EP 749 A Case Report of Septic Arthritis of the Knee with Unusual Microbial Findings

Abstract

A lady in her early 50s presented with a 2-day history of pain and swelling of the left knee. There was no recent history of trauma in the time leading up to admission. A knee aspirate was attempted but returned no fluid, and she was treated as a case of severe cellulitis. Blood tests showed biochemical worsening and progressing infection, though blood cultures remained negative.

An MRI was performed due to worsening swelling, which showed soft tissue oedema, medial and suprapatellar collections. After these results, the patient was taken to theatres for arthroscopic washout. Initial joint fluids cultures were negative, but she further deteriorated with medical management. Three further washouts were required, with future cultures growing streptococcus anginosus, haemophilus parainfluenzae, corynebacterium, anaerobes, coagulase negative staphylococci and diphtheroids, anaerobes, eikenella corrodens, prevotella, veillonella, enterobacter cloacae, and staphylococcus aureus.

A thorough antibiotic regiment guided by microbiology advice was followed throughout admission. The patient eventually improved and progressed, with regular follow-ups as an outpatient.