (n = 19, 2 to <5 years; n = 30, 5 to <18 years) received ≥1 dose of anidulafungin (median 11 days; range 1-35 days) and were assessed for safety. Among 48 patients with a Candida species isolated, C. albicans (37.5%), C. parapsilosis (25.0%), C. tropicalis (14.6%) and C. lusitaniae (10.4%) were the most frequent Candida spp. All patients reported ≥1 treatment-emergent adverse event, with diarrhea (22.4%), vomiting (24.5%) and pyrexia (18.4%) being most frequent. Five patients discontinued treatment because of adverse events, of which 4 discontinuations were considered related to anidulafungin. All-cause mortality was 8.2% (4/49) by EOIVT and 14.3% (7/49) by week 6 follow-up. None of 7 deaths during the study period were considered treatment related. Global response success rate was 70.8% at EOIVT.

CONCLUSIONS

These data support the use of anidulafungin as a treatment option for ICC in children 2 to <18 years old at the studied dose.

Changing Epidemiology of Invasive Candidiasis in Children during a 10-Year Period

Candida species are a common cause of invasive infection in neonates and children. The aim of our study was to evaluate the epidemiology and microbiology of invasive candidiasis (IC) in the largest tertiary Greek pediatric hospital during a 10-year period. A retrospective cohort study was performed from January 2008 to December 2017. Identification of species and antifungal susceptibility testing was performed according to the Clinical and Laboratory Standards Institute (CLSI) methodology. During the study period, 178 cases of IC were recorded. The tissue distribution included blood (87.1%), cerebrospinal (7.9%), peritoneal (3.9%) and pleural fluids (1.1%). Candida albicans and Candida parapsilosis (sensu lato) were the most frequently isolated species (47.8% and 28.7% respectively). From period 2008⁻2012 to period 2013⁻2017, a significant decrease in IC rates was detected (0.21 cases/1000 hospitalization days VS 0.11 cases/1000 hospitalization days, P = 0.040), while median minimum inhibitory concentrations (MICs) of amphotericin B were significantly increased for both C. albicans and C. parapsilosis (sl) (P = 0.037 and P = 0.004 respectively). The decrease in IC rates may reflect the increased awareness as well as the effective infection control initiatives and antifungal interventions. However, the significant increase in the MICs for amphotericin B and echinocandins such as caspofungin, raises concerns about their common use as first-line treatment. Epidemiologic monitoring is, therefore, critically important in order to evaluate and optimize therapeutic protocols for IC in pediatric populations.

In vitro activity of voriconazole and amphotericin B against Candida albicans, Candida krusei, and Cryptococcus neoformans in human cerebrospinal fluid

PURPOSE

Fungal central nervous system (CNS) infections show a high mortality rate and only a few antifungal agents are available to treat these infections. We hypothesize that the different biochemical properties of human cerebrospinal fluid (CSF) compared to the standard growth medium lead to the altered activity of antifungal agents in CSF. We investigated the in vitro activity of two of these agents, i.e., amphotericin B (AmB) and voriconazole (VOR), against three different fungi in CSF in comparison to sabouraud-dextrose broth (SDB).

METHODS

CSF samples from patients who did not receive any antibiotics were collected. Time-kill curves were performed in CSF and SDB using static antibiotic concentrations of AmB and VOR against ATCC strains of Candida albicans, Candida krusei, and Cryptococcus neoformans.

RESULTS

In our experiments, both AmB and VOR showed superior activity in SDB compared to CSF. Nevertheless, AmB achieved fungicidal activity in CSF after 24 h against all test strains. Voriconazole only achieved fungistatic activity against C. albicans and C. neoformans in CSF.

CONCLUSIONS

In summary, our data demonstrate that growth of fungal pathogens but even more importantly activity of antifungal agents against Candida and Cryptococcus species can differ significantly in CSF compared to the standard growth medium. Both findings should be taken into consideration when applying PK/PD simulations to fungal infections of the CNS.

Candidaemia in an Irish intensive care unit setting between 2004 and 2018 reflects increased incidence of Candida glabrata

The cumulative incidence of candidaemia in an Irish intensive care unit (ICU) setting between January 2004 and August 2018 was 17/1000 ICU admissions. Candida albicans was responsible for 55% (N=41) of cases. C. glabrata (N=21, 28%) was the next most prevalent species, and has been identified most frequently since 2012. C. glabrata was associated with a higher mortality rate (57%) than C. albicans (29%). All isolates were susceptible to caspofungin (0.05 μg/mL). Notably, 37% of C. glabrata isolates were resistant to fluconazole, with 13% resistant to amphotericin B, highlighting the need for prudent antifungal stewardship to impede development of multi-drug-resistant C. glabrata in the ICU setting.

Fluconazole-induced actin cytoskeleton remodeling requires phosphatidylinositol 3-phosphate 5-kinase in the pathogenic yeast Candida glabrata

Known azole antifungal resistance mechanisms include mitochondrial dysfunction and overexpression of the sterol biosynthetic target enzyme and multidrug efflux pumps. Here, we identify, through a genetic screen, the vacuolar membrane‐resident phosphatidylinositol 3‐phosphate 5‐kinase (CgFab1) to be a novel determinant of azole tolerance. We demonstrate for the first time that fluconazole promotes actin cytoskeleton reorganization in the emerging, inherently less azole‐susceptible fungal pathogen Candida glabrata, and genetic or chemical perturbation of actin structures results in intracellular sterol accumulation and azole susceptibility. Further, CgFAB1 disruption impaired vacuole homeostasis and actin organization, and the F‐actin‐stabilizing compound jasplakinolide rescued azole toxicity in cytoskeleton defective‐mutants including the Cgfab1Δ mutant. In vitro assays revealed that the actin depolymerization factor CgCof1 binds to multiple lipids including phosphatidylinositol 3,5‐bisphosphate. Consistently, CgCof1 distribution along with the actin filament‐capping protein CgCap2 was altered upon both CgFAB1 disruption and fluconazole exposure. Altogether, these data implicate CgFab1 in azole tolerance through actin network remodeling. Finally, we also show that actin polymerization inhibition rendered fluconazole fully and partially fungicidal in azole‐susceptible and azole‐resistant C. glabrata clinical isolates, respectively, thereby, underscoring the role of fluconazole‐effectuated actin remodeling in azole resistance.

Responding to the emergence of antifungal drug resistance: perspectives from the bench and the bedside

The incidence of serious fungal infections is increasing rapidly, and yet the rate of new drugs becoming available to treat them is slow. The limited therapeutic armamentarium is a challenge for clinicians, because the available drugs are often toxic, expensive, difficult to administer, ineffective or a combination of all four. Given this setting, the emergence of resistance is especially concerning, and a review of the topic is timely. Here we discuss antifungal drug resistance in Candida spp. and Aspergillus spp. with reference to the most commonly used first-line antifungal agents - azoles and echinocandins. We review the resistance mechanisms of the leading pathogens, how resistance can be identified in the diagnostic lab and the clinical implications of resistance once detected.

