E corrodens occurs as a significant clinical infection more frequently than suspected or cultured at the present time. It is essential that the dentist or physician work closely with the laboratory clinician in order to use proper techniques for its isolation. Inconsistencies between in vitro disk sensitivity and clinical drug response are noted. Because of clinical response, the clinician must carefully follow the patient's daily progress to recognize antibiotic treatment failure so that combination therapy or appropriate incision and drainage procedures may be initiated.