The Menace of Candida auris Epidemic Amidst the COVID-19 Pandemic: A Systematic Review

A simple and sensitive test for Candida auris colonization, surveillance, and infection control suitable for near patient use

Candida auris is a multidrug-resistant fungal pathogen with a propensity to colonize humans and persist on environmental surfaces. C. auris invasive fungal disease is being increasingly identified in acute and long-term care settings. We have developed a prototype cartridge-based C. auris surveillance assay (CaurisSurV cartridge; "research use only") that includes integrated sample processing and nucleic acid amplification to detect C. auris from surveillance skin swabs in the GeneXpert instrument and is designed for point-of-care use. The assay limit of detection (LoD) in the skin swab matrix was 10.5 and 14.8 CFU/mL for non-aggregative (AR0388) and aggregative (AR0382) strains of C. auris, respectively. All five known clades of C. auris were detected at 2-3-5× (31.5-52.5 CFU/mL) the LoD. The assay was validated using a total of 85 clinical swab samples banked at two different institutions (University of California Los Angeles, CA and Wadsworth Center, NY). Compared to culture, sensitivity was 96.8% (30/31) and 100% (10/10) in the UCLA and Wadsworth cohorts, respectively, providing a combined sensitivity of 97.5% (40/41), and compared to PCR, the combined sensitivity was 92% (46/50). Specificity was 100% with both clinical (C. auris negative matrix, N = 31) and analytical (non-C. auris strains, N = 32) samples. An additional blinded study with N = 60 samples from Wadsworth Center, NY yielded 97% (29/30) sensitivity and 100% (28/28) specificity. We have developed a completely integrated, sensitive, specific, and 58-min prototype test, which can be used for routine surveillance of C. auris and might help prevent colonization and outbreaks in acute and chronic healthcare settings.

IMPORTANCE

This study has the potential to offer a better solution to healthcare providers at hospitals and long-term care facilities in their ongoing efforts for effective and timely control of Candida auris infection and hence quicker response for any potential future outbreaks.

Development of a standard evaluation method for microbial UV sensitivity using light-emitting diodes

Ultraviolet (UV) light is an effective disinfection method. In particular, UV light-emitting diodes (UV-LEDs) are expected to have many applications as light sources owing to their compact form factor and wide range of choices of wavelengths. However, the UV sensitivity of microorganisms for each UV wavelength has not been evaluated comprehensively because standard experimental conditions based on LED characteristics have not been established. Therefore, it is necessary to establish a standard evaluation method based on LED characteristics. Here, we developed a new UV-LED device based on strictly controlled irradiation conditions using LEDs for each wavelength (250-365 nm), checked the validity of the device characteristics and evaluated the UV sensitivity of Escherichia coli using this new evaluation method. For this new device, we considered accurate irradiance, accurate spectra, irradiance uniformity, accurate dose, beam angle, surrounding material reflections, and sample condition. From our results, the following UV irradiation conditions were established as standard: 1 mW/cm2 irradiance, bacterial solution with absorbance value of A600 = 0.5 diluted 10 times solution, solution volume of 1 mL, working distance (WD) of 100 mm. In order to compare the effects of irradiation under uniform conditions on inactivation of microorganisms, we assessed inactivation effect of E. coli by LED irradiation at each wavelength using the U280 LED as a standard wavelength. The inactivation effect for U280 LED irradiation was -0.95 ± 0.21 log at a dose of 4 mJ/cm2. Under this condition of dose, our results showed a high wavelength dependence of the inactivation effect at each UV wavelength peaking at 267 nm. Our study showed that this irradiation system was validated for the standard UV irradiation system and could be contributed to the establishment of food and water hygiene control methods and the development of equipment for the prevention of infectious diseases.

The Gordian Knot of C. auris: If You Cannot Cut It, Prevent It

Since its first description in 2009, Candida auris has, so far, resulted in large hospital outbreaks worldwide and is considered an emerging global public health threat. Exceptionally for yeast, it is gifted with a profoundly worrying invasive potential and high inter-patient transmissibility. At the same time, it is capable of colonizing and persisting in both patients and hospital settings for prolonged periods of time, thus creating a vicious cycle of acquisition, spreading, and infection. It exhibits various virulence qualities and thermotolerance, osmotolerance, filamentation, biofilm formation and hydrolytic enzyme production, which are mainly implicated in its pathogenesis. Owing to its unfavorable profile of resistance to diverse antifungal agents and the lack of effective treatment options, the implementation of robust infection prevention and control (IPC) practices is crucial for controlling and minimizing intra-hospital transmission of C. auris. Rapid and accurate microbiological identification, adherence to hand hygiene, use of adequate personal protective equipment (PPE), proper handling of catheters and implantable devices, contact isolation, periodical environmental decontamination, targeted screening, implementation of antimicrobial stewardship (AMS) programs and communication between healthcare facilities about residents' C. auris colonization status are recognized as coherent strategies for preventing its spread. Current knowledge on C. auris epidemiology, clinical characteristics, and its mechanisms of pathogenicity are summarized in the present review and a comprehensive overview of IPC practices ensuring yeast prevention is also provided.

