Candida tropicalis fungaemia: incidence, risk factors and mortality in a general hospital

An 11-Year retrospective analysis of candidiasis epidemiology, risk factors, and antifungal susceptibility in a tertiary care hospital in China

Candidiasis poses a significant threat to human health, especially in immunocompromised patients. However, there is a paucity of epidemiological data concerning the prevalence of candidiasis in developing regions of China. We conducted a retrospective study on patients positive for Candida infections in a tertiary care hospital in Shantou, China, to identify the clinical characteristics and risk factors for candidiasis. Of 5,095 cases of candidiasis, 489 (9.59%) were candidemia infections. Candida albicans (n = 230, 47.0%) was the predominant species identified among all patients. Non-albicans Candida (NAC) was more prevalent in adult patients, while Candida glabrata was slightly more frequent in pediatric patients (n = 10, 14.7%). Pulmonary diseases (n = 200, 47.8%) were the most common underlying comorbidities in adult patients (n = 25, 35.2%). Thrombocytopenia was the only laboratory finding higher in adult patients than in pediatric patients. Respiratory dysfunction, the presence of a central venous catheter, septic shock, and thrombocytopenia were independent risk factors for candidemia-related 30-day mortality. Amphotericin B exhibited high efficacy (100%), and itraconazole exhibited the lowest efficacy against all tested Candida isolates. C. glabrata had a lower susceptibility to azole, although this was not statistically significant. The epidemiological data on candidiasis, specifically candidemia in pediatric and adult patients, varied regarding the prevalence of Candida species and associated risk factors. This study provides guidance for prescribing the appropriate therapy and yields insights into the susceptibility patterns of different Candida isolates to antifungal drugs.

Multi-locus sequence typing of Candida tropicalis among Candiduria shows an outbreak in azole-susceptible isolates and clonal cluster enriched in azole-resistant isolates

BACKGROUND

The increasing detection rate of C. tropicalis and its azole resistance have made clinical treatment difficult. The presence of candiduria seems to correlate with invasive candida infection, especially for patients admitted to ICUs. However, the prevalence and antifungal resistance of C. tropicalis isolates in urine samples has not been well studied.

AIM

To retrospectively investigate the clinical features, antifungal resistance, and genetic relatedness of C. tropicalis isolates from urine samples.

METHODS

A total of 107 clinical C. tropicalis isolates were retrospectively studied, including phenotypes of isolates and characteristics of patients. The genetic profiles of 107 isolates were genotyped using multi-locus sequence typing (MLST). Phylogenetic analysis was inferred using unweighted pair group method with arithmetic averages. MLST clonal clusters (CCs) were analysed by goeBURST.

FINDINGS

Of the 107 isolates, 27.1% were resistant to fluconazole, and there was a notable increasing trend of fluconazole resistance from 16.1% in 2019 to 40.0% in 2021. Forty-seven diploid sequence types (DSTs) were assigned to ten major CCs. CC1 was the predominant fluconazole-susceptible group; 24 isolates from CC1 belonged to DST333, an outbreak clone in NICU ward. The azole-resistant CC4 contained 19 isolates, accounting for 65.5% of the azole-resistant isolates in this study. CC4 belongs to a prevalent FNS CC1 globally, of which the putative founder genotype was DST225.

CONCLUSION

This study revealed an outbreak of azole-susceptible C. tropicalis isolates in urine specimens and a high azole resistance rate of C. tropicalis in candiduria, and the MLST type showed clonal aggregation in azole-resistant isolates from urine samples.

Candida tropicalis-A systematic review to inform the World Health Organization of a fungal priority pathogens list

In response to the growing global burden of fungal infections with uncertain impact, the World Health Organization (WHO) established an Expert Group to identify priority fungal pathogens and establish the WHO Fungal Priority Pathogens List for future research. This systematic review aimed to evaluate the features and global impact of invasive candidiasis caused by Candida tropicalis. PubMed and Web of Science were searched for studies reporting on criteria of mortality, morbidity (defined as hospitalization and disability), drug resistance, preventability, yearly incidence, diagnostics, treatability, and distribution/emergence from 2011 to 2021. Thirty studies, encompassing 436 patients from 25 countries were included in the analysis. All-cause mortality due to invasive C. tropicalis infections was 55%-60%. Resistance rates to fluconazole, itraconazole, voriconazole and posaconazole up to 40%-80% were observed but C. tropicalis isolates showed low resistance rates to the echinocandins (0%-1%), amphotericin B (0%), and flucytosine (0%-4%). Leukaemia (odds ratio (OR) = 4.77) and chronic lung disease (OR = 2.62) were identified as risk factors for invasive infections. Incidence rates highlight the geographic variability and provide valuable context for understanding the global burden of C. tropicalis infections. C. tropicalis candidiasis is associated with high mortality rates and high rates of resistance to triazoles. To address this emerging threat, concerted efforts are needed to develop novel antifungal agents and therapeutic approaches tailored to C. tropicalis infections. Global surveillance studies could better inform the annual incidence rates, distribution and trends and allow informed evaluation of the global impact of C. tropicalis infections.

Risk factors, antifungal susceptibility, complications, and outcome of Candida auris bloodstream infection in a tertiary care center in the western region of Saudi Arabia

BACKGROUND

Candida auris, an emerging multidrug-resistant fungus species that grows as yeast, causes bloodstream infection, and is associated with high mortality rates. In this study, we identified risk factors associated with C. auris bloodstream infection, antifungal susceptibility pattern, complications, and outcome of the infection.

METHODS

This single-center cross-sectional retrospective study was conducted at King Abdulaziz Medical City, a tertiary care facility in Jeddah, Saudi Arabia, which included all patients 18 years or above who have had one or more blood cultures for C. auris between January 2021 and December 2022. We aimed to identify the risk factors associated with C. auris bloodstream infection, antifungal susceptibility patterns, complications, and outcomes at our center.

RESULTS

Forty-six patients with C. auris-positive blood cultures were included. All the patients had healthcare-associated infections. The mean age was 64.67 years, and the majority of patients were male (73.9 %). The most common concomitant hospital-acquired infections were skin and soft tissue infections (37 %), followed by hospital-acquired pneumonia (34.8 %) and intra-abdominal infections (26.1 %). The mean total white blood cell count, procalcitonin, and C-reactive protein was 10.5 ± 5.99 × 109/L, 2.63 ± 4.82 μg/L, and 90.3 ± 64.1 mg/L, respectively. Hypertension (73.9 %) was the most common comorbidity, followed by diabetes mellitus (58.7 %) and renal dysfunction (54.3 %). Risk factors associated with C. auris candidemia included antibiotic use (91.3 %), especially for > 14 days (78.3 %), C. auris colonization (60.9 %), use of central venous catheters, especially when the catheter was in place for >30 days (80.4 %), ICU admission in the last 30 days before C. auris-positive blood culture (93.5 %), especially for more than two weeks (76.1 %), mechanical ventilation (89.1 %), total parenteral nutrition (13 %), previous intra-abdominal surgery (30.4 %), and immunosuppressive therapy (56.5 %). A total of 97.8 % of C. auris isolates were resistant to fluconazole and 17.4 % were resistant to amphotericin B. Endocarditis and endophthalmitis were reported in one (2.2 %) patient each. The all-cause mortality at 30 days was 47.8 %.

CONCLUSION

Our study is one of the few studies available globally on C. auris bloodstream infection that investigated risk factors, antifungal susceptibility, complications, and outcomes. A thorough screening and risk assessment strategy should aid infection control, preventing it from becoming a major concern in the future.

Fungemia in Hospitalized Adult Patients with Hematological Malignancies: Epidemiology and Risk Factors

Fungemia in hematologic malignancies (HM) has high mortality. This is a retrospective cohort of adult patients with HM and fungemia between 2012 and 2019 in institutions of Bogotá, Colombia. The epidemiological, clinical, and microbiological characteristics are described, and risk factors related to mortality are analyzed. One hundred five patients with a mean age of 48 years (SD 19.0) were identified, 45% with acute leukemia and 37% with lymphomas. In 42%, the HM was relapsed/refractory, 82% ECOG > 3, and 35% received antifungal prophylaxis; 57% were in neutropenia, with an average duration of 21.8 days. In 86 (82%) patients, Candida spp. was identified, and other yeasts in 18%. The most frequent of the isolates were non-albicans Candida (61%), C. tropicalis (28%), C. parapsilosis (17%), and C. krusei (12%). The overall 30-day mortality was 50%. The survival probability at day 30 in patients with leukemia vs. lymphoma/multiple myeloma (MM0 group was 59% (95% CI 46-76) and 41% (95% CI 29-58), p = 0.03, respectively. Patients with lymphoma or MM (HR 1.72; 95% CI 0.58-2.03) and ICU admission (HR 3.08; 95% CI 1.12-3.74) were associated with mortality. In conclusion, in patients with HM, non-albicans Candida species are the most frequent, and high mortality was identified; moreover, lymphoma or MM and ICU admission were predictors of mortality.

