Listeria innocua infection in an old case of total knee replacement – an unusual case report

Prosthetic implant-associated arthritis due to Listeria is mostly reported for Listeria monocytogenes . Here, we describe a patient who underwent total knee replacement 12 years ago and presented with pain, tenderness, redness and local rise in temperature in the right knee. Purulent fluid was aspirated. Upon microbiological analysis, culture yielded Listeria innocua . L. innocua is rare. Listeria is not reported as a contaminant and routine cultures may be negative. Because of the long interval between surgery and the onset of symptoms, clinical suspicion, radiological investigations and analysing multiple samples are of immense help.