Invasive Candidiasis in pediatric patients at King Fahad Medical City in Central Saudi Arabia. A 5-year retrospective study

Objectives:

To identify predisposing factors, species distribution, antifungal susceptibility, and outcome.

Methods:

This study is a retrospective chart review that was conducted at a children’s hospital at King Fahad Medical City, Riyadh, Kingdom of Saudi Arabia. One hundred twenty-nine children with invasive candidiasis who were admitted between January 2010 and January 2015.

Results:

The statistical analysis results have revealed a group of risk factors; prematurity in 37 (28.7%) of patients, low birth weight in 42 (32.6%), central venous catheter in 59 (45.7%), malignancy in 21 (16.3%), immunotherapy in 20 (15.5%), and ventilator support in 60 (46.5%). More than 2-fold mortality rate in patients who had heart vegetation (odds ratio [OR]: 2.9) and patients who had Candida isolated from their blood were more than twice as likely to die as patients with Candida isolated from other sites (OR: 2.2). A total of 48.3% of patients on ventilator died versus 26.1% who were not on ventilator (p=0.009); and 43.8% of patients in the ICU died versus only 24.5% of patients who were not in the ICU (p=0.03). Candida parapsilosis exhibited the highest mortality rate (56.2%).

Conclusion:

Candida albicans is the most common isolate among all Candida species. Gender, low birth weight, prolonged ICU stay, presence of vegetation, positive blood culture, and mechanical ventilation as a strong predictive risk factors for death in children with invasive candidiasis, a finding that could be applied as prophylactic indicator in critically ill children especially neonates.

Fluconazole impacts the extracellular matrix of fluconazole-susceptible and -resistant Candida albicans and Candida glabrata biofilms

Background: Fluconazole (FLZ) is a drug commonly used for the treatment of Candida infections. However, β-glucans in the extracellular matrices (ECMs) hinder FLZ penetration into Candida biofilms, while extracellular DNA (eDNA) contributes to the biofilm architecture and resistance. Methods: This study characterized biofilms of FLZ-sensitive (S) and -resistant (R) Candida albicans and Candida glabrata in the presence or absence of FLZ focusing on the ECM traits. Biofilms of C. albicans American Type Culture Collection (ATCC) 90028 (CaS), C. albicans ATCC 96901 (CaR), C. glabrata ATCC 2001 (CgS), and C. glabrata ATCC 200918 (CgR) were grown in RPMI medium with or without FLZ at 5× the minimum inhibitory concentration (37°C/48 h). Biofilms were assessed by colony-forming unit (CFU)/mL, biomass, and ECM components (alkali-soluble polysaccharides [ASP], water-soluble polysaccharides [WSP], eDNA, and proteins). Scanning electron microscopy (SEM) was also performed. Data were analyzed by parametric and nonparametric tests (α  =  0.05). Results: In biofilms, FLZ reduced the CFU/mL of all strains (p < 0.001), except for CaS (p = 0.937). However, the ASP quantity in CaS was significantly reduced by FLZ (p = 0.034), while the drug had no effect on the ASP levels in other strains (p > 0.05). Total biomasses and WSP were significantly reduced by FLZ in the ECM of all yeasts (p < 0.001), but levels of eDNA and proteins were unaffected (p > 0.05). FLZ affected the cell morphology and biofilm structure by hindering hyphae formation in CaS and CaR biofilms, by decreasing the number of cells in CgS and CgR biofilms, and by yielding sparsely spaced cell agglomerates on the substrate. Conclusion: FLZ impacts biofilms of C. albicans and C. glabrata as evident by reduced biomass. This reduced biomass coincided with lowered cell numbers and quantity of WSPs. Hyphal production by C. albicans was also reduced.

Difunctional bacteriophage conjugated with photosensitizers for Candida albicans-targeting photodynamic inactivation

Background

Candida albicans is the most prevalent fungal pathogen of the human microbiota, causing infections ranging from superficial infections of the skin to life-threatening systemic infections. Due to the increasing occurrence of antibiotic-resistant C. albicans strains, new approaches to control this pathogen are needed. Photodynamic inactivation is an emerging alternative to treat infections based on the interactions between visible light and photosensitisers, in which pheophorbide a (PPA) is a chlorophyll-based photosensitizer that could induce cell death after light irradiation. Due to PPA’s phototoxicity and low efficiency, the main challenge is to implement photosensitizer cell targeting and attacking.

Methods

In this study, PPA was conjugated with JM-phage by EDC/NHS crosslinking. UV-Vis spectra was used to determine the optimum conjugation percentages of PPA and JM-phage complex for photodynamic inactivation. After photodynamic inactivation, the efficacy of PPA-JM-phage was assessed by performing in vitro experiments, such as MTS assay, scanning electron microscopy, measurement of dysfunctional mitochondria, ROS accumulation, S cell arrest and apoptotic pathway.

Results

A single-chain variable-fragment phage (JM) with high affinity to MP65 was screened from human single-fold single-chain variable-fragment libraries and designed as a binding target for C. albicans cells. Subsequently, PPa was integrated into JM phage to generate a combined nanoscale material, which was called PPA-JM-phage. After photodynamic inactivation, the growth of C. albicans was inhibited by PPA-JM-phage and apoptosis was observed. Scanning electron microscopy analysis revealed shrinking and rupturing of C. albicans. We also found that depolarization of mitochondrial membrane potential was decreased and intracellular reactive oxygen species levels were elevated significantly in C. albicans inhibited by PPA-JM-phage. Additionally, PPA-JM-phage also lead to S-phase arrest, and metacaspase activation resulting from mitochondrial dysfunction was also found to be involved in C. albicans apoptosis.

Conclusion

PPa-JM-phage may induce C. albicans apoptosis through a caspase-dependent pathway and the results herein shed light on the potential application of phtototherapeutic nanostructures in fungal inactivation.

Candida albicans β-Glucan-Containing Particles Increase HO-1 Expression in Oral Keratinocytes via a Reactive Oxygen Species/p38 Mitogen-Activated Protein Kinase/Nrf2 Pathway

Oral keratinocytes provide the first line of host defense against oral candidiasis. We speculated that interactions of fungal cell wall components with oral keratinocytes regulate the stress response against Candida infection and examined the expression of genes induced by heat-killed Candida albicans in oral immortalized keratinocytes using a cDNA microarray technique. Of 24,000 genes revealed by that analysis, we focused on HO-1, a stress-inducible gene, as its expression was increased by both heat-killed and live C. albicans In histological findings, HO-1 expression in the superficial layers of the oral epithelium following Candida infection was elevated compared to that in healthy epithelium. We then investigated fungal cell wall components involved in induction of HO-1 expression and found that β-glucan-containing particles (β-GPs) increased its expression. Furthermore, β-glucan was observed on the surface of both heat-killed C. albicans and Candida cells that had invaded the oral epithelium. Fungal β-GPs also promoted induction of intracellular reactive oxygen species (ROS), NADPH oxidase activation, and p38 mitogen-activated protein kinase (MAPK) phosphorylation, while those specific inhibitors inhibited the HO-1 expression induced by fungal β-GPs. Moreover, fungal β-GPs induced Nrf2 translocation into nuclei via p38 MAPK signaling, while the HO-1 expression induced by fungal β-GPs was inhibited by Nrf2-specific small interfering RNA (siRNA). Finally, knockdown of cells by HO-1- and Nrf2-specific siRNAs resulted in increased β-GP-mediated ROS production compared to that in the control cells. Our results show that the HO-1 induced by fungal β-GPs via ROS/p38 MAPK/Nrf2 from oral keratinocytes may have important roles in host defense against the stress caused by Candida infection in the oral epithelium.

