Twelve years of fluconazole in clinical practice: global trends in species distribution and fluconazole susceptibility of bloodstream isolates of Candida

Antibiotic overuse as a risk factor for candidemia in an Indian pediatric ICU

OBJECTIVE

To identify risk factors and mycological characteristics of candidemia in Pediatric ICU of a tertiary-care hospital.

METHODS

Patients were screened for candidemia by blood culture. Recovered isolates were speciated and subjected to antifungal susceptibility testing. For every candidemic patient, three controls were matched for age, underlying diagnosis and period of hospitalization. Premature neonates were also matched for birth-weight. Proportion of cases and controls on specific antibiotics or indwelling devices was compared using Chi-square test, while unpaired t-test was used for comparing the number of antibiotics used and the number of days of antibiotic administration. Concordance between susceptibility testing methods was evaluated using Chi-square test.

RESULTS

Significantly wider spectrum of antibiotic coverage was observed among the 28 candidemic patients. While every patient received antibiotic against enteric gram-negative bacilli, antibiotic usage for additional groups of microorganisms was significantly higher among cases. Association of candidemia with increasing use of indwelling devices was also observed. Endogenous colonization was higher in candidemic infants. Candida albicans was the commonest species (n = 18), followed by C. tropicalis (n = 7). Fluconazole and ketoconazole resistance was observed in 10.7 % cases.

CONCLUSIONS

This information on pediatric candidemia could be used to devise locally-tailored strategies for identifying at-risk patients, underline the importance of routine antifungal susceptibility testing and formulate appropriate guidelines for management.

Candida glabrata candidemia: An emerging threat in critically ill patients

Background:

Candidemia is an important nosocomial blood stream infection in critically ill patients. Although several studies have addressed candidemia, very few have reviewed the impact of Candida glabrata candidemia in Intensive Care Unit (ICU) patients.

Materials and Methods:

The medical records of ICU patients between 2006 and 2010 were reviewed retrospectively. The epidemiology, clinical features and mortality related risk factors among our adult ICU patients were seen.

Results:

Among 144 episodes of candidemia, C. glabrata (n = 26; 18.05%) was the third most common species isolated. The incidence of C. glabrata candidemia was 0.21/1000 ICU admissions. The most common risk factors were prior exposure to broad spectrum antibiotics (100%), central venous catheter (100%), mechanical ventilation (76.9%), diabetes mellitus (50%), age >65 years (46.15%). Urine (23%) was the most common source of C. glabrata candidemia. Overall in hospital 30 days mortality rate due to C. glabrata fungemia was 53.8%. Patients who were treated with fluconazole showed better outcome than patients treated with amphotericin B. Renal failure requiring hemodialysis was the significantly associated with mortality in our study.

Conclusion:

Candida glabrata was the 3^rd most common Candida causing candidemia in our ICUs with a incidence of 0.21/1000 ICU admissions. The outcome of ICU acquired C. glabrata candidemia was poor with 30 days mortality rate of 53.8%. Renal failure requiring hemodialysis was the only risk factor associated with mortality. Further studies are required to identify the other risk factors associated with mortality in C. glabrata candidemia.

Ibuprofen-mediated reversal of fluconazole resistance in clinical isolates of Candida

INTRODUCTION

In view of the increasing prevalence of invasive Candidiasis in today's health-care scenario and the emergence of fluconazole resistance among clinical isolates of Candida, we sought to determine if Ibuprofen could elicit a reversal of fluconazole resistance and thereby offer a potential therapeutic breakthrough in fluconazole-resistant Candidiasis.

MATERIALS AND METHODS

We selected 69 clinical isolates of Candida, which demonstrated an MIC of >32 μg/ml for fluconazole, and subjected them to broth microdilution in presence and absence of Ibuprofen.

RESULTS

Forty two of the 69 isolates (60.9%) demonstrated reversal of Fluconazole resistance with concomitant use of Ibuprofen. This was characterized by significant species-wise variation (p=0.00008), with all the C. albicans isolates and none of the C. glabrata isolates demonstrating such reversal. Only 22.2% and 37.7% of C. krusei and C. tropicalis isolates respectively showed Ibuprofen-mediated reversal of Fluconazole resistance.

CONCLUSION

Since Ibuprofen is a known efflux pump inhibitor, our findings hint at the possible mechanism of Fluconazole resistance in most of our Candida isolates and suggest a potential therapeutic alternative that could be useful in the majority of Fluconazole-resistant clinical isolates of Candida.

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.

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.

