Author(s): Mohamed Askar


Background: False negative culture results in Periprosthetic Joint Infection (PJI) are not uncommon particularly when patients have received long term antibiotics. Polymerase Chain Reaction (PCR) has a lower specificity partly due to detection of residual DNA from dead bacteria. Propidium monoazide (PMA) prevents DNA from dead bacteria from being amplified during the Polymerase Chain Reaction (PCR).
Questions/purpose: Determination of role of PMA in PCR for diagnosis of PJI.
Patients and Methods: Clinical samples were tested with and without prior treatment with PMA and compared to conventional microbiological culture. 208 periprosthetic tissues and explanted prostheses from 62 episodes in 60 patients undergoing revision arthroplasties for either PJI or non-infective causes were tested, by culture, PCR, and PMA-PCR.
Results: 16 of the 62 episodes satisfied the Musculoskeletal Infection Society (MSIS) criteria for PJI and 46 did not. Sensitivity of culture, PCR, and PMA-PCR were 50%, 71%, and 79% respectively. Specificities were 98%, 72%, and 89% respectively. PMA-PCR enhanced both the specificity and
the sensitivity of PCR.

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