Investigating Clinical Issues by Genotyping of Medically Important Fungi: Why and How?

Genotyping studies of medically important fungi have addressed elucidation of outbreaks, nosocomial transmissions, infection routes, and genotype-phenotype correlations, of which secondary resistance has been most intensively investigated. Two methods have emerged because of their high discriminatory power and reproducibility: multilocus sequence typing (MLST) and microsatellite length polymorphism (MLP) using short tandem repeat (STR) markers. MLST relies on single-nucleotide polymorphisms within the coding regions of housekeeping genes. STR polymorphisms are based on the number of repeats of short DNA fragments, mostly outside coding regions, and thus are expected to be more polymorphic and more rapidly evolving than MLST markers. There is no consensus on a universal typing system. Either one or both of these approaches are now available for Candida spp., Aspergillus spp., Fusarium spp., Scedosporium spp., Cryptococcus neoformans, Pneumocystis jirovecii, and endemic mycoses. The choice of the method and the number of loci to be tested depend on the clinical question being addressed. Next-generation sequencing is becoming the most appropriate method for fungi with no MLP or MLST typing available. Whatever the molecular tool used, collection of clinical data (e.g., time of hospitalization and sharing of similar rooms) is mandatory for investigating outbreaks and nosocomial transmission.

Comparison of CHROMagar, polymerase chain reaction-restriction fragment length polymorphism, and polymerase chain reaction-fragment size for the identification of Candida species

BACKGROUND AND PURPOSE

The epidemiological alteration in the distribution of Candida species, as well as the significantly increasing trend of either intrinsic or acquired resistance of some of these fungi highlights the need for a reliable method for the identification of the species. Polymerase chain reaction (PCR) is one of the methods facilitating the quick and precise identification of Candida species. The aim of this study was to compare the efficiency of CHROMagar, PCR-restriction fragment length polymorphism (PCR-RFLP), and PCR-fragment size polymorphism (PCR-FSP) assays in the identification of Candida species to determine the benefits and limitations of these methods.

MATERIALS AND METHODS

This study was conducted on 107 Candida strains, including 20 standard strains and 87 clinical isolates. The identification of the isolates was accomplished by using CHROMagar as a conventional method. The PCR-RFLP assay was performed on the entire internal transcribed spacer (ITS) region of ribosomal DNA (rDNA), and the consequent enzymatic digestion was compared with PCR-FSP results in which ITS1 and ITS2 regions were separately PCR amplified. In both molecular assays, yeast identification was carried out through the specific electrophoretic profiles of the PCR products.

RESULTS

According to the results, the utilization of CHROMagar resulted in the identification of 29 (33.3%) Candida isolates, while the PCR-RFLP and PCR-FSP facilitated the identification of 83 (95.4%) and 80 (91.9%) clinical isolates, respectively. The obtained concordances between CHROMagar and PCR-RFLP, between CHROMagar and PCR-FSP, as well as between PCR-RFLP and PCR-FSP were 0.23, 0.20, and 0.77, respectively.

CONCLUSION

The recognition of the benefits and limitations of PCR methods allows for the selection of the most efficient technique for a fast and correct differentiation. The PCR-RFLP and PCR-FSP assays had satisfactory concordance. The PCR-FSP provides a rapid, technically simple, and cost-effective method for the identification of Candida species. Nevertheless, to accurately differentiate among the taxonomically related species, PCR-RFLP should be implemented.

Potential of Ravuconazole and its Prodrugs as the New OralTherapeutics for Onychomycosis

Onychomycosis is a fungal infection of the nail apparatus caused by dermatophytes, Candida and non-dermatophytic molds. It is highly prevalent in the general population worldwide and also responsible for significant morbidity and complications and does not usually cure itself. Thus, the condition needs to be treated in view of physical and psychological problems produced. Currently, oral medications using terbinafine are the most effective therapy, but it has relatively limited therapeutic success, particularly for long-term management. Such existing oral therapies are associated with high recurrence rates and treatment failure, as well as with potential adverse events and drug-drug interactions. In the light of these issues, development of more efficacious and safer alternatives for the treatment of onychomycosis is warranted.Ravuconazole and its prodrugs are promising new drug candidates for oral therapy of onychomycosis, among which a water-soluble prodrug, mono-lysine phosphoester derivative (E1224 or BFE1224) is in the most advanced stage of clinical development; a Phase II dose-finding study has been successfully completed and Phase III comparative studies are in progress in Japan.This review aims to summarize our current status of knowledge and information on ravuconazole and its prodrugs, particularly BFE1224, as the potential oral treatment option for onychomycosis. It also summarize the clinical features of onychomycosis with particular stress on its etiology, epidemiology, and current therapeutic options and their limitations. Given its clinical usefulness, BFE1224 may become a valuable addition to the current armamentarium for the treatment of onychomycosis.

Voriconazole

Each month, subscribers to The Formulary Monograph Service receive five to six well-documented monographs on drugs that are newly released or are in late Phase III trials. The monographs are targeted to your Pharmacy and Therapeutics Committee. Subscribers also receive monthly one-page summary monographs on the agents that are useful for agendas and pharmacy/nursing in-ser-vices. A comprehensive target drug utilization evaluation (DUE) is also provided each month. The monographs are published in printed form and on diskettes that allow customization. Subscribers to the The Formulary Monograph Service also receive access to a pharmacy bulletin board, The Formulary Information Exchange (The F.I.X.). All topics pertinent to clinical and hospital pharmacy are discussed on The F.I.X.

Through the cooperation of The Formulary, Hospital Pharmacy publishes selected reviews in this column. If you would like information about The Formulary Monograph Service or The F.I.X., call The Formulary at 800-322-4349. The September 2002 monograph topics are ziprasidone mesylate for injection; lanthanum carbonate, artesunate rectal capsules, ZD1839, and memantine. The DUE is on ziprasidone.

