Candida auris Transmission in Germany

Introduction

Candida auris is an emerging fungal pathogen, which is resilient to environmental stress and rapidly develops antifungal drug resistance. Unlike most other Candida species, C. auris causes nosocomial transmissions and infections leading to severe hospital outbreaks. However, in comparison to other European countries, the number of reported C. auris infections in Germany is still considered low.

Goals

We analysed fungal isolates and patient data from C. auris cases reported to the German National Reference Center for Invasive Fungal Infections (NRZMyk) to (i) monitor C. auris epidemiology in Germany (ii) record and classify possible/ probable transmission events (iii) to gain insights into colonisation and infection dynamics.

Materials & Methods

Strains were genetically and phenotypically characterized and subdivided into clades. Whole genome sequencing was performed on selected isolates recording the diversity between closely related isolates from patient-to-patient transmission events. Antifungal drug susceptibility was tested with broth microdilution according to EUCAST or other commercially available assays.

Results

Whin the last two years (2022/23) the number of C. auris primary isolates increased over six-fold from 12 to 77 cases. The majority (66) belonged to Clade I. Non outbreak related clinical data were available for 28 and signs of invasive infection were suspected in 13 cases. 49 isolates were assigned to overall 3 suspected events of transmission. Of these, two events were rapidly contained affecting 5 patients in total. However, the so far biggest recorded outbreak in Germany had an impact on 44 patients and over 4 different university hospital units. Whole genome sequencing revealed close relationships between the patients strains and thus proofed transmission.

Summary

We observed a further rise of C. auris cases in the last years. Increased awareness for colonization and infection with C. auris is required for a timely development of appropriate strategies regarding containment and surveillance. This will also contribute to a better understanding of patient-to-patient transmissions.