Polymicrobial Periprosthetic Infection with Pasteurella canis Following Total Knee Arthroplasty: A Case Report

Background and clinical significance:Pasteurella spp. are Gram-negative coccobacilli, aerobic facultatively anaerobic, belonging to the Pasteurellaceae family. In humans, they are known to cause zoonotic diseases, which usually develop after dog or cat bites, licks or scratches. Case presentation: We present the case of a 61-year-old patient, with cardiovascular comorbidities, who presented to the Orthopedics Department, 38 days after knee replacement surgery, with recurrence of pain on walking, an antalgic gait with auxiliary support, and local signs of inflammation at the level of the left knee joint. The patient admitted to owning a dog who accidentally licked the post-surgical wound. The symptoms were suggestive of a post-surgical wound infection with extension to the periprosthetic area. A purulent discharge was collected from the wound during surgical debridement and sent to the microbiological laboratory for diagnosis, where Pasteurella canis was identified using MALDI-TOF MS. Antibiotic susceptibility testing (AST) was performed according to the EUCAST guidelines and empiric antibiotic treatment was started with Cefuroxime. During his future admissions to the Orthopedics and Infectious Diseases departments, two more samples were collected, in which Pasteurella canis was isolated, along with Klebsiella oxytoca (second sample), and Klebsiella oxytoca and Pseudomonas aeruginosa (third sample). Patient evolution was favorable due to the debridement of the wound and combined antibiotic treatment, with Ceftazidime and Gentamicin. Conclusions: Infections with Pasteurella canis are rare but slowly increasing due to more and more humans owning pets. The present case underlines the importance of interdisciplinary collaborations when rare pathogens are identified.