We report a rare case of suppurative thrombophlebitis of the posterior neck caused by Streptococcus constellatus. A 69-year-old female patient was admitted to the hospital with neck pain and fever, which had persisted for 16 days prior to hospitalization. On day 1 (day of admission), blood cultures (later identifying S. constellatus) were performed, and ceftriaxone (CTRX) IV (2 g SID) was started. On day 3, suppurative thrombophlebitis of the posterior neck was diagnosed by CT scan. The antimicrobials were changed from CTRX to ampicillin/sulbactam IV (12 g QID) to guard against the possibility of complicated infection with Fusobacterium spp. or Prevotella spp. On day 17, a CT scan revealed that the thrombus remained. Therefore, oral edoxaban (30 mg SID) was started. On day 27, the patient was discharged after her medication was changed to oral amoxicillin/clavulanate (1500 mg/375 mg TID). On day 33, the amoxicillin/clavulanate was changed to oral cefaclor (1500 mg TID) and edoxaban was discontinued due to itching. On day 45, the course of cefaclor was completed. The patient went on to follow an uneventful course with no relapses or complications for two years since the conclusion of treatment. These results suggest that when a patient presents with persistent neck pain accompanied by fever, suppurative thrombophlebitis of the posterior neck should be considered. In antimicrobial therapy, the treatment could be switched from intravenous to oral. In addition, direct-acting oral anticoagulants may be an alternative to other forms of anticoagulants.
Keywords: Streptococcus constellatus; amoxicillin/clavulanate; cefaclor; edoxaban; oral switch; suppurative thrombophlebitis.