The Role of Blood Agar in Demonstrating Phenotypic Characteristics of Human Pathogenic Fungi: Morphological and Growth Comparison with Sabouraud Dextrose Agar

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Published: Oct 31, 2026
Keywords:
Human pathogenic fungi, Blood agar, Sabouraud dextrose agar, Fungal morphology, Medical mycology

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Panyawat Boontanom
Educational Technology and Art Unit, Dean Office, Faculty of Tropical Medicine, Mahidol University, Bangkok 10400
Watcharamat Muangkaew
Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, Bangkok 10400
Pronpan Khum-eam
Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, Bangkok 10400
Natthapaninee Thanomsridetchai
Faculty of Allied Health Sciences, Burapha University, Chonburi 20131

Abstract

Despite advances in modern diagnostic technologies, the diagnosis of human pathogenic fungi still relies substantially on culture, morphological assessment, and direct microscopic examination. Sabouraud dextrose agar (SDA) remains the standard medium for evaluating fungal morphology. However, blood agar is widely used in clinical microbiology laboratories and may be one of the first routine media on which fungi are unexpectedly detected. Understanding how fungi express their phenotypes on blood agar may therefore help laboratory personnel recognize medium-dependent phenotypic variation and reduce potential errors in preliminary interpretation.


This study aimed to compare the growth rates and morphological characteristics of diverse groups of human pathogenic fungi cultured on SDA and blood agar. The organisms included yeasts, dermatophytes, hyaline molds, dematiaceous molds, thermally dimorphic molds, non-septate molds, neglected molds, and an entomopathogenic mold. The initial inocula were standardized to comparable levels. Yeasts were incubated at 37°C, whereas filamentous fungi were incubated at 25°C. Growth rate, colony morphology, surface and reverse coloration, and microscopic structures were subsequently evaluated.


Most fungi were able to grow on blood agar; however, SDA provided clearer visualization of pigmentation, reverse colony morphology, and sporulating structures in many molds. In contrast, blood agar revealed foot-like projections in Candida albicans and a mucoid colony phenotype in Cryptococcus gattii, and greater colony expansion or growth in Candida tropicalis, Pichia kudriavzevii, Microsporum canis, and Aspergillus niger.


In conclusion, SDA remains the primary standard medium for fungal morphological assessment, whereas blood agar may serve as a supplementary medium that reveals selected phenotypic characteristics. Its use may enhance observational skills, result interpretation, and diagnostic evaluation of pathogenic fungi commonly encountered in routine clinical microbiology workflows.

Article Details

Issue
Vol.34 No.5 (September-October 2026)
Section
บทความวิจัย

References

[1] Donnelly, J.P., Chen, S. C., Kauffman, C.A., Steinbach, W.J., Baddley, J.W., Verweij, P.E., Clancy, C.J., Wingard, J.R., Lockhart, S.R., Groll, A.H., Sorrell, T.C., Bassetti, M., Akan, H., Alexander, B.D., Andes, D., Azoulay, E., Bialek, R., Bradsher, R.W., Bretagne, S., Calandra, T., Caliendo, A.M., Castagnola, E., Cruciani, M., Cuenca-Estrella, M., Decker, C.F., Desai, S.R., Fisher, B., Harrison, T., Heussel, C.P., Jensen, H.E., Kibbler, C.C., Kontoyiannis, D.P., Kullberg, B.J., Lagrou, K., Lamoth, F., Lehrnbecher, T., Loeffler, J., Lortholary, O., Maertens, J., Marchetti, O., Marr, K.A., Masur, H., Meis, J.F., Morrisey, C.O., Nucci, M., Ostrosky-Zeichner, L., Pagano, L., Patterson, T.F., Perfect, J.R., Racil, Z., Roilides, E., Ruhnke, M., Prokop, C.S., Shoham, S., Slavin, M.A., Stevens, D.A., Thompson, G.R., Vazquez, J.A., Viscoli, C., Walsh, T.J., Warris, A., Wheat, L.J., White, P.L., Zaoutis, T.E. and Pappas, P. G., 2020, Revision and Update of the Consensus Definitions of Invasive Fungal Disease From the European Organization for Research and Treatment of Cancer and the Mycoses Study Group Education and Research Consortium, Clin. Infect. Dis. 71(6): 1367–76. https://doi.org/10.1093/cid/ciz1008.

[2] Bupha-Intr, O., Butters, C., Reynolds, G., Kennedy, K., Meyer, W., Patil, S., Bryant, P., Morrissey, C. O., and Australasian Antifungal Guidelines Steering Committee, 2021, Consensus guidelines for the diagnosis and management of invasive fungal disease due to moulds other than Aspergillus in the haematology/oncology setting, Intern. Med. J. 51 Suppl 7: 177–219. https://doi.org/10.1111/imj.15592.

