Post-mortem diagnosis of septic arthritis by Pasteurella multocida: a case report and literature review of fatal septic arthritis

The diagnosis of septic arthritis remains challenging in the clinical setting, often leading to a suspicion for medical liability. Our purpose is to describe an unusual case of a post-mortem diagnosis of P. multocida fatal septic arthritis, in a healthy 67-year-old woman presenting with pain in the right shoulder. Moreover, a literature review of cases of fatal septic arthritis is provided. The multidisciplinary approach consisted of a forensic autopsy and additional post-mortem analyses (microbiology, biochemical analyses, histopathology, and revision of radiological images) carried out during the prosecutor's investigation for medical liability. A systematic review of the literature was performed to collect cases of fatal septic arthritis and to understand its frequency and characteristics. No clear cause of death was determined after the autopsy, that only highlighted swelling and purulent exudation in the right glenohumeral joint. The microbiological swab performed on the shoulder tested positive for P. multocida, while histopathological and biochemical data were consistent with a sepsis. These results guided the interview with the woman's relatives, until a history of a previous contact with a stray cat emerged. The cause of death was deemed as fatal septic arthritis caused by P. multocida, occurred after cat scratches and bites and only diagnosed post-mortem. The review of the literature provided 15 articles about fatal septic arthritis, only 1 caused by P. multocida, and all with ante-mortem diagnosis. Given the nonspecific symptoms, usually including a localized pain, and the absence of a clear history, e.g. of animal contact, septic arthritis might represent an under-reported clinical and pathological diagnosis, leading to a judicial autopsy for the suspicion for medical liability. The post-mortem examination, following a multidisciplinary approach including integration of the clinical history, microbiological and histopathological analysis, could represent the only opportunity for the diagnosis of the cause of death.