agalactiae and S. pneumoniae. .
Many physiological tests were performed for the identification of the organisms isolated from the pharynx and of the unknown streptococci samples. The pharyngeal isolates were obtained from the posterior wall of the pharynx with a wooden swab while the tongue was depressed (1). Hemolysis was examined on the petri plates of blood agar, inoculated with the pharyngeal isolates, to help narrow the identification range of possible streptococcal species present. Alpha hemolysis is when some red blood cells occupy the hemolytic zone, beta hemolysis is when no red blood cells are found in the hemolytic zone. Alpha hemolysis is much more likely to be present in the throat than beta hemolysis (1).
Inoculations were made on the basis of the two types oh hemolysis. The pharyngeal isolates were tested through the alpha hemolytic type inoculations and the unknown cultures (x, y, z) were all found to be beta, henceforth, the beta hemolytic type inoculations were performed on the unknown samples. Next, these plates were used to perform further various physiological tests. Such as the organisms reaction to CAMP. If the organisms produced an arrowhead shaped hemolytic area at its closest point to the streak of Staphylococcus aureus, then it is said to be Streptococci agalactiae.
Bacitracin susceptibility was tested next. This was easily done by the placement of a taxos-A disk onto the streaked area of the plate. Any zone of inhibition formed around this taxos-A disk proves to be a positive result, indicating that the unknown organisms must belong to either group A (S. pyogenes) or to Pneumonococci (S. pneumoniae).
Further, SXT sensitivity testing was used to distinguish between group A and B from other beta hemolytic streptococci (1). Any of the beta hemolytic streptococci that prove to be susceptible to the SXT and resistant to the bacitracin likely belong to group C of the streptococci.
