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Candida spp. are human commensals and are commonly found on skin and throughout the gastrointestinal tract. Central venous catheters (CVC) and an immunocompromised state are major risk factors for candidemia [1, 2]. Thus, bloodstream infections (BSI) due to Candida spp. are more common in patients with hematological malignancies (1.4 vs. 0.83 cases/1,000 admissions) [2]. Candida BSI is associated with a higher 28-day all-cause mortality in hospitalized patients with hematological malignancies (45 vs. 11%) [2]. Early diagnosis, rapid initiation of appropriate treatment, and prompt source control (e.g. CVC removal) is key for reducing mortality in candidemia [3, 4].
Blood cultures (BC) are the gold standard to diagnose BSI, including candidemia [5]. The time-to-result, or turnaround time (TAT), for the microscopic result, in BC diagnostics depends on several factors: First, the incubation delay (“time-to-machine”), i.e. the time needed until the BC bottle is inoculated, transported to the BC instrument, and incubation is started. Second, the “time-to-positivity” (TTP), i.e. the time needed by the BC instrument to detect microorganisms in the BC bottle. Third, the “result-to-report” time, i.e. the time needed for processing and reporting a Gram stain. The incubation delay and the result-to-report time are heavily dependent on organizational processes like transport and laboratory working hours.
Aerobic and anaerobic BC media are not optimal for the growth of all yeast species [5]. This can be exploited for predicting the presence of C. glabrata with high specificity when earlier detection of growth occurs in anaerobic BC media [6]. However, false-negative BC results are life-threatening, especially in high-risk, neutropenic patients. About 50% of BC in candidemia are false-negative, but BC positivity can be increased by culturing a higher volume of blood (i.e. two aerobic bottles and one anaerobic BC bottle), or by using a broth medium designed for an enhanced yield of yeasts (so-called fungus or mycosis BC) [5].
So far, guidelines do not recommend a higher blood volume or mycosis BC for hematology patients [7, 8], or patients with CVC [9, 10], who are at higher risk for candidemia.
In this study, we aimed to evaluate the influence of different BC media and incubation delays on the ability to detect yeasts. In brief, blood from healthy donors was warmed up to 38.3 °C, mimicking a febrile patient [8] with hematogenous dissemination of yeasts due to e.g. chemotherapy-induced mucositis, graft-vs.-host disease, or an indwelling CVC. Then, the blood was immediately inoculated with C. albicans, the most common causative species found in candidemia [1]. The prepared blood sample was transferred into BACTEC™ Plus Aerobic/F (“Aerobic”), Anaerobic/F (“Anaerobic”), Lytic 10 Anaerobic/F (“Lytic”), and Mycosis-IC/F (“Mycosis”) BC bottles and incubated in a BC instrument immediately (hour 0), or stored at 20–25 °C and transferred with a delay of 2, 4, 8, 12, and 16 h, respectively. BC bottles were incubated until positivity or for a maximum of 5 days. All BC were sub-cultured to verify the growth in every bottle. Each experiment was repeated three times for each of the six different time points. In a simulated scenario, the TAT was calculated considering an incubation delay due to transport times of 2, 4, 8, 12, and 16 h as well as laboratory working hours from 07:00 a.m. to 6:00 p.m. on workdays with the TTP data form this experiment. Details for materials and methods are described in the Supplementary Material.
In total, 72 BC were spiked with C. albicans. None of the 18 Lytic BC bottles became positive, however, growth was detected in 5/18 (27.8%) in subcultures, indicating that yeasts are viable in the lytic medium for several days. Only 7/18 (38.9%) Anaerobic BC turned positive. However, in all 11 subcultures with no positive signal growth was possible (100%).
In all 18 Mycosis BC as well as in all 18 Aerobic BC a positive signal was detected. We found a shorter TTP for Mycosis BC compared to Aerobic BC for all time points; with a mean 13.71 h (23.22 vs. 36.93 h; p < 0.001) shorter TTP over all time points (Table 1).