Incidence, susceptibility and outcomes of candidemia in adults living in Calgary, Alberta, Canada (2010-2018)

BACKGROUND

Candidemia is increasing in frequency and is associated with high mortality. We sought to determine the burden of illness, the population it affects and its resistance profile in our region.

METHODS

The Calgary Zone (CZ) provides all care for residents of Calgary and surrounding communities (~ 1.69 million) via five tertiary hospitals each served by a common single laboratory for acute care microbiology. All adult patients in the CZ with at least one Candida spp.-positive blood culture between January 1, 2010, and December 31, 2018, were identified using microbiological data from Calgary Lab Services, the laboratory that processes > 95% of all blood culture samples in the CZ, were reviewed for the study.

RESULTS

The overall annual incidence of candidemia among individuals living in the CZ was 3.8 per 100,000 persons (Median age 61 years (IQR 48-72) and 221/455 (47.4%) were female). C. albicans was the most common species (50.6%), followed by C. glabrata, (24.0%). No other species accounted for more than 7% of cases. Overall mortality at 30, 90, and 365 days was 32.2, 40.1, and 48.1% respectively. Mortality rate did not differ by Candida species. Of individuals who developed candidemia, more than 50% died within the next year. No new resistance pattern has emerged in the most common Candida species in Calgary, Alberta.

CONCLUSIONS

In Calgary, Alberta, the incidence of candidemia has not increased in the last decade. C. albicans was the most common species and it remains susceptible to fluconazole.

Pathogenic Drug Resistant Fungi: A Review of Mitigation Strategies

Fungal pathogens cause significant human morbidity and mortality globally, where there is a propensity to infect vulnerable people such as the immunocompromised ones. There is increasing evidence of resistance to antifungal drugs, which has significant implications for cutaneous, invasive and bloodstream infections. The World Health Organization (WHO) published a priority list of fungal pathogens in October 2022, thus, highlighting that a crisis point has been reached where there is a pressing need to address the solutions. This review provides a timely insight into the challenges and implications on the topic of antifungal drug resistance along with discussing the effectiveness of established disease mitigation modalities and approaches. There is also a need to elucidate the cellular and molecular mechanisms of fungal resistance to inform effective solutions. The established fungal decontamination approaches are effective for medical device processing and sterilization, but the presence of pathogenic fungi in recalcitrant biofilms can lead to challenges, particularly during cleaning. Future design ideas for implantable and reusable medical devices should consider antifungal materials and appropriates for disinfection, and where it is relevant, sterilization. Preventing the growth of mycotoxin-producing fungi on foods through the use of appropriate end-to-end processes is advisable, as mycotoxins are recalcitrant and challenging to eliminate once they have formed.

The Impact of Corticosteroids on the Outcome of Fungal Disease: a Systematic Review and Meta-analysis

Purpose of Review

Corticosteroids have a complex relationship with fungal disease - risk for many, benefit for others. This systematic review aims to address the effect of corticosteroids on mortality and visual outcome in different fungal diseases.

Recent Findings

Corticosteroids are a risk factor of aspergillosis for patients who have COVID-19, and they also led to a worse outcome. Similarity, corticosteroids are a risk factor for candidemia and mucormycosis. Some researchers reported that using topical corticosteroid in keratitis was associated with worse visual outcome if fungal keratitis. Some studies showed that corticosteroids are linked to a negative outcome for non-HIV patients with Pneumocystis jirovecii pneumonia (PCP), in contrast to those with HIV and PCP.

Summary

In 59 references, we found that corticosteroid therapy showed a worse clinical outcome in invasive aspergillosis (IA) (HR: 2.50, 95%CI: 1.89-3.31, p < 0.001) and chronic pulmonary aspergillosis (CPA) (HR: 2.74, 95%CI: 1.48-5.06, p = 0.001), PCP without HIV infection (OR: 1.29, 95%CI: 1.09-1.53, p = 0.003), invasive candidiasis and candidaemia (OR: 2.13, 95%CI: 1.85-2.46, p < 0.001), mucormycosis (OR: 4.19, 95%CI: 1.74-10.05, p = 0.001) and early in the course of fungal keratitis (OR: 2.99, 95%CI: 1.14-7.84, p = 0.026). There was equivocal outcome in cryptococcal meningoencephalitis in AIDS and primary coccidioidomycosis, while corticosteroid therapy showed a better outcome in PCP in HIV-infected patients (RR: 0.62, 95%CI: 0.46-0.83, p=0.001) and fungal keratitis patients after keratoplasty surgery (OR: 0.01, 95%CI: 0.00-0.41, p = 0.041) and probably in cryptococcal meningoencephalitis in non-immunocompromised patients. A sub-analysis in invasive aspergillosis and CPA showed that use of more than 2 mg/kg/day of prednisolone equivalents per day is a significant factor in increasing mortality (HR: 2.94, 95%CI: 2.13-4.05, p < 0.001). Corticosteroid therapy during invasive fungal disease was usually associated with a slightly or greatly increased mortality or worse visual outcome (in fungal keratitis), with two disease exceptions. Avoiding the addition of corticosteroids, or minimising dose and duration in those who require them, is likely to improve the outcome of most life- and vision-threatening fungal diseases. This review provides a cornerstone for further research in exploring the accuracy of suitable dose and duration of corticosteroids treatment in fungal diseases.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12281-023-00456-2.

High prevalence of fluconazole resistant Candida tropicalis among candiduria samples in China: An ignored matter of concern

Introduction

The rapid rise of azole resistance in Candida tropicalis causing invasive infections has become a public health concern; however, the prevalence of resistant isolates in urine samples was not well studied, because the clinical significance of candiduria was not unambiguous due to possible host colonization.

Methods

We performed a 12-year laboratory-based surveillance study of C. tropicalis causing either invasive infection or candiduria and studied their susceptibility profiles to common antifungal drugs. The complete coding domain sequence of the ERG11 gene was amplified in all fluconazole resistant isolates, and aligned with the wild-type sequence to detect nucleotide mutations.

Results

A total of 519 unique C. tropicalis strains isolates, 69.9% of which were isolated from urine samples and remaining 30.1% were invasive strains. Overall, 16.5% isolates were confirmed to be resistant to fluconazole, of which 91.9% were cross-resistant voriconazole. Of note, at the beginning of surveillance (2010-2011), the fluconazole resistance rates were low in both candiduria and invasive groups (6.8% and 5.9%, respectively). However, the resistant rate in the candiduria group significantly increased to 29.5% since 2012-2013 (p = 0.001) and stayed high since then, whilst the resistance rate in the invasive group only showed a gradually increasing trends till 2021 (p > 0.05). Sequence analysis of ERG11 from fluconazole-resistant strains revealed the prevalence of A395T/W mutations were relatively low (16.7%) in the beginning but reached 87.5-100% after 2014. Moreover, the A395W heterozygous mutation isolates became predominant (>60% of resistant strains) after 2016, and indeed isolates carrying corresponding amino acid substitution (Y132F) was highly resistant to fluconazole with MIC₅₀ exceeded 256 μg/ml.

Conclusion

Our study revealed high azole resistant rate in candiduria with its increasing trends observed much earlier than stains causing invasive infections. Given antimicrobial resistance as a critical "One Health" issue, the emergence of antifungal resistance in Candida species that are common commensal colonizers in the human body should be concerned.

Time to Positivity Facilitates an Early Differential Diagnosis of Candida tropicalis from Other Candida species

Background

Candidemia caused by Candida tropicalis has more serious adverse consequences and an even higher mortality. Time to positivity (TTP) has been widely used to identify microbial species, resistant microorganisms and distinguish real pathogens and pollutants. However, few studies have demonstrated TTP as a presumptive diagnosis of C. tropicalis in patients with candidemia.