Environmental azole fungicide, prochloraz, can induce cross-resistance to medical triazoles in Candida glabrata

Acquisition of azole resistance by clinically relevant yeasts in nature may result in a significant, yet undetermined, impact in human health. The main goal of this study was to assess the development of cross-resistance between agricultural and clinical azoles by Candida spp. An in vitro induction assay was performed, for a period of 90 days, with prochloraz (PCZ) - an agricultural antifungal. Afterward, the induced molecular resistance mechanisms were unveiled. MIC value of PCZ increased significantly in all Candida spp. isolates. However, only C. glabrata developed cross-resistance to fluconazole and posaconazole. The increased MIC values were stable. Candida glabrata azole resistance acquisition triggered by PCZ exposure involved the upregulation of the ATP binding cassette multidrug transporter genes and the transcription factor, PDR1. Single mutation previously implicated in azole resistance was found in PDR1 while ERG11 showed several synonymous single nucleotide polymorphisms. These results might explain why C. glabrata is so commonly less susceptible to clinical azoles, suggesting that its exposure to agricultural azole antifungals may be associated to the emergence of cross-resistance. Such studies forward potential explanations for the worldwide increasing clinical prevalence of C. glabrata and the associated worse prognosis of an infection by this species.

Association of KPC-producing Klebsiella pneumoniae colonization or infection with Candida isolation and selection of non-albicans species

Clinical specimens from 565 patients hospitalized in 2 intensive care units (ICUs A and B) during a 28-month period were cultured on appropriate media for isolation of Candida. Forty-nine (9%) patients had at least a Candida spp.-positive sample. Candida albicans was the predominant species isolated from 26 (53%) patients. Seventeen patients (3%) developed candidemia. Multivariate analysis showed that obesity, female gender, hospitalization during summer months, admission at ICU B, parenteral nutrition, administration of metronidazole, transplantation, and KPC-producing Klebsiella pneumoniae (KPC-Kp) infection were independently associated with Candida spp. isolation. Candidemia was associated with cortisone administration, KPC-Kp infection, and presence of colostomy or abdominal catheter. Administration of fluconazole was a protective factor for both Candida spp. isolation and infection, leading to selection of Candida non-albicans species. Among several risk factors, KPC-Kp infection and colonization are identified as statistically significant factors associated with Candida isolation, especially of non-albicans species.

Genome structure and dynamics of the yeast pathogen Candida glabrata

The yeast pathogen Candida glabrata is the second most frequent cause of Candida infections. However, from the phylogenetic point of view, C. glabrata is much closer to Saccharomyces cerevisiae than to Candida albicans. Apparently, this yeast has relatively recently changed its life style and become a successful opportunistic pathogen. Recently, several C. glabrata sister species, among them clinical and environmental isolates, have had their genomes characterized. Also, hundreds of C. glabrata clinical isolates have been characterized for their genomes. These isolates display enormous genomic plasticity. The number and size of chromosomes vary drastically, as well as intra- and interchromosomal segmental duplications occur frequently. The observed genome alterations could affect phenotypic properties and thus help to adapt to the highly variable and harsh habitats this yeast finds in different human patients and their tissues. Further genome sequencing of pathogenic isolates will provide a valuable tool to understand the mechanisms behind genome dynamics and help to elucidate the genes contributing to the virulence potential.

Breakthrough candidemia due to multidrug-resistant Candida glabrata during prophylaxis with a low dose of micafungin

We identified a case of breakthrough candidemia in a 25-year-old patient receiving micafungin prophylaxis (50 mg/day). Five Candida glabrata isolates were obtained from blood cultures and were classified as multidrug-resistant isolates, since all of them exhibited high MICs for echinocandin and azole drugs. A mutation (S663F) in hot spot 1 of the FKS2 gene was found in all five isolates. This mutation yielded a 1,3-β-D-glucan synthase enzyme with highly reduced sensitivities to echinocandin drugs.

Immune evasion, stress resistance, and efficient nutrient acquisition are crucial for intracellular survival of Candida glabrata within macrophages

Candida glabrata is both a human fungal commensal and an opportunistic pathogen which can withstand activities of the immune system. For example, C. glabrata can survive phagocytosis and replicates within macrophages. However, the mechanisms underlying intracellular survival remain unclear. In this work, we used a functional genomic approach to identify C. glabrata determinants necessary for survival within human monocyte-derived macrophages by screening a set of 433 deletion mutants. We identified 23 genes which are required to resist killing by macrophages. Based on homologies to Saccharomyces cerevisiae orthologs, these genes are putatively involved in cell wall biosynthesis, calcium homeostasis, nutritional and stress response, protein glycosylation, or iron homeostasis. Mutants were further characterized using a series of in vitro assays to elucidate the genes' functions in survival. We investigated different parameters of C. glabrata-phagocyte interactions: uptake by macrophages, replication within macrophages, phagosomal pH, and recognition of mutant cells by macrophages as indicated by production of reactive oxygen species and tumor necrosis factor alpha (TNF-α). We further studied the cell surface integrity of mutant cells, their ability to grow under nutrient-limited conditions, and their susceptibility to stress conditions mirroring the harsh environment inside a phagosome. Additionally, resistance to killing by neutrophils was analyzed. Our data support the view that immune evasion is a key aspect of C. glabrata virulence and that increased immune recognition causes increased antifungal activities by macrophages. Furthermore, stress resistance and efficient nutrient acquisition, in particular, iron uptake, are crucial for intraphagosomal survival of C. glabrata.

