Injection-site abscess caused by group A beta-hemolytic Streptococcus. An unusual complication of tonsillectomy and intramuscular injection.

The epidemiologic investigation of any IM injection site infection can be quite complex. In this particular case, one potential source of the organism was established (the patient herself), another source was shown to be less likely (the nurses administering the medications), and a third possible source (the single-dose unit medications) could not be eliminated.