The Changing Epidemiology of Invasive Fungal Infections

Invasive fungal infections (IFI) are an emerging problem worldwide with invasive candidiasis and candidemia responsible for the majority of cases. This is predominantly driven by the widespread adoption of aggressive immunosuppressive therapy among certain patient populations (e.g., chemotherapy, transplants) and the increasing use of invasive devices such as central venous catheters (CVCs). The use of new immune modifying drugs has also opened up an entirely new spectrum of patients at risk of IFIs. While the epidemiology of candida infections has changed in the last decade, with a gradual shift from C. albicans to non-albicans candida (NAC) strains which may be less susceptible to azoles, these changes vary between hospitals and regions depending on the type of population risk factors and antifungal use. In certain parts of the world, the incidence of IFI is strongly linked to the prevalence of other disease conditions and the ecological niche for the organism; for instance cryptococcal and pneumocystis infections are particularly common in areas with a high prevalence of HIV disease. Poorly controlled diabetes is a major risk factor for invasive mould infections. Environmental factors and trauma also play a unique role in the epidemiology of mould infections, with well-described hospital outbreaks linked to the use of contaminated instruments and devices. Blastomycosis is associated with occupational exposure (e.g., forest rangers) and recreational activities (e.g., camping and fishing).The true burden of IFI is probably an underestimate because of the absence of reliable diagnostics and lack of universal application. For example, the sensitivity of most blood culture systems for detecting candida is typically 50 %. The advent of new technology including molecular techniques such as 18S ribosomal RNA PCR and genome sequencing is leading to an improved understanding of the epidemiology of the less common mould and dimorphic fungal infections. Molecular techniques are also providing a platform for improved diagnosis and management of IFI.Many factors affect mortality in IFI, not least the underlying medical condition, choice of therapy, and the ability to achieve early source control. For instance, mortality due to pneumocystis pneumonia in HIV-seronegative individuals is now higher than in seropositive patients. Of significant concern is the progressive increase in resistance to azoles and echinocandins among candida isolates, which appears to worsen the already significant mortality associated with invasive candidiasis. Mortality with mould infections approaches 50 % in most studies and varies depending on the site, underlying disease and the use of antifungal agents such as echinocandins and voriconazole. Nevertheless, mortality for most IFIs has generally fallen with advances in medical technology, improved care of CVCs, improved diagnostics, and more effective preemptive therapy and prophylaxis.

Epidemiology, Risk Factors, and Outcomes of Candida albicans Versus Non-albicans Candidemia in Nonneutropenic Patients

Background:

Candidemia is a major cause of morbidity and mortality in hospitalized patients.

Objectives:

To describe the epidemiology of and risk factors for non-albicans candidemia (NAC) in nonneutropenic adults and the impact of NAC on patient outcomes and treatment cost.

Methods:

We conducted a retrospective cohort analysis comparing demographics and risk factors for Candida albicans candidemia (CAC) versus NAC in 144 nonneutropenic patients with candidemia over a 6 year period (1997–2002) at Detroit Receiving Hospital.

Results:

Candida species distribution included albicans (50%), parapsilosis (13%), tropicalis (10%), and glabrata (13%). Predominant species varied by patient care unit, with C. glabrata more common in the medical intensive care unit (ICU) and C. parapsilosis in the burn ICU. In multivariate analysis, NAC was associated with the absence of antibiotic use at the onset of candidemia, recent history of solid tumor, and male sex, NAC was not associated with an increase in mortality or length of stay compared with CAC, but was found to have a higher cost of antifungal therapy ($2030 vs $780; p = 0.05).

Conclusions:

The epidemiology of candidemia is complex and varies among the different patient care units. Specifically, patients appear less likely to develop NAC if they are receiving antibiotics at the onset of candidemia. Increased awareness of risk factors for NAC can be used to guide adequate initial antifungal therapy.

Nosocomial candidemia in patients admitted to medicine wards compared to other wards: a multicentre study

PURPOSE

Risk factors for nosocomial candidemia, severity of sepsis, treatment, and outcome were compared between patients admitted to medicine wards and those to surgical and intensive care units (ICUs).

METHODS

Data were retrospectively collected from patients belonging to six referral hospitals in Italy between January 2011 and December 2013. Risk factors for 30-day mortality were evaluated in the whole patient population.

RESULTS

A total of 686 patients (mean age 70 ± 15 years) with candidemia were included. 367 (53.5 %) patients were in medicine wards, and 319 in surgery and ICUs. Host-related risk factors for candidemia were more common in medicine patients whereas healthcare-related factors in surgery/ICU patients. These patients showed severe sepsis and septic shock more commonly (71.7 %) than medicine patients (59.9 %) (p 0.003). The latter underwent central venous catheter (CVC) removal and adequate antifungal therapy less frequently than surgery/ICU patients. 149 (40.6 %) patients died with candidemia in medicine wards and 69 (21.6 %) in other wards (p < 0.001). Overall, the 30-day mortality was 36.3 %. At multivariate analysis, independent risk factors for death were aging, higher Charlson score, severe sepsis and septic shock, and no antifungal therapy, while major surgery and CVC removal were associated with higher probability of survival.

CONCLUSIONS

The burden of risk factors for candidemia was different between medicine patients and those in other wards. Despite the lower severity of candidemia in medicine patients, their mortality turned out to be higher than in surgery or ICU patients. Awareness of the best management of candidemia should be pursued, especially in medicine wards.

[Update on invasive candidiasis in non-neutropenic critically ill adult patients]

Invasive candidiasis in non-neutropenic critically ill patients remains a challenge for clinicians due to its association with high morbidity and mortality rates, increased incidence, and health-care costs. It is well known that early diagnosis and treatment are associated with a better prognosis. For these reasons a thorough update has been performed in this setting focused on recent Spanish epidemiology, new predictive scores and microbiological tests such as mannan antigen, mannan antibodies, Candida albicans germ-tube antibodies or (1→3)-β-D-glucan detection, molecular techniques for the detection of fungal-specific DNA, advances in antifungal treatment and educational programs in Spain. An early diagnostic and therapeutic algorithm is proposed based on the combination of scores and microbiological test. The aim of this review is to provide physicians with the best information available in order to improve the prognosis of these patients.

