[Cervical actinomycosis due to Actinomyces naeslundii].

Actinomyces naeslundii, an oral biofilm bacterium of, can be cured using intravenous piperacillin, clindamycin, and surgery. We report a case of cervical actinomycosis due to Actinomyces naeslundii. A 56-year-old man seen for right cervical swelling had undergone dental work. Computed tomography indicated an abscess, from which we aspirated pus using a needle. Although no sulfur granules were found, pus yielded Actinomyces naeslundii. This case is, to our knowledge, the first reported in Japan of cervical actinomycosis due to A. naeslundii.