Candida glabrata: a review of its features and resistance

Candida species belong to the normal microbiota of the oral cavity and gastrointestinal and vaginal tracts, and are responsible for several clinical manifestations, from mucocutaneous overgrowth to bloodstream infections. Once believed to be non-pathogenic, Candida glabrata was rapidly blamable for many human diseases. Year after year, these pathological circumstances are more recurrent and problematic to treat, especially when patients reveal any level of immunosuppression. These difficulties arise from the capacity of C. glabrata to form biofilms and also from its high resistance to traditional antifungal therapies. Thus, this review intends to present an excerpt of the biology, epidemiology, and pathology of C. glabrata, and detail an approach to its resistance mechanisms based on studies carried out up to the present.

Interactions between copy number and expression level of genes involved in fluconazole resistance in Candida glabrata

Objectives: This study aimed to elucidate the relative involvement of drug resistance gene copy number and overexpression in fluconazole resistance in clinical C. glabrata isolates using a population-based approach.

Methods: Fluconazole resistance levels were quantified using the minimal inhibitory concentration (MIC) via Etest method. Both gene expression levels and gene copy number of CgCDR1, CgPDH1, CgERG11, and CgSNQ2 were assessed via quantitative real-time PCR. The influence of the main effects and first-level interactions of both the expression level and copy number of these genes on fluconazole resistance levels were analyzed using a multivariate statistical model.

Results: Forty-three C. glabrata isolates were collected from 30 patients during in a hospital survey. In the multivariate analysis, C. glabrata fluconazole MICs were independently increased by CgSNQ2 overexpression (p < 10⁻⁴) and the interaction between CgPDH1 gene copy number and CgPDH1 expression level (p = 0.038). In contrast, both CgPDH1 overexpression (p = 0.049) and the interaction between CgSNQ2 and CgERG11 expression (p = 0.003) led to a significant decrease in fluconazole MICs.

Conclusion: Fluconazole resistance in C. glabrata involves complex interactions between drug resistance gene expression and/or copy number. The population-based multivariate analysis highlighted the involvement of the CgSNQ2 gene in fluconazole resistance and the complex effect of the other genes such as PDH1 for which overexpression was associated with reduced fluconazole resistance levels, while the interaction between PDH1 overexpression and copy number was associated with increased resistance levels.

A research agenda on the management of intra-abdominal candidiasis: results from a consensus of multinational experts

INTRODUCTION

intra-abdominal candidiasis (IAC) may include Candida involvement of peritoneum or intra-abdominal abscess and is burdened by high morbidity and mortality rates in surgical patients. Unfortunately, international guidelines do not specifically address this particular clinical setting due to heterogeneity of definitions and scant direct evidence. In order to cover this unmet clinical need, the Italian Society of Intensive Care and the International Society of Chemotherapy endorsed a project aimed at producing practice recommendations for the management of immune-competent adult patients with IAC.

METHODS

A multidisciplinary expert panel of 22 members (surgeons, infectious disease and intensive care physicians) was convened and assisted by a methodologist between April 2012 and May 2013. Evidence supporting each statement was graded according to the European Society of Clinical Microbiology and Infection Diseases (ESCMID) grading system.

RESULTS

Only a few of the numerous recommendations can be summarized in the Abstract. Direct microscopy examination for yeast detection from purulent and necrotic intra-abdominal specimens during surgery or by percutaneous aspiration is recommended in all patients with nonappendicular abdominal infections including secondary and tertiary peritonitis. Samples obtained from drainage tubes are not valuable except for evaluation of colonization. Prophylactic usage of fluconazole should be adopted in patients with recent abdominal surgery and recurrent gastrointestinal perforation or anastomotic leakage. Empirical antifungal treatment with echinocandins or lipid formulations of amphotericin B should be strongly considered in critically ill patients or those with previous exposure to azoles and suspected intra-abdominal infection with at least one specific risk factor for Candida infection. In patients with nonspecific risk factors, a positive mannan/antimannan or (1→3)-β-D-glucan (BDG) or polymerase chain reaction (PCR) test result should be present to start empirical therapy. Fluconazole can be adopted for the empirical and targeted therapy of non-critically ill patients without previous exposure to azoles unless they are known to be colonized with a Candida strain with reduced susceptibility to azoles. Treatment can be simplified by stepping down to an azole (fluconazole or voriconazole) after at least 5-7 days of treatment with echinocandins or lipid formulations of amphotericin B, if the species is susceptible and the patient has clinically improved.

CONCLUSIONS

Specific recommendations were elaborated on IAC management based on the best direct and indirect evidence and on the expertise of a multinational panel.

