First report of Anaerococcus tetradius in bilateral tubo-ovarian abscess following intra-uterine device insertion

Tubo-ovarian abscess (TOA) is a life-threatening complication of pelvic inflammatory disease. A 30-year-old woman presented with bilateral tubo-ovarian abscesses, one week after the insertion of a levonorgestrel-releasing intrauterine device. The patient required intensive care management with intravenous antibiotics, along with ultrasound-guided abscess drainage. Anaerobic culture of the aspirated pus samples (3) yielded Anaerococcus tetradius . The patient recovered fully after 17 days of hospital stay. This is the first documented case of Anaerococcus tetradius isolated from a bilateral TOA, likely from subclinical bacterial vaginosis exacerbated by IUD insertion. This report raises the possibility of the unrecognised pathogenic potential of A. tetradius . • First reported case of monomicrobial bilateral tubo-ovarian abscess (TOA) caused by Anaerococcus tetradius • Identification made using MALDI-TOF MS with a high confidence score (99.9%) in three pus samples • IUD insertion may introduce anaerobic flora into the upper genital tract, particularly in the presence of subclinical bacterial vaginosis • Maintain high suspicion for anaerobic pathogens in post-IUD PID