Patients and Methods

A retrospective study of 136 episodes of candidemia and simulated blood cultures with 314 episodes of confirmed Candida strains were applied to explore the role of TTPs in diagnosing C. tropicalis. TTPs were recorded as the shorter one if both aerobic and anaerobic vials were positive. Lastly, relationships were tested between TTPs and resistance and initial inocula concentration.

Results

For the retrospective study, the mean of TTPs for C. tropicalis from 136 patients with candidemia was significantly shorter than other Candida species. The area under the receiver operating characteristics (ROC) curve was 0.8896 ± 0.030 with a sensitivity of 92.86% and a specificity of 77.87%, respectively, indicating TTPs with a cut-off value of <25.50 h had a strong diagnostic power for C. tropicalis in patients with candidemia. Moreover, TTPs from 314 simulated blood cultures showed similar results as the retrospective study, demonstrating TTP is a powerful diagnostic tool in early diagnosing C. tropicalis in patients with candidemia. Additionally, our results showed no statistical significance between TTPs and initial inocula concentration and resistance of Candida species, suggesting initial inocula concentration does not impact TTPs, and TTPs may not be promising in predicting the resistance of all Candida species.

Conclusion

TTP can be employed to early distinguish C. tropicalis from other Candida species in patients with candidemia, which is extremely helpful to initiate empiric antifungal treatments to improve clinical outcomes.

The emerging threat antifungal-resistant Candida tropicalis in humans, animals, and environment

Antifungal resistance in humans, animals, and the environment is an emerging problem. Among the different fungal species that can develop resistance, Candida tropicalis is ubiquitous and causes infections in animals and humans. In Asia and some Latin American countries, C. tropicalis is among the most common species related to candidemia, and mortality rates are usually above 40%. Fluconazole resistance is especially reported in Asian countries and clonal spread in humans and the environment has been investigated in some studies. In Brazil, high rates of azole resistance have been found in animals and the environment. Multidrug resistance is still rare, but recent reports of clinical multidrug-resistant isolates are worrisome. The molecular apparatus of antifungal resistance has been majorly investigated in clinical C. tropicalis isolates, revealing that this species can develop resistance through the conjunction of different adaptative mechanisms. In this review article, we summarize the main findings regarding antifungal resistance and Candida tropicalis through an "One Health" approach.

Is Natural Population of Candida tropicalis Sexual, Parasexual, and/or Asexual?

Candida tropicalis is one of the most common opportunistic yeast pathogens of humans, especially prevalent in tropical and subtropical regions. This yeast has broad ecological distributions, can be found in both terrestrial and aquatic ecosystems, including being associated with a diversity of trees, animals, and humans. Evolutionary theory predicts that organisms thriving in diverse ecological niches likely have efficient mechanisms to generate genetic diversity in nature. Indeed, abundant genetic variations have been reported in natural populations (both environmental and clinical) of C. tropicalis. However, at present, our understanding on how genetic diversity is generated in natural C. tropicalis population remains controversial. In this paper, I review the current understanding on the potential modes of reproduction in C. tropicalis. I describe expectations of the three modes of reproduction (sexual, parasexual, and asexual) and compare them with the observed genotypic variations in natural populations. Though sexual and parasexual reproduction cannot be excluded, the analyses suggest asexual reproduction alone could explain all the observations reported so far. The results here have implications for understanding the evolution and epidemiology of C. tropicalis and other related human fungal pathogens.

Impact of Nutritional Assessment on the Clinical Outcomes of Patients with Non-albicans Candidemia: A Multicenter Study

Several studies have demonstrated that malnutrition is a negative prognostic factor for clinical outcomes. However, there is limited evidence for the effect of malnutrition on clinical outcomes in patients with candidemia. We investigated the relationship between malnutrition and all-cause 28-day mortality among patients with non-albicans candidemia. Between July 2011 and June 2014, all adult patients with non-albicans candidemia, including C. tropicalis, C. glabrata, C. parapsilosis and so on, were enrolled. The Malnutrition Universal Screening Tool (MUST) scores were used to determine the patients' nutritional status before the onset of candidemia. A total of 378 patients were enrolled; 43.4% developed septic shock and 57.1% had a high risk of malnutrition (MUST ≥ 2). The all-cause 28-day mortality rate was 40.7%. The Cox proportional hazards model revealed that C. tropicalis (HR, 2.01; 95% CI, 1.24-3.26; p = 0.005), Charlson comorbidity index (HR, 1.10; 95% CI, 1.03-1.18; p = 0.007), Foley catheter use (HR, 1.68; 95% CI, 1.21-1.35; p = 0.002), concomitant bacterial infections (HR, 1.55; 95% CI, 1.11-2.17; p = 0.010), low platelet count (HR, 3.81; 95% CI, 2.45-5.91; p < 0.001), not receiving antifungals initially (HR, 4.73; 95% CI, 3.07-7.29; p < 0.001), and MUST ≥ 2 (HR, 1.54; 95% CI, 1.09-2.17; p = 0.014) were independently associated with all-cause 28-day mortality. A simple screening tool for nutritional assessment should be used for patients with non-albicans candidemia to detect early clinical deterioration, and a tailored nutritional care plan should be established for malnourished individuals, to improve their clinical outcomes.

Dynamics and Predictors of Mortality Due to Candidemia Caused by Different Candida Species: Comparison of Intensive Care Unit-Associated Candidemia (ICUAC) and Non-ICUAC

We investigated mortality and predictors of mortality due to intensive care unit-associated candidemia (ICUAC) versus non-ICUAC by Candida species. This study included all candidemia cases in 11 hospitals from 2017 to 2018 in South Korea. The all-cause mortality rates in all 370 patients with ICUAC were approximately twofold higher than those in all 437 patients with non-ICUAC at 7 days (2.3-fold, 31.1%/13.3%), 30 days (1.9-fold, 49.5%/25.4%), and 90 days (1.9-fold, 57.8%/30.9%). Significant species-specific associations with 7- and 30-day ICUAC-associated mortality were not observed. Multivariate analysis revealed that ICU admission was an independent predictor of Candida glabrata (OR, 2.07–2.48) and Candida parapsilosis-associated mortality (OR, 6.06–11.54). Fluconazole resistance was a predictor of C. glabrata-associated mortality (OR, 2.80–5.14). Lack (less than 3 days) of antifungal therapy was the strongest predictor of 7-day mortality due to ICUAC caused by Candida albicans (OR, 18.33), Candida tropicalis (OR, 10.52), and C. glabrata (OR, 21.30) compared with 30- and 90-day mortality (OR, 2.72–6.90). C. glabrata ICUAC had a stronger association with lack of antifungal therapy (55.2%) than ICUAC caused by other species (30.6–36.7%, all p < 0.05). Most predictors of mortality associated with ICUAC were distinct from those associated with non-ICUAC and were mediated by Candida species.

Species Distribution, Antifungal Susceptibility, and Molecular Epidemiology of Candida Species Causing Candidemia in a Tertiary Care Hospital in Bangkok, Thailand

Candida species represent a common cause of bloodstream infection (BSI). Given the emergence of non-albicans Candida (NAC) associated with treatment failure, investigations into the species distribution, fungal susceptibility profile, and molecular epidemiology of pathogens are necessary to optimize the treatment of candidemia and explore the transmission of drug resistance for control management. This study evaluated the prevalence, antifungal susceptibility, and molecular characteristics of Candida species causing BSI in a tertiary-level hospital in Bangkok, Thailand. In total, 54 Candida isolates were recovered from 49 patients with candidemia. C. tropicalis was the most prevalent species (33.3%), followed by C. albicans (29.6%). Most Candida species were susceptible to various antifungal agents, excluding C. glabrata and C. tropicalis, which had increased rates of non-susceptibility to azoles. Most C. glabrata isolates were non-susceptible to echinocandins, especially caspofungin. The population structure of C. albicans was highly diverse, with clade 17 predominance. GoeBURST analysis of C. tropicalis revealed associations between genotype and fluconazole resistance in a particular clonal complex. The population structure of C. glabrata appeared to have a low level of genetic diversity in MLST loci. Collectively, these data might provide a fundamental database contributing to the development of novel antifungal agents and diagnostic tests.

