Safety assessment of dairy microorganisms: Geotrichum candidum

Geotrichum candidum is a ubiquitous filamentous yeast-like fungus commonly isolated from soil, air, water, milk, silage, plant tissues, digestive tract in humans and other mammals. This species is widely used as adjunct culture in the maturation of cheese. The genus Geotrichum is composed of 18 species. A recent taxonomic revision concluded that the old Galactomyces geotrichum/G. candidum complex contained four separate species of which Galactomyces candidus sp. nov./G. candidum. M13 primer can be used for identifying species of the Geotrichum genus. Used in combination, RAPD-PCR and RAM-PCR permit strains to be differentiated. The species can be unambiguous differentiated from the two species most frequently described in human pathology: Geotrichum clavatum (reclassified Saprochaete clavata) and Geotrichum capitatum (reclassified Magnusiomyces capitatus/Saprochaete capitata). Sources of exposure are food ingestion – cheese consumption playing a major role – inhalation and contact. A bibliographic survey was conducted to assess corresponding hazards and risks. G. candidum infections (mainly pulmonary or bronchopulmonary, but also cutaneous, oral, disseminates) are very rare: fewer than 100 cases reported between 1842 and 2006. Moreover, cases were not all confirmed by repeated isolations and demonstration of the fungus' presence in tissues, a prerequisite to establish a true diagnosis of geotrichosis. Immunocompromised population was recently shown as a target for opportunistic infection. The most effective treatments include either azole drogs as ketonazole, iconazole and clotrimazole, or polyene antibiotics as amphotericin B, nystatin and pimaricin, or voriconazole–amphotericin B association. Less than 1 case/year of disease was possibly caused by G. candidum and it never included dairy products or foodborne infection. The risk of developing an infection due to G. candidum in connection with its technological use and consumption of dairy products is virtually nil. For these reasons, G. candidum should be proposed for QPS status.