An episode of group C streptococcal colonization occurred in a newborn nursery. Because these organisms were sensitive to bacitracin in the concentration used in the disk method, they were presumptively identified as group A streptococci. This was interpreted as the onset of a nursery outbreak of group A streptococcal infection. The presence of bacitracin-sensitive group C streptococci in a potentially significant clinical situation emphasizes the importance of performing Lancefield classification before positively identifying organisms as group A streptococci.
Drusin LM, Ribble JC, Topf B. Group C Streptococcal Colonization in a Newborn Nursery. Am J Dis Child. 1973;125(6):820-821. doi:10.1001/archpedi.1973.04160060032006