Comparison of species-level identification and antifungal susceptibility results from diagnostic and reference laboratories for bloodstream Candida surveillance isolates, South Africa, 2009-2010

From February 2009 through August 2010, we compared species-level identification of bloodstream Candida isolates and susceptibility to fluconazole, voriconazole, and caspofungin between diagnostic and reference South African laboratories during national surveillance for candidemia. Diagnostic laboratories identified isolates to genus/species level and performed antifungal susceptibility testing, as indicated. At a reference laboratory, viable Candida isolates were identified to species-level using automated systems, biochemical tests, or DNA sequencing; broth dilution susceptibility testing was performed. Categorical agreement (CA) was calculated for susceptibility results of isolates with concordant species identification. Overall, 2172 incident cases were detected, 773 (36%) by surveillance audit. The Vitek 2 YST system (bioMérieux Inc, Marcy l'Etoile, France) was used for identification (360/863, 42%) and susceptibility testing (198/473, 42%) of a large proportion of isolates. For the five most common species (n = 1181), species-level identification was identical in the majority of cases (Candida albicans: 98% (507/517); Candida parapsilosis: 92% (450/488); Candida glabrata: 89% (89/100); Candida tropicalis: 91% (49/54), and Candida krusei: 86% (19/22)). However, diagnostic laboratories were significantly less likely to correctly identify Candida species other than C. albicans versus C. albicans (607/664, 91% vs. 507/517, 98%; P < .001). Susceptibility data were compared for isolates belonging to the five most common species and fluconazole, voriconazole, and caspofungin in 860, 580, and 99 cases, respectively. Diagnostic laboratories significantly under-reported fluconazole resistance in C. parapsilosis (225/393, 57% vs. 239/393, 61%; P < .001) but over-reported fluconazole non-susceptibility in C. albicans (36/362, 10% vs. 3/362, 0.8%; P < .001). Diagnostic laboratories were less likely to correctly identify Candida species other than C. albicans, under-reported fluconazole resistance for C. parapsilosis and over-reported fluconazole resistance for C. albicans.

Cinnamaldehyde and its derivatives, a novel class of antifungal agents

The last few decades have seen an alarming rise in fungal infections, which currently represent a global health threat. Despite extensive research towards the development of new antifungal agents, only a limited number of antifungal drugs are available in the market. The routinely used polyene agents and many azole antifungals are associated with some common side effects such as severe hepatotoxicity and nephrotoxicity. Also, antifungal resistance continues to grow and evolve and complicate patient management, despite the introduction of new antifungal agents. This suitation requires continuous attention. Cinnamaldehyde has been reported to inhibit bacteria, yeasts, and filamentous molds via the inhibition of ATPases, cell wall biosynthesis, and alteration of membrane structure and integrity. In this regard, several novel cinnamaldehyde derivatives were synthesized with the claim of potential antifungal activities. The present article describes antifungal properties of cinnamaldehyde and its derivatives against diverse classes of pathogenic fungi. This review will provide an overview of what is currently known about the primary mode of action of cinnamaldehyde. Synergistic approaches for boosting the effectiveness of cinnamaldehyde and its derivatives have been highlighted. Also, a keen analysis of the pharmacologically active systems derived from cinnamaldehyde has been discussed. Finally, efforts were made to outline the future perspectives of cinnamaldehyde-based antifungal agents. The purpose of this review is to provide an overview of current knowledge about the antifungal properties and antifungal mode of action of cinnamaldehyde and its derivatives and to identify research avenues that can facilitate implementation of cinnamaldehyde as a natural antifungal.

In Vitro Activities of Six Antifungal Drugs Against Candida glabrata Isolates: An Emerging Pathogen

Background

Candida glabrata is a pathogenic yeast with several unique biological features and associated with an increased incidence rate of candidiasis. It exhibits a great degree of variation in its pathogenicity and antifungal susceptibility.

Objectives

The aim of the present study was to evaluate the in vitro antifungal susceptibilities of the following six antifungal drugs against clinical C. glabrata strains: amphotericin B (AmB), ketoconazole (KTZ), fluconazole (FCZ), itraconazole (ITZ), voriconazole (VCZ), and caspofungin (CASP).

Materials and Methods

Forty clinical C. glabrata strains were investigated using DNA sequencing. The in vitro antifungal susceptibility was determined as described in clinical laboratory standard institute (CLSI) documents (M27-A3 and M27-S4).

Results

The sequence analysis of the isolate confirmed as C. glabrata and deposited on NCBI GenBank under the accession number no. KT763084-KT763123. The geometric mean MICs against all the tested strains were as follows, in increasing order: CASP (0.17 g/mL), VCZ (0.67 g/mL), AmB (1.1 g/mL), ITZ (1.82 g/mL), KTZ (1.85 g/mL), and FCZ (6.7 g/mL). The resistance rates of the isolates to CASP, FCZ, ITZ, VZ, KTZ, and AmB were 5%, 10%, 72.5%, 37.5%, 47.5%, and 27.5%, respectively.

Conclusions

These findings confirm that CASP, compared to the other antifungals, is the potent agent for treating candidiasis caused by C. glabrata. However, the clinical efficacy of these novel antifungals remains to be determined.

Antioxidant and antifungal activities of Camellia sinensis (L.) Kuntze leaves obtained by different forms of production

Abstract The antioxidant and anticandidal activities of leaves obtained from Camellia sinensis by non-fermentation (green and white teas), semi-fermentation (red tea) and fermentation method (black tea) were investigated. It was evaluated the total phenolic content by Folin-Ciocalteau assay; antioxidant capacities were evaluated in vitro using DPPH and ABTS radicals, hypochlorous acid and superoxide anion scavenger assays, induced hemolysis, lipid peroxidation by conjugated diene formation and myeloperoxidase activity. Anticandidal activity was performed on three strains of Candida spp. The results showed that non-fermented teas have a higher concentration of phenolic compounds, and then presented the best inhibitory activity of AAPH-induced hemolysis, the best inhibition of conjugated diene formation and more pronounced antioxidant activity in all tests. The highest anticandidal activity was obtained from fermented tea, followed by non-fermented tea. These results indicate that the antioxidant activity demonstrated has no direct relation with the anticandidal activity.

Antifungal Susceptibility Analysis of Clinical Isolates of Candida parapsilosis in Iran

BACKGROUND

Candida parapsilosis is an emergent agent of invasive fungal infections. This yeast is one of the five most widespread yeasts concerned in invasive candidiasis. C. parapsilosis stands out as the second most common yeast species isolated from patients with bloodstream infections especially in neonates with catheter. Recently several reports suggested that its reduced susceptibility to azoles and polyene might become a cause for clinical concern, although C. parapsilosis is not believed to be intensely prone to the development of antifungal resistance.

METHODS

In the present report, One hundred and twenty clinical isolates of C. parapsilosis complex were identified and differentiated by using PCR-RFLP analysis. The isolates were then analyzed to determine their susceptibility profile to fluconazole (FLU), itraconazole (ITC) and amphotericin B. The minimum inhibitory concentration (MIC) results were analyzed according to the standard CLSI guide.

RESULTS

All of isolates were identified as C. parapsilosis. No C. metapsilosis and C. orthopsilosis strains were found. Evaluation of the antifungal susceptibility profile showed that only three (2.5%) C. parapsilosis were resistant to fluconazole, three (2.5%) C. parapsilosis were resistant to itraconazole and two (1.7%) C. parapsilosis were amphotericin B resistant.

CONCLUSION

Profiles in clinical isolates of C. parapsilosis can provide important information for the control of antifungal resistance as well as distribution and susceptibility profiles in populations.