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

BACKGROUND

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSION

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

Risk Factors and Outcomes of Non-albicans Candida Bloodstream Infection in Patients with Candidemia at Siriraj Hospital-Thailand's Largest National Tertiary Referral Hospital

This study aimed to investigate the risk factors for and the outcomes of patients with candidemia caused by non-albicans Candida. Candidemia patients treated at Siriraj Hospital (Bangkok, Thailand) during January 2016 to December 2017 were enrolled. A total of 156 patients (mean age: 65 years, 56.4% male) were included. The most prevalent underlying conditions were diabetes (32.1%), chronic cardiac disease (28.2%), chronic kidney disease (26.9%), and hematologic malignancies (21.2%). Candida species isolated from patient blood were C. tropicalis (49.4%), C. albicans (28.8%), C. glabrata (16.7%), and C. parapsilosis (5.1%). Fluconazole resistance was significantly increased in C. tropicalis (37.8%). No independent risk factors were associated with patients with non-albicans Candida candidemia compared to those with C. albicans candidemia. There was no significant difference in mortality between patients with non-albicans Candida candidemia and patients with C. albicans candidemia (OR: 1.35, 95% CI: 0.64-2.85). When compared with C. albicans candidemia, multivariate analysis revealed chronic liver disease (OR: 11.39, 95% CI: 1.38-94.02), neutropenia (OR: 4.31, 95% CI: 1.34-13.87), and male gender (OR: 2.34, 95% CI: 1.04-5.29) to be independent risk factors for C. tropicalis candidemia. The observed high resistance of C. tropicalis to fluconazole indicates that fluconazole should not be used for empirical antifungal treatment in these patients.

Population genomics of the pathogenic yeast Candida tropicalis identifies hybrid isolates in environmental samples

Candida tropicalis is a human pathogen that primarily infects the immunocompromised. Whereas the genome of one isolate, C. tropicalis MYA-3404, was originally sequenced in 2009, there have been no large-scale, multi-isolate studies of the genetic and phenotypic diversity of this species. Here, we used whole genome sequencing and phenotyping to characterize 77 isolates of C. tropicalis from clinical and environmental sources from a variety of locations. We show that most C. tropicalis isolates are diploids with approximately 2-6 heterozygous variants per kilobase. The genomes are relatively stable, with few aneuploidies. However, we identified one highly homozygous isolate and six isolates of C. tropicalis with much higher heterozygosity levels ranging from 36-49 heterozygous variants per kilobase. Our analyses show that the heterozygous isolates represent two different hybrid lineages, where the hybrids share one parent (A) with most other C. tropicalis isolates, but the second parent (B or C) differs by at least 4% at the genome level. Four of the sequenced isolates descend from an AB hybridization, and two from an AC hybridization. The hybrids are MTLa/α heterozygotes. Hybridization, or mating, between different parents is therefore common in the evolutionary history of C. tropicalis. The new hybrids were predominantly found in environmental niches, including from soil. Hybridization is therefore unlikely to be associated with virulence. In addition, we used genotype-phenotype correlation and CRISPR-Cas9 editing to identify a genome variant that results in the inability of one isolate to utilize certain branched-chain amino acids as a sole nitrogen source.

Changes in Adhesion of Candida tropicalis Clinical Isolates Exhibiting Switch Phenotypes to Polystyrene and HeLa Cells

BACKGROUND

Candida tropicalis is an important human pathogen that can undergo multiple forms of phenotypic switching.

AIM

We aimed to evaluate the effect of phenotypic switching on the adhesion ability of C. tropicalis.

METHODS

C. tropicalis morphotypes included parental phenotypes (clinical isolates) and switch phenotypes (crepe, revertant of crepe-CR, rough, revertant of rough-RR, irregular center and revertant of irregular center-ICR). Adhesion to polystyrene and HeLa cells was determined by crystal violet assay. The percentage of HeLa cells with adhered yeasts and the number of adhered yeasts per HeLa cell were determined by light microscopy. Filamentation among adhered cells was assessed by direct counting.

RESULTS

On polystyrene, 60% of the switch strains showed difference (p < 0.05) on adhesion ability compared to their parental counterpart strains, and altered thickness of adhered cells layers. Filamentation was increased among adhered cells of the switched strains compared to parental strains. A positive correlation was observed between adhesion on polystyrene and filamentation for morphotypes of the system 49.07. The majority of the switched strains showed higher adhesion capability to HeLa cells in comparison to the adherence of the clinical strains. All revertant strains showed a higher number of yeast cells per HeLa cell compared to their variant counterparts (p < 0.05), with exception of the ICR.

CONCLUSIONS

Our findings indicate that switching events in C. tropicalis affect adhesion and filamentation of adhered cells on polystyrene and HeLa cells. The rise of switch strains with increased adhesion ability may contribute to the success of infection associated with C. tropicalis.

Molecular epidemiology of Candida tropicalis isolated from urogenital tract infections

Candida tropicalis is a common human pathogenic yeast, and its molecular typing is important for studying the population structure and epidemiology of this opportunistic yeast, such as epidemic genotype, population dynamics, nosocomial infection, and drug resistance surveillance. In this study, the antifungal susceptibility test and multilocus sequence typing (MLST) analysis were carried out on C. tropicalis from central China. Among 64 urogenital isolates, 45 diploid sequence types (DST) were found, of which 20 DSTs (44.4%) were new to the central database. The goeBURST analysis showed that CC1 (clonal complex) was the only azole‐resistant (100%, 10/10) cluster in Wuhan, which was composed of DST546, DST225, DST376, and DST506, and most of the strains (90%, 9/10) were isolated from the urinary tract. Potential nosocomial infections were mainly caused by CC1 strains. The azole resistance rate of urinary isolates (50.0%, 21/42) was higher than that of vaginal isolates (27.3%, 6/22). The genotype diversity and novelty of vaginal isolates were higher than those of urinary isolates. C. tropicalis population in Wuhan was genetically diverse and divergent from that seen in other countries. In this study, there were significant differences in genotype and azole susceptibility between urine and vaginal strains. The azole‐resistant cluster (CC1) found in urine is of great significance for the clinical treatment and prevention of nosocomial infection. The newly discovered DSTs will contribute to further study the similarity, genetic relationship, and molecular epidemiology of C. tropicalis worldwide.

Candida spp bloodstream infections in a Latin American Pediatric Oncology Reference Center: Epidemiology and associated factors

BACKGROUND

Invasive fungal disease is a significant cause of morbidity and mortality in immunosuppressed children. The recognition of patients at risk for candidaemia is paramount to a better prognosis.

OBJECTIVES

To characterize Candida spp bloodstream infections (BSI) in a reference centre for paediatric oncology and to describe the most prevalent risk factors associated with candida infections.

PATIENTS/METHODS

This is a retrospective cohort study carried out with paediatric patients followed up with at the Institute of Pediatric Oncology, Brazil, who presented positive blood culture for Candida spp from January 2004 to December 2016.

RESULTS

Ninety episodes of candidaemia were analysed; patients had a median age of 4.5 years, and 57.8% were males, with a diagnosis of solid tumours in 54.5% of cases. The most common Candida species were C albicans (35.6%), C parapsilosis (30.0%) and C tropicalis (16.7%). C tropicalis BSI was associated with neutropenia and skin lesions. Therapy was successful in 67.1% of the episodes. Older age and thrombocytopenia were associated with therapeutic failure. Death within 30 days occurred in 24.4% of patients; predictive factors were older age and admission to an ICU C parapsilosis candidaemia was a protective factor for death when compared to C albicans.

CONCLUSION

The main species isolated were C albicans, C parapsilosis and C tropicalis. C tropicalis BSI was associated with neutropenia and skin lesions. The death rate was significant, and a worse prognosis was associated with older age, thrombocytopenia and admission to an ICU C parapsilosis infection proved to be a protective factor against mortality.