[3] Knoll, M.A., Steixner, S., Lass-Flörl, C., 2023, How to use direct microscopy for diagnosing fungal infections, Clin. Microbiol. Infect. 29(8): 1031-8. https://doi.org/10.1016/j.cmi.2023.05.012.

[4] Borman, A.M., Mohammed, S., Palmer, M.D., Childs, N. and Johnson, E.M., 2022, The importance of appropriate processing and direct microscopic examination for the timely diagnosis and management of invasive infections caused by filamentous fungi, Med. Mycol. 60(12): myac081. https://doi.org/10.1093/mmy/myac081.

[5] Chen, H., Zhou, X., Ren, B. and Cheng, L., 2020, The regulation of hyphae growth in Candida albicans, Virulence. 11(1): 337–48. https://doi.org/10.1080/21505594.2020.1748930.

[6] Villa, S., Hamideh, M., Weinstock, A., Qasim, M.N., Hazbun, T.R., Sellam, A., Hernday, A.D. and Thangamani, S., 2020, Transcriptional control of hyphal morphogenesis in Candida albicans, FEMS Yeast Res. 20(1): foaa005. https://doi.org/10.1093/femsyr/foaa005.

[7] Chow, E.W.L., Pang, L.M. and Wang, Y., 2021, From Jekyll to Hyde: The Yeast-Hyphal Transition of Candida albicans, Pathogens (Basel, Switzerland). 10(7): 859. https://doi.org/10.3390/pathogens10070859.

[8] Talapko, J., Juzbašić, M., Matijević, T., Pustijanac, E., Bekić, S., Kotris, I. and Škrlec, I., 2021, Candida albicans-The Virulence Factors and Clinical Manifestations of Infection, J. Fungi (Basel, Switzerland). 7(2): 79. https://doi.org/10.3390/jof7020079.

[9] Ciurea, C.N., Kosovski, I.B., Mare, A.D., Toma, F., Pintea-Simon, I.A. and Man, A., 2020, Candida and Candidiasis-Opportunism Versus Pathogenicity: A Review of the Virulence Traits, Microorganisms. 8(6): 857. https://doi.org/10.3390/microorganisms8060857.

[10] Richardson, J.P., 2022, Candida albicans: A Major Fungal Pathogen of Humans, Pathogens. 11(4): 459. https://doi.org/10.3390/pathogens11040459.

[11] Chang, C.C., Harrison, T.S., Bicanic, T.A., Chayakulkeeree, M., Sorrell, T.C., Warris, A., Hagen, F., Spec, A., Oladele, R., Govender, N.P., Chen, S.C., Mody, C.H., Groll, A.H., Chen, Y.C., Lionakis, M.S., Alanio, A., Castañeda, E., Lizarazo, J., Vidal, J.E., Takazono, T., Hoenigl, M., Alffenaar, J.W., Gangneux, J.P., Soman, R., Zhu, L.P., Bonifaz, A., Jarvis, J.N., Day, J.N., Klimko, N., Salmanton-García, J., Jouvion, G., Meya, D.B., Lawrence, D., Rahn, S., Bongomin, F., McMullan, B.J., Sprute, R., Nyazika, T.K., Beardsley, J., Carlesse, F., Heath, C.H., Ayanlowo, O.O., Mashedi, O.M., Queiroz-Telles, Filho. F., Hosseinipour, M.C., Patel, A.K., Temfack, E., Singh, N., Cornely, O.A., Boulware, D.R., Lortholary, O., Pappas, P.G. and Perfect, J.R., 2024, Global guideline for the diagnosis and management of cryptococcosis: an initiative of the ECMM and ISHAM in cooperation with the ASM, Lancet. Infect. Dis. 24(8): e495-e512. https://doi.org/10.1016/S1473-3099(23)00731-4. Epub 2024 Feb 9. Erratum in: Lancet. Infect. Dis. 24(8): e485. https://doi.org/10.1016/S1473-3099(24)00426-2.

[12] Oliveira, L.S.S., Pinto, L.M., de Medeiros, M.A.P., Toffaletti, D.L., Tenor, J.L., Barros, T.F., Neves, R.P., Neto, R.G.L., Milan, E.P., Padovan, A.C.B., Rocha, W.P.D.S., Perfect, J.R. and Chaves, G.M., 2021, Comparison of Cryptococcus gattii/neoformans Species Complex to Related Genera (Papiliotrema and Naganishia) Reveal Variances in Virulence Associated Factors and Antifungal Susceptibility, Front. Cell. Infect. Microbiol. 11: 642658. https://doi.org/10.3389/fcimb.2021.642658.

