Candida auris: what have we learned so far?

A cluster investigation of Candida auris among hospitalized incarcerated patients

Objective

Investigate and mitigate a cluster of Candida auris cases among incarcerated patients in a maximum-security prison hospital utilizing contact tracing, screening, whole genome sequencing, and environmental sampling and decontamination.

Design

Outbreak investigation.

Setting

Inpatient prison hospital affiliated with an academic tertiary referral center.

Patients

Inmates of the Texas Department of Criminal Justice.

Methods

Epidemiologic and environmental investigations were conducted including contact tracing, point prevalence surveys, and environmental sampling. Whole genome sequencing was performed on positive patient isolates.

Results

Following a clinical case of C. auris fungemia, 344 patients underwent C. auris surveillance screening. Eight (2.3%) patients were identified with C. auris colonization. All patients were male. Our index patient was the only clinical case and death. Whole genome sequencing was performed on the nine patient isolates. All isolates were clade III (Africa) and clustered together with the largest SNP difference being 21. Environmental cultures from 7 of 61 rooms (11.5%) were positive following terminal disinfection with bleach. Sites nearest to the patient were most often positive including the hospital bed rails and bedside table. The transmission cluster was successfully mitigated within 60 days of identification.

Conclusions

Implementation of an aggressive surveillance and decontamination program resulted in mitigation of a C. auris transmission cluster among our incarcerated patients. This investigation provides valuable insight into C. auris transmission in the incarcerated population, which is not considered a classic high-risk population as well as the challenges faced to stop transmission in a facility that requires the use of shared patient environments.

What Do We Know about Candida auris? State of the Art, Knowledge Gaps, and Future Directions

Candida auris has unprecedently emerged as a multidrug resistant fungal pathogen, considered a serious global threat due to its potential to cause nosocomial outbreaks and deep-seated infections with staggering transmissibility and mortality, that has put health authorities and institutions worldwide in check for more than a decade now. Due to its unique features not observed in other yeasts, it has been categorised as an urgent threat by the Centers for Disease Control and Prevention and other international agencies. Moreover, epidemiological alerts have been released in view of the increase of healthcare-associated C. auris outbreaks in the context of the COVID-19 pandemic. This review summarises the current evidence on C. auris since its first description, from virulence to treatment and outbreak control, and highlights the knowledge gaps and future directions for research efforts.

Outbreaks in Health Care Settings

Outbreaks and pseudo-outbreaks in health care settings are complex and should be evaluated systematically using epidemiologic and molecular tools. Outbreaks result from failures of infection prevention practices, inadequate staffing, and undertrained or overcommitted health care personnel. Contaminated hands, equipment, supplies, water, ventilation systems, and environment may also contribute. Neonatal intensive care, endoscopy, oncology, and transplant units are areas at particular risk. Procedures, such as bronchoscopy and endoscopy, are sources of infection when cleaning and disinfection processes are inadequate. New types of equipment can be introduced and lead to contamination or equipment and medications can be contaminated at the manufacturing source.

How urgent is the need for new antifungals?

Introduction: Invasive fungal infection carries a high morbidity, mortality and economic cost. In recent times, a rising incidence of fungal infection and antifungal resistance is occurring which has prompted the development of novel antifungal agents.Areas covered:In this perspective, the authors describe the current status of registered antifungals and their limitations in the treatment of invasive fungal infection. They also go on to describe the new antifungal agents that are in the clinical stage of development and how they might be best utilized in patient care in the future.Expert opinion: The antifungal drug development pipeline has responded to a growing need for new agents to effectively treat fungal disease without concomitant toxicity or issues with drug tolerance. Olorofim (F901318), ibrexafungerp (SCY-078), fosmanogepix (APX001), rezafungin (CD101), oteseconazole (VT-1161), encochleated amphotericin B (MAT2203), nikkomycin Z (NikZ) and ATI-2307 are all in the clinical stage of development and offer great promise in offering clinicians better agents to treat these difficult infections.

