Indoor damp surfaces harbor molds with clinical significance

Abstract

Background and purpose: Fungal contamination in damp places in buildings has become an increasing problem worldwide. Dampness facilitates the growth of fungi, which can cause adverse effects not only on the buildings but also on their occupants. The aim of this study was to identify indoor mold species in the buildings of Kerman province, Iran.

Materials and methods: In this study, 110 samples were obtained from surfaces of damp indoor areas in buildings randomly selected in Kerman province. The identification of fungal species was based on the macroscopic and microscopic characteristics of the isolates, such as colony morphology, hyphae, conidia, and conidiophores, as well as molecular sequence data.

Results: Based on the results, a total of 218 fungal isolates were obtained. Apart from frequently isolated fungi, such as Alternaria, Aspergillus, and Penicillium, 13 species, including Cladosporium sphaerospermum, Cladosporium herbarum, Cladosporium halotolerans, Engyodontium album, Collariella bostrychodes, Stachybotrys xigazenensis, Ramularia eucalypti, Fusarium merismoides, Fusarium solani, Ochroconis musae, Mucor racemosus, Acremonium zonatum, and Acremonium persicinum were identified, and the selected species were described. Among these 13 species, Cladosporium was the most common species (43%) in indoor surfaces, followed by Ochroconis musae (10.8%) and Engyodontium album (7.4%). To the best of our knowledge, Stachybotrys xigazenensis was reported in the present study for the first time in Iran. In addition, E. album and O. musae were isolated for the first time from indoor surfaces in Iran.

Conclusion: According to the results, the level of overall fungal richness across indoor surfaces was high. Some of the isolated taxa were clinically significant. It was concluded that the damp residential surfaces were potentially passive collectors of clinically significant molds.

Keywords: Fungal diversity; Molecular identification; Mycoses.

Figure 1

Incidence rate of indoor fungal species in the damp environments of buildings in Kerman, Iran

Figure 2

Cladosporium sphaerospermum: a) colony incubated for 14 days at 25°C grown on Potato Dextrose Agar (PDA), b-d) conidiophores and conidia, e) ramoconidia and conidia; Cladosporium halotolerans: f) colony incubated for 16 days at 25°C grown on PDA, g) conidiophores with denticles, h) conidia; Cladosporium herbarum: i) colony incubated for 21 days at 25°C grown on PDA, j) nodulose conidiogenous cells with sympodial proliferation, k) ramoconidia, l) conidia with distal hila (scale bars=10 µm)

Figure 3

Ramularia eucalypti: a) colony incubated for 10 days at 25°C grown on Potato Dextrose Agar (PDA), b-c) conidiophores and conidia; Ochroconis musae: d) colony incubated for 14 days at 25°C grown on PDA, e-f) conidiophores and conidia; Engyodontium album: g) colony incubated for 7 days at 25°C grown on PDA, h) conidia, i) conidiophores and conidia (scale bars=10 µm, c=50 µm)

Figure 4

Collariella bostrychodes: a-b) colony incubated for 14 days and 25 days at 25°C grown on Potato Dextrose Agar (PDA), c) asci, d) ascomata mounted in lactophenol acid fuchsin, e) ascospores; Stachybotrys xigazenensis: f) colony incubated for 7 days at 25°C grown on PDA, g-h) conidiophores, conidia, and conidiogenous cells (scale bars=10 µm, h=50 µm)

Figure 5

Fusarium merismoides: a) colony incubated for 60 days at 25°C grown on Potato Dextrose Agar (PDA), b) macroconidia; Fusarium solani: c) colony incubated for 5 days at 25°C grown on PDA, d) macroconidia, e) false head, f) chlamidospore; Acremonium persicinum: g) colony incubated for 10 days at 25°C grown on PDA, h) phialid and spores; Acremonium zonatum: i) colony incubated for 10 days at 25°C grown on PDA, j) phialid and spores; Mucor racemosus: k) colony incubated for 5 days at 25°C grown on PDA, l-m) sporangium and sporangiospores (scale bars=10 µm, e=50 µm)