[13] Saidykhan, L., Onyishi, C.U. and May, R.C., 2022, The Cryptococcus gattii species complex: Unique pathogenic yeasts with understudied virulence mechanisms, PLoS Neglected Trop. Dis.16(12): e0010916. https://doi.org/10.1371/journal.pntd.0010916.

[14] Al-Huthaifi, A.M., Radman, B.A., Al-Alawi, A.A., Mahmood, F. and Liu, T.B., 2024, Mechanisms and Virulence Factors of Cryptococcus neoformans Dissemination to the Central Nervous System, J. Fungi (Basel, Switzerland). 10(8): 586. https://doi.org/10.3390/jof10080586.

[15] Sprute, R., Cornely, O.A., Chen, S.C., Seidel, D., Schuetz, A.N. and Zhang, S.X., 2021, All You Need To Know and More about the Diagnosis and Management of Rare Yeast Infections, mBio. 12(4): e0159421. https://doi.org/10.1128/mBio.01594-21.

[16] Segal, E., and Elad, D., 2021, Human and Zoonotic Dermatophytoses: Epidemiological Aspects, Front. Microbiol. 12: 713532. https://doi.org/10.3389/fmicb.2021.713532.

[17] Getso, M.I., Hashemi, S.J., Ghazvini, R.D., Yusuf, S.M., Khodavaisy, S., Gerami-Shoar, M., Kibiya, F.S., Aliyu, U.T., Sarvestani, H.K. and Aliyu, M., 2021, Determination of dermatophytes isolated from tinea capitis using conventional and ITS-based sequencing methods in Kano, Nigeria, J. Mycol. Med. 31(3): 101157. https://doi.org/10.1016/j.mycmed.2021.101157.

[18] Jacobs, S.E., Wengenack, N.L. and Walsh, T.J., 2020, Non-Aspergillus Hyaline Molds: Emerging Causes of Sino-Pulmonary Fungal Infections and Other Invasive Mycoses, Semin. Respir. Crit. Care Med. 41(1): 115–30. https://doi.org/10.1055/s-0039-3401989.

[19] Morrissey, C.O., Kim, H.Y., Duong, T.N., Moran, E., Alastruey-Izquierdo, A., Denning, D.W., Perfect, J.R., Nucci, M., Chakrabarti, A., Rickerts, V., Chiller, T.M., Wahyuningsih, R., Hamers, R.L., Cassini, A., Gigante, V., Sati, H., Alffenaar, J.W. and Beardsley, J., 2024, Aspergillus fumigatus-a systematic review to inform the World Health Organization priority list of fungal pathogens, Med. Mycol. 62(6): myad129. https://doi.org/10.1093/mmy/myad129.

[20] Hoenigl, M., Salmanton-García, J., Walsh, T.J., Nucci, M., Neoh, C.F., Jenks, J.D., Lackner, M., Sprute, R., Al-Hatmi, A.M.S., Bassetti, M., Carlesse, F., Freiberger, T., Koehler, P., Lehrnbecher, T., Kumar, A., Prattes, J., Richardson, M., Revankar, S., Slavin, M.A., Stemler, J., Spiess B., Taj-Aldeen, S.J., Warris, A., Woo, P.C.Y., Young, J.H., Albus, K., Arenz, D., Arsic-Arsenijevic, V., Bouchara, J.P., Chinniah, T.R., Chowdhary, A., de Hoog, G.S., Dimopoulos, G.,, Duarte R.F., Hamal, P., Meis, J.F., Mfinanga, S., Queiroz-Telles, F., Patterson, T.F., Rahav, G., Rogers, T.R., Rotstein, C., Wahyuningsih, R., Seidel, D. and Cornely OA., 2021, Global guideline for the diagnosis and management of rare mould infections: an initiative of the European Confederation of Medical Mycology in cooperation with the International Society for Human and Animal Mycology and the American Society for Microbiology, Lancet. Infect. Dis. 21(8): e246–e57. https://doi.org/10.1016/S1473-3099(20)30784-2.

[21] Hoenigl, M., Levitz, S.M., Schuetz, A.N., Zhang, S.X. and Cornely, O.A., 2021, All You Need to Know and More about the Diagnosis and Management of Rare Mold Infections, mBio. 12(1): e02920-20. https://doi.org/10.1128/mBio.02920-20.

[22] Skiada, A., Pavleas, I. and Drogari-Apiranthitou, M., 2020, Epidemiology and Diagnosis of Mucormycosis: An Update, J. Fungi. (Basel, Switzerland). 6(4): 265. https://doi.org/10.3390/jof6040265f6040265.