The antifungal peptide CGA-N12 inhibits cell wall synthesis of Candida tropicalis by interacting with KRE9

CGA-N12, an antifungal peptide derived from chromogranin A, has specific antagonistic activity against Candida spp., especially against Candida tropicalis, by inducing cell apoptosis. However, the effect of CGA-N12 on the Candida cell wall is unknown. The Candida protein KRE9, which possesses β-1,6-glucanase activity, was screened by affinity chromatography after binding to CGA-N12. In this study, the effect of CGA-N12 on KRE9 and the interaction between CGA-N12 and KRE9 was studied to clarify the effect of CGA-N12 on C. tropicalis cell wall synthesis. The effect of CGA-N12 on recombinant KRE9 β-1,6-glucanase activity was investigated by analyzing the consumption of glucose. The results showed that CGA-N12 inhibited the activity of KRE9. After C. tropicalis was treated with CGA-N12, the structure of the C. tropicalis cell wall was damaged. The interaction between CGA-N12 and KRE9 was analyzed by isothermal titration calorimetry (ITC). The results showed that their interaction process was involved an endothermic reaction, and the interaction force was mainly hydrophobic with a few electrostatic forces. The results of the fluorescence resonance energy transfer (FRET) assay showed that the distance between CGA-N12 and KRE9 was 7 ∼ 10 nm during their interaction. Therefore, we concluded that the target of CGA-N12 in the C. tropicalis cell membrane is KRE9, and that CGA-N12 weakly binds to KRE9 within a 7 ∼ 10 nm distance and inhibits KRE9 activity.

Breakthrough Bloodstream Infections Caused by Echinocandin-Resistant Candida tropicalis: An Emerging Threat to Immunocompromised Patients with Hematological Malignancies

Background. Candida tropicalis is a virulent fungal pathogen for which echinocandins are the primary therapy. Emergence of resistance to echinocandins of C. tropicalis carries potentially ominous therapeutic implications. Methods. We describe herein two patients with breakthrough C. tropicalis fungemia during echinocandin therapy, characterize their molecular mechanism of resistance, and systematically review 13 previously reported cases of echinocandin-resistant C. tropicalis bloodstream infections (BSIs) and other diseases. Results. Among these 15 patients with echinocandin-resistant C. tropicalis infections, the median age was 61 years (ages 28–84 years) and 13 (86%) were immunocompromised. Thirteen (86%) of all patients had a history of pervious or concurrent exposure to echinocandins. Isolates of C. tropicalis from 11 cases, including the two index cases, underwent DNA sequencing of the FKS1 gene for mutations known to confer echinocandin resistance. The amino acid substitution Ser654Pro was shown in four cases, while other FKS1 mutations encoded Ser80S/Pro, Phe641Leu, Phe641Ser, Ser80S/Pro substitutions. These mutational events were not associated with collateral increases in minimum inhibitory concentrations to antifungal triazoles and amphotericin B. Overall mortality in patients with echinocandin-resistant C. tropicalis infections was 40%. Among those six patients who died, two received monotherapy with voriconazole, one was treated with fluconazole, one remained on caspofungin, and two were switched to liposomal amphotericin B. Nine patients (60%) survived after being treated with an antifungal agent other than an echinocandin. Conclusions. Emergence of resistance to echinocandins by C. tropicalis, occurs during antifungal therapy, is associated with high mortality, is mediated by a diverse range of FKS1 mutations, retains in vitro susceptibility to triazoles and amphotericin B, and constitutes an emerging threat to patients with hematological malignancies.

Fluoroaryl analogs of sulforaphane - A group of compounds of anticancer and antimicrobial activity

A series of new sulforaphane analogs bearing various (poly)fluoroaryl substituents bonded to the sulfinyl sulfur atom in place of the original methyl group and having different number of methylene groups in the central alkyl chain were synthesized and fully characterized. The new compounds were tested in vitro for their anticancer, antibacterial, antifungal and antiviral properties. Some of them demonstrated a much higher anticancer activity against selected lines of cancer: skin (MALME-3M), colon (HT-29) and breast (MCF7 and MDA-MB-231) cells than that exhibited by native sulforaphane (SFN). Related lines of untransformed (normal) cells, taken from the same organs as the cancer ones, i.e. MALME3, CRL-1790 and MCF10, respectively, were checked, which allowed for the determination of the selectivity indexes (SI). In certain cases, the latter exceeded 3.2. Concerning the antibacterial activity, gram-positive bacteria, including methicillin-resistant Staphylococcus aureus (MRSA) were susceptible to some newly synthesized SFN analogs, while the selected probiotic strains were from 10 to 100 fold more resistant to them, which gives a possibility of protection of symbiont strains during a potential therapy with such compounds. The antifungal activity of the new compounds possessing the fluorophenyl substituent was found to be higher than the activity of the parent SFN. In turn, most of the new compounds showed generally no anti-HIV activity. The influence of the particular structural differences in the new molecules, analogs of SFN, on their biological activity is discussed.

Molecular mechanisms of azole resistance in Candida tropicalis isolates causing invasive candidiasis in China

OBJECTIVE

We investigated molecular mechanisms responsible for azole resistance in Candida tropicalis isolates.

METHODS

We studied 507 C. tropicalis isolates causing invasive candidiasis from ten hospitals over 5 years. Antifungal susceptibility was determined by broth microdilution methods. Point mutations in the C. tropicalis ERG11 gene that may confer azole resistance were explored and verified. The expression levels of ERG11, CYTb, MDR1 and CDR1 genes were compared in 20 fluconazole-susceptible and 20 fluconazole-resistant isolates.

RESULTS

Fluconazole-susceptible, -susceptible dose-dependent and -resistant strains accounted for 76.7% (389/507), 10.5% (53/507) and 12.8% (65/507) of C. tropicalis isolates, respectively. The ERG11 mutation A395T/W occurred in 10.7% (54/507) of isolates, all of which were resistant to fluconazole. The nucleotide mutation C461T/Y was the second most common (50/507 isolates, 9.9%), and all isolates carrying C461T/Y also had the mutation A395T/W. However, the presence of C461T did not contribute to the azole-resistant phenotype. Substitutions V125A, Y257H and G464S (<2% of isolates), which were reported for the first time in C. tropicalis, also conferred fluconazole non-susceptible phenotypes. Compared with fluconazole susceptible isolates, fluconazole-resistant isolates had higher ERG11 (fold expression level 1.42 versus 0.79, p < 0.01) but lower CYTb (fold expression level 1.26 versus 2.67, p < 0.01) gene expression levels. Three azole-resistant isolates carrying the wild-type ERG11 gene had higher levels of CDR1 and MDR1 expression.

CONCLUSIONS

ERG11 missense mutations were the major mechanism responsible for azole resistance in C. tropicalis isolates, but overexpression of ERG11, CDR1 and MDR1, as well as reduced expression of CYTb, also contributed to resistance.

The continuous changes in the aetiology and epidemiology of invasive candidiasis: from familiar Candida albicans to multiresistant Candida auris

Recent changes in the aetiology and epidemiology of invasive candidiasis have serious implications for current and future diagnosis, treatment and prognosis. The aim of the current review was to discuss the epidemiology of invasive candidiasis, the distribution of Candida species in different regions of the world, the medical concerns of the changing aetiology and the emergence of antifungal resistance. Overall burden of invasive candidiasis remains high, especially in vulnerable persons, such as the elderly, immunosuppressed or debilitated patients. Moreover, there is a progressive shift in the aetiology of invasive candidiasis from Candida albicans to other species of Candida, probably related to the increased use of azole drugs with a clear trend towards increased antifungal resistance. Finally, the emergence and rise of multiresistant species, such as Candida auris or Candida glabrata, is a major threat making necessary invasive candidiasis worldwide surveillances. These changes have serious implications for the diagnosis, treatment and prognosis of invasive candidiasis. Updated knowledge of the current local epidemiology of invasive candidiasis is critical for the clinical management.

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

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

Epidemiological Study onCandidaSpecies in Patients with Cancer in the Intensive Care Unit

Objectives

Although cancer survival rates have increased, serious infection complications can arise in cancer patients. Candida can occur in various tissues and has significant effects on the prognosis of patients with cancer. Thus, we conducted an epidemiological study on Candida infections in patients with cancer admitted to the intensive care unit.

Methods

A retrospective study was conducted in adult patients with cancer admitted to the intensive care unit between January 1, 2013, and December 31, 2015. Candida infection status and predictive factors for mortality were examined in 634 patients.

Results

The predictive factors for mortality included the use of steroids, use of a central venous catheter or mechanical ventilator, and identification of Candida in the blood. Patients who stayed in the surgical and intensive care unit for more than 7 days had a lower risk of death than that in those with shorter days.