Biomedical applications of nisin

Nisin is a bacteriocin produced by a group of Gram-positive bacteria that belongs to Lactococcus and Streptococcus species. Nisin is classified as a Type A (I) lantibiotic that is synthesized from mRNA and the translated peptide contains several unusual amino acids due to post-translational modifications. Over the past few decades, nisin has been used widely as a food biopreservative. Since then, many natural and genetically modified variants of nisin have been identified and studied for their unique antimicrobial properties. Nisin is FDA approved and generally regarded as a safe peptide with recognized potential for clinical use. Over the past two decades the application of nisin has been extended to biomedical fields. Studies have reported that nisin can prevent the growth of drug-resistant bacterial strains, such as methicillin-resistant Staphylococcus aureus, Streptococcus pneumoniae, Enterococci and Clostridium difficile. Nisin has now been shown to have antimicrobial activity against both Gram-positive and Gram-negative disease-associated pathogens. Nisin has been reported to have anti-biofilm properties and can work synergistically in combination with conventional therapeutic drugs. In addition, like host-defence peptides, nisin may activate the adaptive immune response and have an immunomodulatory role. Increasing evidence indicates that nisin can influence the growth of tumours and exhibit selective cytotoxicity towards cancer cells. Collectively, the application of nisin has advanced beyond its role as a food biopreservative. Thus, this review will describe and compare studies on nisin and provide insight into its future biomedical applications.

Pediatric Invasive Candidiasis: Epidemiology and Diagnosis in Children

Pediatric patients present with differing underlying conditions and cytotoxic therapeutic protocols, so the differing epidemiology of invasive candidiasis in children versus adults is not surprising. Understanding the Candida species epidemiology is critical, as we often begin empiric therapy or therapy before antifungal susceptibilities are known. Reports with newer molecular diagnostic assays for invasive candidiasis are rare and require more study to develop firm pediatric-specific guidance. Antifungal treatment of pediatric candidiasis is reviewed in the context of larger epidemiologic studies and the few trials completed to date.

Comparative effectiveness of fungicidal vs. fungistatic therapies for the treatment of paediatric candidaemia

Adult data suggest that echinocandins for treatment of candidaemia are associated with decreased mortality, attributed to their fungicidal activity. There are limited data comparing antifungals in children. We compared 30-day all-cause mortality among paediatric candidaemia patients treated with fungicidal vs. fungistatic agents. All inpatients (>6 months and <19 years of age) with candidaemia between 2000 and 2012 at The Children's Hospital of Philadelphia were retrospectively identified. Definitive therapy with fungicidal (amphotericin B and caspofungin) agents was compared with fungistatic (fluconazole) agents. A propensity score model generated the inverse probability of receiving a fungicidal agent, which was included in a weighted logistic regression model. Among 203 children meeting inclusion criteria, 151 (74.4%) and 52 (25.6%) received a fungicidal and fungistatic agent, respectively. Overall, 18 (8.9%) patients died within 30 days. There was no statistically significant difference in mortality between patients started on a fungicidal or fungistatic agent (OR: 2.19, 95% CI: 0.42-11.48). In a propensity score-weighted model, definitive therapy with a fungicidal agent did not result in a significant decrease in mortality. These data suggest that both agents can be considered definitive therapy for paediatric candidaemia. The results should be interpreted with caution given the small sample size. Larger cohort studies are needed.

Genotype-Directed Dosing Leads to Optimized Voriconazole Levels in Pediatric Patients Receiving Hematopoietic Stem Cell Transplantation

Invasive fungal infections are a significant cause of morbidity and mortality in recipients of hematopoietic stem cell transplantation (HSCT), warranting antifungal prophylaxis as a standard of care in these patients. Voriconazole is commonly used in this setting because of its broad-spectrum activity and available dosage forms. There is wide well-known inter- and intrapatient variability in voriconazole concentrations, in part because concentrations are affected by common CYP2C19 polymorphisms. In 2 successive studies we have optimized voriconazole dosing to achieve target voriconazole serum concentrations using a genotype-specific dosing algorithm for antifungal prophylaxis in the post-HSCT period. In our pilot study all patients undergoing HSCT who received voriconazole antifungal prophylaxis were prospectively followed. Voriconazole concentrations were monitored weekly and doses adjusted until concentrations reached between 1 and 5.5 μg/L. The most common CYP2C19 polymorphisms were determined and correlated with voriconazole dose and time required to reach the target concentration range. In the subsequent study patients receiving voriconazole prophylaxis were dosed based on their CYP2C19 genotype and followed prospectively. In the pilot study 25 patients received voriconazole as antifungal prophylaxis for a median of 49 days (range, 15 to 196 days). The median time to reach the target concentration was 34 days for extensive metabolizers and 11 days for poor metabolizers. Three patients were genotyped as intermediate metabolizers; they reached the target concentration in a median of 56 days. Similarly, 2 patients who were genotyped as ultrarapid metabolizers reached the target range in 18 and 25 days. The time and dose required to reach the adequate concentration showed a trend toward correlation with individual CYP2C19 genotype, although voriconazole concentrations showed large interpatient variability in wild-type patients (extensive metabolizers). In our follow-up study, 20 patients received voriconazole prophylaxis prospectively dosed based on their CYP2C19 genotype. The median times to reach the target concentration using genotype-guided dosing were 9, 6.5, and 4 days for ultrarapid, extensive, and intermediate metabolizers, respectively. Overall, the median time to reach the target concentration with genotype-guided dosing was 6.5 days compared with a median time of 29 days when all patients were started on the same dose regardless of CYP2C19 genotype (P < .001). Our data show that traditional voriconazole dosing does not lead to timely achievement of target levels for fungal prophylaxis. However, a genotype-directed dosing algorithm allows patients to reach the voriconazole target range significantly sooner, providing better prophylaxis against fungal infections in the immediate post-transplant period.

Posaconazole: An Update of Its Clinical Use

Posaconazole (PCZ) is a relatively new addition to the azole antifungals. It has fungicidal activities against Aspergillus fumigatus, Blastomyces dermatitidis, selected Candida species, Crytopcoccus neoformans, and Trichosporon. PCZ also has fungistatic activities against Candida, Coccidioides, selected Fusarium spp., Histoplasma, Scedosporium and Zygomycetes. In addition, combining the drug with caspofungin or amphotericin B results in a synergistic interaction against A. fumigatus, C. glabrata and C. neoformans. The absorption of PCZ suspension is enhanced when given with food, nutritional supplements, and carbonated beverages. Oral administration of PCZ in divided doses also increases its bioavailability. PCZ has a large volume of distribution and is highly protein bound (>95%). The main elimination route of PCZ is fecal. PCZ is an inhibitor of the CYP3A4 enzyme; therefore, monitoring for drug-drug interactions is warranted with other CYP3A4 substrates/inhibitors/inducers. The most common adverse effects include headache, fatigue, nausea, vomiting and elevated hepatic enzymes. PCZ, with its unique antifungal activities, expands the azole class of antifungal agents. Because of its limit in formulation, PCZ oral suspension is recommended in immunocompromised patients with functional gastrointestinaltracts who fail conventional antifungal therapies or who are suspected to have a breakthrough fungal infection. However, a delayed-release tablet formulation and intravenous (IV) injection became available in 2014, expanding the use of PCZ in other patient populations, including individuals who are unable to take oral formulations.

