Air samples were collected in occupied and unoccupied rooms
in a suburban elementary school in Columbia, SC, using an N6
Single Stage, Viable Impactor (Thermo Fisher Scientific, Inc., Waltham,
MA), which has a nominal flow rate of 28.3 l/min. Sheep
blood agar [SBA] plates were used with the viable impactor and
subsequently incubated at 37 C for 24e48 h. Individual b-hemolytic
colonies were re-streaked several times until pure cultures
were obtained. Gram-positive cocci occurring in tetrads or clusters
are predominantly staphylococci and micrococci, and were selected
for further characterization [3].