Conclusion

The present study shows that invasive procedures, bloodstream infections, and the use of steroids increase the risk of mortality in Candida-infected patients with cancer. To improve the quality of life and reduce mortality, further studies are needed on the factors affecting the risk of mortality associated with Candida infection.

Profile of GenMark's ePlex® blood culture identification fungal pathogen panel

INTRODUCTION

Fungemia presents high morbi-mortality and thus rapid microbiological diagnosis may contribute to appropriate patient management. In the last decade, kits based on molecular technologies have become available and health care institutes are increasingly facing critical investment choices. Although all these tools aim to achieve rapid fungal detection and species identification, they display different inherent characteristics. Areas covered: Considering technologies allowing detection and identification of fungal species in a sepsis context, the market proposes either tests on positive blood culture or tests on patient's whole blood. In this review, the authors describe and compare the ePlex® Blood Culture Identification Fungal Pathogen (BCID-FP) test, a fully automated one-step single-use cartridge assay that has been designed to detect identify frequent or rare but emerging, fungal species, from positive blood culture. A comparison with the competing kits is provided. Expert commentaries: The ePlex BCID-FP test provides a diversified and rather relevant panel. Its easy-to-use cartridges allow flexible use around the clock. Nevertheless, prospective clinical studies assessing the time-to-result benefit on antifungal stewardship and on hospital length of stay are not available yet. New tools aim to benefit clinicians and patients, but they should be accompanied by supervision of result interpretation and adaptation of antifungal stewardship.

Population structure and molecular genetic characterization of clinical Candida tropicalis isolates from a tertiary-care hospital in Kuwait reveal infections with unique strains

Candida tropicalis is a frequently isolated yeast species causing bloodstream, urinary tract and other infections particularly in patients admitted to intensive care units (ICUs) and those requiring prolonged urinary catheterization (UC) or receiving broad-spectrum antibiotics (BSA). This study investigated clinical characteristics and genetic relatedness among C. tropicalis strains isolated from patients at Al-Amiri Hospital in Kuwait. C. tropicalis strains (n = 63) isolated from blood, genito-urinary, respiratory (RT) and digestive (GIT) tracts and wound sites from 54 patients were used. All isolates were phenotypically identified and tested against six antifungal drugs by using Vitek 2 system. Molecular identification was performed by PCR amplification of rDNA. Fingerprinting was achieved by 6-loci-based multilocus sequence typing (MLST) and data were analyzed by BioNumerics software for phylogenetic relationships. Patients mean age was >65 years and >20% patients were hospitalized in ICUs. Most patients had underlying conditions that included UC, BSA, diabetes and RT/GIT abnormalities. Most candiduria cases had UC, ureteric stent or suprapubic catheters. All isolates were identified as C. tropicalis by Vitek 2 and by species-specific PCR. Sixty-two isolates were susceptible to all tested antifungal drugs. MLST identified 59 diploid sequence types (DSTs) including 54 newly-identified DSTs. C. tropicalis isolates from multiple sites of same patient usually belonged to different DSTs. Interestingly, 56 of 57 isolates from 48 patients belonged to unique genotypes. Only six isolates from six patients belonged to three DSTs (clusters), however, C. tropicalis strains in each cluster were isolated >3 months apart. Our data show diverse origins of C. tropicalis infections in Kuwait as most isolates were unique strains. There was no obvious correlation between cluster isolates with time of isolation and/or hospital ward of their origin. This study presents the first MLST analysis of C. tropicalis isolates from Middle East and may be useful for studying genetic relationships among global C. tropicalis strains.

Evaluation of candidemia in epidemiology and risk factors among cancer patients in a cancer center of China: an 8-year case-control study

BACKGROUND

Candidemia is the worldwide life-threaten disease, especially in cancer patients. This study was aimed to identify and evaluate the risk factors of candidemia in cancer patients, which will prompt the improvement on current therapeutic strategies and prognosis.

METHODS

A retrospective, case-control study was conducted from inpatients of Tianjin Medical University Cancer Institute and Hospital, during 2006 to 2013. Analyses were performed between cancer patients with candidemia as study case, and patients with bacterial bloodstream infections as control. Each case was matched up with two controls, for gender and inpatient duration. Candida species, clinical characteristics, risk factors and outcomes were reviewed in details.

RESULTS

Total number of 80 cases and 160 controls were enrolled and analyzed in this study. Candida albicans was identified as the most prevalent species and account for 55.0% candidemia, followed by Candida parapsilosis complex (21.3%), Candida tropicalis (8.8%), Candida glabrata complex (7.5%), Candida lusitaniae (3.8%), and Candida famata (3.8%). The crude mortality at 30-days of candidemia was up to 30.0%, which is significantly higher than bacterial bloodstream infections (p = 0.006). Logistical analysis demonstrated that total parenteral nutrition >5 days (p = 0.036), urinary catheter >2 days (p = 0.001), distant organ metastasis of cancer (p = 0.002) and gastrointestinal cancer (p = 0.042) were the independent risk factors for candidemia.

CONCLUSIONS

Candidemia showed significant higher mortality than bacterial bloodstream infections, C. albicans was cited as the primary pathogen. Total parenteral nutrition, urinary catheter, distant organ metastasis of cancer and gastrointestinal cancer are independent predictors for candidemia, this findings provides potential therapeutic targets for improving the outcome.

Notable Increasing Trend in Azole Non-susceptible Candida tropicalis Causing Invasive Candidiasis in China (August 2009 to July 2014): Molecular Epidemiology and Clinical Azole Consumption

Objectives: To report the notable increasing trends of C. tropicalis antifungal resistance in the past 5 years, and explore molecular epidemiology, and the relationship between clinical azoles consumption and increased resistance rate. Methods: Between August 2009 and July 2014, 507 non-duplicated C. tropicalis isolates causing invasive candidiasis were collected from 10 hospitals in China. The in vitro antifungal susceptibility of nine common agents was determined by Sensititre YeastOne™ using current available species-specific clinical breakpoint (CBPs) or epidemiological cut-off values (ECVs). A high discriminatory three-locus (ctm1, ctm3, and ctm24) microsatellite scheme was used for typing of all isolates collected. Clinical consumption of fluconazole and voriconazole was obtained and the Defined Daily Dose measurement units were assigned to the data. Results: Overall, 23.1 and 20.7% of isolates were non-susceptible to fluconazole and voriconazole, respectively. And over 5 years, the non-susceptible rate of C. tropicalis isolates to fluconazole and voriconazole continuously increased from 11.2 to 42.7% for fluconazole (P < 0.001), and from 10.4 to 39.1% for voriconazole (P < 0.001). Four genotype clusters were observed to be associated with fluconazole non-susceptible phenotype. However, the increase in azole non-susceptible rate didn't correlate with clinical azole consumption. Conclusions: The rapid emergence of azole resistant C. tropicalis strains in China is worrying, and continuous surveillance is warranted and if the trend persists, empirical therapeutic strategies for C. tropicalis invasive infections should be modified.

The risk and clinical outcome of candidemia depending on underlying malignancy

Purpose

To assess the risk factors and outcomes associated with fungemia caused by the six most commonly occurring Candida species in patients with and without malignancies.

Methods

Analysis of the episodes of fungemia due to common Candida species in adults, based on an active hospital-based surveillance program (Paris area, France, 2002 to 2014).

Results

Of the 3417 patients (3666 isolates), 1164 (34.1%) had a solid tumor (45.7% digestive tract) and 586 (17.1%) a hematological malignancy (41.8% lymphoma, 33.5% acute leukemia). The hematology patients were significantly younger, more often pre-exposed to antifungals, more often infected by C. tropicalis, C. krusei, or C. kefyr, and more often treated in the first instance with an echinocandin. Compared with inpatients who were not in ICU at the time of fungemia, those in ICU were less frequently infected by C. parapsilosis (p < 0.02), had more recent surgery (p < 0.03), and died more frequently before day 8 and day 30 (p < 0.0001). An increase in crude mortality over time in ICU was observed only in oncology patients (p < 0.04). For all patients, lack of prescription of antifungals despite knowledge of positive blood culture increased the risk of death. The odds of being infected by a given Candida species compared with C. albicans were uneven regarding age, gender, type of malignancy, hospitalization in ICU, central venous catheter, HIV status, intravenous drug addiction, and previous exposure to antifungal drugs. Compared with C. albicans, C. glabrata (OR = 0.69 [0.54–0.89]) and C. parapsilosis (OR = 0.49 [0.35–0.67]) were associated with a decreased risk of death by day 8 and day 30.