Evaluation of bactec mycosis IC/F and Plus Aerobic/F blood culture bottles for detection of Candida in the presence of antifungal agents

Clinical practice guidelines recommend performing follow-up cultures for patients with candidemia in order to determine the time when Candida is cleared from the bloodstream. Since this requires culturing blood samples from patients undergoing antifungal treatment, we evaluated two blood culture bottles (the Bactec Mycosis IC/F [MICF], specifically adapted to the growth of fungi, and the Bactec Plus Aerobic/F [PAF], containing resins to inactivate anti-infective agents) for their effectiveness in detecting Candida albicans and Candida glabrata when seeded in concentrations of 1 CFU/ml and 10 CFU/ml, respectively, together with human whole blood and various antifungal agents in therapeutic peak serum concentrations (Cmax). Significant differences between the MICF and PAF vials for the detection of Candida spp. were found when inoculated with caspofungin (0/12 versus 8/12) (P < 0.001) or amphotericin B (3/12 versus 12/12) (P < 0.001). Inoculation of fluconazole or voriconazole did not influence the effectiveness of detection in the MICF and PAF bottles (P = 1.0). Neither the MICF nor the PAF bottles detected Candida spp. reliably when seeded together with anidulafungin (1/12 versus 1/12) (P = 1.0) or micafungin (0/12 versus 1/12) (P = 1.0). The times to positivity of both bottles were significantly prolonged when antifungal agents were added compared to those of controls without antimycotic drugs (P < 0.001). Overall, the results of this in vitro study indicate that the PAF bottles detected Candida spp. more reliably than the MICF bottles when supplemented with certain antifungal agents. Consequently, clinical studies should evaluate whether this holds true when blood cultures from patients undergoing antifungal treatment are performed.

Flucytosine antagonism of azole activity versus Candida glabrata: role of transcription factor Pdr1 and multidrug transporter Cdr1

Infections with the opportunistic yeast Candida glabrata have increased dramatically in recent years. Antifungal therapy of yeast infections commonly employs azoles, such as fluconazole (FLC), but C. glabrata frequently develops resistance to these inhibitors of ergosterol biosynthesis. The pyrimidine analog flucytosine (5-fluorocytosine [5FC]) is highly active versus C. glabrata but is now rarely used clinically due to similar concerns over resistance and, a related concern, the toxicity associated with high doses used to counter resistance. Azole-5FC combination therapy would potentially address these concerns; however, previous studies suggest that 5FC may antagonize azole activity versus C. glabrata. Here, we report that 5FC at subinhibitory concentrations antagonized the activity of FLC 4- to 16-fold versus 8 of 8 C. glabrata isolates tested. 5FC antagonized the activity of other azoles similarly but had only indifferent effects in combination with unrelated antifungals. Since azole resistance in C. glabrata results from transcription factor Pdr1-dependent upregulation of the multidrug transporter gene CDR1, we reasoned that 5FC antagonism might be similarly mediated. Indeed, 5FC-FLC antagonism was abrogated in pdr1Δ and cdr1Δ strains. In further support of this hypothesis, 5FC exposure induced CDR1 expression 6-fold, and this upregulation was Pdr1 dependent. In contrast to azoles, 5FC is not a Cdr1 substrate and so its activation of Pdr1 was unexpected. We observed, however, that 5FC exposure readily induced petite mutants, which exhibit Pdr1-dependent CDR1 upregulation. Thus, mitochondrial dysfunction resulting in Pdr1 activation is the likely basis for 5FC antagonism of azole activity versus C. glabrata.

Yeasts isolated from nosocomial urinary infections: antifungal susceptibility and biofilm production

BACKGROUND

Urinary Candida infections in the hospital environment are frequent and need to be better understood.

AIMS

To compare the results of antifungal susceptibility profiles of yeasts isolated from patients with urinary infections obtained by broth microdilution method (BM) and by disk diffusion (DD), and also evaluate the capacity of these yeasts to form biofilms.

METHODS

Only yeasts obtained from pure urine cultures with counts higher than 10(5) colony-forming units per milliliter, without bacteria development, of symptomatic patients were included. The isolates were identified by classical methods and the antifungal susceptibility tests were performed with the following drugs: amphotericin B, ketoconazole, fluconazole, itraconazole, voriconazole and caspofungin. The biofilm studies were carried out in polystyrene microtitration plates.

RESULTS

Ninety-five yeasts isolates were analyzed, including 40 Candida albicans, 31 Candida glabrata, 24 Candida tropicalis. In general, the majority of the isolates were susceptible to the tested drugs but some resistance was observed, especially against fluconazole. Great variability in the antifungal susceptibility results was observed with the different tested drugs and a few discrepancies were observed between both methods. We suggest that in case of DD resistance this result should be confirmed by BM, the standard method. C. tropicalis isolates showed high biofilm production (91.7%) compared to C. albicans (82.5%) and C. glabrata (61.3%), with statistical significance (p=0.0129).

CONCLUSIONS

Candiduria in critical patients requires major attention and a better control. The different susceptibility results obtained in this study showed the need to identify yeasts up to the species level, especially in patients with urinary tract infection. The development of techniques of antifungal susceptibility tests can help the clinicians in the empiric treatment of candiduria.

Molecular fingerprints to identify Candida species

A wide range of molecular techniques have been developed for genotyping Candida species. Among them, multilocus sequence typing (MLST) and microsatellite length polymorphisms (MLP) analysis have recently emerged. MLST relies on DNA sequences of internal regions of various independent housekeeping genes, while MLP identifies microsatellite instability. Both methods generate unambiguous and highly reproducible data. Here, we review the results achieved by using these two techniques and also provide a brief overview of a new method based on high-resolution DNA melting (HRM). This method identifies sequence differences by subtle deviations in sample melting profiles in the presence of saturating fluorescent DNA binding dyes.

