Isolation of Arcanobacterium haemolyticum from calves with pneumonia and proposal of a diagnostic protocol.

The aims of this study are the isolation and identification of possible bacteriological agents in respiratory infections of calves and the optimization of a diagnostic protocol to identify Arcanobacterium haemolyticum. Lesions of lungs from calves with pneumonia were examined. Cultural, morphological and conventional biochemical testing were done. The investigation was complemented by the double CAMP test. Five strains of Arcanobacterium haemolyticum in pure culture were found. The presence of Arcanobacterium haemolyticum in the lungs of calves with pneumonia was established and, consequently, more attention should be paid to this species in everyday laboratory work. The cultural similarity of Arcanobacterium haemolyticum to common bacteria like beta-hemolytic Streptococcus spp. and Arcanobacterium pyogenes is probably responsible for rare reports on the isolation of Arcanobacterium haemolyticum in veterinary microbiology. Our results indicate that Arcanobacterium haemolyticum could be or is the etiological agent of pneumonia. Therefore, we suggest the diagnostic protocol available for routine work in most microbiological laboratories. [Projekat Ministarstva nauke Republike Srbije, br. 41012]