Mycobiota and Ochratoxin A in laboratory mice feed: preliminary study.

The occurrence of mycotoxin-producing moulds in animal feed is a hazard for animals. When these undesirable substances contaminate laboratory animal feed, convey an additional problem in experimental animal assays confidence levels. The aim of this study was to evaluate fungal contamination and to determine natural occurrence of Ochratoxin A (OTA) in 31 samples. OTA is a mycotoxin produced by fungi of two genera: Penicillium and Aspergillus. OTA has been shown to be nephrotoxic, hepatotoxic, teratogenic and immunotoxic to a number of animal species and to cause kidney and liver tumors in mice and rats. In this preliminary study, feed mould counts ranged from 3 to 4.2 log(10) cfu/g (colonies forming units per gram). When these species are present, there is a significant risk of contamination with mycotoxins resulting in both acute diseases called mycotoxicoses and chronic conditions, often recognized as situations involving mycotoxins. The most frequent genus isolated was Cladosporium sp. (84%), followed by Aspergillus niger and Penicillium (81%) and Mucor sp. (77%). All rat feed samples were examined for OTA, using High Performance Liquid Chromatography (HPLC). The detection limit was 2.0 microg OTA kg(-1) and all samples revealed to be negative for this mycotoxin. These mycotoxicological researches put in evidence the importance of the use contaminant-free experimental animal feed in order to prevent any interference on the health of experimental animals and emphasizes the need for systematic control of the feed as a key issue in animal experimentation.