In vitro fluconazole and voriconazole susceptibilities of Candida bloodstream isolates in Korea: use of the CLSI and EUCAST epidemiological cutoff values

Background

At present, the clinical breakpoints (CBPs) of both fluconazole and voriconazole are available only for 3 common Candida species in the Clinical and Laboratory Standards Institute (CLSI) and the European Committee on Antimicrobial Susceptibility Testing (EUCAST) methods. Epidemiological cutoff values (ECVs) were recently applied to both methods to detect the emergence of acquired resistance (i.e., non-wild-type isolates) among 5 common Candida species.

Methods

We performed a nationwide study to determine the fluconazole and voriconazole susceptibility of Candida bloodstream isolates (BSIs) using both the CLSI and EUCAST methods. A total of 423 BSIs of 5 Candida species were collected from 8 hospitals. The azole susceptibilities were assessed on the basis of the species-specific CBPs and ECVs.

Results

Of the 341 BSIs of 3 common Candida species (i.e., C. albicans, C. tropicalis, and C. parapsilosis), 0.3% and 0.9%, 0.0% and 1.5% of isolates were categorized as fluconazole and voriconazole resistant according to the CLSI and EUCAST CBPs, respectively. Of 423 total BSIs, 1.4% and 2.6% had fluconazole minimum inhibitory concentrations (MICs) exceeding the ECVs according to the CLSI and EUCAST, respectively; 1.0% and 2.1% had voriconazole MICs exceeding the ECVs according to the CLSI and EUCAST, respectively. Categorical agreement between the methods using ECVs was 98.3% for fluconazole and 98.3% for voriconazole.

Conclusions

The EUCAST and CLSI methods using ECVs provide highly concordant results. Moreover, non-wild-type isolates with possibly acquired azole resistance were rare among the BSIs of 5 common Candida species in Korea.

Yarrowia lipolytica: safety assessment of an oleaginous yeast with a great industrial potential

Yarrowia lipolytica has been developed as a production host for a large variety of biotechnological applications. Efficacy and safety studies have demonstrated the safe use of Yarrowia-derived products containing significant proportions of Yarrowia biomass (as for DuPont's eicosapentaenoic acid-rich oil) or with the yeast itself as the final product (as for British Petroleum's single-cell protein product). The natural occurrence of the species in food, particularly cheese, other dairy products and meat, is a further argument supporting its safety. The species causes rare opportunistic infections in severely immunocompromised or otherwise seriously ill people with other underlying diseases or conditions. The infections can be treated effectively by the use of regular antifungal drugs, and in some cases even disappeared spontaneously. Based on our assessment, we conclude that Y. lipolytica is a "safe-to-use" organism.

A review of Candida species causing blood stream infection

The incidence of candidemia has been on a rise worldwide. The epidemiology of invasive fungal infections in general and of candidemia in particular has changed in the past three decades because of a variety of factors like the AIDS epidemic, increased number of patients receiving immunosuppressive therapy for transplantation and the increasing use of antimicrobials in the hospital setups and even in the community. The important risk factors for candidemia include use of broad-spectrum antimicrobials, cancer chemotherapy, mucosal colonization by Candida species, indwelling vascular catheters like central venous catheters, etc. More than 90% of the invasive infections due to Candida species are attributed to five species-Candida albicans, Candida glabrata, Candida parapsilosis, Candida tropicalis and Candida krusei. However, the list of new species of Candida isolated from clinical specimens continues to grow every year. Early diagnosis and proper treatment is the key for management of candidemia cases.

Nationwide study of candidemia, antifungal use, and antifungal drug resistance in Iceland, 2000 to 2011

Candidemia is often a life-threatening infection, with highly variable incidence among countries. We conducted a nationwide study of candidemia in Iceland from 2000 to 2011, in order to determine recent trends in incidence rates, fungal species distribution, antifungal susceptibility patterns, and concurrent antifungal consumption. A total of 208 infection episodes in 199 patients were identified. The average incidence during the 12 years was 5.7 cases/100,000 population/year, which was significantly higher than that from 1990 to 1999 (4.3/100,000/year; P = 0.02). A significant reduction in the use of blood cultures was noted in the last 3 years of the study, coinciding with the economic crisis in the country (P < 0.001). Age-specific incidence rates were highest among patients at the extremes of age, 20.7/100,000 for <1 year of age and 18.1/100,000 for >60 years, and varied by gender. Age-specific incidence among males >80 years old was 28.6/100,000/year, and it was 8.3/100,000/year for females in this age group (P = 0.028). The 30-day survival rate among adult patients remained unchanged compared to that from 1990 to 1999 (70.4% versus 69.5%, P = 0.97). Candida albicans was the predominant species (56%), followed by C. glabrata (16%) and C. tropicalis (13%). The species distribution remained stable compared to that from previous decades. Fluconazole use increased 2.4-fold from 2000 to 2011, with no increase in resistance. In summary, the incidence of candidemia in Iceland has continued to increase but may have reached a steady state, and no increase in antifungal drug resistance has been noted. Decreased use of blood cultures toward the end of the study may have influenced detection rates.