Description of Candida auris Occurrence in a Tertiary Health Institution in Riyadh, Saudi Arabia

BACKGROUND

Candida auris is an emerging multidrug-resistant fungal pathogen that represents a current serious threat to healthcare settings.

OBJECTIVE

The objective was to determine the prevalence of C. auris in a Riyadh hospital since its initial detection in late 2019.

METHODS

Using an adapted risk assessment tool, we reviewed the charts and medical files of all suspected and confirmed cases of C. auris infections reported at King Khalid University Hospital, Riyadh, between November 2019 and December 2022. Anonymized data were retrieved in a pre-established datasheet and analyzed to determine the epidemiological characteristics of C. auris infections in our facility. We analyzed prevalence by age, gender, risk factors, and according to sampling source.

RESULTS

Of the 53 confirmed C. auris-positive cases during the study period, 33 (62%) were males. Their ages ranged between 15 and 98, with most positive cases occurring in those aged 50 and above. Only one of the confirmed cases was hospital-acquired. All patients had at least one risk factor, and urine samples yielded the greatest number of positive cases, while admission to healthcare facilities constituted the highest risk in our study.

CONCLUSION

Establishing a local prevalence pattern could serve as a baseline/benchmark to compare with regional and international benchmarks.

Emerging infectious diseases, focus on infection prevention, environmental survival and germicide susceptibility: SARS-CoV-2, Mpox, and Candida auris

BACKGROUND

New and emerging infectious diseases continue to represent a public health threat. Emerging infectious disease threats include pathogens increasing in range (eg, Mpox), zoonotic microbes jumping species lines to cause sustained infections in humans via person-to-person transmission (SARS-CoV-2) and multidrug-resistant pathogens (eg, Candida auris).

MATERIALS AND METHODS

We searched the published English literature and reviewed the selected articles on SARS-CoV-2, Mpox, and Candida auris with a focus on environmental survival, contamination of the patient's hospital environment, susceptibility of the pathogen to antiseptics and disinfectants and infection prevention recommendations.

RESULTS

All three pathogens (ie, SARS-CoV-2, Mpox, and Candida auris) can survive on surfaces for minutes to hours and for Mpox and C auris for days. Currently available antiseptics (eg, 70%-90% alcohol hand hygiene products) are active against SARS-CoV-2, Mpox and C auris. The U.S Environmental Protection Agency provides separate lists of surface disinfectants active against SARS-CoV-2, Mpox, and C auris.

DISCUSSION

The risk of environment-to-patient transmission of SARS-CoV-2, Mpox and Candida auris, is very low, low-moderate and high, respectively. In the absence of appropriate patient isolation and use of personal protection equipment, the risk of patient-to-health care provider transmission of SARS-CoV-2, Mpox, and C auris is high, moderate and low, respectively.

CONCLUSIONS

Appropriate patient isolation, use of personal protective equipment by health care personnel, hand hygiene, and surface disinfection can protect patients and health care personnel from acquiring SARS-CoV-2, Mpox, and C auris from infected patients.

Severe Candida infections in critically ill patients with COVID-19

The frequency of co-infections with bacterial or fungal pathogens has constantly increased among critically ill patients with coronavirus disease 2019 (COVID-19) during the pandemic. Candidemia was the most frequently reported invasive fungal co-infection. The onset of candidemia in COVID-19 patients was often delayed compared to non-COVID-19 patients. Additionally, Candida invasive infections in COVID-19 patients were more often linked to invasive procedures (e.g., invasive mechanical ventilation or renal replacement therapy) during the intensive care stay and the severity of illness rather than more "classic" risk factors present in patients without COVID-19 (e.g., underlying diseases and prior hospitalization). Moreover, apart from the increased incidence of candidemia during the pandemic, a worrying rise in fluconazole-resistant strains was reported, including a rise in the multidrug-resistant Candida auris. Regarding outcomes, the development of invasive Candida co-infection had a negative impact, increasing morbidity and mortality compared to non-co-infected COVID-19 patients. In this narrative review, we present and critically discuss information on the diagnosis and management of invasive fungal infections caused by Candida spp. in critically ill COVID-19 patients.