Sensitive and rapid RT-qPCR quantification of pathogenic Candida species in human blood

For accurate diagnosis and appropriate treatment of candidiasis, we developed a highly sensitive quantitative RT-PCR (RT-qPCR) system for five Candida species that have been reported to be the major causes of bloodstream fungal infection (Candida albicans, Candida glabrata, Candida tropicalis, Candida parapsilosis, and Candida krusei), together with a system for all pathogenic Candida species. Cells of each fungal species spiked into human peripheral blood (PB) were specifically detected at a lower detection limit of 10(0) cell/1 mL PB by this system using the newly developed specific primer sets targeting 18S or 26S rRNA of the five Candida species, together with the existing group primer set. The total count of the five Candida spp. as the sum of those obtained by using the five species primer sets was equivalent to the count obtained by using the group primer set, indicating that the group set covered the major five Candida spp. in human blood with the same degree of accuracy as the species primer sets. The RT-qPCR counts of the Candida species were in good agreement with CFU counts obtained by their culture on CHROMagar™, with a lower detection limit of 10(0)cell/mL of PB. Candida rRNA molecules were stably stored for at least 7 days at 4°C by keeping the blood specimens in an RNA stabilizing reagent. These results strongly suggest that this sensitive system is useful for accurate and rapid diagnosis of Candida bloodstream infections.

Retrospective analysis of mortality and Candida isolates of 75 patients with candidemia: a single hospital experience

The mortality rate for candidemia is approximately 30%–60%. However, prognostic factors in patients with candidemia have not yet been elucidated in detail. The aim of the present study was to analyze prognostic factors for candidemia using the mortality rate and Candida isolates of patients with candidemia. Seventy-five patients with candidemia were analyzed between January 2007 and December 2013. The main outcome of this study was the 30-day mortality rate after the diagnosis of candidemia. The acute physiology and chronic health evaluation II score (APACHE II score) was measured in 34 patients (45.3%). Odds ratios (ORs) for death due to candidemia were analyzed using a multivariate stepwise logistic regression analysis. Twenty (26.6%) patients died within 30 days of being diagnosed with candidemia. Non-survivors had a significantly higher APACHE II score (n=7, mean; 18.9±4.5) than that of survivors (n=27, mean; 14.0±5.0). Advanced age (OR =1.1, 95% confidence interval =1.01–1.23, P=0.04) was a significant risk factor for a high mortality rate, whereas removal of a central venous catheter (OR =0.03, 95% confidence interval =0.002–0.3, P=0.01) was associated with a lower mortality rate. Seventy-six Candida spp. were isolated from blood cultures: Candida albicans 28 (36.8%), Candida parapsilosis 23 (30.2%), Candida guilliermondii 16 (21.0%), Candida glabrata four (5.2%), Candida tropicalis two (2.6%), and Candida spp. three (3.9%) that could not be identified. C. parapsilosis was the most frequently isolated species in younger patients (<65 years), whereas C. albicans was the most frequently isolated in elderly patients (≥65 years). Physicians who treat candidemia need to consider removing the central venous catheter and pay attention to the general condition of patients, particularly that of elderly patients.

Investigation of ERG11 gene expression among fluconazole-resistant Candida albicans: first report from an Iranian referral paediatric hospital

The multiplicity of mechanisms of resistance to azole antifungal agents has been described. As fluconazole-resistant clinical Candida albicans isolates that constitutively over-express ERG11 have been identified in previous studies, the aim of this study is to investigate this molecular mechanism involved in fluconazole resistance of C. albicans clinical isolates. Fluconazole susceptibility testing was carried out on clinical isolates of Candida spp. obtained from hospitalised children in an Iranian referral children's hospital. A polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) technique was used to differentiate Candida spp. The resistant C. albicans isolates were subjected to RT-qPCR using primers that identify ERG11 gene expression. Of the 142 Candida spp. isolates studied, C. albicans was the most predominant isolate, occurring in 68.3% (97/142) of the patients. According to the CLSI method, the majority of the C. albicans isolates (91.7%, 89/97), categorised as susceptible (minimum inhibitory concentration [MIC] ≤8 μg/mL), five isolates were considered resistant (MIC ≤64 μg/mL) and three had dose-dependent susceptibility (MIC = 8.16-32 μg/mL). The ERG11 gene in the five fluconazole-resistant C. albicans isolates was upregulated 4.15-5.84-fold relative to the ATCC 10231 control strain. In this study, the expression of ERG11 was upregulated in all the fluconazole-resistant C. albicans isolates. There are limited data on the antifungal susceptibility of Candida spp. as well as the molecular mechanism of azole resistance in Iran, especially for isolates causing infections in children. Therefore, the surveillance of antifungal resistance patterns and investigation of other mechanisms of azole resistance in all Candida spp. isolates is recommended.

Complementary amplicon-based genomic approaches for the study of fungal communities in humans

Recent studies highlight the importance of intestinal fungal microbiota in the development of human disease. Infants, in particular, are an important population in which to study intestinal microbiomes because microbial community structure and dynamics during this formative window of life have the potential to influence host immunity and metabolism. When compared to bacteria, much less is known about the early development of human fungal communities, owing partly to their lower abundance and the relative lack of established molecular and taxonomic tools for their study. Herein, we describe the development, validation, and use of complementary amplicon-based genomic strategies to characterize infant fungal communities and provide quantitative information about Candida, an important fungal genus with respect to intestinal colonization and human disease. Fungal communities were characterized from 11 infant fecal samples using primers that target the internal transcribed spacer (ITS) 2 locus, a region that provides taxonomic discrimination of medically relevant fungi. Each sample yielded an average of 27,553 fungal sequences and Candida albicans was the most abundant species identified by sequencing and quantitative PCR (qPCR). Low numbers of Candida krusei and Candida parapsilosis sequences were observed in several samples, but their presence was detected by species-specific qPCR in only one sample, highlighting a challenge inherent in the study of low-abundance organisms. Overall, the sequencing results revealed that infant fecal samples had fungal diversity comparable to that of bacterial communities in similar-aged infants, which correlated with the relative abundance of C. albicans. We conclude that targeted sequencing of fungal ITS2 amplicons in conjunction with qPCR analyses of specific fungi provides an informative picture of fungal community structure in the human intestinal tract. Our data suggests that the infant intestine harbors diverse fungal species and is consistent with prior culture-based analyses showing that the predominant fungus in the infant intestine is C. albicans.