In a simulated scenario taking into account the transport time and the laboratory working hours, the mean TAT for Mycosis BC were significant shorter compared to Aerobic BC (p < 0.001 for all), with a difference up to 24 h (Table S1).
Furthermore, we analyzed data from 948 BC drawn in clinical routine from 08/02/2020 to 07/28/2021 in the Department of Hematology and Oncology. Roughly half (463/948, 48.8%) of all BC were drawn in the late afternoon and evening, i.e. between 4:00 p.m. and 10:00 p.m. Only 62 of these 463 (13.4%) BC arrived at the laboratory on the same day; 320 (69.9%) BC arrived the next day in the morning hours (between 7:00 a.m. and 10:00 a.m.). Blood cultures received in the morning hours had a median transport time of 10.0 h (range 1–23).
As in other institutions [11], the “time to machine” shows potential for improvement, with a TAT of 1.5 days for a microscopic result. Although, an incubation delay results in a shorter TTP [11], our analysis shows, that this cannot compensate for an increased TAT. Key drivers for a longer TAT were the reduced availability of transportation and laboratory workforce during evening and nighttime. This could be partially compensated for by satellite BC systems, however, their clinical utility remains to be determined [12].
Our results show that the detection of C. albicans can be markedly improved by using Mycosis BC bottles. However, previous antifungal therapy, especially with echinocandins, was reported to increase TTP in Mycosis BC bottles [13, 14]. Further, our results cannot be extrapolated to other fungal species and other BC systems. For example, the recovery rate for C. glabrata was significantly lower in the BACTEC™ than in the BacT/ALERT® system, and it is recommended to include the mycosis medium in BC at centers that use the BACTEC™ system and for patients at risk for candidemia [15]. Given our results, we propose to incorporate the use of specialized BC media into relevant guidelines for patients without previous antifungal treatment with a high risk for candidemia, e.g. in hematology. This may result in earlier treatment and source control with improved prognosis.
Data availability
The data that support the findings of this study are available from the corresponding author upon reasonable request.
References
Pfaller M, Neofytos D, Diekema D, et al. Epidemiology and outcomes of candidemia in 3648 patients: data from the Prospective Antifungal Therapy (PATH Alliance®) registry, 2004–2008. Diagn Microbiol Infect Dis. 2012;74:323–31. https://doi.org/10.1016/j.diagmicrobio.2012.10.003.
Gamaletsou MN, Walsh TJ, Zaoutis T, et al. A prospective, cohort, multicentre study of candidaemia in hospitalized adult patients with haematological malignancies. Clin Microbiol Infect. 2014;20:O50–7. https://doi.org/10.1111/1469-0691.12312.
Mikulska M, Del Bono V, Ratto S, Viscoli C. Occurrence, presentation and treatment of candidemia. Expert Rev Clin Immunol. 2012;8:755–65. https://doi.org/10.1586/eci.12.52.
Mellinghoff SC, Cornely OA, Jung N. Essentials in Candida bloodstream infection. Infection. 2018;46:897–9. https://doi.org/10.1007/s15010-018-1218-1.
Miller JM, Binnicker MJ, Campbell S, et al. A guide to utilization of the microbiology laboratory for diagnosis of infectious diseases: 2018 update by the Infectious Diseases Society of America and the American Society for Microbiology. Clin Infect Dis. 2018;67:e1-94. https://doi.org/10.1093/cid/ciy381.
Cobos-Trigueros N, Kaasch AJ, Soriano A, et al. Time to positivity and detection of growth in anaerobic blood culture vials predict the presence of Candida glabrata in candidemia: a two-center European cohort study. J Clin Microbiol. 2014;52:3082–4. https://doi.org/10.1128/JCM.01198-14.
