Abstract
Aim
Analysis of the effect of administration of antibiotics before collection of microbiology samples in patients with septic arthritis of the native and prosthetic knee.
Method and Results
A retrospective analysis of patients admitted to the unit with a diagnosis of septic arthritis of the knee. There were 27 infections in 26 native knees and 27 infections in 26 prosthetic knees. Sixty-three percent of the native knees had received antibiotics prior to collection of microbiology samples. Fifty-three percent of these grew an organism from at least one of their aspirate, washout fluid or swab. Of the 37% that did not have antibiotics 100% grew an organism. There was no difference in the type or length of treatment required between the groups. Forty-one percent of the prosthetic knees had received antibiotics prior to collection of microbiology samples. Forty-five percent of these had an organism identified. Of the 59% that did not have antibiotics 81% had an organism identified. Overall 67% had an organism isolated, fifty-six percent of these retained their implant. Thirty-three percent of those with no organism identified retained their implant.
Conclusion
Administration of antibiotics before samples have been collected for microbiology has a significant effect on the likelihood of isolating a responsible organism in both native and prosthetic knees. This does not have an effect on the outcome in the native knee but does have a significant effect in the prosthetic knee.