A Cluster of Neonatal Infections Caused by Candida auris at a Large Referral Center in Colombia

BACKGROUND

Globally, Candida auris is an emerging pathogen that poses an essential threat in healthcare settings presenting as outbreaks requiring significant allocation of infection control interventions to curb transmission. This fungal pathogen was initially identified in 2009 in Japan, but it has spread to all continents. Candida auris poses significant diagnostic and treatment challenges. Conventional microbiology laboratories often misidentify this pathogen as Candida haemulonii or as other Candida spp., Rhodoturola glutinis, and even with some bacterial pathogens, including Neisseria meningitidis serogroup A. Furthermore, C. auris displays distinct mechanisms of antifungal resistance to azoles and amphotericin B formulations. Most of the case series and outbreak reports have included invasive infections in adult populations.

METHODS

Herein, we present a cluster of neonatal infections caused by Candida auris at a large referral center in Colombia.

RESULTS

We report a case series of 8 neonates and infant patients who were seen at a large referral center in Colombia and who develop invasive infections caused by C. haemulonii and C. auris.

DISCUSSION

Our report highlights the diagnostic challenges in identifying this fungal pathogen correctly, its clinical spectrum of disease, recommendations for empiric antifungal therapy, and it is not always associated with a high case fatality rate.

Pathogenicity Assessment of Colombian Strains of Candida auris in the Galleria mellonella Invertebrate Model

Candida auris, first described in 2009, is an opportunistic pathogenic yeast that causes nosocomial outbreaks around the world, with high mortality rates associated with therapeutic failure. In this study, we evaluated the pathogenicity of 107 isolates from two cities in Colombia, associated with fungemia or colonization processes; to achieve this, we used the Galleria mellonella invertebrate model to compare pathogenicity. Our results showed that less than half of the total isolates of C. auris presented a high pathogenicity compared to the reference strain SC5314, and most of those highly pathogenic strains were from colonization processes. We observed that there was formation of large aggregates of cells that cannot be disrupted easily, without statistically significant differences between the pathogenicity of the aggregated and non-aggregated strains. In addition, protease activity was observed in 100% of the C. auris strains; phospholipase and hemolysin activity were observed in 67.3 and 68.2% of the studied strains, respectively. In conclusion, these results highlight the utility of determining survival using G. mellonella, which allowed us to provide new information on the pathogenicity, enzymatic activity, and the relationship of the aggregated and non-aggregated phenotypes of C. auris in this model.

Evaluation of Synergistic Activity of Isavuconazole or Voriconazole plus Anidulafungin and the Occurrence and Genetic Characterization of Candida auris Detected in a Surveillance Program

A total of 15 Candida auris isolates from the SENTRY antimicrobial surveillance program between 2006 and 2019 were combined with 21 isolates from other collections for the evaluation of antifungal susceptibility and synergy against anidulafungin plus voriconazole or isavuconazole using the checkerboard method. Surveillance isolates were analyzed for genetic relatedness and resistance mechanisms. Applying the tentative statistical epidemiological cutoff values and the Centers for Disease Control tentative breakpoints, 32/36 isolates were resistant to fluconazole, 5/36 were resistant to amphotericin B, 5/36 were non-wild-type (NWT) to anidulafungin, 3/36 were NWT to micafungin, and 1/36 and 10/36 were NWT to isavuconazole and voriconazole, respectively. Of these, 10 isolates were multidrug resistant, which means that these isolates were resistant to 2 antifungal classes. Synergy or partial synergy was noted in 5/36 and 22/36, respectively, of the isolates with the combination of anidulafungin plus voriconazole, and 11/36 and 19/36 isolates, respectively, for the combination of anidulafungin plus isavuconazole. Multilocus sequence type (MLST) analysis of the 15 SENTRY isolates demonstrated that the isolates from the US were genetically related to, but different from, isolates from Latin America (Panama and Colombia) and Germany. Single nucleotide polymorphism (SNP) analysis showed that the 15 SENTRY isolates belonged to the described international clades and had associated Erg11 alterations, including 11 isolates displaying K143R, one displaying F126L, and one displaying Y501H alterations and a fluconazole MIC result of ≥64 mg/liter. Resistance mechanisms were not observed in the two isolates displaying fluconazole MIC values at 4 and 16 mg/liter. Isavuconazole displayed activity and greater synergy when tested with anidulafungin than seen with anidulafungin plus voriconazole against the C. auris clinical isolates that displayed resistance phenotypes.

