Periprosthetic Hip Joint Infection Involving Fusobacterium nucleatum With Subsequent Isolation of Acinetobacter baumannii: A Case Report.

Periprosthetic joint infection (PJI) is a serious complication following total hip arthroplasty and is most commonly caused by Gram-positive organisms. Infections involving anaerobic bacteria or multidrug-resistant Gram-negative pathogens are rare and particularly challenging to manage. We report a case of periprosthetic hip infection in a female patient in whom Fusobacterium nucleatum (F. nucleatum) was initially isolated, followed by Acinetobacter baumannii (A. baumannii) later in the treatment course. Initial management with debridement, antibiotics, and implant retention (DAIR) was unsuccessful, necessitating implant removal, placement, and subsequent removal of a cement spacer, as well as prolonged targeted antimicrobial therapy, including cefiderocol. Following staged revision arthroplasty, successful infection eradication was achieved with an excellent functional outcome. This report highlights the complexity of PJI management, the potential for microbiologic evolution under antimicrobial pressure, and the importance of tailored surgical and antimicrobial strategies.