Fungemia by Candida pelliculosa (Pichia anomala) in a neonatal intensive care unit: a possible clonal origin

Neonatal candidemia can occur, however, infections caused by Candida pelliculosa are rare. Here, we describe an outbreak of candidemia caused by C. pelliculosa among babies hospitalized in a neonatal intensive care unit.

Characterization of microbial communities and fungal metabolites on field grown strawberries from organic and conventional production

The background levels of culturable indigenous microbial communities (microbiotas) on strawberries were examined in a field survey with four conventional and four organic growers with different production practise and geographic distribution. The microbiota on apparently healthy strawberries was complex including potential plant pathogens, opportunistic human pathogens, plant disease biocontrol agents and mycotoxin producers. The latter group was dominated by Penicillium spp. and Aspergillus niger was also isolated. As expected, bacteria were the most abundant and diverse group of the strawberry microbiota followed by yeasts and filamentous fungi. No obvious correlation between grower practice and the strawberry microbiota was observed. Differences between microbiotas on strawberries from conventional systems with up to 10 fungicide spray treatments and organic production systems were insignificant. Mycotoxins were not detected in mature strawberries from any of the eight different growers neither in additional samples of low quality berries. However, isolates of Penicillium expansum and A. niger produced high amounts of mycotoxins when incubated on strawberries at 25°C. Penicillium polonicum produced cyclopenol, cyclopenin, and viridicatin on the artificially infected berries, while Alternaria arborescens produced tenuazonic acid, Alternaria tenuissima produced altertoxin I and altenuene, and Trichoderma spp. produced several peptaibols. In conclusion, native strawberry microbiotas are highly diverse both in terms of taxonomic groups and functional traits that are important in relation to plant and human health.

Candida infections and their prevention

Infections caused by Candida species have been increased dramatically worldwide due to the increase in immunocompromised patients. For the prevention and cure of candidiasis, several strategies have been adopted at clinical level. Candida infected patients are commonly treated with a variety of antifungal drugs such as fluconazole, amphotericin B, nystatin, and flucytosine. Moreover, early detection and speciation of the fungal agents will play a crucial role for administering appropriate drugs for antifungal therapy. Many modern technologies like MALDI-TOF-MS, real-time PCR, and DNA microarray are being applied for accurate and fast detection of the strains. However, during prolonged use of these drugs, many fungal pathogens become resistant and antifungal therapy suffers. In this regard, combination of two or more antifungal drugs is thought to be an alternative to counter the rising drug resistance. Also, many inhibitors of efflux pumps have been designed and tested in different models to effectively treat candidiasis. However, most of the synthetic drugs have side effects and biomedicines like antibodies and polysaccharide-peptide conjugates could be better alternatives and safe options to prevent and cure the diseases. Furthermore, availability of genome sequences of Candida   albicans and other non-albicans strains has made it feasible to analyze the genes for their roles in adherence, penetration, and establishment of diseases. Understanding the biology of Candida species by applying different modern and advanced technology will definitely help us in preventing and curing the diseases caused by fungal pathogens.

Molecular species identification of Candida from blood samples of intensive care unit patients by polymerase chain reaction - restricted fragment length polymorphism

Introduction:

Candida spp is an emerging cause of blood stream infections worldwide. Delay in speciation of Candida isolates by conventional methods and resistance to antifungal drugs (especially fluconazole, amphotericin B, etc.) in various Candida species are some of the factors responsible for the increase in morbidity and mortality due to candidemia. So, the rapid detection and identification of Candida isolates from blood is very important for the proper management of patients having candidemia.

Materials and Methods:

In this study, we have used polymerase chain reaction (PCR) – restriction fragment length polymorphism (RFLP) as a method for the speciation of Candida isolates from blood samples of intensive care unit (ICU) patients. PCR was used to amplify the ITS-1 and ITS-2 regions of Candida spp using universal primers ITS-1 and ITS-4. The amplified product was digested using Msp I restriction enzyme by RFLP.

Results and Discussion:

The method PCR-RFLP helped in identifying five medically important Candida spp (C. tropicalis, C. albicans, C. parapsilosis, C. krusei and C. glabrata) from blood. This method is rapid, reliable, easy and cost-effective and can be used in routine laboratory diagnostics for the rapid identification of Candida isolates from blood.

Conclusion:

PCR-RFLP is an easy, rapid and highly valuable tool which can be used in routine diagnostic laboratories to speciate Candida isolates obtained from blood. This rapid method of speciation will help clinicians to decide on empirical therapy in candidemia cases before antifungal susceptibility results are available.