Design of a lipid nano-delivery system containing recombinant Candida albicans chitinase 3 as a potential vaccine against fungal infections

Opportunistic fungi cause lethal systemic infections and impose high medical costs to health systems. The World Health Organization has recognized the importance of fungal infections, including them in its global priority list guiding research, development, and discovery of new therapeutic approaches. Fungal vaccine development has been proposed as one of the treatment and prevention strategies in the last decade. In this study, we present the design of a lipid antigen delivery system based on Dioctadecyldimethylammonium bromide: Monoolein (DODAB: MO) containing recombinant Candida albicans Chitinase 3 (Cht3) for modulation the immune response against fungal infections. Several DODAB:MO liposomes containing Cht3 were prepared and those prepared by the incubation method and containing 5 µg/mL Cht3 were selected due to their favorable size, ζ-potential and stability, suited for antigen delivery applications. The encapsulation of Cht3 in these liposomes resulted in a significant increase in cellular uptake compared to empty liposomes, demonstrating their efficacy in delivering the antigen. Moreover, the liposomes proved to be safe for use in immunization procedures. Subcutaneous administration of Cht3 liposomes elicited a Th1/Th17 immune response profile, associated with the production of high levels of antibodies against Cht3. These antibodies recognized both the native and the recombinant forms of the protein, opsonizing mother-yeast at the cell scars, which has the potential to disrupt cell separation and hinder yeast growth. The findings suggest that the designed lipid antigen delivery system shows promise as a potential candidate for enhancing immune responses against fungal infections, offering a valuable strategy for future fungal vaccine development.

Use of antibiotics in hospitalized patients with COVID-19: evolving concepts in a highly dynamic antimicrobial stewardship scenario

INTRODUCTION

Excessive use of antibiotics has been frequently reported in hospitalized patients with COVID-19 worldwide, compared to the actual number of bacterial co-infections or super-infections.

AREAS COVERED

In this perspective, we discuss the current literature on the use of antibiotics and antimicrobial stewardship interventions in hospitalized patients with COVID-19. A search was conducted in PubMed up to March 2023.

EXPERT OPINION

The COVID-19 pandemic has witnessed an excessive use of antibiotics in hospitals worldwide, especially before the advent of COVID-19 vaccination, although according to the most recent data there is still an important disproportion between the prevalence of antibiotic use and that of proven bacterial coinfection or superinfections. An important reduction in the prevalence of antibiotic use in COVID-19 patients reported in the literature, from 70-100% to 50-60%, has been observed after successful vaccination campaigns, likely related to the reduced median disease severity of hospitalized COVID-19 patients and some successful interventions of antimicrobial and diagnostic stewardship. However, the disproportion between antibiotic use and the prevalence of bacterial infections (4-6%) is still uncomfortable from an antimicrobial stewardship perspective and requires further attention.

Candida auris: a novel emerging nosocomial pathogen - properties, epidemiological situation and infection control

Immunosuppression and critical illnesses in combination with ecological imbalance open the door for novel opportunistic fungal infections, as in case of Candida (C). auris. C. auris has emerged globally as a multidrug-resistant yeast, causing infections and outbreaks in health care facilities. This narrative review discusses the properties of the yeast, the development of the epidemiological situation, the nosocomial spread and causes for nosocomial outbreaks triggered by C. auris in the hospital environment, and summarizes international recommendations for infection control, supplemented by suggestions on diagnostic, screening and antibiotic stewardship.

Candida auris biofilm: a review on model to mechanism conservation

INTRODUCTION

Candida auris is included in the fungal infection category 'critical' by WHO because of associated high drug tolerance and spread at an alarming rate which if remains untouched may result in serious outbreaks. Since its discovery in 2009, several assiduous efforts by mycologists across the world have deciphered its biology including growth physiology, drug tolerance, biofilm formation, etc. The differential response of various strains from different clades poses a hurdle in drawing a final conclusion.

AREAS COVERED

This review provides brief insights into the understanding of C. auris biofilm. It includes information on various models developed to understand the biofilms and conservation of different signaling pathways. Significant development has been made in the recent past with the generation of relevant in vivo and ex vivo models. The role of signaling pathways in the development of biofilm is largely unknown.

EXPERT OPINION

The selection of an appropriate model system is a must for the accuracy and reproducibility of results. The conservation of major signaling pathways in C. auris with respect to C. albicans and S. cerevisiae highlights that initial inputs acquired from orthologs will be valuable in getting insights into the mechanism of biofilm formation and associated pathogenesis.

Nanotechnology-Based Approaches for Voriconazole Delivery Applied to Invasive Fungal Infections

Invasive fungal infections increase mortality and morbidity rates worldwide. The treatment of these infections is still limited due to the low bioavailability and toxicity, requiring therapeutic monitoring, especially in the most severe cases. Voriconazole is an azole widely used to treat invasive aspergillosis, other hyaline molds, many dematiaceous molds, Candida spp., including those resistant to fluconazole, and for infections caused by endemic mycoses, in addition to those that occur in the central nervous system. However, despite its broad activity, using voriconazole has limitations related to its non-linear pharmacokinetics, leading to supratherapeutic doses and increased toxicity according to individual polymorphisms during its metabolism. In this sense, nanotechnology-based drug delivery systems have successfully improved the physicochemical and biological aspects of different classes of drugs, including antifungals. In this review, we highlighted recent work that has applied nanotechnology to deliver voriconazole. These systems allowed increased permeation and deposition of voriconazole in target tissues from a controlled and sustained release in different routes of administration such as ocular, pulmonary, oral, topical, and parenteral. Thus, nanotechnology application aiming to delivery voriconazole becomes a more effective and safer therapeutic alternative in the treatment of fungal infections.