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Volume 32, Number 3—March 2026

Research

Environmental and Phylogenetic Investigations of Aspergillus flavus Outbreak Linked to Contaminated Building Materials, Denmark, 2025

Alexander Gewecke, Raphael Niklaus Sieber, Søren Hallstrøm, Marc Stegger, Barbara Kolarik, Jenny D. Knudsen, Birgitte Andersen, Astrid Hall, Nadja Hawwa Vissing, and Maiken Cavling ArendrupComments to Author 
Author affiliation: Statens Serum Institut, Copenhagen, Denmark (A. Gewecke, R.N. Sieber, S. Hallstrøm, M. Stegger, M.C. Arendrup); Harry Butler Institute, Murdoch University, Perth, Western Australia, Australia (M. Stegger); dansk MiljøAnalyse, Vedbæk, Denmark (B. Kolarik); Copenhagen University Hospital, Rigshospitalet, Copenhagen (J.D. Knudsen, A. Hall, N.H. Vissing, M.C. Arendrup); Aalborg University, Copenhagen (B. Andersen); University of Copenhagen, Copenhagen (M.C. Arendrup)

Main Article

Table 2

Aspergillus flavus genotypes found in 145 isolates in study of environmental and phylogenetic investigations of Aspergillus flavus outbreak linked to contaminated building materials, Denmark, 2025*

Source of isolate(s) (genotype) No. isolates STRAfla-markers
Comments
2A 2B 2C 3A 3B 3C 4A 4B 4C
Patients 1, 2, 4, 6, 9, 10, 16, 17, 18, 20, 21 (genotype A)† 19 26 11 12 12 26 9 9 5 9
Patient 21 3 26 11 12 12 25 9 9 5 9
Patients 5, 7 ,12–14, 15, 19 (genotype B) 8 25 11 12 12 26 9 9 5 9
Patient 11 1 26 11 12 12 27 9 9 5 9
Patient 11 1 27 11 12 12 27 9 9 5 9
Patient 8 1 26 11 14 12 26 9 9 5 9
Patient 3 1 25 11 12 12 26 9 9 5 NA‡
Patient 15
1
25
11
12
12
26
13
9
5
9

Air samples (genotype A)† 9 26 11 12 12 26 9 9 5 9 Pediatric hematology ward
Plywood cupboard in room A§ (genotype A)† 2 26 11 12 12 26 9 9 5 9 Pediatric hematology ward
Vacuum cleaner bag (genotype A)† 2 26 11 12 12 26 9 9 5 9 Pediatric hematology ward
DCM laboratory incubator (genotype B)
5
25
11
12
12
26
9
9
5
9

Hospital interior (genotype A)† 69 26 11 12 12 26 9 9 5 9 Adult/pediatric hematology ward
Hospital interior 1 62 11 12 9 20 9 7 12 10 Central complex
Hospital interior 1 40 12 11 8 13 4 7 7 9 South complex¶
Hospital interior 1 31 11 10 8 13 14 7 12 10 Adult hematology ward
Hospital interior 2 27 13 8 14 29 9 9 5 9 Central complex
Hospital interior 1 20 16 11 10 22 32 7 8 8 Pediatric hematology ward
Hospital interior 2 15 16 28 11 17 15 7 8 9 South complex¶
Hospital interior
1
14
11
10
8
22
9
7
12
10
Adult hematology ward
MDF (genotype C) 1 26 11 13 12 28 9 9 5 9 Retailer 1
MDF (genotype D) 1 NA‡ NA‡ NA‡ 12 27 9 9 5 9 Retailer 2
OSB (genotype E) 1 26 11 12 12 27 9 9 5 9 Retailer 1
PW (genotype E)
1
26
11
12
12
27
9
9
5
9
Retailer 1
Soil-1a 1 15 7 22 16 12 16 9 5 8
Soil-1b 1 15 7 23 17 13 5 9 5 8
Soil-6a 1 15 11 12 8 30 14 8 7 10
Soil-7a 1 16 7 11 19 6 5 7 5 8
Soil-7b 1 30 11 11 8 24 15 7 7 10
Soil-7c 1 15 7 21 18 12 11 10 5 8
Soil-7d 1 28 11 11 8 20 9 7 12 10
Soil-7e 1 29 11 11 8 23 15 7 7 10
Soil-7f 1 16 7 33 14 6 11 17 5 8
Soil-7g
1
39
11
10
8
45
9
7
12
10

Total 145

*Including 33 isolates compiled from Gewecke et al. (6). Patient numbers in bold indicate cases in which culture-plate contamination was assumed because of lack of symptoms, lack of statements in the medical records, or both. Gray shading indicates STRAfla marker overlaps with outbreak. MDF, medium-density fiberboard; OSB, oriented strand board; PW, plywood. †Principal South complex outbreak cluster genotype A. 
‡No STRAfla profile. 
§Microscopy-confirmed growth of A. flavus on kitchen plywood cupboard in room A (see Figure 4).
¶South complex but different floor than outbreak ward.

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Page created: January 21, 2026
Page updated: March 20, 2026
Page reviewed: March 20, 2026
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