Increasing Number of Cases Due to Candida auris in North Italy, July 2019-December 2022

Candida auris Outbreaks: Current Status and Future Perspectives

Candida auris has been identified by the World Health Organization (WHO) as a critical priority pathogen on its latest list of fungi. C. auris infections are reported in the bloodstream and less commonly in the cerebrospinal fluid and abdomen, with mortality rates that range between 30% and 72%. However, no large-scale epidemiology studies have been reported until now. The diagnosis of C. auris infections can be challenging, particularly when employing conventional techniques. This can impede the early detection of outbreaks and the implementation of appropriate control measures. The yeast can easily spread between patients and in healthcare settings through contaminated environments or equipment, where it can survive for extended periods. Therefore, it would be desirable to screen patients for C. auris colonisation. This would allow facilities to identify patients with the disease and take appropriate prevention and control measures. It is frequently unsusceptible to drugs, with varying patterns of resistance observed among clades and geographical regions. This review provides updates on C. auris, including epidemiology, clinical characteristics, genomic analysis, evolution, colonisation, infection, identification, resistance profiles, therapeutic options, prevention, and control.

First imported case of Candida auris infection in Milan, Italy: genomic characterisation

PURPOSE

Candida auris, an emerging multidrug-resistant yeast, has been reported worldwide. In Italy, the first case was reported in 2019. We describe the first case of C. auris, imported from Greece, in Milan, using whole genome sequencing to characterise mutations associated with antifungal resistance.

CASE PRESENTATION

On October 2022 an 80-year-old Italian man was hospitalised in Greece. In the absence of clinical improvement, the patient was transferred to our hospital, in Italy, where blood culture resulted positive for C. auris. Despite therapy, the patient died of septic shock. In a phylogenetic analysis the genome was assigned to Clade I with strains from Kenya, United Arab Emirates and India. D1/D2 region resulted identical to a Greek strain, as for many other strains from different World regions, highlighting the diffusion of this strain.

CONCLUSION

Importation of C. auris from abroad has been previously described. We report the first case of C. auris imported into Italy from Greece, according to phylogenetic analysis. This case reinforces the need for monitoring critically ill hospitalised patients also for fungi and addresses the need for the standardisation of susceptibility testing and strategies for diagnosis and therapy.

Skin and hard surface disinfection against Candida auris - What we know today

Candida auris has emerged as a global healthcare threat, displaying resistance to important healthcare antifungal therapies. Infection prevention and control protocols have become paramount in reducing transmission of C. auris in healthcare, of which cleaning and disinfection plays an important role. Candida albicans is used as a surrogate yeast for yeasticidal claims of disinfection products, but reports have been made that sensitivity to disinfectants by C. auris differs from its surrogate. In this review, we aimed to compile the information reported for products used for skin and hard surface disinfection against C. auris in its planktonic or biofilm form. A comparison was made with other Candida species, and information were gathered from laboratory studies and observations made in healthcare settings.

Enhanced antifungal activity of posaconazole against Candida auris by HIV protease inhibitors, atazanavir and saquinavir

The increasing incidence and dissemination of multidrug-resistant Candida auris represents a serious global threat. The emergence of pan-resistant C. auris exhibiting resistance to all three classes of antifungals magnifies the need for novel therapeutic interventions. We identified that two HIV protease inhibitors, atazanavir and saquinavir, in combination with posaconazole exhibited potent activity against C. auris in vitro and in vivo. Both atazanavir and saquinavir exhibited a remarkable synergistic activity with posaconazole against all tested C. auris isolates and other medically important Candida species. In a time-kill assay, both drugs restored the fungistatic activity of posaconazole, resulting in reduction of 5 and 5.6 log10, respectively. Furthermore, in contrast to the individual drugs, the two combinations effectively inhibited the biofilm formation of C. auris by 66.2 and 81.2%, respectively. Finally, the efficacy of the two combinations were tested in a mouse model of C. auris infection. The atazanavir/posaconazole and saquinavir/posaconazole combinations significantly reduced the C. auris burden in mice kidneys by 2.04- (99.1%) and 1.44-log10 (96.4%) colony forming unit, respectively. Altogether, these results suggest that the combination of posaconazole with the HIV protease inhibitors warrants further investigation as a new therapeutic regimen for the treatment of C. auris infections.

Candida auris: the new fungal threat

Candida auris is an emergent fungal pathogen of particular concern. Since its first identification in Japan in 2009, it rapidly spread all over the world, including Italy. The main concern related to the diffusion of this fungus is its antifungal resistance. It is speculated that about 90% of isolates are resistant to fluconazole, 30% to amphotericin B and 5% to echinocandins; furthermore, some cases of pan-antifungal resistance have been described. Critically ill patients are particularly at risk of being colonized by this yeast and person-to-person transmission may generate hospital outbreaks. In fact, C. auris can survive on inanimate surfaces for a long time and commonly used disinfectants are not effective. Additionally, devices such as central venous catheters (CVCs) or urinary catheters are particularly at risk of being colonized, representing a possible source for the development of bloodstream infections caused by C. auris, which carries a high mortality rate. Given its capability to spread in the hospital setting and the limited therapeutic options it is of outmost importance to promptly identify C. auris. However, commonly used biochemical tests frequently misidentify C. auris as other Candida species; currently the best identification techniques are MALDI-TOF and molecular methods, such as PCR of the ITS and D1/D2 regions of the 28s ribosomal DNA. Whole genome sequencing remains the gold standard for the phylogenetic investigation of outbreaks. The majority of cases of colonization by C. albicans will not cause bloodstream infections and contact precautions and surveillance of contacts will be sufficient. When invasive fungal infections occur, echinocandins still represent the first therapeutic choice. A combination therapy or the use of novel antifungals (such as ibrexafungerp or fosmanogepix) would be required for echinocandin resistant strains. In conclusion, C. auris represents a growing threat because of its antifungal resistance characteristics, its difficult identification and its easy spread from person to person. The aim of this mini-review is to summarize the main aspects concerning this pathogen.