Skin and Soft Tissue Infections in Non-Human Immunodeficiency Virus Immunocompromised Hosts

Skin and soft tissue infections among the non-human immunodeficiency virus infected immunosuppressed population are a serious and growing concern. Many pathogens can cause cutaneous infections in these patients owing to the highly varied and profound immune deficits. Although patients can be infected by typical organisms, the diversity and antimicrobial-resistant nature of the organisms causing these infections result in significant morbidity and mortality. The diagnostic approach to these infections in immunocompromised hosts can differ dramatically depending on the potential causative organisms. An understanding of new immunosuppressive treatments and evolving antimicrobial resistance patterns are required to optimally manage these difficult cases.

Clade-specific variation in susceptibility of Candida auris to broad-spectrum ultraviolet C light (UV-C)

Background:

Candida auris is an emerging and often multidrug-resistant fungal pathogen with an exceptional ability to persist on hospital surfaces. These surfaces can act as a potential source of transmission. Therefore, effective disinfection strategies are urgently needed. We investigated the efficacy of ultraviolet C light (UV-C) disinfection for C. auris isolates belonging to 4 different clades.

Methods:

In vitro testing of C. auris isolates was conducted using 10⁶ colony-forming units (CFU) spread on 20-mm diameter steel carriers and exposed to a broad-spectrum UV-C light source for 10, 20, and 30 minutes at a 1.5 m (5 feet) distance. Post-UV survivors on the coupons were subsequently plated. Colony counts and log reductions were recorded, calculated, and compared to untreated control carriers. Identification of all isolates were confirmed by MALDI-TOF and morphology was visualized by microscopy.

Results:

We observed an increased susceptibility of C. auris to UV-C in 8 isolates belonging to clades I, II and IV with increasing UV exposure time. The range of log kill (0.8–1.19) was highest for these isolates at 30 minutes. But relatively no change in log kill (0.04–0.35) with increasing time in isolates belonging to clade III were noted. Interestingly, C. auris isolates susceptible to UV-C were mostly nonaggregating, but the isolates that were more resistant to UV exposure formed aggregates.

Conclusions:

Our study suggests variability in susceptibility to UV-C of C. auris isolates belonging to different clades. More studies are needed to assess whether a cumulative impact of prolonged UV-C exposure provides additional benefit.

Management of Candida auris outbreak in a tertiary-care setting in Saudi Arabia

OBJECTIVE

To describe local experience in managing an outbreak of Candida auris in a tertiary-care setting.

METHODS

In response to emerging Candida auris, an outbreak investigation was conducted at our hospital between March 2018 and June 2019. Once a patient was confirmed to have Candida auris, screening of exposed patients and healthcare workers (HCWs) was conducted. Postexposure screening included those who had had direct contact with or shared the same unit or ward with a laboratory-confirmed case. In response to the increasing number of cases, new infection control measures were implemented.

RESULTS

In total, 23 primary patients were detected over 15 months. Postexposure screening identified 11 more cases, and all were patients. Furthermore, ~28.6% of patients probably caught infection in another hospital or in the community. Infection control measures were strictly implemented including hand hygiene, personal protective equipment, patient hygiene, environmental cleaning, cohorting of patients and HCWs, and avoiding the sharing of equipment. The wave reached a peak in April 2019, followed by a sharp decrease in May 2019 and complete clearance in June 2019. The case patients were equally distributed between intensive care units (51.4%) and wards (48.6%). More infections (62.9%) occurred than colonizations (37.1%). Urinary tract infection (42.9%) and candidemia (17.1%) were the main infections. In total, 7 patients (20.0%) died during hospitalization; among them, 6 (17.1%) died within 30 days of diagnosis.

CONCLUSIONS

Active screening of exposed patients followed by strict infection control measures, including environmental cleaning, was successful in ending the outbreak. Preventing future outbreaks is challenging due to outside sources of infection and environmental resistance.