Two-stage revision using aminoglycoside-cement spacers (A-CSs) is widely used to manage chronic periprosthetic joint infection (PJI). However, aminoglycoside-resistance in gram-positive cocci (GPC) seems to be increasing. Moreover, the contribution of these A-CSs to select resistant mutants is a matter of concern. We study the antibiotic susceptibility profile of GPC after 113 chronic hip and knee PJIs. Aminoglycoside susceptibility-profiles were compared between cases where A-CSs had previously been used (n: 52), and cases of primary infection (n: 61). 32% of isolates were resistant to gentamicin and 40.6% to tobramycin. Gentamicin resistance after previous A-CS use was significantly higher (49.2% [30/61] vs. 19.3% [16/83]; P: 0.0001) as well as with tobramycin (52.7% [29/55] vs. 30.9% [21/66]; P: 0.014). A high rate of gentamicin-tobramycin resistance exists among the most common bacteria involved in chronic-PJI. The risk of selection for aminoglycoside-resistant mutants in cases of infection relapse is a concern following A-CS use.
Keywords: antibiotic loaded spacers; antibiotic resistance; gentamicin; periprosthetic joint infection; tobramycin.
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