Prevalence of pulmonary mycotic lesions and antifungal susceptibility pattern of fungi isolated from nigerian trade cattle

Abstract

Pulmonary mycosis is a major cause of deaths in many livestock herds, especially in immune-compromised animals. A total of 138 lung samples (6mm in size) were collected from cattle slaughtered for meat at Nsukka abattoir. Swab sticks were dipped into each lung sample and streaked on freshly prepared Sabouraud Dextrose Agar (SDA) for fungal isolation. Isolated fungi were identified using morphological and microscopic features. Disc diffusion method was used to test the antifungal susceptibility pattern of a randomly selected isolates with voriconazole (1μg), fluconazole (25μg) and methanol extract of Garcinia kola, using disc diffusion method. The lung samples were examined for lesions using histopathological procedures. Out of the 138 lung samples, 23 had fungal growths while 115 had no growth of any sort. A total of 34 fungi were isolated as pure cultures. Aspergillus spp. had the highest frequency of isolation, 44.92%, followed by Penicillium spp. 11.76%, Trichophyton spp. 5.88%, Conidiobolus and Sporothrix species had 2.94% isolation rate each. About 29.6% of the isolated fungi could not be identified. Fungal positive lungs showed acute to sub-acute inflammatory responses with bronchiolar septal, alveolar interstitium and peribronchial inflammatory cell infiltration and thickening of the lung tissues. All the screened fungal isolates were sensitive to voriconazole with the zone of inhibition ranging from 12-27mm. The fungal isolates were all resistant to fluconazole and G. kola extract, except one that showed sensitivity to the extract. Voriconazole showed strong antifungal effect on all the fungi; but the efficacy of the G. kola on the fungal isolates was very low compared to voriconazole.