Comparison of New and Old BacT/Alert Aerobic Bottles for Detection of Candida spp.

Purpose A new version of aerobic blood culture media has been developed for the BacT/Alert (bioMérieux) blood culture system. We evaluated the TTD and yeast cell counts in positive blood cultures for each Candida spp. according to changes in media. Methods Isolates from defibrinated horse blood were inoculated into three types of bottles: the old version of FA Plus (Old FA Plus), New FA Plus, and FN Plus. All bottles were incubated in the BacT/Alert Virtuo blood culture system. The TTD was monitored for each bottle, and yeast cell counts were performed immediately after testing positive, determined via the plate count method. Clinical retrospective data of the candidemia samples before and after aerobic bottle change also were analyzed. Results The mean TTD was 51.2 hours in the Old FA Plus bottles versus 19.5 hours in the New FA Plus bottles (P < 0.001) for Candida glabrata, and standard and clinical strains showed similar results. C. albicans (27.6 to 25.1 hours) and C. guilliermondii (28.8 to 27.3 hours) had shorter TTDs. However, C. auris (25.6 to 28.1 hours) had a longer TTD in the New FA Plus bottle. The retrospective clinical analysis showed a significant decrease in TTD (45.0 to 19.4 hours) for C. glabrata, which is consistent with our simulated study. Conclusion This study shows that the TTD of C. glabrata was markedly reduced in the New FA Plus bottle due to the optimized growth performance. The reduction of TTD enables faster detection and therapeutic approach for C. glabrata infections.


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Candidemia is an increasingly major healthcare-associated fungal infection associated with 45 high morbidity and mortality [1,2]. The epidemiology of candidemia varies according to the 46 geographical region, period, and population; however, recent studies have reported a global shift towards other Candida spp. from Candida albicans, although C. albicans is still the 48 predominant species [2,3].

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C. glabrata is a common pathogen whose proportions are increasing among non-C. albicans 50 infections and is causing bloodstream infections worldwide, including South Korea [4][5][6]. 51 Candidemia caused by C. glabrata has clinical significance due to antifungal resistances, 52 including intrinsic decreases in susceptibility to azole agents and resistances to amphotericin 53 B [6]. It has been reported that C. glabrata was more affected by the blood culture system and 54 medium than C. albicans [7,8].

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The new version of aerobic blood culture media has been developed for the BacT/Alert 56 (bioMérieux) blood culture system. The primary purpose of the formulation changes was to 57 increase the growth performance of several microorganisms particularly C. glabrata. The new 58 BacT/Alert aerobic media (New FA Plus) has been shown to have equivalent performance 59 compared with the old version, except for the reduced time to detection (TTD) of some 60 microorganisms.

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There have been no studies on the effects that the change in aerobic blood culture bottle has 62 on the TTD and growth performance of various Candida spp. Therefore, we aimed to analyze 63 the changes in TTD and yeast cell count for several Candida spp. according to media changes 64 through a simulated blood spiking study and clinical retrospective data analysis. immediately after testing positive via the plate count method using SDA as the culture medium.

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The blood culture medium was also subcultured on blood agar plates to exclude contamination 89 and to confirm the true-positive or true-negative detection results.

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Yeast cell count 91 The positive blood culture was mixed and serially diluted in saline to dilutions of 10 -3 , 10 -4 , 92 and 10 -5 , the dilutions were vortexed, and 100 uL of each dilution was spread onto a separate 93 SDA plate. After overnight incubation, the plates were examined for colonies. The number of 94 CFU per milliliter was calculated based on the dilution factor [10].

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Retrospective data analysis for clinical blood culture results 96 We performed blood culture positive data analysis on the Candida spp. to confirm whether 97 the data verified through the procedures using horse blood can be applied to clinical candidemia 98 cases between 1 September 2020 and 15 June 2022. We divided the data into two periods:

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Simulated study data 113 The TTD values were compared among the 14 isolates performed in triplicate for each bottle 114 type ( The yeast cell count showed no significant difference between the aerobic and anaerobic bottles 138 for C. dubliniensis and C. lusitaniae.

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The TTD of C. glabrata in the FN Plus bottle was shorter than that of the Old and New FA

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In total, 100 isolates of candidemia were analyzed (Fig 1). shorter detection time in the Virtuo device compared with the simulated data.

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The simulation study revealed that C. albicans and C. gullicromondii were detected faster in