Candida auris Fungemia and a local spread taken under control with infection control measures: First report from Turkey

The laboratory investigation, management, and infection prevention and control of Candida auris: a narrative review to inform the 2024 national guidance update in England

The emergent fungal pathogen Candida auris is increasingly recognised as an important cause of healthcare-associated infections globally. It is highly transmissible, adaptable, and persistent, resulting in an organism with significant outbreak potential that risks devastating consequences. Progress in the ability to identify C. auris in clinical specimens is encouraging, but laboratory diagnostic capacity and surveillance systems are lacking in many countries. Intrinsic resistance to commonly used antifungals, combined with the ability to rapidly acquire resistance to therapy, substantially restricts treatment options and novel agents are desperately needed. Despite this, outbreaks can be interrupted, and mortality avoided or minimised, through the application of rigorous infection prevention and control measures with an increasing evidence base. This review provides an update on epidemiology, the impact of the COVID-19 pandemic, risk factors, identification and typing, resistance profiles, treatment, detection of colonisation, and infection prevention and control measures for C. auris. This review has informed a planned 2024 update to the United Kingdom Health Security Agency (UKHSA) guidance on the laboratory investigation, management, and infection prevention and control of Candida auris. A multidisciplinary response is needed to control C. auris transmission in a healthcare setting and should emphasise outbreak preparedness and response, rapid contact tracing and isolation or cohorting of patients and staff, strict hand hygiene and other infection prevention and control measures, dedicated or single-use equipment, appropriate disinfection, and effective communication concerning patient transfers and discharge.

Evaluation of the first Candida auris isolates reported from Türkiye in terms of identification by various methods and susceptibility to antifungal drugs

PURPOSE

Candida auris is increasingly being isolated from patients all over the world. It has five clades. In this study, it was aimed to compare the results of biochemical tests obtained using different methods and the antifungal susceptibility profiles of C. auris strains isolated from the first seven cases reported in Türkiye, and evaluate whether this information could be useful as preliminary data in determining the clade of strains in centers that lack the opportunity to apply molecular methods.

METHODS

Identification test results obtained using API ID 32 C, API 20 C AUX, VITEK-2 YST, and MALDI-TOF MS; colony color and morphology on Chromagar Candida, CHROMagar Candida Plus media, and cornmeal-Tween 80 agar; susceptibility to antifungals were tested and compared. Antifungal susceptibility test was studied using microdilution method according to the recommendations of EUCAST. Additionally, a pilot study was conducted to investigate the value of CHROMagar Candida Plus.

RESULTS

All seven strains were identified as Lachancea kluyveri with API ID 32 C, Rhodotorula glutinis; Cryptococcus neoformans with API 20 C AUX, and C. auris with both VITEK-2 YST and MALDI-TOF MS. MIC values for fluconazole were very high (≥64 mg/L) for all seven strains. It was observed that 11 (37.9%) of 29 Candida parapsilosis strains formed colonies with morphology similar to C. auris on CHROMagar Candida Plus medium, leading to false positivity.

CONCLUSIONS

Although there have been many isolations of C. auris in our country in recent years, clade distribution of only a small number of strains is known yet. In this study, when the biochemical properties and antifungal susceptibility profiles of the seven strains were evaluated, it was concluded that they exhibited some characteristics compatible with clade I. It was also observed that strains 1 and 2 may belong to a different clade.

Phenotypic Investigation of Virulence Factors, Susceptibility to Ceragenins, and the Impact of Biofilm Formation on Drug Efficacy in Candida auris Isolates from Türkiye

Candida auris has emerged as a significant fungal threat due to its rapid worldwide spread since its first appearance, along with its potential for antimicrobial resistance and virulence properties. This study was designed to examine virulence characteristics, the efficacy of ceragenins, and biofilm-derived drug resistance in seven C. auris strains isolated from Turkish intensive care patients. It was observed that none of the tested strains exhibited proteinase or hemolysis activity; however, they demonstrated weak phospholipase and esterase activity. In addition, all strains were identified as having moderate to strong biofilm formation characteristics. Upon determining the minimum inhibitory concentrations (MIC) of ceragenins, it was discovered that CSA-138 exhibited the highest effectiveness with a MIC range of 1-0.5 µg/mL, followed by CSA-131 with a MIC of 1 µg/mL. Also, antimicrobial agents destroyed mature biofilms at high concentrations (40-1280 µg/mL). The investigation revealed that the strains isolated from Türkiye displayed weak exoenzyme activities. Notably, the ceragenins exhibited effectiveness against these strains, suggesting their potential as a viable treatment option.

Nosocomial infection of C. auris in COVID-19 Intensive Care Unit in Türkiye and Phylogenetic Analysis of Isolates

BACKGROUND

The difficulties in the identification of C. auris and the delays in the implementation of infection control precautions contribute to outbreaks. This study analyzed 10 patients with COVID-19 and C. auris candidemia, their characteristic and clinical features and phylogenetic features, and the antifungal susceptibilities of the isolates.