Conclusion

The clinical context of underlying malignancy and hospitalization in ICU may be relevant to the initial management of candidemia.

Electronic supplementary material

The online version of this article (doi:10.1007/s00134-017-4743-y) contains supplementary material, which is available to authorized users.

Prevalence of fungemia in a tertiary hospital: Analysis of the last decade

INTRODUCTION

The prevalence of nosocomial fungemia has increased worldwide, and mortality caused by this disease is high.

OBJECTIVE

To assess progress in the last decade, and the prevalence and profile of fungal agents isolated in blood cultures performed in a tertiary university hospital.

METHOD

All the results of blood cultures processed at Hospital das Clínicas, Universidade Federal de Minas Gerais (HC-UFMG), in the time intervals 2001-2003 and 2011-2013 were analyzed retrospectively. For each three-year period, the number of collected blood cultures, the overall positivity rate and the percentage of fungemia were recorded. In addition, all identified fungal species were cataloged. All blood samples were incubated in the BacT/ALERT® (bioMérieux) automation system.

RESULTS

In 2001-2003, 34,822 samples were evaluated, with 5,510 (15.8%) positive results. In 2011-2013, the number of blood cultures processed increased to 55,052 samples, with 4,873 (8.9%) positive results. There was an increase in the number of positive cultures for fungi in the analyzed period (2001-2003: 4.16%; 2011-2013: 5.95%; p<0.001). Among the agents, candidemias were predominant, especially those caused by non-albicans Candida species (2001-2003: 57.64%; 2011-2013: 65.17%; p<0.05). There was also an increase in fungemia caused by other genera (2001-2003: 2.62%; 2011-2013: 4.48%; p<0.01).

CONCLUSION

There was an increase in the prevalence of fungemia in the last decade at HC-UFMG. Although candidemias have been responsible for most of the cases, there has been an increase in fungemias caused by other species.

Novel Polymorphic Multilocus Microsatellite Markers to Distinguish Candida tropicalis Isolates

Candida tropicalis is an important pathogen. Here we developed and evaluated a polymorphic multilocus microsatellite scheme employing novel genetic markers for genotyping of C. tropicalis. Using 10 isolates from 10 unique (separate) patients to screen over 4000 tandem repeats from the C. tropicalis genome (strain MYA-3404), six new candidate microsatellite loci (ctm1, ctm3, ctm8, ctm18, ctm24 and ctm26) were selected according to amplification success, observed polymorphisms and stability of flanking regions by preliminary testing. Two known microsatellite loci CT14 and URA3 were also studied. The 6-locus scheme was then tested against a set of 82 different isolates from 32 patients. Microsatellite genotypes of isolates from the same patient (two to five isolates per patient) were identical. The six loci produced eight to 17 allele types and identified 11 to 24 genotypes amongst 32 patients’ isolates, achieving a discriminatory power (DP) of 0.76 to 0.97 (versus 0.78 for both CT14 and URA3 loci, respectively). Testing of a combination of only three loci, ctm1, ctm3 and ctm24, also achieved maximum typing efficiency (DP = 0.99, 29 genotypes). The microsatellite typing scheme had good correlation compared with pulsed-field gel electrophoresis, although was slightly less discriminatory. The new six-locus microsatellite typing scheme is a potentially valuable tool for genotyping and investigating microevolution of C. tropicalis.

Effect of Voriconazole on Candida tropicalis Biofilms: Relation with ERG Genes Expression

Candida tropicalis has emerged as the third most prevalent fungal pathogens and its ability to form biofilms has been considered one of the most important virulence factors, since biofilms represent high tolerance to antifungal agents. However, the mechanisms of C. tropicalis biofilm resistance to antifungals remain poorly understood. Thus, the main aim of this work was to infer about the effect of voriconazole on the formation and control of C. tropicalis biofilms and disclose its relationship with ERG genes' expression. Planktonic cells tolerance of several C. tropicalis clinical isolates to voriconazole was determined through of antifungal susceptibility test, and the effect of this azole against C. tropicalis biofilm formation and pre-formed biofilms was evaluated by cultivable cells determination and total biomass quantification. ERG genes expression was analyzed by quantitative real-time polymerase chain reaction. This work showed that C. tropicalis resistance to voriconazole is strain dependent and that voriconazole was able to partially control biofilm formation, but was unable to eradicate C. tropicalis pre-formed biofilms. Moreover, C. tropicalis biofilms resistance to voriconazole seems to be associated with alterations of sterol content in the cell membrane, resulting in ERG genes overexpression. Voriconazole is unable to control C. tropicalis biofilms, and the overexpression of ERG genes is a possible mechanism of biofilm resistance.

Comparison of the antifungal activity of micafungin and amphotericin B against Candida tropicalis biofilms

OBJECTIVES

Candida tropicalis is the fourth most common cause of candidaemia in hospitalized patients and associated mortality is high. C. tropicalis frequently causes biofilm-related infections. Echinocandins and amphotericin B show potent in vitro activity against C. albicans biofilms, but their activity against C. tropicalis biofilms has received little attention.

METHODS

We studied production of biofilm by 54 C. tropicalis isolates from blood and the antifungal susceptibility of these isolates to micafungin, amphotericin B and liposomal amphotericin B. Biofilm production was measured using the crystal violet assay to determine biomass and the XTT reduction assay to determine metabolic activity. The antifungal susceptibility of planktonic and sessile cells was measured using the EUCAST EDef 7.2 procedure and XTT reduction assay, respectively. The sessile MIC endpoint of SMIC80 was defined as an 80% reduction in the metabolic activity of the biofilm treated with the antifungal compared with the control well.

RESULTS

The three drugs were very active against the isolates in planktonic form, with micafungin showing the highest activity (P < 0.001). Micafungin was the most active agent against C. tropicalis biofilms (P < 0.001). In contrast, liposomal amphotericin B showed poor antifungal activity.

CONCLUSIONS

Micafungin was the most active drug against C. tropicalis biofilm. Although the echinocandins and liposomal amphotericin B are considered very active against Candida spp. biofilms, this is not true for C. tropicalis, as liposomal amphotericin B showed poor antifungal activity against biofilms.

Detection of triazole resistance among Candida species by matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS)

MALDI-TOF MS can rapidly identify microorganisms to the species level and may be able to detect antimicrobial resistance. We evaluated the ability of this technology to detect triazole resistance in Candida species.35 C. albicans, 35 C. glabrata, and 37 C. tropicalis strains were exposed to fluconazole, voriconazole, or posaconazole at two different concentrations plus a drug-free control: a midrange concentration (CLSI clinical breakpoint or epidemiologic cut-off value), and a high concentration (fluconazole 64 μg/ml, voriconazole & posaconazole 16 μg/ml). The MALDI-TOF MS spectra at these concentrations were used to create the individual composite correlation index (CCI) matrices for each isolate. When the CCI of the midrange/highest concentration was lower than that of the midrange/null concentration, the strain was classified as resistant. These results were then compared to the classifications for susceptible or resistant obtained by measuring the MICs according to the CLSI M27-A3 antifungal susceptibility testing (AFST) method.The MALDI-TOF MS assay was able to classify triazole susceptibility against all strains. Overall, essential agreement between MALDI-TOF MS and AFST varied between 54% and 97%, and was highest for posaconazole against C. glabrata. The reproducibility of the MALDI-TOF MS assay varied between 54.3 and 82.9% and was best for fluconazole against C. albicans and posaconazole against C. glabrata. Reproducibility was also higher for C. glabrata isolates compared to C. albicans and C. tropicalis.These results demonstrate that MALDI-TOF MS may be used to simultaneously determine the Candida species and classification as susceptible or resistant to triazole antifungals. Further studies are needed to refine the methodology and improve the reproducibility of this assay.

