Potential interactions between vancomycin and meropenem in culture-negative periprosthetic joint infection: an in vitro study.

BACKGROUND

Culture-negative periprosthetic joint infections (CN-PJIs) represent a critical subtype of PJI, and their high prevalence poses substantial challenges for treatment. CN-PJI is commonly managed utilizing antibiotic combinations, however, the interactions between these antibiotics have not been investigated. The aim of study was to investigate the synergistic and antagonistic effects of vancomycin (VAN) and meropenem (MEM), in an in vitro model of CN-PJI.

METHODS

Minimum Inhibitory Concentration (MIC), Minimum Bactericidal Concentration (MBC), Minimum Biofilm Inhibitory Concentration (MBIC), and Minimum Biofilm Eradication Concentration (MBEC) were determined for VAN and MEM. Fractional Inhibitory Concentration (FIC) and Fractional Biofilm Eradication Concentration (FBEC) indices were calculated to assess the synergistic or antagonistic effects of VAN in combination with MEM on Staphylococcus aureus (S. aureus), Staphylococcus epidermidis (S. epidermidis), and Escherichia coli (E. coli) incubated alone or in combination.

RESULTS

In the planktonic bacterial phase, MEM showed higher activity than VAN. Resistance increased when the bacteria were cultured together. The combination of VAN and MEM exhibited an indifferent effect against individual Staphylococci but an antagonistic effect against polymicrobial cultures. In biofilm, MEM demonstrated better antibiofilm activity than VAN, especially against E. coli biofilms. The combination of VAN and MEM showed an indifferent effect against E. coli and S. epidermidis-E. coli biofilms, but an antagonistic effect against S. aureus, S. epidermidis, S. aureus-S. epidermidis, and S. aureus-E. coli biofilms.

CONCLUSION

This study provides valuable insights into the effectiveness of VAN and MEM combinations in treating CN-PJIs, highlighting the need for careful consideration when selecting antibiotic treatments for these infections.

CLINICAL TRIAL NUMBER: Not applicable.