METHOD

C. auris were detected in the COVID-19 ICU of a university hospital between January and August 2021. Identification to species level was performed using MALDI-TOF MS. Antifungal susceptibilities were determined by the Sensititre YeastOne YO10 panel. The isolates were whole genome sequenced to assess genetic relatedness and a phylogenetic tree was drawn including various C. auris clades.

RESULTS

The mean growth time in blood cultures was 38.8 h. C. auris candidemia developed on the average 27th day of ICU admission. All were susceptible to anidulafungin and micafungin, while they were resistant to fluconazole and amphotericin B. Only three isolates were found to be resistant to caspofungin. All patients died. With the WGS method, all isolates were found in a close resemblance to each other in terms of total nucleotide similarity (with a minimum of 96% pairwise alignment). Our isolates showed the closest similarity to South Asian clade (Clade I).

CONCLUSIONS

This study is the first to evaluate the phylogenetic characteristics of C. auris using WGS and to determine antifungal susceptibilities in Türkiye on COVID-19 patients. The mortality rate was very high in patients who have both COVID-19 and C. auris candidemia.

Overestimation of Amphotericin B Resistance in Candida auris with Sensititre YeastOne Antifungal Susceptibility Testing: a Need for Adjustment for Correct Interpretation

Significant variation in minimal inhibitory concentrations (MIC) has been reported for amphotericin B (AMB) and C. auris, depending on the antifungal susceptibility testing (AFST) method. Although the Sensititre YeastOne (SYO) is widely used in routine laboratory testing, data regarding its performance for the AFST of C. auris are scarce. We tested AMB against 65 C. auris clinical isolates with the SYO and the reference methodology by the Clinical and Laboratory Standards Institute (CLSI). The essential agreement (EA, ±1 dilution) between the two methods and the categorical agreement (CA) based on the Centers for Disease Control and Prevention (CDC)'s tentative breakpoint of MIC ≥ 2 mg/L were determined. The SYO wild type upper limit value (WT-UL) was determined using the ECOFFinder. The modal (range) CLSI growth inhibitory MIC was lower than the SYO colorimetric MIC [1(0.25-1) versus 2(1-8) mg/L, respectively]). The CLSI-colorimetric SYO EA was 29% and the CA was 11% (89% major errors; MaE). MaE were reduced when the SYO WT-UL of 8 mg/L was used (0% MaE). Alternatively, the use of SYO growth inhibition endpoints of MIC-1 (75% growth inhibition) or MIC-2 (50% growth inhibition) resulted in 88% CA with 12% MaE and 97% CA with 3% MaE, respectively. In conclusion, SYO overestimated AMB resistance in C. auris isolates when colorimetric MICs, as per SYO instructions and the CDC breakpoint of 2 mg/L, were used. This can be improved either by using the method-specific WT-UL MIC of 8 mg/L for colorimetric MICs or by determining growth inhibition MIC endpoints, regardless of the color. IMPORTANCE Candida auris is an emerging and frequently multidrug-resistant fungal pathogen that accounts for life-threatening invasive infections and nosocomial outbreaks worldwide. Reliable AF is important for the choice of the optimal treatment. Commercial methods are frequently used without prior vigorous assessment. Resistance to AMB was over-reported with the commercial colorimetric method Sensititre YeastOne (SYO). SYO produced MICs that were 1 to 2 twofold dilutions higher than those of the reference CLSI method, resulting in 89% MaE. MaE were reduced using a SYO-specific colorimetric wild type upper limit MIC value of 8 mg/L (0%) or a 50% growth inhibition endpoint (3%).

COVID-19-Associated Fungal Infections: An Urgent Need for Alternative Therapeutic Approach?

Secondary fungal infections may complicate the clinical course of patients affected by viral respiratory diseases, especially those admitted to intensive care unit. Hospitalized COVID-19 patients are at increased risk of fungal co-infections exacerbating the prognosis of disease due to misdiagnosis that often result in treatment failure and high mortality rate. COVID-19-associated fungal infections caused by predominantly Aspergillus and Candida species, and fungi of the order Mucorales have been reported from several countries to become significant challenge for healthcare system. Early diagnosis and adequate antifungal therapy is essential to improve clinical outcomes, however, drug resistance shows a rising trend highlighting the need for alternative therapeutic agents. The purpose of this review is to summarize the current knowledge on COVID-19-associated mycoses, treatment strategies and the most recent advancements in antifungal drug development focusing on peptides with antifungal activity.

Candida auris and other phylogenetically related species - a mini-review of the literature

The lesser-known non-albicans Candida species are often overlooked and difficult to diagnose in most microbiology laboratories. Candida auris, a relatively newly discovered species, is responsible for outbreaks in various geographical regions. Because of its increased resistance to antifungal drugs, C. auris is responsible for hard-to-treat infections and its pathogenicity is still incompletely elucidated. Non-albicans species phylogenetically related to C. auris, like the C. haemulonii complex might also play a role in human pathology. The current summary of the literature presents the emergence, virulence, laboratory identification, and molecular mechanisms responsible for antifungal resistance of emergent rare non-albicans Candida species.