Freifeld AG, Bow EJ, Sepkowitz KA, et al. Clinical practice guideline for the use of antimicrobial agents in neutropenic patients with cancer: 2010 update by the Infectious Diseases Society of America. Clin Infect Dis. 2011;52:e56-93. https://doi.org/10.1093/cid/cir073.
Heinz WJ, Buchheidt D, Christopeit M, et al. Diagnosis and empirical treatment of fever of unknown origin (FUO) in adult neutropenic patients: guidelines of the Infectious Diseases Working Party (AGIHO) of the German Society of Hematology and Medical Oncology (DGHO). Ann Hematol. 2017;96:1775–92. https://doi.org/10.1007/s00277-017-3098-3.
Mermel LA, Allon M, Bouza E, et al. Clinical practice guidelines for the diagnosis and management of intravascular catheter-related infection: 2009 update by the Infectious Diseases Society of America. Clin Infect Dis. 2009;49:1–45. https://doi.org/10.1086/599376.
Böll B, Schalk E, Buchheidt D, et al. Central venous catheter-related infections in hematology and oncology: 2020 updated guidelines on diagnosis, management, and prevention by the Infectious Diseases Working Party (AGIHO) of the German Society of Hematology and Medical Oncology (DGHO). Ann Hematol. 2021;100:239–59. https://doi.org/10.1007/s00277-020-04286-x.
Rönnberg C, Mildh M, Ullberg M, Özenci V. Transport time for blood culture bottles: underlying factors and its consequences. Diagn Microbiol Infect Dis. 2013;76:286–90. https://doi.org/10.1016/j.diagmicrobio.2013.03.031.
Guo Z, Guo B, Wang S, Zhang H, Zhang W, Qin B, Shao H. Impact of satellite blood culture on early diagnosis of sepsis. J Intensive Med. 2021;2:56–60. https://doi.org/10.1016/j.jointm.2021.11.003.
Köck R, Eißing LC, Boschin MG, Ellger B, Horn D, Idelevich EA, Becker K. Evaluation of bactec Mycosis IC/F and Plus Aerobic/F blood culture bottles for detection of Candida in the presence of antifungal agents. J Clin Microbiol. 2013;51:3683–7. https://doi.org/10.1128/JCM.02048-13.
Laroche L, Mercier V, Sasso M. BD BACTEC™ Mycosis IC/F culture vials for fungemia diagnosis and follow-up: a retrospective study from 2013 to 2020. Diagn Microbiol Infect Dis. 2023;105: 115863. https://doi.org/10.1016/j.diagmicrobio.2022.115863.
Arendrup MC, Bruun B, Christensen JJ, et al. National surveillance of fungemia in Denmark (2004 to 2009). J Clin Microbiol. 2011;49:325–34. https://doi.org/10.1128/JCM.01811-10.
Acknowledgements
We thank Lisa Fröhlich for their technical support.
Funding
Open Access funding enabled and organized by Projekt DEAL. BACTEC™ Lytic 10 Anaerobic/F Culture Vials were provided free of charge by Becton Dickinson, Heidelberg, Germany.
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JF designed the study, carried out the experiments, interpreted the data, and revised the manuscript. AJK interpreted the data and revised the manuscript. ES designed the study, recruited the donors, collected the blood samples, analyzed and interpreted the data, and wrote the manuscript. All authors approved the final version of the manuscript.
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Ethics approval
The study protocol (ENTRY, Effects of Delayed Entry into Blood Culture Systems on Culture Positivity) was approved by the Ethics Committee of the Medical Faculty of the Otto von Guericke University Magdeburg, Magdeburg, Germany (approval no. 115/14).
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All blood donors gave written informed consent.
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Färber, J., Kaasch, A.J. & Schalk, E. Shorter time-to-positivity and turnaround time with mycosis blood culture bottles when detecting Candida albicans. Infection 52, 701–703 (2024). https://doi.org/10.1007/s15010-024-02216-x
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DOI: https://doi.org/10.1007/s15010-024-02216-x