Prophylactic Antibiofilm Activity of Antibiotic-Loaded Bone Cements against Gram-Negative Bacteria

Abstract

Gram-negative bacilli can be responsible for prosthetic joint infection (PJI) even if staphylococci are the main involved pathogens. Gram-negative PJIs (GN-PJI) are considered difficult-to-treat infections due to the increase in antimicrobial resistance and biofilm formation. To minimize the risk of infection in cases of arthroplasties with cemented prosthesis, bone cement can be loaded with antibiotics, especially gentamicin. In this study, we aimed to compare the prophylactic antibiofilm activity of ready-to-use antibiotic-loaded bone cements (ALBC), already commercialized or new prototypes. We compared ALBCs containing gentamicin alone, gentamicin plus vancomycin, gentamicin plus clindamycin, gentamicin plus Fosfomycin, and fosfomycin alone, to plain cement (no antibiotic); these comparisons were conducted to investigate the biofilm formation of three strains of Escherichia coli, three strains of Pseudomonas aeruginosa and two strains of Klebsiella pneumoniae, with or without specific resistance to gentamicin or fosfomycin. We reported that ALBC containing gentamicin and clindamycin (COPAL G+C) seems to be the most interesting ALBC of our tested panel for the prevention of biofilm formation by gentamicin-susceptible strains, even if clindamycin is not effective against Gram-negative bacteria. However, gentamicin-resistant strains are still a problem, and further studies are needed to identify an antibiotic to associate with gentamicin for an efficient dual ALBC against Gram-negative bacteria.

Keywords: Escherichia coli; Klebsiella pneumoniae; Pseudomonas aeruginosa; antibiotic-loaded bone cement; biofilm; prosthetic joint infection.

Figure 1

Prophylactic antibiofilm effect of ALBCs against gentamicin-susceptible E. coli (A), K. pneumoniae (B) and P. aeruginosa (C). Results were presented as number of colony-forming units (CFU) in the well after the solubilization of the formed biofilm. Three independent experiments in technical experiments (3 wells for each condition for each experiment) were performed. Non-parametric Kruskal–Wallis tests were performed to compare the data from each day. Dunn’s multiple comparisons tests were performed as follow up tests. For each day, *, **, *** or **** means p < 0.05, p < 0.01, p < 0.001 and p < 0.0001, respectively. Color of the stars corresponds to the condition used for the statistical comparison.

Figure 2

Prophylactic antibiofilm effect of ALBCs against gentamicin-resistant E. coli (A), K. pneumoniae (B) and P. aeruginosa (C). Results were presented as number of colony-forming units (CFU) in the well after the solubilization of the formed biofilm. Three independent experiments in technical experiments (3 wells for each condition for each experiment) were performed. Non-parametric Kruskal–Wallis tests were performed to compare the data from each day. Dunn’s multiple comparisons tests were performed as follow up tests. For each day, *, **, *** or **** means p < 0.05, p < 0.01, p < 0.001 and p < 0.0001, respectively. Color of the stars corresponds to the condition used for the statistical comparison. NS means not significant.

Figure 3

Prophylactic antibiofilm effect of ALBCs against fosfomycin-resistant E. coli (A) and P. aeruginosa (B). Results were presented as number of colony-forming units (CFU) in the well after the solubilization of the formed biofilm. Three independent experiments in technical experiments (3 wells for each condition for each experiment) were performed. Non-parametric Kruskal–Wallis tests were performed to compare the data from each day. Dunn’s multiple comparisons tests were performed as follow up tests. For each day, *, **, *** or **** means p < 0.05, p < 0.01, p < 0.001 and p < 0.0001, respectively. Color of the stars corresponds to the condition used for the statistical comparison.