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. 2021 Sep 3;9(1):e0008021.
doi: 10.1128/Spectrum.00080-21. Epub 2021 Aug 4.

Recovery and Its Dynamics of Filamentous Fungi from Clinical Specimen Cultures: An Extensive Study

Affiliations

Recovery and Its Dynamics of Filamentous Fungi from Clinical Specimen Cultures: An Extensive Study

Jian R Bao et al. Microbiol Spectr. .

Abstract

The culture method remains vital in diagnosing fungal infections, but extensive data-based evaluation of the method, especially for filamentous fungi (molds), is minimal. The purpose of this study was to characterize mold recoveries from fungal cultures and the impact of media and incubation duration. Clinical specimens for fungal cultures were submitted primarily from the eastern and central United States, and mold isolation data were prospectively collected and analyzed. A total of 1,821 molds in 59 genera were isolated from 1,687 positive specimens, accounting for approximately 5.6% of our cohort of 30,000 fungal cultures. Within 2 weeks, nearly 90% of molds and 97.3% of Aspergillus fumigatus complex were recovered (>95% confidence interval [CI]). All Mucorales fungi were recovered within 11 days of incubation. The recovery peak time was day 3 for Mucorales fungi, day 4 for hyaline molds, day 5 for dematiaceous molds, and day 7 for Onygenales fungi. The recovery of Histoplasma capsulatum and Trichophyton species in the fourth week of incubation reveals that a 3-week incubation time is insufficient. Inhibitory mold agar was the best medium for recovering all mold types among all tested specimen types, yielding nearly 78% of mold growth overall, indicating the necessity of selective medium for fungal cultures. IMPORTANCE Fungal culture is the gold standard method of diagnosing fungal infections, but important information, such as the impact of media and incubation times on fungal recovery, is not well documented. This study addressed these gaps using extensive data-based evaluation focused on molds. We identified the best medium types and incubation times for better fungal culture practice. We analyzed 1,821 molds from 1,687 positive specimens in our cohort of approximately 30,000 fungal cultures. Mold recovery peaked between 3 and 7 days of incubation, dependent upon the type of mold. Some well-defined fungal pathogens, such as Histoplasma capsulatum and Trichophyton species, were isolated in the fourth week of incubation. Inhibitory mold agar was identified as the best medium for recovering all mold types among all tested specimen sources. As we are aware, this is the largest study of fungal culture methods and supports 4 weeks of incubation for optimal mold recovery.

Keywords: culture media; filamentous fungi (molds); fungal culture; incubation time; mold types.

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Figures

FIG 1
FIG 1
Geographic origins of the positive filamentous fungus culture specimens. Puerto Rico (18 positives) not shown.
FIG 2
FIG 2
Number of molds recovered over incubation time.

References

    1. Terrero-Salcedo D, Powers-Fletcher MV. 2020. Updates in laboratory diagnostics for invasive fungal infections. J Clin Microbiol 24:e01487-19. doi:10.1128/JCM.01487-19. - DOI - PMC - PubMed
    1. Douglas AP, Chen SCA, Slavin MA. 2016. Emerging infections caused by non-Aspergillus filamentous fungi. Clin Microbiol Infect 22:670–680. doi:10.1016/j.cmi.2016.01.011. - DOI - PubMed
    1. Fisher MC, Hawkins NJ, Sanglard D, Gurr SJ. 2018. Worldwide emergence of resistance to antifungal drugs challenges human health and food security. Science 360:739–742. doi:10.1126/science.aap7999. - DOI - PubMed
    1. Robert MG, Romero C, Dard C, Garnaud C, Cognet O, Girard T, Rasamoelina T, Cornet M, Maubon D. 2020. Evaluation of ID fungi plates medium for identification of molds by MALDI Biotyper. J Clin Microbiol 58:e01687-19. doi:10.1128/JCM.01687-19. - DOI - PMC - PubMed
    1. Kelly BT, Pennington KM, Limper AH. 2020. Advances in the diagnosis of fungal pneumonias. Expert Rev Respir Med 14:703–714. doi:10.1080/17476348.2020.1753506. - DOI - PMC - PubMed