Actinomyces neuii: An emerging pathogen in total hip arthroplasty-related infections

Actinomyces is a gram-positive bacterium that is part of the normal human flora. However, Actinomyces spp. are not among the microorganisms commonly cultured from periprosthetic joint infections. Here, we reported a case of a 67-year-old male who underwent left total hip arthroplasty three years ago and recently developed pain in the left hip. The diagnosis of periprosthetic infection was indicated after two joint fluid aspirations cultured for Actinomyces neuii (A. neuii). A 2-week regimen with vancomycin and penicillin was prescribed postoperatively and oral amoxicillin was continued after hospital discharge. This is the first reported case of periprosthetic hip joint infection caused by A. neuii in China. We also provide a systematic review of recently published cases of A. neuii infections. Our case report highlights that A. neuii infection is a potential differential diagnosis in periprosthetic joint infection.