Antimicrobial susceptibility and clinical outcomes of Candida parapsilosis bloodstream infections in a tertiary teaching hospital in Northern Taiwan

BACKGROUND

Candida parapsilosis is an emerging non-albicans Candida that is associated with central line-associated infection. C. parapsilosis has higher minimal inhibitory concentration to echinocandin than Candida albicans, and the effects of echinocandin on C. parapsilosis are ambiguous. Therefore, in this study, we aimed to investigate the susceptibility and the correlation between incidence and drug consumption.

METHODS

This retrospective study was conducted in a tertiary teaching hospital in northern Taiwan between 2008 and 2012. The Candida species distribution, the correlation between the use of antifungal agents and the incidence of C. parapsilosis bloodstream infection, demographic information, clinical characteristics, mortality rate, and in vitro susceptibility of C. parapsilosis were analyzed.

RESULTS

A total of 77 episodes from 77 patients were included for analysis. The overall 90-day mortality rate was 41.6%. The incidence of C. parapsilosis bloodstream infection showed a moderate positive correlation with the increased defined daily dose of echinocandin. The risk factors associated with mortality included malignancy or a metastatic tumor. Multivariate logistical regression analysis showed that patients with malignancy had higher odds ratios in terms of mortality. The rate of C. parapsilosis resistance to fluconazole was 3%, whereas the susceptibility rate was 95.5%.

CONCLUSION

Underlying comorbidity and malignancy were factors leading to death in patients with C. parapsilosis bloodstream infection. Catheter removal did not influence the mortality rate. The survival rate of patients receiving echinocandin was lower than the group receiving fluconazole. Fluconazole remains the drug of choice to treat C. parapsilosis bloodstream infections.

Evaluation of microbial load in oropharyngeal mucosa from tannery workers

Background

Animal skin provides an ideal medium for the propagation of microorganisms and it is used like raw material in the tannery and footware industry. The aim of this study was to evaluate and identify the microbial load in oropharyngeal mucosa of tannery employees.

Methods

The health risk was estimated based on the identification of microorganisms found in the oropharyngeal mucosa samples. The study was conducted in a tanners group and a control group. Samples were taken from oropharyngeal mucosa and inoculated on plates with selective medium. In the samples, bacteria were identified by 16S ribosomal DNA analysis and the yeasts through a presumptive method. In addition, the sensitivity of these microorganisms to antibiotics/antifungals was evaluated.

Results

The identified bacteria belonged to the families Enterobacteriaceae, Pseudomonadaceae, Neisseriaceae, Alcaligenaceae, Moraxellaceae, and Xanthomonadaceae, of which some species are considered as pathogenic or opportunistic microorganisms; these bacteria were not present in the control group. Forty-two percent of bacteria identified in the tanners group are correlated with respiratory diseases. Yeasts were also identified, including the following species: Candida glabrata, Candida tropicalis, Candida albicans, and Candida krusei. Regarding the sensitivity test of bacteria identified in the tanners group, 90% showed sensitivity to piperacillin/tazobactam, 87% showed sensitivity to ticarcillin/clavulanic acid, 74% showed sensitivity to ampicillin/sulbactam, and 58% showed sensitivity to amoxicillin/clavulanic acid.

Conclusion

Several of the bacteria and yeast identified in the oropharyngeal mucosa of tanners have been correlated with infections in humans and have already been reported as airborne microorganisms in this working environment, representing a health risk for workers.

The Candida pathogenic species complex

Candida species are the most common causes of fungal infection. Approximately 90% of infections are caused by five species: Candida albicans, Candida glabrata, Candida tropicalis, Candida parapsilosis, and Candida krusei. Three (C. albicans, C. tropicalis, and C. parapsilosis) belong to the CTG clade, in which the CTG codon is translated as serine and not leucine. C. albicans remains the most commonly isolated but is decreasing relative to the other species. The increasing incidence of C. glabrata is related to its reduced susceptibility to azole drugs. Genome analysis suggests that virulence in the CTG clade is associated with expansion of gene families, particularly of cell wall genes. Similar independent processes took place in the C. glabrata species group. Gene loss and expansion in an ancestor of C. glabrata may have resulted in preadaptations that enabled pathogenicity.

Resistance to antifungals that target CYP51

Fungal diseases are an increasing global burden. Fungi are now recognised to kill more people annually than malaria, whilst in agriculture, fungi threaten crop yields and food security. Azole resistance, mediated by several mechanisms including point mutations in the target enzyme (CYP51), is increasing through selection pressure as a result of widespread use of triazole fungicides in agriculture and triazole antifungal drugs in the clinic. Mutations similar to those seen in clinical isolates as long ago as the 1990s in Candida albicans and later in Aspergillus fumigatus have been identified in agriculturally important fungal species and also wider combinations of point mutations. Recently, evidence that mutations originate in the field and now appear in clinical infections has been suggested. This situation is likely to increase in prevalence as triazole fungicide use continues to rise. Here, we review the progress made in understanding azole resistance found amongst clinically and agriculturally important fungal species focussing on resistance mechanisms associated with CYP51. Biochemical characterisation of wild-type and mutant CYP51 enzymes through ligand binding studies and azole IC50 determinations is an important tool for understanding azole susceptibility and can be used in conjunction with microbiological methods (MIC50 values), molecular biological studies (site-directed mutagenesis) and protein modelling studies to inform future antifungal development with increased specificity for the target enzyme over the host homologue.

Pivotal role for a tail subunit of the RNA polymerase II mediator complex CgMed2 in azole tolerance and adherence in Candida glabrata

Antifungal therapy failure can be associated with increased resistance to the employed antifungal agents. Candida glabrata, the second most common cause of invasive candidiasis, is intrinsically less susceptible to the azole class of antifungals and accounts for 15% of all Candida bloodstream infections. Here, we show that C. glabrata MED2 (CgMED2), which codes for a tail subunit of the RNA polymerase II Mediator complex, is required for resistance to azole antifungal drugs in C. glabrata. An inability to transcriptionally activate genes encoding a zinc finger transcriptional factor, CgPdr1, and multidrug efflux pump, CgCdr1, primarily contributes to the elevated susceptibility of the Cgmed2Δ mutant toward azole antifungals. We also report for the first time that the Cgmed2Δ mutant exhibits sensitivity to caspofungin, a constitutively activated protein kinase C-mediated cell wall integrity pathway, and elevated adherence to epithelial cells. The increased adherence of the Cgmed2Δ mutant was attributed to the elevated expression of the EPA1 and EPA7 genes. Further, our data demonstrate that CgMED2 is required for intracellular proliferation in human macrophages and modulates survival in a murine model of disseminated candidiasis. Lastly, we show an essential requirement for CgMed2, along with the Mediator middle subunit CgNut1 and the Mediator cyclin-dependent kinase/cyclin subunit CgSrb8, for the high-level fluconazole resistance conferred by the hyperactive allele of CgPdr1. Together, our findings underscore a pivotal role for CgMed2 in basal tolerance and acquired resistance to azole antifungals.