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This time we present two different cases of calves with granulomatous lesions in lymph nodes, in both cases the same etiological agent could be isolated. Can you guess which one?

Unilateral pyogranulomatous lesion in the retropharyngeal lymph node of a 12-month-old Friesian calf.

 

Mineralized lesions in the left tracheobronchial lymph node of a 14-month-old crossbred calf.

 

What is your diagnosis? (86)

%%RATING%%

Microscopically, the lesions did not rule out tuberculosis as they consisted of areas of necrosis, with mineralization and with the presence of inflammatory infiltrate rich in neutrophilic polymorphonuclear leukocytes but also macrophages and multinucleated giant cells. Ziehl Neelsen's staining gave a negative result. PCR to detect genome of the M.tuberculosis complex also tested negative. However, abundant colonies of bacteria compatible with Rhodococcus equii could be isolated from standard microbiological culture. In these cases it is ALWAYS necessary to carry out laboratory analyzes to differentiate them from tuberculosis. A propper anatomopathological and microbiological diagnosis will rule out the suspicion of tuberculosis on the farm and maintain the rating without having to wait for a negative result from the culture of mycobacteria, which usually lasts takes longer.
 

Microbiological culture allowed pure isolation of Rhodococcus equii.


Your answers are highlighted below.
Question 1
Which ethioligcal agent was cultured from these lesions?
A
Nocardia spp.
B
Mycobacterium caprae
C
Mycobacterium bovis
D
Corynebacterium pseudotuberculosis
E
Rhodococcus equii
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