[23] Pham, D., Howard-Jones, A.R., Sparks, R., Stefani, M., Sivalingam, V., Halliday, C.L., Beardsley, J. and Chen, S.C, 2023, Epidemiology, Modern Diagnostics, and the Management of Mucorales Infections, J. Fungi (Basel, Switzerland). 9(6): 659. https://doi.org/10.3390/jof9060659.

[24] Abdillah, A., Khelaifia, S., Raoult, D., Bittar, F. and Ranque, S., 2020, Comparison of Three Skin Sampling Methods and Two Media for Culturing Malassezia Yeast, J. Fungi (Basel, Switzerland). 6(4): 350. https://doi.org/10.3390/jof6040350.

[25] Abdillah, A. and Ranque, S., 2021, MalaSelect: A Selective Culture Medium for Malassezia Species. J. Fungi. (Basel, Switzerland). 7(10): 824. https://doi.org/10.3390/jof7100824.

[26] Atsü, N., Ergin, Ç., Caf, N., Türkoğlu, Z., Döğen, A. and İlkit, M., 2022, Effectiveness of FastFung agar in the isolation of Malassezia furfur from skin samples, Mycoses. 65(7): 704–8. https://doi.org/10.1111/myc.13450.

[27] Roth, M., Daas, L., MacKenzie, C.R., Balasiu, A., Stachon, T., Neumann, I., Steindor, F., Seitz, B. and Geerling, G., 2020, Development and Assessment of a Simulator for in Vivo Confocal Microscopy in Fungal and Acanthamoeba Keratitis, Curr. Eye Res. 45(12): 1484–9. https://doi.org/10.1080/02713683.2020.1772830.

[28] Chandler, D., 2022, Direct microscopy in the dermatology clinic: enhancing the management of skin infections and infestations, Clin. Exp. Dermatol. 47(6): 1023-9. https://doi.org/10.1111/ced.151185118.

[29] Cornely, O.A., Sprute, R., Bassetti, M., Chen, S.C., Groll, A.H., Kurzai, O., Lass-Flörl, C., Ostrosky-Zeichner, L., Rautemaa-Richardson, R., Revathi, G., Santolaya, M.E., White, P.L., Alastruey-Izquierdo, A., Arendrup, M.C., Baddley, J., Barac, A., Ben-Ami, R., Brink, A.J., Grothe, J.H., Guinea, J., Hagen, F., Hochhegger, B., Hoenigl, M., Husain, S., Jabeen, K., Jensen, H.E., Kanj, S.S., Koehler, P., Lehrnbecher, T., Lewis, R.E., Meis, J.F., Nguyen, M.H., Pana, Z.D., Rath, P.M., Reinhold, I., Seidel, D., Takazono, T., Vinh, D.C., Zhang, S.X., Afeltra, J., Al-Hatmi, A.M.S., Arastehfar, A., Arikan-Akdagli, S., Bongomin, F., Carlesse, F., Chayakulkeeree, M., Chai, L.Y.A., Chamani-Tabriz, L., Chiller, T., Chowdhary, A., Clancy, C.J., Colombo, A.L., Cortegiani, A., Corzo Leon, D.E., Drgona, L., Dudakova, A., Farooqi, J., Gago, S., Ilkit, M., Jenks, J.D., Klimko, N., Krause, R., Kumar, A., Lagrou, K., Lionakis, MS., Lmimouni, B.E., Mansour, M.K., Meletiadis, J., Mellinghoff, S.C., Mer, M, Mikulska, M., Montravers, P., Neoh, C.F., Ozenci, V., Pagano, L., Pappas, P., Patterson, T.F., Puerta-Alcalde, P., Rahimli, L., Rahn, S., Roilides, E., Rotstein, C., Ruegamer, T., Sabino, R., Salmanton-García, J., Schwartz, I.S., Segal, E., Sidharthan, N., Singhal, T., Sinko, J., Soman, R., Spec, A., Steinmann, J., Stemler, J., Taj-Aldeen, S.J., Talento, A.F., Thompson, G.R. 3rd, Toebben, C., Villanueva-Lozano, H., Wahyuningsih, R., Weinbergerová, B., Wiederhold, N., Willinger, B., Woo, P.C.Y., Zhu, L.P., 2025, Global guideline for the diagnosis and management of candidiasis: an initiative of the ECMM in cooperation with ISHAM and ASM, Lancet. Infect. Dis. 25(5): e280–93. https://doi.org/10.1016/S1473-3099(24)00749-7.

[30] Kruithoff, C., Gamal, A., McCormick, T.S. and Ghannoum, M.A, 2023, Dermatophyte Infections Worldwide: Increase in Incidence and Associated Antifungal Resistance, Life (Basel, Switzerland). 14(1): 1. https://doi.org/10.3390/life14010001.