Aspergillus fumigatus in dairy herd's environment in relation with the somatic cell counts and gliotoxin production

M. PELLEGRINO; V. ALONSO; C. RASPANTI; A. M. SALCERO; S. CHIACCHIERA; C. BOGNI; L. CAVAGLIERI

Mendoza

Congreso; Strategies to reduce the impact of mycotoxins in Latin America in a global context; 2011

Universidad Nacional de Río Cuarto

Several species of Aspergillus genera can behave as pathogenic agents, emphasizing A. fumigatus among them. This environmental microorganism is a ubiquitous fungus which produces a wide variety of infections, both in humans and in animals. In ruminants, they have been reported as causing mastitis, respiratory processes, abort, and other clinical processes, being the more numerous references in cattle that in sheep and goats. Experimentally infection assays with A. fumigatus in sheep and goat, verified that it can cause abortion and mastitis. In addition, many reports have described cases of mastitis caused by A. fumigatus in cows. The inhibition of bacterial growth by antibiotics may promote the growth of the fungi into the mammary gland, thus influencing the pathogenesis and severity of the intramammary infections. On the other hand, A. fumigatus spores are easily spread in the air and pose a high risk of exposure for both animals and humans. At the present there are not reports that describe the fungal microbiota of bovine milk. Fungi are dispersed throughout the cow’s environment; the alone presence of them might be indicating the contamination of the milk with mycotoxins. A. fumigatus might induce, through their toxins, neurological syndromes to farm workers who have manipulated mouldy feed. The aim of this study was to establish the role of A. fumigatus in the cow’s environment and the interaction with the SCC in milk. Bacterial and fungal strains were isolated from 901 cows milk concerned to 44 dairy establishments. Associations among A. fumigatus, coagulase negative Staphylococcus (CNS) and somatic cell counts (SCC) were performed through a principal component analysis. Numerous establishments (75%) had SCC≥250000 cells/ml in bulk tank milk. The CNS were isolated from the 58% of the milk samples and they were present in the 100% establishments. Eight species of Aspergillus were identified from individual milk samples. Aspergillus flavus and A. fumigatus were the predominant with 37.8% and 26.1% relative densities, respectively. was isolated from 61.4% of the bulk milk tank samples. All A. fumigatus isolated were able to produce gliotoxin in levels from 5.1 to 44.56 ng Kg-1.Many tank samples (45%) had A. fumigatus associated with high SCC. A high association between A. fumigatus and high SCC was observed. On the other hand, A. fumigatus and CNS were associated in 66.7% samples with high SCC. A high percentage of dairy farms had A. fumigatus in milk tank samples. A closely interaction among A. fumigatus, CNS and SCC was found. This fact could be related to the opportunistic nature of both microorganisms that might be in association to produce damage in the udders and therefore increase the SCC. Because these fungi are dispersed throughout the cow’s environment, it is probably that the contamination of milk comes from these toxigenic fungi mainly when hygiene measures are not suitable for dairy herd’s animals. The importance of this, is that the alone presence of fungi might be indicating contamination of the milk with mycotoxins