DiagnosticMedium for Arcanobacterium haemolyticum and for Other Bacterial Species Reac-ting by Haemolytic Synergism with equi Factor of Rhodococcus equi

Overview

Colonies of Arcanobacterium haemolyticum on common blood agar can be easily overlooked.Therefore a diagnostic medium was developed, on which A. haemolyticum colonies produce a con-spicuous zone of complete hemolysis. The medium under question is blood agar prepared from theColumbia Blood Agar Base and 5% washed sheep erythrocytes sensitised with equi factor (EF) ofRhodococcus equi. Optimally, 10 activity units (AU) of EF per 1 ml were used. EF was titrated ona non-nutrient medium consisting of agar Purified (Difco) and 5% washed sheep erythrocytessensitized with b-haemolysin (BL) of Staphylococcus aureus, 10 AU/ml. On the same medium,staphylococcal BL was titrated on the basis of its direct haemolytic effect. Despite the very distincthaemolytic reaction of the control strains evident on the diagnostic medium with EF, A. haemolyti-cum failed to grow from 2.597 throat swabs examined especially for the particular microbe duringthe a period of two years. However, A. haemolyticum was isolated on this medium twice from 223swabs from wounds and skin lesions. The proposed medium makes also the rapid diagnosis of speciesCorynebacterium ulcerans, Dermatophilus congolensis and Listeria monocytogenes on the basis ofhaemolytic synergism possible.

Key words:
Arcanobacterium haemolyticum – diagnostic medium – haemolytic synergism – equi