Invasive fungal infections following liver transplantation: incidence, risk factors, survival, and impact of fluconazole-resistant Candida parapsilosis (2003-2007)

Invasive fungal infections (IFIs) are associated with a high mortality rate for liver transplantation (LT) recipients. To study the incidence of and risk factors for IFIs in LT recipients and the associated mortality rates, we retrospectively reviewed the records of first-time deceased donor LT recipients (January 2003 to December 2007). The incidence of IFIs was 12%. Non-albicans Candida species accounted for 55% of IFIs; 50% of these IFIs were Candida parapsilosis. Only 43% of Candida isolates were fluconazole-susceptible (minimum inhibitory concentration ≤ 8 μ/mL). All C. parapsilosis isolates were fluconazole-resistant, and this coincided with a surge of these isolates during a peak period of LT. Factors associated with IFIs included a creatinine level > 2 mg/mL [hazard ratio (OR) = 2.4, 95% confidence interval (CI) = 1.2-5.0, P = 0.01], a Model for End-Stage Liver Disease score > 25 (OR = 2.4, 95% CI = 1.2-4.9, P = 0.02), pretransplant fungal colonization (OR = 7.0, 95% CI = 3.2-15.3, P < 0.001), and a daily prophylactic fluconazole dosage < 200 mg (OR = 2.8, 95% CI = 1.1-7.4, P = 0.03). According to a multivariate analysis, only pretransplant fungal colonization was associated with IFIs (OR = 7.8, 95% CI = 3.9-16.2, P < 0.001). The 1-year patient survival rates with and without IFIs were 41% and 80%, respectively, and the survival rates with C. parapsilosis, other non-albicans Candida, and Candida albicans IFIs were 28%, 50%, and 75%, respectively. In conclusion, IFIs after LT (especially non-albicans Candida species and fluconazole-resistant C. parapsilosis) were associated with reduced survival. The risk factors highlight the importance of pretransplant risk assessments. The identification of pretransplant fungal colonization may allow for risk modifications before or at the time of LT. Additionally, the number of LT procedures and prophylactic strategies may affect institutional outbreaks of resistant Candida strains.

Canadian clinical practice guidelines for invasive candidiasis in adults

Candidemia and invasive candidiasis (C/IC) are life-threatening opportunistic infections that add excess morbidity, mortality and cost to the management of patients with a range of potentially curable underlying conditions. The Association of Medical Microbiology and Infectious Disease Canada developed evidence-based guidelines for the approach to the diagnosis and management of these infections in the ever-increasing population of at-risk adult patients in the health care system. Over the past few years, a new and broader understanding of the epidemiology and pathogenesis of C/IC has emerged and has been coupled with the availability of new antifungal agents and defined strategies for targeting groups at risk including, but not limited to, acute leukemia patients, hematopoietic stem cell transplants and solid organ transplants, and critical care unit patients. Accordingly, these guidelines have focused on patients at risk for C/IC, and on approaches of prevention, early therapy for suspected but unproven infection, and targeted therapy for probable and proven infection.

Amino acid-derived 1,2-benzisothiazolinone derivatives as novel small-molecule antifungal inhibitors: identification of potential genetic targets

We have identified four synthetic compounds (DFD-VI-15, BD-I-186, DFD-V-49, and DFD-V-66) from an amino acid-derived 1,2-benzisothiazolinone (BZT) scaffold that have reasonable MIC(50) values against a panel of fungal pathogens. These compounds have no structural similarity to existing antifungal drugs. Three of the four compounds have fungicidal activity against Candida spp., Cryptococcus neoformans, and several dermatophytes, while one is fungicidal to Aspergillus fumigatus. The kill rates of our compounds are equal to those in clinical usage. The BZT compounds remain active against azole-, polyene-, and micafungin-resistant strains of Candida spp. A genetics-based approach, along with phenotype analysis, was used to begin mode of action (MOA) studies of one of these compounds, DFD-VI-15. The genetics-based screen utilized a homozygous deletion collection of approximately 4,700 Saccharomyces cerevisiae mutants. We identified mutants that are both hypersensitive and resistant. Using FunSpec, the hypersensitive mutants and a resistant ace2 mutant clustered within a category of genes related directly or indirectly to mitochondrial functions. In Candida albicans, the functions of the Ace2p transcription factor include the regulation of glycolysis. Our model is that DFD-VI-15 targets a respiratory pathway that limits energy production. Supporting this hypothesis are phenotypic data indicating that DFD-VI-15 causes increased cell-reactive oxidants (ROS) and a decrease in mitochondrial membrane potential. Also, the same compound has activity when cells are grown in a medium containing glycerol (mitochondrial substrate) but is much less active when cells are grown anaerobically.

The effect of biomaterials and antifungals on biofilm formation by Candida species: a review

Candida albicans, C. glabrata, C. parapsilosis, and C. tropicalis are able to form biofilms on virtually any biomaterial implanted in a human host. Biofilms are a primary cause of mortality in immunocompromised and hospitalized patients, as they cause recurrent and invasive candidiasis, which is difficult to eradicate. This is due to the fact that the biofilm cells show high resistance to antifungal treatments and the host defense mechanisms, and exhibit an excellent ability to adhere to biomaterials. Elucidation of the mechanisms of antifungal resistance in Candida biofilms is of unquestionable importance; therefore, this review analyzes both the chemical composition of biomaterials used to fabricate the medical devices, as well as the Candida genes and proteins that confer drug resistance.

