Accuracy of hair sheep blood agar in CAMP, reverse
CAMP, and satellite colony formation tests
In the clinical laboratory, certain organisms can be identified by
specialized tests that take advantage of metabolic requirements or
virulence factors characteristic of that pathogen. These tests are
simple and low-cost to perform but can be invaluable in
identification of certain pathogens. As discussed previously, Group
B streptococci secrete CAMP factor that results in increased
hemolysis when grown near S. aureus on blood agar [5–7]. As
shown in Figure 2A, both defibrinated and citrated hair sheep
blood agar demonstrated a positive CAMP reaction for Group B
streptococcus, as seen by an arrowhead area of clearing on the
agar (indicating enhanced hemolysis) where Group B streptococcus
and S. aureus grow closest to each other. In contrast,
Arcanobacterium haemolyticum secretes an inhibitory factor that
suppresses the secondary b-hemolysin of S. aureus [13]. In the
reverse CAMP test, there is an area of suppressed hemolysis by S.
aureus when the colonies are growing adjacent to A. haemolyticum,
seen as an indentation in the linear area of hemolytic clearing by S.
aureus