Paper of the week: Failure after two-stage exchange arthroplasty for treatment of periprosthetic joint infection: the role of antibiotics in the cement spacer. Wouthuyzen-Bakker M, Kheir MM, Moya I, Rondon AJ, Kheir M, Lozano L, Parvizi J, Soriano A.Clin Infect Dis. 2018 Oct 3. doi: 10.1093/cid/ciy851.

Summary and Editorial by Sreeram Penna

This retrospective multicenter trial looked at the incidence of positive cultures at the time of reimplantation and their relation to antibiotics in the spacer and also at failure following reimplantation. All patients who had a two-stage revision as a primary procedure for periprosthetic joint infection (PJI) or as salvage therapy following failed surgical irrigation debridement for acute PJIs were included in the study. Researchers excluded culture-negative PJIs, cases where no cultures were obtained during reimplantation and cases with no data on cement spacers. The final cohort consists of 344 patients.

Results showed that forty cases (11.6%) had positive cultures at reimplantation. Based on the results positive cultures consists of coagulase-negative Staphylococcus (CoNS) (35%), followed by Gram-negative rods (25.0%) and S. aureus (17.5%). Results based antibiotics in cement spacers showed 9.5% for cement spacers containing a glycopeptide (27/284) either monotherapy or combined with aminoglycoside versus 21.7% for those containing monotherapy with an aminoglycoside (13/60) (p 0.008). Also, the lower incidence of positive cultures in the glycopeptide group at reimplantation was mostly attributed to a decrease of spacer infections with CoNS (17% versus 2%, p < 0.001).

Researchers identified that failure was, significantly higher in those patients with positive cultures during reimplantation (40.0% [16/40]) compared to 15.8% [48/304] with negative cultures, p < 0.001) despite the use of post-operative antibiotics in positive cases. This study notes that use of a glycopeptide in the cement spacer was not associated with a lower failure rate after reimplantation. However, it was noted that in cases where glycopeptide was added to the spacer, had a lower failure rate due to CoNS compared to those without a glycopeptide (2.5% versus 13.3%, respectively, p < 0.001).

This study highlights the importance of adding glycopeptide antibiotic into spacer in addition to an aminoglycoside. In cases where only monotherapy of aminoglycoside was used, there was a higher incidence of positive infections with CoNS and the resulting failure of reimplantation procedure. Another study by Corona et al. showed that increase in resistance against aminoglycosides in the bacteria that commonly cause chronic PJI, particularly in gram-positive cocci.[1] The current study further provides evidence to combining glycopeptide antibiotic along with aminoglycoside in the cement spacer.

Reference
[1] Corona PS, Espinal L, Rodríguez-Pardo D, Pigrau C, Larrosa N, Flores X. Antibiotic Susceptibility in Gram-Positive Chronic Joint Arthroplasty Infections: Increased Aminoglycoside Resistance Rate in Patients With Prior Aminoglycoside-Impregnated Cement Spacer Use. The Journal of Arthroplasty 2014;29:1617–21. doi:10.1016/j.arth.2014.03.029.