Topological and mutational analysis of Saccharomyces cerevisiae Fks1

Fks1, with orthologs in nearly all fungi as well as plants and many protists, plays a central role in fungal cell wall formation as the putative catalytic component of β-1,3-glucan synthase. It is also the target for an important new antifungal group, the echinocandins, as evidenced by the localization of resistance-conferring mutations to Fks1 hot spots 1, 2, and 3 (residues 635 to 649, 1354 to 1361, and 690 to 700, respectively). Since Fks1 is an integral membrane protein and echinocandins are cyclic peptides with lipid tails, Fks1 topology is key to understanding its function and interaction with echinocandins. We used hemagglutinin (HA)-Suc2-His4C fusions to C-terminally truncated Saccharomyces cerevisiae Fks1 to experimentally define its topology and site-directed mutagenesis to test function of selected residues. Of the 15 to 18 transmembrane helices predicted in silico for Fks1 from evolutionarily diverse fungi, 13 were experimentally confirmed. The N terminus (residues 1 to 445) is cytosolic and the C terminus (residues 1823 to 1876) external; both are essential to Fks1 function. The cytosolic central domain (residues 715 to 1294) includes newly recognized homology to glycosyltransferases, and residues potentially involved in substrate UDP-glucose binding and catalysis are essential. All three hot spots are external, with hot spot 1 adjacent to and hot spot 3 largely embedded within the outer leaflet of the membrane. This topology suggests a model in which echinocandins interact through their lipid tails with hot spot 3 and through their cyclic peptides with hot spots 1 and 2.

First case report of bloodstream infection due to a Candida species closely related to the novel species Candida pseudorugosa

Candida pseudorugosa is a novel species closely related to Candida rugosa for which only one case has been reported. We report the first case of a bloodstream infection in humans caused by a Candida sp. closely related to C. pseudorugosa. We contribute evidence to show this organism as a potential human pathogen that may be misidentified by conventional methods, also pointing out its lower sensitivity to azoles and other antifungal agents.

Evaluation of fungaemia infections in a Hungarian university hospital between 1996 and 2009

The incidence of Candida species causing bloodstream infections in the University Hospital of Szeged, Hungary, between 1996 and 2009, and the susceptibilities of these isolates to antifungal agents were evaluated.Automated blood culture systems (Vital, bioMérieux, Marcy-l'Etoile, France; and BACTEC 9120, Becton-Dickinson Diagnostic Systems, Sparks, USA) were used. The in vitro susceptibilities of the yeast isolates to antifungal agents were determined by the Etest method (AB Biodisk, Solna, Sweden).Bloodstream infections were caused by yeast strains in 231 cases during this period, and 226 Candida strains were cultured from 216 candidaemia patients. Bloodstream infections caused by multiple Candida spp. were diagnosed almost every year. Of the 216 patients, 67 were children; and 55 infants needed intensive care. In 2005, C. glabrata caused an increase in the incidence of invasive fungal infections in the Neonatal Intensive Care Unit. The PFGE analysis of 12 isolates distinguished 4 different karyotypes. The incidence of bloodstream infections caused by fungi did not change during the 14-year study period. The most frequent species cultured from blood samples were C. albicans and C. glabrata. The incidence of resistant isolates remained constant. The local trends of fungaemia must be monitored and compared with global reports.

An observational study on the epidemiological and mycological profile of Candidemia in ICU patients

Background

This study aimed to analyze the epidemiological and mycological profile of candidemia in intensive care unit (ICU) patients attending a tertiary care teaching hospital in the Himalayan region of northern India.

Material/Methods

A 15-bed medico-surgical ICU and a 5-bed pediatric ICU. Ninety-one consecutively admitted ICU patients were screened for the presence of candidemia by performing blood cultures at periodic intervals.

Results

The recovered Candida isolates were speciated and subjected to antifungal susceptibility testing using standard procedures. Forty-one of the recruited patients (45%) were found to be candidemic, with the majority of patients being in the extremes of age (13 neonates and 15 >65 years of age). Four risk factors were found to be significantly associated with the occurrence of candidemia in our patients – a period of hospitalization exceeding 7 days (p=0.0008), previous use of antibiotics (p=0.001), presence of chronic renal failure (p=0.003), and ongoing cancer chemotherapy (p= 0.041). Ninety-six Candida isolates were recovered from the 41 culture-positive patients, with Candida albicans being the commonest isolate recovered (n=75, 78.1%), followed by Candida tropicalis (n=15, 16%), and Candida glabrata (n=6, 6.5%). Fluconazole resistance was observed among 26% of all Candida isolates and 17.3% of C. albicans isolates.

Conclusions

Contrary to the majority of recent reports, species shift towards non-albicans candidemia has not been observed in our center, though the prevalence of azole resistance is alarmingly high even among the C. albicans isolates.