Hypersensitivity pneumonitis caused by occupational exposure to phytase

Abstract

A 43-yr-old male presented with a 6-month history of episodes of coughing, shortness of breath and fever. He suffered from dyspnoea on minor exertion. The patient worked in a cattle feed factory and noticed that he had more complaints after his working hours. His symptoms could be ascribed to hypersensitivity pneumonitis due to contact with phytase, an enzyme added to cattle feed to strengthen bone and diminish phosphorus excretion.The diagnosis was supported by bibasal lung crackles on physical examination, restrictive ventilatory defect (with decreased diffusion capacity for carbon monoxide), typical radiographical findings, lymphocytosis in bronchoalveolar lavage fluid and a positive exposure test performed at the workplace. Blood examination showed high immunoglobulin G levels to phytase.After treatment and cessation of phytase contact the patient became symptom free and lung function normalised. Phytase should be considered as a cause of occupational hypersensitivity pneumonitis in the animal feed industry.KEYWORDS: Extrinsic allergic alveolitis, hypersensitivity pneumonitis, phytase CASE REPORT A 43-yr-old male without prior illness was referred to the outpatient clinic of our department with symptoms of cough and shortness of breath on minor exertion, fever and malaise (especially fatigue). He had lost 8 kg of weight since his complaints had started 6 months earlier and had been a non-smoker for 20 yrs. There was a relationship between his complaints and his working hours. He had worked in a factory that produces cattle feed for .20 yrs where his role was to take samples of the cattle feed at different departments on different floors for quality control. He noticed that after having taken samples on one particular floor, 6-8 h later, his complaints started. The next morning the complaints had almost disappeared. He had no symptoms during the holidays. None of his colleagues (n521) had similar symptoms.At physical examination pulse and blood pressure were normal. At auscultation of the lungs normal breath sounds were heard but with bibasal crackles. Erythrocyte sedimentation rate was 33 mm?h -1 and C-reactive protein was 11 mg?L ). Blood leukocytes, total immunoglobulin (Ig)E, antinuclear antibodies and specific IgE for common aeroallergens were all within reference values.

Addressing Molecular Diagnosis of Occupational Allergies

“… *Phytase produced in Trichoderma reesei has been reported as cause of hypersensitivity pneumonitis in a patient working in a factory producing cattle feed [ 81 ]; phytase is so far not commercially available for IgE antibody testing **Material is purified from a swine extract for IgE antibody testing …”

Berufsbedingte Allergie gegen Phytase: Fallserie von acht Produktionsmitarbeitern, die Futtermittelzusatzstoffen ausgesetzt waren

“…Eine Sensibilisierung tritt nicht nur bei stark exponierten Arbeitern in der Produktion, sondern auch bei Büroangestellten enzymverarbeitender Betriebe mit geringer Exposition auf[1,6,9,10]. Wie im Fall der hier vorgestellten Patienten handelte es sich bei den Symptomen überwiegend um allergische Reaktionen vom Typ I. Allerdings wurde auch ein Fall einer IgG-vermittelten exogen-allergischen Alveolitis nach Exposition gegenüber Phytase beschrieben[17].Arbeitsschutzmaßnahmen müssen darauf abzielen, Inhalation und Hautexposition zu vermeiden. Das Einatmen von Allergenen kann durch das Tragen von Gebläseeinheiten mit geeigneten Filtersystemen verhindert werden.…”

Update in Environmental and Occupational Medicine 2009

“…Two novel potential causes of hypersensitivity pneumonitis (HP) were reported, including HP related to phytase, a bonestrengthening enzyme added to cattle feed (78), and HP with only indirect person-to-person contact to the putative antigen (''consort HP'') (79).…”