Comparison of hair sheep with commercial blood agar in
growth studies
Several human pathogens were evaluated for their growth,
colony morphology, and hemolytic reactions on hair sheep blood
agar. On standard wool sheep blood media, both Group B
streptococcus and Group A streptococcus grow as translucent
colonies exhibiting b-hemolysis. Group A streptococcus colonies
tend to be smaller (,0.5 mm) with a sharply demarcated zone of
hemolysis surrounding each colony and extending beyond the
colony, while Group B streptococcus colonies are slightly larger
(.0.5 mm) with soft b-hemolysis directly underneath the colony.
These characteristics of their growth and hemolytic pattern on
wool sheep blood agar were also apparent on both citrated and
defibrinated hair sheep blood agar. Similarly, Streptococcus anginosus
which is distinguished by its pinpoint colonies and characteristic
sweet smell on standard blood agar could also be accurately
identified by these features on hair sheep blood agar. The growth
of two different strains of S. pneumoniae, ATCC 49619 and a clinical
isolate, were also compared on standard media and hair sheep
blood media. Both grew as transparent colonies and exhibited ahemolysis
typical of S. pneumoniae on citrated and defibrinated hair
sheep agar. In addition, the clinical strain had a type 3
polysaccharide capsule mucoid phenotype on standard blood
media that was also visible on hair sheep media. Finally, Listeria
monocytogenes grew as large (1 mm) colonies with b-hemolysis
limited to the area underneath the colony on both standard wool
sheep blood agar and hair sheep agar.
Accuracy of hair sheep blood agar in CAMP, rever