Proposed Topic (Most preferred): :
Research and Innovations (new projects / technology / innovations / service models)
Proposed Topic (Second preferred): :
HA Young Investigators Session (Projects to be presented by HA staff who had joined HA for 10 years or less)
Authors (including presenting author) :
Luk HKH(1), Won SF(1), Lau KT(1), Chu CMK(1), Fung WY(1)(2), Wong SCY(1)(2), Lung DC(1)(2)
Affiliation :
(1)Department of Pathology, Queen Elizabeth Hospital, (2)Department of Pathology, Hong Kong Children’s Hospital
Introduction :
Candida auris is an emerging multidrug-resistant yeast that can cause invasive infections with high mortality and is associated with hospital outbreaks. Culture-based protocol is currently the main method for active surveillance and screening of asymptomatic patients from non-sterile sites, and timely identify potential carriers is a key step in containing hospital spread of C. auris. Two culture-based methods had been used in the Microbiology laboratory of the Queen Elizabeth Hospital (QEH) for Candida auris surveillance, namely the direct put-up and turbidity examination method (method 1) and blind subculture method (method 2). Both protocols have its merit in terms of accuracy, turnaround time (TAT), workload and cost, while the blind subculture method may have a potential advantage of higher sensitivity in the detection of cases where broth did not turn turbid.
Objectives :
A prospective study has been conducted from 13th November, 2023 to 1st January, 2024 to compare the two different culture-based protocols in the Microbiology laboratory of QEH for the screening of C. auris from non-sterile site.
Methodology :
During the study period, combined swabs submitted for C. auris screening (nasal swab + axilla and groin combined swab) from patients in 3B ward of Kowloon Hospital (KH) were tested in parallel using the two culture-based protocols. Performance was evaluated in terms of concordance rate, turnaround time (TAT), cost and hands-on time.
Result & Outcome :
A total of 263 samples were received during the study period. The positive rate was 18.25% (48/263) with 100% concordance between the two methods. In particular, none of the blind sub-cultured clear salt broths were culture positive, i.e., no additional positives were identified using method 2. The average TAT for positives was 3.56 and 4.38 days for method 1 and 2, respectively. Of the 48 culture positive cases, longer TATs were observed more frequently with method 2, where 31 (64.58%) cultures with method 2 had TAT 1 – 4 days (average 1.26 days) longer than method 1, compared with only 7 (14.58%) cultures with longer TAT with method 1 (range 1-2 days, average 1.29 days). Method 1 had lower reagent cost for chromogenic agar ($1156.4 vs $1960) and shorter total hands-on time (770.03 vs 912.68 minutes) per 100 samples, excluding susceptibility testing. Blind subculture method did not demonstrate superior sensitivity in the current parallel evaluation in this study. Moreover, the direct put-up and turbidity examination method demonstrated shorter TAT in 64% of specimen, lower reagent cost and shorter hands-on times in out setting. The critical difference in TAT could lead to clinical impact as timely identification and isolation of C. auris positive patients is the key step in containing the spread of C. auris in healthcare setting.
