Assessment of Aspergillus fumigatus burden in lungs of intratracheally-challenged turkeys (Meleagris gallopavo) by quantitative PCR, galactomannan enzyme immunoassay, and quantitative culture

Aspergillus fumigatus remains a major respiratory pathogen in birds and treatment is still difficult. We challenged different groups of few-day-old turkeys via intratracheal aerosolisation with increasing concentrations (105 up to 108) of conidia using a MicroSprayer® device. The fungal burden was assessed by real-time PCR, galactomannan dosage, CFU counting and histopathological evaluation in order to provide a comparison of these results within each inoculum groups. Significant mortality, occurring in the first 96 h after inoculation, was only observed at the highest inoculum dose. Culture counts, GM index and qPCR results on the one hand and inoculum size on the other hand appeared to be clearly correlated. The mean fungal burden detected by qPCR was 1.3 log10 units higher than the mean values obtained by CFU measurement. The new model and the markers will be used to evaluate the efficacy of antifungal treatments that could be used in poultry farms.