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. 2022 Oct 28;12(4):e43.
doi: 10.5415/apallergy.2022.12.e43. eCollection 2022 Oct.

Identification of fungi causing humidifier lung: 2 rare cases and a review of the literature

Kai Ryu  1   2 , Yuma Fukutomi  1 , Kiyoshi Sekiya  1 , Akemi Saito  1 , Yuto Hamada  1 , Kentaro Watai  1 , Yosuke Kamide  1 , Masami Taniguchi  1   3 , Jun Araya  2 , Kazuyoshi Kuwano  2 , Katsuhiko Kamei  4
Affiliations

Identification of fungi causing humidifier lung: 2 rare cases and a review of the literature

Kai Ryu et al. Asia Pac Allergy. .

Abstract

Background: Humidifier lung (HL) is a hypersensitivity pneumonitis resulting from exposure to humidifiers, with fungi from the humidifier as one of the etiologic agents. However, identification of the fungal species responsible for each case can be challenging because of difficulties in culturing fungi, their accurate identification, and interpreting the results of specific serum IgG testing.

Objective: To clarify the best way to determine the causative fungal species of each HL case.

Methods: We report 2 cases with HL in which rare fungi were identified as causative agents. In addition, we searched MEDLINE for previous publications on HL caused by fungi and performed a literature review focusing on clinical testing for the determination of causal fungal species.

Results: In our 2 cases, we identified Fusarium oxysporum species complex, Purpureocillium lilacinum, Acremonium sclerotigenum/egyptiacum as the causative fungal species, based on findings that these could be cultured from humidifier water (HW) and precipitins against these fungi were also positive. The literature review identified 31 HL cases in which the causative fungal species had been documented. In more than half of the cases (17 of 31) there was a concordance between the fungal species cultured from HW and the presence of specific IgG in the blood.

Conclusion: We recommend performing culture of fungi from HW and specific serum IgG testing for the accurate determination of the causative fungal species in HL, and concordance between them serves as a rationale for the determination of causative fungal species.

Keywords: Air conditioner; Fungi; Humidifier lung; Hypersensitivity pneumonitis; Mycoses.

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Conflict of interest statement

Conflict of Interest: YF received contracts from any entity from Novartis Pharma KK. YF received payment or honoraria for lectures, presentations, speakers bureaus, manuscript writing or educational events from Thermo Fisher Diagnostics KK, Torii Pharmaceutical Co, Ltd, Novartis Pharma KK, Kyorin Pharmaceutical Co, Ltd, Sanofi KK, and Taiho Pharmaceutical Co, Ltd. YK received payment or honoraria for lectures, presentations, speakers bureaus, manuscript writing or educational events from payment or honoraria for lectures, presentations, speakers bureaus, manuscript writing or educational events from Sanofi KK, GlaxoSmithKline KK, and AstraZeneca KK. MT (To National Hospital Organization Sagamihara National Hospital) received grants or contracts from any entity GlaxoSmithKline K.K, Sanofi, and Novartis. Received payment or honoraria for lectures, presentations, speakers bureaus, manuscript writing or educational events from GlaxoSmithKline K.K, Sanofi, and Novartis. JA received grants or contracts from any entity from The Uehara Memorial Foundation, Japanese Respiratory Foundation, Grant-in-Aid for Scientific Research (KAKENHI), Philips K.K., Boehringer-ingelheim. JA received payment or honoraria for lectures, presentations, speakers bureaus, manuscript writing or educational events from Sanofi K.K., Kyorin Pharmaceutical Co, Ltd, GlaxoSmithKline K.K., AstraZeneca K.K., Boehringer-ingelheim. JA served participation on a Data Safety Monitoring Board or Advisory Board from Janssen Pharmaceutical K.K. JA received receipt of equipment, materials, drugs, medical writing, gifts or other services from Kowa Company, Ltd. KR, KS, AS, YH, KW, KK (Kazuyoshi Kuwano), and KK (Katsuhiko Kamei) have stated that no potential conflicts of interest exist with any companies/organizations whose products or services may be discussed in this publication.

Figures

Fig. 1
Fig. 1. Flow-chart for the inclusion of articles in the literature review.
Fig. 2
Fig. 2. Causative fungi for cases with humidifier lung in the literature by humidifier type. †Including fungi reported as Cephalosporim spp.
Fig. 3
Fig. 3. Proposal for procedures for the diagnosis of humidifier lung and the identification of causative fungi. Refers to the latest diagnostic criteria †(AJRCCM 2020;202:e36-69). ‡(Chest 2021;160:e97-156), performed by inhalation of nebulized humidifier water, by exposure in a challenge chamber, or environmental provocation.
See this image and copyright information in PMC

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