Candida tropicalis biofilm's matrix--involvement on its resistance to amphotericin B

Candida tropicalis has emerged as one of the most prevalent fungal pathogens, and its ability to form biofilms has been considered one of the most important virulence factors, since they represent high tolerance to antifungal agents. However, the mechanisms of biofilm resistance to antifungal agents remain poorly understood. Thus, the main goal of this study was to infer about the ability of amphotericin B (AMB) to control and combat C. tropicalis biofilms. Additionally, it was also intended to determine the influence of matrix components in biofilm resistance. AMB was unable to totally prevent biofilm formation and to eradicate C. tropicalis preformed biofilms. Moreover, AMB led to a significant increase of the biofilm production due to an augment of the total protein and carbohydrate contents of the matrix. The C. tropicalis biofilm matrix assumes an important role on its resistance to AMB.

Molecular surveillance of candidemia due to Candida albicans among cancer patients during 2009 to 2013 by microsatellite typing

BACKGROUND

Since the high morbidity and mortality of candidemia among cancer patients, the epidemiology has been underlined. In recent years, Candida species genotyping has been established, which could provide detail characteristics of epidemiology and has been underscored for candidemia preventing strategies.

METHODS

Data of cancer patients with candidemia and hospitalized in Tianjin Medical University Cancer Institute and Hospital (TMUCIH) during 2009-2013 were reviewed. Species identification was carried out by using VITEK-2 Compact. Microsatellite typing was performed for molecular analysis. SPSS 20.0 and MVSP 3.22 software were used for statistical and clustering analysis, respectively.

RESULTS

Total of 36 isolates of Candida albicans were recovered from 36 cancer patients with nosocomial candidemia in TMUCIH during the period of 2009-2013 included in the study. Total of 17 genotypes were identified and 2 of them were endemic genotypes, which caused 21 (58.3%) of 36 episodes of candidemia. Hepatobiliary oncology, ICU and gastrointestinal oncology were the main wards of infections due to endemic strains. Gastrointestinal cancer and insertion of a nasogastric tube were the predictors of infections caused by endemic strains (p = 0.014 and p = 0.041, respectively). For the 36 cases, crude mortality was up to 30.6%, and there was no significant difference between infections due to endemic and non-endemic strains (p = 0.077).

CONCLUSIONS

This study proved that endemic stains of C. albicans could exist for a long period and mainly in a few wards. Patients with gastrointestinal cancer or nasogastric tube insertion were more sensitive to endemic C. albicans.

Fungemia caused by Candida species in a children's public hospital in the city of São Paulo, Brazil: study in the period 2007-2010

Candidemia remains a major cause of morbidity and mortality in the health care environment. The epidemiology of Candida infection is changing, mainly in relation to the number of episodes caused by species C. non-albicans. The overall objective of this study was to evaluate the frequency of yeasts of the genus Candida, in a four-year period, isolated from blood of pediatric patients hospitalized in a public hospital of the city of São Paulo, Brazil. In this period, yeasts from blood of 104 patients were isolated and, the identified species of Candida by phenotypic and genotypic methods were: C. albicans (39/104), C. tropicalis (25/104), C. parapsilosis (23/104), Pichia anomala (6/104), C. guilliermondii (5/104), C. krusei (3/104), C. glabrata (2/104) and C. pararugosa (1/104). During the period of the study, a higher frequency of isolates of C. non-albicans (63.55%) (p = 0.0286) was verified. In this study we verified the increase of the non-albicans species throughout the years (mainly in 2009 and 2010). Thus, considering the peculiarities presented by Candida species, a correct identification of species is recommended to lead to a faster diagnosis and an efficient treatment.

Production of biofilm by Candida and non-Candida spp. isolates causing fungemia: comparison of biomass production and metabolic activity and development of cut-off points

Biofilm production in Candida spp. can be studied by measuring the biomass produced after application of crystal violet stain or by measuring metabolic activity with XTT. Our study is the first in which crystal violet and XTT are compared to analyze the ability of clinically relevant Candida and non-Candida species to produce biofilm. We studied 577 isolates causing fungemia in 512 patients admitted from January 2007 to July 2013. Based on the biomass production measured by crystal violet and the metabolic activity measured by XTT, strains were divided into terciles to establish tentative cut-offs to classify isolates as being low, moderate, or high biofilm-forming and as having low, moderate, or high metabolic activity. Considerable variability in biofilm production and metabolic activity was found both between species and within species. C. tropicalis showed the highest biomass production, whereas C. glabrata showed the highest metabolic activity, and non-Candida species isolates showed the lowest metabolic activity (P<0.0023). The isolates were classified as low metabolic activity, moderate metabolic activity, and high metabolic activity according to their cut-offs by XTT (<0.097, 0.097-0.2, and >0.2) and as low biofilm-forming, moderate biofilm-forming, and high biofilm-forming according to their cut-offs by crystal violet (<0.44, 0.44-1.17, and >1.17). The overall categorical agreement between the procedures was 43.7%, which increased to >50% for C. albicans and C. parapsilosis. XTT and crystal violet are complementary procedures for the study of biofilm production.

Worrisome trends in incidence and mortality of candidemia in intensive care units (Paris area, 2002-2010)

Purpose

To analyze trends in incidence and mortality of candidemia in intensive care units (ICUs) vs. non-ICU hospitalized patients and to determine risk factors for infection by specific species and for death.

Methods

Active hospital-based surveillance program of incident episodes of candidemia due to common species in 24 tertiary care hospitals in the Paris area, France between October 2002 and September 2010.

Results

Among 2,507 adult cases included, 2,571 Candida isolates were collected and species were C. albicans (56 %), C. glabrata (18.6 %), C. parapsilosis (11.5 %), C. tropicalis (9.3 %), C. krusei (2.9 %), and C. kefyr (1.8 %). Candidemia occurred in ICU in 1,206 patients (48.1 %). When comparing ICU vs. non-ICU patients, the former had significantly more frequent surgery during the past 30 days, were more often preexposed to fluconazole and treated with echinocandin, and were less frequently infected with C. parapsilosis. Risk factors and age remained unchanged during the study period. A significant increased incidence in the overall population and ICU was found. The odds of being infected with a given species in ICU was influenced by risk factors and preexposure to fluconazole and caspofungin. Echinocandins initial therapy increased over time in ICU (4.6 % first year of study, to 48.5 % last year of study, p < 0.0001). ICU patients had a higher day-30 death rate than non-ICU patients (odds ratio [OR] 2.12; 95 % confidence interval [CI] 1.66–2.72; p < 0.0001). The day-30 and early (<day 8) death rates increased over time in ICU (from 41.5 % the first to 56.9 % the last year of study (p = 0.001) and 28.7–38.8 % (p = 0.0292), respectively). Independent risk factors for day-30 death in ICU were age, arterial catheter, Candida species, preexposure to caspofungin, and lack of antifungal therapy at the time of blood cultures results (p < 0.05).

Conclusions

The availability of new antifungals and the publication of numerous guidelines did not prevent an increase of candidemia and death in ICU patients in the Paris area.

Prognostic factors and historical trends in the epidemiology of candidemia in critically ill patients: an analysis of five multicenter studies sequentially conducted over a 9-year period

PURPOSE

To describe temporal trends in the epidemiology, clinical management and outcome of candidemia in intensive care unit (ICU) patients.

METHODS

This study was a retrospective analysis of 1,392 episodes of candidemia in 647 adult ICU patients from 22 Brazilian hospitals. The characteristics of candidemia in these ICU patients were compared in two periods (2003-2007, period 1; 2008-2012, period 2), and the predictors of 30-day mortality were assessed.

RESULTS

The proportion of patients who developed candidemia while in the ICU increased from 44 % in period 1 to 50.9 % in period 2 (p = 0.01). Prior exposure to fluconazole before candidemia (22.3 vs. 11.6 %, p < 0.001) and fungemia due to Candida glabrata (13.1 vs. 7.8 %, p = 0.03) were more frequent in period 2, as was the proportion of patients receiving an echinocandin as primary therapy (18.0 vs. 5.9 %, p < 0.001). The 30-day mortality rate decreased from 76.4 % in period 1 to 60.8 % in period 2 (p < 0.001). Predictors of 30-day mortality by multivariate analysis were older age, period 1, treatment with corticosteroids and higher APACHE II score, while treatment with an echinocandin were associated with a higher probability of survival.

CONCLUSIONS

We found a clear change in the epidemiology and clinical management of candidemia in ICU patients over the 9-year period of the study. The use of echinocandins as primary therapy for candidemia appears to be associated with better outcomes.