APPLICATION OF THE API YEASTIDENT SYSTEM IN DETERMINING THE ENZYMATICPROFILES OF NOCARDIA-ASTEROIDES ISOLATES

Glucose represses production of ammonium in many clinical isolates of Nocardia asteroides growing on bromcresol-purple casein glucose agar. Strains exhibiting this property are designated as group A, while grou p B represents isolates showing a high degree of proteolytic activity and a resulting rapid increase in pH. Twenty isolates of N, asteroides were characterized as group A or B. Enzymatic profiles obtained using the API Yeastldent system showed significant enzymatic variation betw een 12 group B and 8 group A isolates. Proteolytic enzymes which most varied in activity between groups were glycine aminopeptidase, histidi ne aminopeptidase and leucyl glycine aminopeptidase. As some of the N. asteroides isolates were isolated from asymptomatic patients, it is o f interest to consider the possibility of one group being of low virul ence while the other is more strongly associated with infection.