Enhancing ICU Candida spp. surveillance: a cost-effective approach focused on Candida auris detection

Abstract

Introduction: Candida auris is an emerging pathogen that represents a worldwide health problem due to its global expansion, multidrug resistance, and difficult laboratory identification. Among the risk factors for colonization/infection by C. auris, a stay in an intensive care unit (ICU) stands out. This prospective multicenter study aimed to monitor the trend of the local epidemiology of Candida spp. and unveil the prevalence of C. auris.

Methods: From 2020 to 2022, axillar/inguinal swabs were collected from adult patients at three points: upon admission (D1) and on the fifth (D5) and eighth (D8) days of their ICU stay. We employed culture-based screening methods combined with molecular techniques to identify Candida spp. down to the species level. Specific screening for Candida auris was conducted using a real-time PCR assay in combination with an improved selective culture medium, mannitol salt agar auris (MSAA). To validate the effectiveness of MSAA, a collection of reference C. auris strains representing the four major geographical clades was used.

Results: We enrolled 675 patients, and 355 Candida isolates were retrieved from the 988 swab samples collected. From those, 185/355 (52.1%) were identified as C. albicans and 170/355 (47.9%) as non-albicans Candida (NAC). MSAA medium showed a specificity of 94.8%, albeit C. auris was not detected in this cohort. The dynamics of Candida spp. colonization by ICU were significant at the three collection points. Upon admission, C. albicans was associated with the Beatriz Ângelo Hospital ICU (p=0.003) and C. tropicalis with the general Hospital Professor Doutor Fernando Fonseca (FFH) ICU (p=0.006). C. parapsilosis and C. lusitaniae were associated with FFH ICUs, with the general ICU at D5 (p=0.047) and surgical ICU at D8 (p=0.012). The dynamics of NAC colonization by ICU were significantly different at D1 (p=0.011), D5 (p=0.047), and D8 (p=0.012).

Conclusion: We developed and implemented a screening protocol for C. auris while uncovering the colonization patterns of Candida in the ICU. Our findings contribute to the optimization of overall patient management, ensuring that ICU protocols are resilient and adaptive to emerging fungal threats.

Keywords: Candida auris; Candida spp.; colonization; intensive care unit; mannitol salt agar auris; prevalence; surveillance.

Figure 1

Scheme of the mycological algorithm used to screen Candida auris. The algorithm for the molecular identification of C. auris from clinical isolates (blue arrow). C. auris screening from surveillance samples using a specific real-time PCR (green arrow).

Figure 2

Distribution of Candida spp. isolates by ICU (general and surgical FFH and General BAH).

Figure 3

Distribution of Candida spp. isolates by month and hospital ICU. (A) General and surgical FFH and (B) General BAH.

Figure 4

(A, A.1) MSAA plate inoculated with C. auris DSMZ 105986 (Clade II) and DSMZ 105987 (Clade I), and Candida haemulonii DSMZ 70624); (A.2) MSAA plate inoculated with C. auris DSMZ 105988 (Clade III) and DSMZ 105990 (Clade IV), and Candida duobushaemulonii CBS 7798. The MSAA plates were incubated for 48 h at 40°C; (A.3, A.4) MSAA sensitivity, growth at 0.1 McFarland. The Candida spp. tested were: 1 = Candida albicans; 2 = Candida duobushaemulonii; 3 = C. auris DSMZ 105990 (Clade IV); 4 = C. auris DSMZ 105987 (Clade I); 5 = C. auris DSMZ 105988 (Clade III); 6 = Candida haemulonii DSMZ 70624; 7 = Candida glabrata; 8 = Candida parapsilosis; 9 = C. auris DSMZ 105986 (Clade II); 10 = Candida krusei; 11= Candida tropicalis; 12 = Trichosporon mucoides; and 13 = Saccharomyces cerevisiae. (B) Macroscopic observation of C. auris clades I, II, III, and IV after 48 h of incubation at 37°C. MSAA plates inoculated by streaking from suspensions with 10⁶ CFU/ml of the control strains (top row). In CHROMagar Candida, C. auris cultures usually develop an appearance of various shades of pink (center row). On Sabouraud Dextrose Agar (SDA), the colonies generally remain white and creamy (bottom row).